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Sample records for aerospace alloys composites

  1. NASA-UVa light aerospace alloy and structures technology program

    NASA Technical Reports Server (NTRS)

    Gangloff, Richard P.; Haviland, John K.; Herakovich, Carl T.; Pilkey, Walter D.; Pindera, Marek-Jerzy; Scully, John R.; Stoner, Glenn E.; Swanson, Robert E.; Thornton, Earl A.; Wawner, Franklin E., Jr.

    1991-01-01

    The general objective of the NASA-UVa Light Aerospace Alloy and Structures Technology Program was to conduct research on the performance of next generation, light weight aerospace alloys, composites, and associated thermal gradient structures. The following research areas were actively investigated: (1) mechanical and environmental degradation mechanisms in advanced light metals and composites; (2) aerospace materials science; (3) mechanics of materials and composites for aerospace structures; and (4) thermal gradient structures.

  2. Advances in processing of NiAl intermetallic alloys and composites for high temperature aerospace applications

    NASA Astrophysics Data System (ADS)

    Bochenek, Kamil; Basista, Michal

    2015-11-01

    Over the last few decades intermetallic compounds such as NiAl have been considered as potential high temperature structural materials for aerospace industry. A large number of investigations have been reported describing complex fabrication routes, introducing various reinforcing/alloying elements along with theoretical analyses. These research works were mainly focused on the overcoming of main disadvantage of nickel aluminides that still restricts their application range, i.e. brittleness at room temperature. In this paper we present an overview of research on NiAl processing and indicate methods that are promising in solving the low fracture toughness issue at room temperature. Other material properties relevant for high temperature applications are also addressed. The analysis is primarily done from the perspective of NiAl application in aero engines in temperature regimes from room up to the operating temperature (over 1150 °C) of turbine blades.

  3. NASA-UVA light aerospace alloy and structures technology program

    NASA Technical Reports Server (NTRS)

    Gangloff, Richard P.; Haviland, John K.; Herakovich, Carl T.; Pilkey, Walter D.; Pindera, Marek-Jerzy; Stoner, Glenn E.; Swanson, Robert E.; Thornton, Earl A.; Wawner, Franklin E., Jr.; Wert, John A.

    1990-01-01

    The objective of the Light Aerospace Alloy and Structures Technology Program is to conduct interdisciplinary graduate student research on the performance of next generation, light weight aerospace alloys, composites, and associated thermal gradient structures. Individual technical objectives are established for each project. Efforts aim to produce basic understanding of material behavior, monolithic and composite alloys, processing methods, solid and mechanics analyses, measurement advances, and a pool of educated graduate students. Progress is reported for 11 areas of study.

  4. Fatigue crack propagation in aerospace aluminum alloys

    NASA Technical Reports Server (NTRS)

    Gangloff, R. P.; Piascik, R. S.; Dicus, D. L.; Newman, J. C., Jr.

    1990-01-01

    This paper reviews fracture mechanics based, damage tolerant characterizations and predictions of fatigue crack growth in aerospace aluminum alloys. The results of laboratory experimentation and modeling are summarized in the areas of: (1) fatigue crack closure, (2) the wide range crack growth rate response of conventional aluminum alloys, (3) the fatigue behavior of advanced monolithic aluminum alloys and metal matrix composites, (4) the short crack problem, (5) environmental fatigue, and (6) variable amplitude loading. Remaining uncertainties and necessary research are identified. This work provides a foundation for the development of fatigue resistant alloys and composites, next generation life prediction codes for new structural designs and extreme environments, and to counter the problem of aging components.

  5. Statistical Analysis of Strength Data for an Aerospace Aluminum Alloy

    NASA Technical Reports Server (NTRS)

    Neergaard, Lynn; Malone, Tina; Gentz, Steven J. (Technical Monitor)

    2000-01-01

    Aerospace vehicles are produced in limited quantities that do not always allow development of MIL-HDBK-5 A-basis design allowables. One method of examining production and composition variations is to perform 100% lot acceptance testing for aerospace Aluminum (Al) alloys. This paper discusses statistical trends seen in strength data for one Al alloy. A four-step approach reduced the data to residuals, visualized residuals as a function of time, grouped data with quantified scatter, and conducted analysis of variance (ANOVA).

  6. Statistical Analysis of Strength Data for an Aerospace Aluminum Alloy

    NASA Technical Reports Server (NTRS)

    Neergaard, L.; Malone, T.

    2001-01-01

    Aerospace vehicles are produced in limited quantities that do not always allow development of MIL-HDBK-5 A-basis design allowables. One method of examining production and composition variations is to perform 100% lot acceptance testing for aerospace Aluminum (Al) alloys. This paper discusses statistical trends seen in strength data for one Al alloy. A four-step approach reduced the data to residuals, visualized residuals as a function of time, grouped data with quantified scatter, and conducted analysis of variance (ANOVA).

  7. Ultrasonic Characterization of Aerospace Composites

    NASA Technical Reports Server (NTRS)

    Leckey, Cara; Johnston, Patrick; Haldren, Harold; Perey, Daniel

    2015-01-01

    Composite materials have seen an increased use in aerospace in recent years and it is expected that this trend will continue due to the benefits of reduced weight, increased strength, and other factors. Ongoing work at NASA involves the investigation of the large-scale use of composites for spacecraft structures (SLS components, Orion Composite Crew Module, etc). NASA is also involved in work to enable the use of composites in advanced aircraft structures through the Advanced Composites Project (ACP). In both areas (space and aeronautics) there is a need for new nondestructive evaluation and materials characterization techniques that are appropriate for characterizing composite materials. This paper will present an overview of NASA's needs for characterizing aerospace composites, including a description of planned and ongoing work under ACP for the detection of composite defects such as fiber waviness, reduced bond strength, delamination damage, and microcracking. The research approaches include investigation of angle array, guided wave, and phase sensitive ultrasonic methods. The use of ultrasonic simulation tools for optimizing and developing methods will also be discussed.

  8. Advanced lightweight alloys for aerospace applications

    NASA Astrophysics Data System (ADS)

    Frazier, William E.; Lee, Eui W.; Donnellan, Mary E.; Thompson, James J.

    1989-05-01

    The design requirements of the next generation of advanced aerospace vehicles and propulsion systems necessitate the development of structural materials with properties vastly superior to those which are currently achievable. Recognizing that each class of materials possesses its own unique set of advantages and disadvantages, the designers of tomorrow's aircraft must choose wisely from the plethora of available alloys.

  9. Nondestructive Evaluation for Aerospace Composites

    NASA Technical Reports Server (NTRS)

    Leckey, Cara; Cramer, Elliott; Perey, Daniel

    2015-01-01

    Nondestructive evaluation (NDE) techniques are important for enabling NASA's missions in space exploration and aeronautics. The expanded and continued use of composite materials for aerospace components and vehicles leads to a need for advanced NDE techniques capable of quantitatively characterizing damage in composites. Quantitative damage detection techniques help to ensure safety, reliability and durability of space and aeronautic vehicles. This presentation will give a broad outline of NASA's range of technical work and an overview of the NDE research performed in the Nondestructive Evaluation Sciences Branch at NASA Langley Research Center. The presentation will focus on ongoing research in the development of NDE techniques for composite materials and structures, including development of automated data processing tools to turn NDE data into quantitative location and sizing results. Composites focused NDE research in the areas of ultrasonics, thermography, X-ray computed tomography, and NDE modeling will be discussed.

  10. NASA-UVA light aerospace alloy and structures technology program (LA(sup 2)ST)

    NASA Technical Reports Server (NTRS)

    Gangloff, Richard P.; Haviland, John K.; Herakovich, Carl T.; Pilkey, Walter D.; Pindera, Marek-Jerzy; Scully, John R.; Starke, Edgar A., Jr.; Stoner, Glenn E.; Thornton, Earl A.; Wawner, Franklin E., Jr.

    1992-01-01

    The general objective of the Light Aerospace Alloy and Structures Technology (LA(sup 2)ST) Program is to conduct interdisciplinary graduate student research on the performance of next generation, light weight aerospace alloys, composites, and thermal gradient structures in collaboration with Langley researchers. Specific technical objectives are established for each research project. We aim to produce relevant data and basic understanding of material behavior and microstructure, new monolithic and composite alloys, advanced processing methods, new solid and fluid mechanics analyses, measurement advances, and critically, a pool of educated graduate students for aerospace technologies. Four research areas are being actively investigated, including: (1) Mechanical and Environmental Degradation Mechanisms in Advanced Light Metals and Composites; (2) Aerospace Materials Science; (3) Mechanics of Materials and Composites for Aerospace Structures; and (4) Thermal Gradient Structures.

  11. NASA-UVA light aerospace alloy and structures technology program

    NASA Technical Reports Server (NTRS)

    Gangloff, Richard P.; Haviland, John K.; Herakovich, Carl T.; Pilkey, Walter D.; Pindera, Marek-Jerzy; Thornton, Earl A.; Stoner, Glenn E.; Swanson, Robert E.; Wawner, Franklin E., Jr.; Wert, John A.

    1989-01-01

    The report on progress achieved in accomplishing of the NASA-UVA Light Aerospace Alloy and Structures Technology Program is presented. The objective is to conduct interdisciplinary graduate student research on the performance of next generation, light weight aerospace alloys and associated thermal gradient structures in close collaboration with researchers. The efforts will produce basic understanding of material behavior, new monolithic and composite alloys, processing methods, solid and fluid mechanics analyses, measurement advances, and a pool of educated graduate students. The presented accomplishments include: research on corrosion fatigue of Al-Li-Cu alloy 2090; research on the strengthening effect of small In additions to Al-Li-Cu alloys; research on localized corrosion of Al-Li alloys; research on stress corrosion cracking of Al-Li-Cu alloys; research on fiber-matrix reaction studies (Ti-1100 and Ti-15-3 matrices containing SCS-6, SCS-9, and SCS-10 fibers); and research on methods for quantifying non-random particle distribution in materials that has led to generation of a set of computer programs that can detect and characterize clusters in particles.

  12. NASA-UVA Light Aerospace Alloy and Structures Technology Program (LA2ST)

    NASA Technical Reports Server (NTRS)

    Scully, John R.; Shiflet, Gary J.; Stoner, Glenn E.; Wert, John A.

    1996-01-01

    The NASA-UVA Light Aerospace Alloy and Structures Technology (LA2ST) Program was initiated in 1986 and continues with a high level of activity. The objective of the LA2ST Program is to conduct interdisciplinary graduate student research on the performance of next generation, light-weight aerospace alloys, composites and thermal gradient structures in collaboration with NASA-Langley researchers. Specific technical objectives are presented for each research project. We generally aim to produce relevant data and basic understanding of material mechanical response, environmental/corrosion behavior, and microstructure; new monolithic and composite alloys; advanced processing methods; new solid and fluid mechanics analyses; measurement and modeling advances; and a pool of educated graduate students for aerospace technologies. Three research areas are being actively investigated, including: (1) Mechanical and environmental degradation mechanisms in advanced light metals, (2) Aerospace materials science, and (3) Mechanics of materials for light aerospace structures.

  13. Aerospace applications of advanced aluminum alloys

    NASA Technical Reports Server (NTRS)

    Chellman, D. J.; Langenbeck, S. L.

    1993-01-01

    Advanced metallic materials within the Al-base family are being developed for applications on current and future aerospace vehicles. These advanced materials offer significant improvements in density, strength, stiffness, fracture resistance, and/or higher use temperature which translates into improved vehicle performance. Aerospace applications of advanced metallic materials include space structures, fighters, military and commercial transport aircraft, and missiles. Structural design requirements, including not only static and durability/damage tolerance criteria but also environmental considerations, drive material selections. Often trade-offs must be made regarding strength, fracture resistance, cost, reliability, and maintainability in order to select the optimum material for a specific application. These trade studies not only include various metallic materials but also many times include advanced composite materials. Details of material comparisons, aerospace applications, and material trades will be presented.

  14. NASA-UVA Light Aerospace Alloy and Structures Technology program (LA2ST)

    NASA Technical Reports Server (NTRS)

    Starke, Edgar A., Jr.; Gangloff, Richard P.; Herakovich, Carl T.; Scully, John R.; Shiflet, Gary J.; Stoner, Glenn E.; Wert, John A.

    1995-01-01

    The objective of the LA2ST Program is to conduct interdisciplinary graduate student research on the performance of next generation, light-weight aerospace alloys, composites, and thermal gradient structures in collaboration with NASA-Langley researchers. The general aim is to produce relevant data and basic understanding of material mechanical response, environment/corrosion behavior, and microstructure; new monolithic and composite alloys; advanced processing methods; new solid and fluid mechanics analyses; measurement and modeling advances; and a pool of educated students for aerospace technologies. Specific technical objectives are presented for each of the following research projects: time-temperature dependent fracture in advanced wrought ingot metallurgy, and spray deposited aluminum alloys; cryogenic temperature effects on the deformation and fracture of Al-Li-Cu-In alloys; effects of aging and temperature on the ductile fracture of AA2095 and AA2195; mechanisms of localized corrosion in alloys 2090 and 2095; hydrogen interactions in aluminum-lithium alloys 2090 and selected model alloys; mechanisms of deformation and fracture in high strength titanium alloys (effects of temperature and hydrogen and effects of temperature and microstructure); evaluations of wide-panel aluminum alloy extrusions; Al-Si-Ge alloy development; effects of texture and precipitates on mechanical property anisotropy of Al-Cu-Mg-X alloys; damage evolution in polymeric composites; and environmental effects in fatigue life prediction - modeling crack propagation in light aerospace alloys.

  15. NASA-UVA Light Aerospace Alloy and Structures Technology Program (LA2ST)

    NASA Technical Reports Server (NTRS)

    Gangloff, Richard P.

    1991-01-01

    The general objective of the Light Aerospace Alloy and Structures Technology (LA2ST) Program is to conduct interdisciplinary graduate student research on the performance of next generation, light weight aerospace alloys, composites, and associated thermal gradient structures in close collaboration with Langley researchers. Specific technical objectives are established for each research project. Relevant data and basic understanding of material behavior and microstructure, new monolithic and composite alloys, advanced processing methods, new solid and fluid mechanic analyses, measurement advances, and a pool of educated graduate students are sought.

  16. NASA-UVA light aerospace alloy and structures technology program (LA2ST)

    NASA Technical Reports Server (NTRS)

    Gangloff, Richard P.

    1992-01-01

    The NASA-UVa Light Aerospace Alloy and Structure Technology (LAST) Program continues to maintain a high level of activity, with projects being conducted by graduate students and faculty advisors in the Departments of Materials Science and Engineering, Civil Engineering and Applied Mechanics, and Mechanical and Aerospace Engineering at the University of Virginia. This work is funded by the NASA-Langley Research Center under Grant NAG-1-745. Here, we report on progress achieved between January 1 and June 30, 1992. The objectives of the LA2ST Program is to conduct interdisciplinary graduate student research on the performance of the next generation, light weight aerospace alloys, composites and thermal gradient structures in collaboration with Langley researchers. Technical objectives are established for each research project. We aim to produce relevant data and basic understanding of material mechanical response, corrosion behavior, and microstructure; new monolithic and composite alloys; advanced processing methods; new solid and fluid mechanics analyses; measurement advances; and critically, a pool of educated graduate students for aerospace technologies. The accomplishments presented in this report cover topics including: (1) Mechanical and Environmental Degradation Mechanisms in Advance Light Metals and Composites; (2) Aerospace Materials Science; (3) Mechanics of Materials and Composites for Aerospace Structures; and (4) Thermal Gradient Structures.

  17. NASA-UVA light aerospace alloy and structures technology program (LA2ST)

    NASA Technical Reports Server (NTRS)

    Gangloff, Richard P.; Starke, Edger A., Jr.

    1996-01-01

    This progress report covers achievements made between January 1 and June 30, 1966 on the NASA-UVA Light Aerospace Alloy and Structures Technology (LA2ST) Program. The objective of the LA2ST Program is to conduct interdisciplinary graduate student research on the performance of next generation, light-weight aerospace alloys, composites and thermal gradient structures in collaboration with NASA-Langley researchers. Specific technical objectives are presented for each research project. . The accomplishments presented in this report are: (1) Mechanical and Environmental Degradation Mechanisms in Advanced Light Metals, (2) Aerospace Materials Science, and (3) Mechanics of Materials for Light Aerospace Structures. Collective accomplishments between January and June of 1996 include: 4 journal or proceedings publications, 1 NASA progress report, 4 presentations at national technical meetings, and 2 PhD dissertations published.

  18. Thermoplastic Composite Materials for Aerospace Applications

    NASA Astrophysics Data System (ADS)

    Casula, G.; Lenzi, F.; Vitiello, C.

    2008-08-01

    Mechanical and thermo-physical properties of composites materials with thermoplastic matrix (PEEK/IM7, TPI/IM7 and PPS/IM7) used for aerospace applications have been analyzed as function of two different process techniques: compression molding and fiber placement process "hot gas assisted."

  19. Nonlinear analyses of composite aerospace structures in sonic fatigue

    NASA Technical Reports Server (NTRS)

    Mei, Chuh

    1993-01-01

    This report summarizes the semiannual research progress, accomplishments, and future plans performed under the NASA Langley Research Center Grant No. NAG-1-1358. The primary research effort of this project is the development of analytical methods for the prediction of nonlinear random response of composite aerospace structures subjected to combined acoustic and thermal loads. The progress, accomplishments, and future plates on four sonic fatigue research topics are described. The sonic fatigue design and passive control of random response of shape memory alloy hybrid composites presented in section 4, which is suited especially for HSCT, is a new initiative.

  20. Metal Matrix Composite Materials for Aerospace Applications

    NASA Technical Reports Server (NTRS)

    Bhat, Biliyar N.; Jones, C. S. (Technical Monitor)

    2001-01-01

    Metal matrix composites (MMC) are attractive materials for aerospace applications because of their high specific strength, high specific stiffness, and lower thermal expansion coefficient. They are affordable since complex parts can be produced by low cost casting process. As a result there are many commercial and Department of Defense applications of MMCs today. This seminar will give an overview of MMCs and their state-of-the-art technology assessment. Topics to be covered are types of MMCs, fabrication methods, product forms, applications, and material selection issues for design and manufacture. Some examples of current and future aerospace applications will also be presented and discussed.

  1. NASA-UVA Light Aerospace Alloy and Structures Technology Program (LA2ST)

    NASA Technical Reports Server (NTRS)

    Gangloff, Richard P.; Scully, John R.; Stoner, Glenn E.; Thornton, Earl A.; Wawner, Franklin E., Jr.; Wert, John A.

    1993-01-01

    The NASA-UVA Light Aerospace Alloy and Structures Technology (LA2ST) Program continues a high level of activity. Progress achieved between 1 Jan. and 30 Jun. 1993 is reported. The objective of the LA2ST Program is to conduct interdisciplinary graduate student research on the performance of next generation, light weight aerospace alloys, composites, and thermal gradient structures in collaboration with NASA-Langley researchers. The following projects are addressed: environmental fatigue of Al-Li-Cu alloys; mechanisms of localized corrosion and environmental fracture in Al-Cu-Li-Mg-Ag alloy X2095 and compositional variations; the effect of zinc additions on the precipitation and stress corrosion cracking behavior of alloy 8090; hydrogen interactions with Al-Li-Cu alloy 2090 and model alloys; metastable pitting of aluminum alloys; cryogenic fracture toughness of Al-Cu-Li + In alloys; the fracture toughness of Weldalite (TM); elevated temperature cracking of advanced I/M aluminum alloys; response of Ti-1100/SCS-6 composites to thermal exposure; superplastic forming of Weldalite (TM); research to incorporate environmental effects into fracture mechanics fatigue life prediction codes such as NASA FLAGRO; and thermoviscoplastic behavior.

  2. Computational composite mechanics for aerospace propulsion structures

    NASA Technical Reports Server (NTRS)

    Chamis, C. C.

    1986-01-01

    Specialty methods are presented for the computational simulation of specific composite behavior. These methods encompass all aspects of composite mechanics, impact, progressive fracture and component specific simulation. Some of these methods are structured to computationally simulate, in parallel, the composite behavior and history from the initial fabrication through several missions and even to fracture. Select methods and typical results obtained from such simulations are described in detail in order to demonstrate the effectiveness of computationally simulating (1) complex composite structural behavior in general and (2) specific aerospace propulsion structural components in particular.

  3. Computational composite mechanics for aerospace propulsion structures

    NASA Technical Reports Server (NTRS)

    Chamis, Christos C.

    1987-01-01

    Specialty methods are presented for the computational simulation of specific composite behavior. These methods encompass all aspects of composite mechanics, impact, progressive fracture and component specific simulation. Some of these methods are structured to computationally simulate, in parallel, the composite behavior and history from the initial frabrication through several missions and even to fracture. Select methods and typical results obtained from such simulations are described in detail in order to demonstrate the effectiveness of computationally simulating: (1) complex composite structural behavior in general, and (2) specific aerospace propulsion structural components in particular.

  4. NASA-UVA Light Aerospace Alloy and Structures Technology Program (LA2ST)

    NASA Technical Reports Server (NTRS)

    Gangloff, Richard P.; Starke, Edgar A., Jr.; Kelly, Robert G.; Scully, John R.; Shiflet, Gary J.; Stoner, Glenn E.; Wert, John A.

    1997-01-01

    The NASA-UVA Light Aerospace Alloy and Structures Technology (LA2ST) Program was initiated in 1986 and continues with a high level of activity. Here, we report on progress achieved between July I and December 31, 1996. The objective of the LA2ST Program is to conduct interdisciplinary graduate student research on the performance of next generation, light-weight aerospace alloys, composites and thermal gradient structures in collaboration with NASA-Langley researchers. Specific technical objectives are presented for each research project. We generally aim to produce relevant data and basic understanding of material mechanical response, environmental/corrosion behavior, and microstructure; new monolithic and composite alloys; advanced processing methods; new solid and fluid mechanics analyses; measurement and modeling advances; and a pool of educated graduate students for aerospace technologies. The accomplishments presented in this report are summarized as follows. Three research areas are being actively investigated, including: (1) Mechanical and Environmental Degradation Mechanisms in Advanced Light Metals, (2) Aerospace Materials Science, and (3) Mechanics of Materials for Light Aerospace Structures.

  5. NASA-UVA Light Aerospace Alloy and Structures Technology Program (LA2ST). Progress Report, 1 Jan. - 30 Jun. 1991

    SciTech Connect

    Not Available

    1991-06-01

    The general objective of the Light Aerospace Alloy and Structures Technology (LA2ST) Program is to conduct interdisciplinary graduate student research on the performance of next generation, light weight aerospace alloys, composites, and associated thermal gradient structures in close collaboration with Langley researchers. Specific technical objectives are established for each research project. Relevant data and basic understanding of material behavior and microstructure, new monolithic and composite alloys, advanced processing methods, new solid and fluid mechanic analyses, measurement advances, and a pool of educated graduate students are sought.

  6. Development and Processing Improvement of Aerospace Aluminum Alloys

    NASA Technical Reports Server (NTRS)

    Lisagor, W. Barry; Bales, Thomas T.

    2007-01-01

    This final report, in multiple presentation format, describes a comprehensive multi-tasked contract study to improve the overall property response of selected aerospace alloys, explore further a newly-developed and registered alloy, and correlate the processing, metallurgical structure, and subsequent properties achieved with particular emphasis on the crystallographic orientation texture developed. Modifications to plate processing, specifically hot rolling practices, were evaluated for Al-Li alloys 2195 and 2297, for the recently registered Al-Cu-Ag alloy, 2139, and for the Al-Zn-Mg-Cu alloy, 7050. For all of the alloys evaluated, the processing modifications resulted in significant improvements in mechanical properties. Analyses also resulted in an enhanced understanding of the correlation of processing, crystallographic texture, and mechanical properties.

  7. NASA-UVA Light Aerospace Alloy and Structures Technology Program: LA(2)ST

    NASA Technical Reports Server (NTRS)

    Gangloff, Richard P.; Haviland, John K.; Herakovich, Carl T.; Pilkey, Walter D.; Pindera, Marek-Jerzy; Scully, John R.; Stoner, Glenn E.; Thornton, Earl A.; Wawner, Franklin E., Jr.; Wert, John A.

    1993-01-01

    The NASA-UVA Light Aerospace Alloy and Structures Technology (LA(2)ST) Program continues a high level of activity, with projects being conducted by graduate students and faculty advisors in the Departments of Materials Science and Engineering, Civil Engineering and Applied Mechanics, and Mechanical and Aerospace Engineering at the University of Virginia. This work is funded by the NASA-Langley Research Center under Grant NAG-1-745. We report on progress achieved between July 1 and December 31, 1992. The objective of the LA(2)ST Program is to conduct interdisciplinary graduate student research on the performance of next generation, light weight aerospace alloys, composites and thermal gradient structures in collaboration with NASA-Langley researchers. Specific technical objectives are presented for each research project. We generally aim to produce relevant data and basic understanding of material mechanical response, corrosion behavior, and microstructure; new monolithic and composite alloys; advanced processing methods; new solid and fluid mechanics analyses; measurement advances; and critically, a pool of educated graduate students for aerospace technologies.

  8. NASA-UVA light aerospace alloy and structures technology program (LA2ST)

    NASA Astrophysics Data System (ADS)

    Gangloff, Richard P.; Scully, John R.; Starke, Edgar A., Jr.; Stoner, Glenn E.; Thornton, Earl A.; Wawner, Franklin E., Jr.; Wert, John A.

    1994-03-01

    The NASA-UVA Light Aerospace Alloy and Structures Technology (LA2ST) Program was initiated in 1986, and continues a high level of activity, with projects being conducted by graduate students and faculty advisors in the Departments of Materials Science and Engineering, and Mechanical and Aerospace Engineering at the University of Virginia. This work is funded by the NASA-Langley Research Center under Grant NAG-1-745. Here, we report on progress achieved between July 1 and December 31, 1993. The objective of the LA2ST Program is to conduct interdisciplinary graduate student research on the performance of next generation, light weight aerospace alloys, composites and thermal gradient structures in collaboration with NASA-Langley researchers. Specific technical objectives are presented for each research project. We generally aim to produce relevant data and basic understanding of material mechanical response, environmental/corrosion behavior, and microstructure; new monolithic and composite alloys; advanced processing methods; new solid and fluid mechanics analyses; measurement and modeling advances; and critically, a pool of educated graduate students for aerospace technologies.

  9. NASA-UVA light aerospace alloy and structures technology program (LA2ST)

    NASA Technical Reports Server (NTRS)

    Gangloff, Richard P.; Scully, John R.; Starke, Edgar A., Jr.; Stoner, Glenn E.; Thornton, Earl A.; Wawner, Franklin E., Jr.; Wert, John A.

    1994-01-01

    The NASA-UVA Light Aerospace Alloy and Structures Technology (LA2ST) Program was initiated in 1986, and continues a high level of activity, with projects being conducted by graduate students and faculty advisors in the Departments of Materials Science and Engineering, and Mechanical and Aerospace Engineering at the University of Virginia. This work is funded by the NASA-Langley Research Center under Grant NAG-1-745. Here, we report on progress achieved between July 1 and December 31, 1993. The objective of the LA2ST Program is to conduct interdisciplinary graduate student research on the performance of next generation, light weight aerospace alloys, composites and thermal gradient structures in collaboration with NASA-Langley researchers. Specific technical objectives are presented for each research project. We generally aim to produce relevant data and basic understanding of material mechanical response, environmental/corrosion behavior, and microstructure; new monolithic and composite alloys; advanced processing methods; new solid and fluid mechanics analyses; measurement and modeling advances; and critically, a pool of educated graduate students for aerospace technologies.

  10. Aerospace applications of beta titanium alloys

    NASA Astrophysics Data System (ADS)

    Boyer, Rodney R.

    1994-07-01

    Beta alloys are beginning to play a significant role in both military and commercial aircraft. Ti-10V-2Fe-3Al forgings, for example, play major roles in the McDonnell Douglas C-17 and the Boeing 777. The attractive properties of Beta-C are increasing the use of titanium, rather than steel, in aircraft springs. Ti-15V-3Cr-3Al-3Sn is subject to increasing usage primarily because of its strip producibility and formability. Beta-21S is gaining importance for high-temperature applications. New alloys such as β-CEZ, SP-700, and Timetal® LCB could become important because of advantageous costs, processing, and/or properties. In the past, the use of beta alloys has largely been driven by their superior properties and weight-savings potential. In the future, cost will become more important. As a result, a greater emphasis will be placed on lower cost alloys and/or taking advantage of the improved processing capabilities of these alloys to minimize final component costs.

  11. Fretting fatigue of 2XXX series aerospace aluminum alloys

    NASA Astrophysics Data System (ADS)

    Giummarra, Cindie

    Fretting is a wear mechanism that occurs at the contact region between two materials subject to minute cyclic relative motion. Fretting causes the initiation of surface cracks within the first few thousand cycles, which in the presence of a fatigue stress, grow to cause material failure approximately 10 to 100 times earlier than expected under standard fatigue conditions. Examples of fretting fatigue have been seen in joints in aircraft, and the aerospace industry acknowledges the possibility of catastrophic failure from this mechanism. Improvements in a material's resistance to fretting would benefit aluminum alloys in aerospace applications. This research investigated the effect of microstructural properties on the fretting response in 2XXX series aerospace aluminum alloys. Fretting wear and fretting fatigue tests were conducted to determine the influence of slip characteristics, alloy purity, grain orientation and yield strength on fretting crack initiation and growth. Crack length measurements and micrographs of the fretting indicated there was no significant difference in the fretting response of these alloys based on their microstructural characteristics. Results showed that fretting initiated cracks in the first 1--8% of the life while standard fatigue initiation took around 90% of the life. This reduction in initiation resulted in a shorter life under fretting conditions. Additionally, fretting normalized the initiation time in all alloys which eliminated any intrinsic initiation resistance. The alloys with the highest stress-life (S-N) fatigue properties exhibiting a greater reduction in fatigue strength under fretting conditions. The fretting stresses appeared to influence the crack growth to a distance below the surface of approximately 17mum under fretting fatigue conditions, after which some cracks changed direction and propagated under the influence of the fatigue stress. Under fretting wear conditions, the cracks tended to arrest at a depth of 8

  12. The use of β titanium alloys in the aerospace industry

    NASA Astrophysics Data System (ADS)

    Boyer, R. R.; Briggs, R. D.

    2005-12-01

    Beta titanium alloys have been available since the 1950s (Ti-13V-11Cr-3Mo or B120VCA), but significant applications of these alloys, beyond the SR-71 Blackbird, have been slow in coming. The next significant usage of a β alloy did not occur until the mid-1980s on the B-1B bomber. This aircraft used Ti-15V-3Cr-3Al-3Sn sheet due to its capability for strip rolling, improved formability, and higher strength than Ti-6Al-4V. The next major usage was on a commercial aircraft, the Boeing 777, which made extensive use of Ti-10V-2Fe-3Al high-strength forgings. Ti-15V-3Cr-3Al-3Sn environmental control system ducting, castings, and springs were also used, along with Ti-3Al-8V-6Cr-4Mo-4Zr (β-C) springs. Beta-21S was also introduced for high-temperature usage. More recent work at Boeing has focused on the development of Ti-5Al-5Mo-5V-3Cr, a high-strength alloy that can be used at higher strength than Ti-10V-2Fe-3Al and is much more robust; it has a much wider, or friendlier, processing window. This, along with additional studies at Boeing, and from within the aerospace industry in general will be discussed in detail, summarizing applications and the rationale for the selection of this alloy system for aerospace applications.

  13. NASA-UVA light aerospace alloy and structures technology program (LA2ST)

    NASA Technical Reports Server (NTRS)

    Starke, Edgar A., Jr.; Gangloff, Richard P.; Herakovich, Carl T.; Scully, John R.; Shiflet, Gary J.; Stoner, Glenn E.; Wert, John A.

    1995-01-01

    The NASA-UVa Light Aerospace Alloy and Structures Technology (LA2ST) Program was initiated in 1986 and continues with a high level of activity. Projects are being conducted by graduate students and faculty advisors in the Department of Materials Science and Engineering, as well as in the Department of Civil Engineering and Applied Mechanics, at the University of Virginia. Here, we report on progress achieved between July 1 and December 31, 1994. The objective of the LA2ST Program is to conduct interdisciplinary graduate student research on the performance of next generation, light-weight aerospace alloys, composites and thermal gradient structures in collaboration with NASA-Langley researchers. Specific technical objectives are presented for each research project. We generally aim to produce relevant data and basic understanding of material mechanical response, environmental/corrosion behavior, and microstructure; new monolithic and composite alloys; advanced processing methods; new solid and fluid mechanics analyses; measurement and modeling advances; and a pool of educated graduate students for aerospace technologies.

  14. NASA-UVA Light Aerospace Alloy and Structures Technology Program (LA2ST)

    NASA Technical Reports Server (NTRS)

    Gangloff, Richard P.

    1994-01-01

    The NASA-UVA Light Aerospace Alloy and Structures Technology (LA2ST) Program was initiated in 1986 and continues with a high level of activity. Projects are being conducted by graduate students and faculty advisors in the Department of Materials Science and Engineering, as well as in the Department of Civil Engineering and Applied Mechanics, at the University of Virginia. This work is funded by the NASA-Langley Research Center under Grant NAG-1-745. Here, we report on progress achieved between January 1 and June 30, 1994. These results were presented at the Fifth Annual NASA LA2ST Grant Review Meeting held at the Langley Research Center in July of 1994. The objective of the LA2ST Program is to conduct interdisciplinary graduate student research on the performance of next generation, lightweight aerospace alloys, composites, and thermal gradient structures in collaboration with NASA-Langley researchers. Specific technical objectives are presented for each research project. We generally aim to produce relevant data and basic understanding of material mechanical response, environmental/corrosion behavior, and microstructure; new monolithic and composite alloys; advanced processing methods; new solid and fluid mechanics analyses; measurement and modeling advances; and a pool of educated graduate students for aerospace technologies.

  15. Controlling remelting processes for superalloys and aerospace Ti alloys

    NASA Astrophysics Data System (ADS)

    Melgaard, D. K.; Williamson, R. L.; Beaman, J. J.

    1998-03-01

    Remelting is performed to facilitate the production of clean, fully dense, homogeneous castings of superalloys and aerospace titanium alloys and is crucial to the defect-free production of these important materials. Modern electroslag remelting and vacuum arc remelting control systems are closed-loop, single input-single output systems that oversimplify the physical properties of the processes; the ever-increasing demand for cleaner, more highly engineered, chemically tuned alloys has pushed these control methodologies to their limit. A new generation of these controllers is being developed by the Specialty Metals Process Consortium and Sandia National Laboratories to answer the challenges of remelting control for the next generation of alloys; these control systems will use multiple sensor inputs and apply material-specific system and process models.

  16. NASA-UVA Light Aerospace Alloy and Structures Technology Program (LA2ST). Progress report, 1 January-30 June 1993

    SciTech Connect

    Gangloff, R.P.; Scully, J.R.; Stoner, G.E.; Thornton, E.A.; Wawner, F.E. Jr.; Wert, J.A.

    1993-07-01

    The NASA-UVA Light Aerospace Alloy and Structures Technology (LA2ST) Program continues a high level of activity. Progress achieved between 1 Jan. and 30 Jun. 1993 is reported. The objective of the LA2ST Program is to conduct interdisciplinary graduate student research on the performance of next generation, light weight aerospace alloys, composites, and thermal gradient structures in collaboration with NASA-Langley researchers. The following projects are addressed: environmental fatigue of Al-Li-Cu alloys; mechanisms of localized corrosion and environmental fracture in Al-Cu-Li-Mg-Ag alloy X2095 and compositional variations; the effect of zinc additions on the precipitation and stress corrosion cracking behavior of alloy 8090; hydrogen interactions with Al-Li-Cu alloy 2090 and model alloys; metastable pitting of aluminum alloys; cryogenic fracture toughness of Al-Cu-Li + In alloys; the fracture toughness of Weldalite (TM); elevated temperature cracking of advanced I/M aluminum alloys; response of Ti-1100/SCS-6 composites to thermal exposure; superplastic forming of Weldalite (TM); research to incorporate environmental effects into fracture mechanics fatigue life prediction codes such as NASA FLAGRO; and thermoviscoplastic behavior.

  17. Light-weight alloys for aerospace applications; Proceedings of the Symposium, Las Vegas, NV, Feb. 28-Mar. 2, 1989

    SciTech Connect

    Lee, E.W.; Chia, E.H.; Kim, N.J.

    1989-01-01

    Various papers on lightweight alloys for aerospace applications are presented. Individual topics addressed include: P/M-aluminum alloy for high-temperature application, elevated temperature behavior of RST Al-Ti-X alloys, microstructural characterization of rapidly solidified Al-Ze-V alloys, high-strength aluminum alloys for aerospace applications, oxidation behavior of some Mg-Li and Mg-Li-SI alloys, the effect of various environments on fatigue crack propagation in a 2090 Al-Li alloy, and surface-generated scratches and their effects on the fatigue life of Al-Li alloys. Consideration is given to the stretch formability of sheet Al-Li, hydrogen solution in Al-Li alloys, particle-reinforced aluminum-based composites, applications for discontinuously reinforced aluminum, age hardening of cast SiC-reinforced Mg-6Zn, superplasticity in high-strength aluminum alloys and in spray-deposited 7075 Al alloys, and superplastic behavior in an aluminum-lithium alloy.

  18. NASA-UVA Light Aerospace Alloy and Structures Technology program (LA2ST). Progress report, 1 January 1995-30 June 1995

    SciTech Connect

    Starke, E.A. Jr.; Gangloff, R.P.; Herakovich, C.T.; Scully, J.R.; Shiflet, G.J.; Stoner, G.E.; Wert, J.A.

    1995-07-01

    The objective of the LA2ST Program is to conduct interdisciplinary graduate student research on the= performance of next generation, light-weight aerospace alloys, composites, and thermal gradient structures in collaboration with NASA-Langley researchers. The general aim is to produce relevant data and basic understanding of material mechanical response, environment/corrosion behavior, and microstructure; new monolithic and composite alloys; advanced processing methods; new solid and fluid mechanics analyses; measurement and modeling advances; and a pool of educated students for aerospace technologies. Specific technical objectives are presented for each of the following research projects: time-temperature dependent fracture in advanced wrought ingot metallurgy, and spray deposited aluminum alloys; cryogenic temperature effects on the deformation and fracture of Al-Li-Cu-In alloys; effects of aging and temperature on the ductile fracture of AA2095 and AA2195; mechanisms of localized corrosion in alloys 2090 and 2095; hydrogen interactions in aluminum-lithium alloys 2090 and selected model alloys; mechanisms of deformation and fracture in high strength titanium alloys (effects of temperature and hydrogen and effects of temperature and microstructure); evaluations of wide-panel aluminum alloy extrusions; Al-Si-Ge alloy development; effects of texture and precipitates on mechanical property anisotropy of Al-Cu-Mg-X alloys; damage evolution in polymeric composites; and environmental effects in fatigue life prediction - modeling crack propagation in light aerospace alloys.

  19. Advances in Computational Stability Analysis of Composite Aerospace Structures

    SciTech Connect

    Degenhardt, R.; Araujo, F. C. de

    2010-09-30

    European aircraft industry demands for reduced development and operating costs. Structural weight reduction by exploitation of structural reserves in composite aerospace structures contributes to this aim, however, it requires accurate and experimentally validated stability analysis of real structures under realistic loading conditions. This paper presents different advances from the area of computational stability analysis of composite aerospace structures which contribute to that field. For stringer stiffened panels main results of the finished EU project COCOMAT are given. It investigated the exploitation of reserves in primary fibre composite fuselage structures through an accurate and reliable simulation of postbuckling and collapse. For unstiffened cylindrical composite shells a proposal for a new design method is presented.

  20. Surface composition of alloys

    NASA Astrophysics Data System (ADS)

    Sachtler, W. M. H.

    1984-11-01

    In equilibrium, the composition of the surface of an alloy will, in general, differ from that of the bulk. The broken-bond model is applicable to alloys with atoms of virtually equal size. If the heat of alloy formation is zero, the component of lower heat of atomization is found enriched in the surface. If both partners have equal heats of sublimination, the surface of a diluted alloy is enriched with the minority component. Size effects can enhance or weaken the electronic effects. In general, lattice strain can be relaxed by precipitating atoms of deviating size on the surface. Two-phase alloys are described by the "cherry model", i.e. one alloy phase, the "kernel" is surrounded by another alloy, the "flesh", and the surface of the outer phase, the "skin" displays a deviating surface composition as in monophasic alloys. In the presence of molecules capable of forming chemical bonds with individual metal atoms, "chemisorption induced surface segregation" can be observed at low temperatures, i.e. the surface becomes enriched with the metal forming the stronger chemisorption bonds.

  1. Post-formed properties of superplastic aluminum aerospace alloys

    SciTech Connect

    Moore, W.L.; Zelin, M.; Chaudhury, P.K.

    1995-12-31

    Post-formed properties of commercially available superplastic aluminum alloys for aerospace applications are reviewed, focusing on the effect of both process variables and microstructural characteristics during superplastic forming. The post-formed properties include mechanical properties such as yield strength (YS), ultimate tensile strength (UTS), ductility, fatigue and fracture toughness (K{sub 1c}), and stress corrosion cracking (SCC) resistance. The microstructural processes, such as cavitation, grain growth, precipitation and texture evolution, that govern these post forming properties are reviewed to discuss the effect of forming process variables such as strain rate, temperature, back pressure, etc. The influence of pre- and post-processing treatments on these microstructural phenomena, hence, the post-formed properties, are also reviewed.

  2. NASA-UVa light aerospace alloy and structures technology program supplement: Aluminum-based materials for high speed aircraft

    NASA Technical Reports Server (NTRS)

    Starke, E. A., Jr. (Editor)

    1995-01-01

    This report on the NASA-UVa light aerospace alloy and structure technology program supplement: Aluminum-Based Materials for High Speed Aircraft covers the period from July 1, 1992. The objective of the research is to develop aluminum alloys and aluminum matrix composites for the airframe which can efficiently perform in the HSCT environment for periods as long as 60,000 hours (certification for 120,000 hours) and, at the same time, meet the cost and weight requirements for an economically viable aircraft. Current industry baselines focus on flight at Mach 2.4. The research covers four major materials systems: (1) Ingot metallurgy 2XXX, 6XXX, and 8XXX alloys, (2) Powder metallurgy 2XXX alloys, (3) Rapidly solidified, dispersion strengthened Al-Fe-X alloys, and (4) Discontinuously reinforced metal matrix composites. There are ten major tasks in the program which also include evaluation and trade-off studies by Boeing and Douglas aircraft companies.

  3. NASA-UVA light aerospace alloy and structures technology program (LA2ST). Progress report, 1 July-31 December 1993

    SciTech Connect

    Gangloff, R.P.; Scully, J.R.; Starke, E.A. Jr.; Stoner, G.E.; Thornton, E.A.; Wawner, F.E. Jr.; Wert, J.A.

    1994-03-01

    The NASA-UVA Light Aerospace Alloy and Structures Technology (LA2ST) Program was initiated in 1986, and continues a high level of activity, with projects being conducted by graduate students and faculty advisors in the Departments of Materials Science and Engineering, and Mechanical and Aerospace Engineering at the University of Virginia. This work is funded by the NASA-Langley Research Center under Grant NAG-1-745. Here, the authors report on progress achieved between July 1 and December 31, 1993. The objective of the LA2ST Program is to conduct interdisciplinary graduate student research on the performance of next generation, light weight aerospace alloys, composites and thermal gradient structures in collaboration with NASA-Langley researchers. Specific technical objectives are presented for each research project. Projects generally aim to produce relevant data and basic understanding of material mechanical response, environmental/corrosion behavior, and microstructure; new monolithic and composite alloys; advanced processing methods; new solid and fluid mechanics analyses; measurement and modeling advances; and critically, a pool of educated graduate students for aerospace technologies.

  4. Eutectic alloys. Citations from the International Aerospace Abstracts data base

    NASA Technical Reports Server (NTRS)

    Moore, P.

    1980-01-01

    These 250 abstracts from the international literature provide summaries of the preparation, treatments, composition and structure, and properties of eutectic alloys. Techniques for directional solidification and treatments including glazing, coating, and fiber reinforcement are discussed. In addition to the mechanical and thermal properties, the superconducting, corrosion, resistance, and thermionic emission and adsorption properties are described.

  5. Graphite fiber reinforced glass matrix composites for aerospace applications

    NASA Technical Reports Server (NTRS)

    Prewo, K. M.; Bacon, J. F.; Dicus, D. L.

    1979-01-01

    The graphite fiber reinforced glass matrix composite system is described. Although this composite is not yet a mature material, it possesses low density, attractive mechanical properties at elevated temperatures, and good environmental stability. Properties are reported for a borosilicate glass matrix unidirectionally reinforced with 60 volume percent HMS graphite fiber. The flexural strength and fatigue characteristics at room and elevated temperature, resistance to thermal cycling and continuous high temperature oxidation, and thermal expansion characteristics of the composite are reported. The properties of this new composite are compared to those of advanced resin and metal matrix composites showing that graphite fiber reinforced glass matrix composites are attractive for aerospace applications.

  6. Key Issues for Aerospace Applications of Ceramic Matrix Composites

    NASA Technical Reports Server (NTRS)

    Clinton, R. G., Jr.; Levine, S. R.

    1998-01-01

    Ceramic matrix composites (CMC) offer significant advantages for future aerospace applications including turbine engine and liquid rocket engine components, thermal protection systems, and "hot structures". Key characteristics which establish ceramic matrix composites as attractive and often enabling choices are strength retention at high temperatures and reduced weight relative to currently used metallics. However, due to the immaturity of this class of materials which is further compounded by the lack of experience with CMC's in the aerospace industry, there are significant challenges involved in the development and implementation of ceramic matrix composites into aerospace systems. Some of the more critical challenges are attachment and load transfer methodologies; manufacturing techniques, particularly scale up to large and thick section components; operational environment resistance; damage tolerance; durability; repair techniques; reproducibility; database availability; and the lack of validated design and analysis tools. The presentation will examine the technical issues confronting the application of ceramic matrix composites to aerospace systems and identify the key material systems having potential for substantial payoff relative to the primary requirements of light weight and reduced cost for future systems. Current programs and future research opportunities will be described in the presentation which will focus on materials and processes issues.

  7. Fracture characteristics of structural aerospace alloys containing deep surface flaws. [aluminum-titanium alloys

    NASA Technical Reports Server (NTRS)

    Masters, J. N.; Bixler, W. D.; Finger, R. W.

    1973-01-01

    Conditions controlling the growth and fracture of deep surface flaws in aerospace alloys were investigated. Static fracture tests were performed on 7075-T651 and 2219-T87 aluminum, and 6Ai-4V STA titanium . Cyclic flaw growth tests were performed on the two latter alloys, and sustain load tests were performed on the titanium alloy. Both the cyclic and the sustain load tests were performed with and without a prior proof overload cycle to investigate possible growth retardation effects. Variables included in all test series were thickness, flaw depth-to-thickness ratio, and flaw shape. Results were analyzed and compared with previously developed data to determine the limits of applicability of available modified linear elastic fracture solutions.

  8. Deployable aerospace PV array based on amorphous silicon alloys

    NASA Technical Reports Server (NTRS)

    Hanak, Joseph J.; Walter, Lee; Dobias, David; Flaisher, Harvey

    1989-01-01

    The development of the first commercial, ultralight, flexible, deployable, PV array for aerospace applications is discussed. It is based on thin-film, amorphous silicon alloy, multijunction, solar cells deposited on a thin metal or polymer by a proprietary, roll-to-roll process. The array generates over 200 W at AM0 and is made of 20 giant cells, each 54 cm x 29 cm (1566 sq cm in area). Each cell is protected with bypass diodes. Fully encapsulated array blanket and the deployment mechanism weigh about 800 and 500 g, respectively. These data yield power per area ratio of over 60 W/sq m specific power of over 250 W/kg (4 kg/kW) for the blanket and 154 W/kg (6.5 kg/kW) for the power system. When stowed, the array is rolled up to a diameter of 7 cm and a length of 1.11 m. It is deployed quickly to its full area of 2.92 m x 1.11 m, for instant power. Potential applications include power for lightweight space vehicles, high altitude balloons, remotely piloted and tethered vehicles. These developments signal the dawning of a new age of lightweight, deployable, low-cost space arrays in the range from tens to tens of thousands of watts for near-term applications and the feasibility of multi-100 kW to MW arrays for future needs.

  9. Recent advancement in optical fiber sensing for aerospace composite structures

    NASA Astrophysics Data System (ADS)

    Minakuchi, Shu; Takeda, Nobuo

    2013-12-01

    Optical fiber sensors have attracted considerable attention in health monitoring of aerospace composite structures. This paper briefly reviews our recent advancement mainly in Brillouin-based distributed sensing. Damage detection, life cycle monitoring and shape reconstruction systems applicable to large-scale composite structures are presented, and new technical concepts, "smart crack arrester" and "hierarchical sensing system", are described as well, highlighting the great potential of optical fiber sensors for the structural health monitoring (SHM) field.

  10. NASA-UVA Light Aerospace Alloy and Structures Technology Program (LA2ST). Progress report, 1 January-30 June 1994

    SciTech Connect

    Gangloff, R.P.

    1994-07-01

    The NASA-UVA Light Aerospace Alloy and Structures Technology (LA2ST) Program was initiated in 1986 and continues with a high level of activity. Projects are being conducted by graduate students and faculty advisors in the Department of Materials Science and Engineering, as well as in the Department of Civil Engineering and Applied Mechanics, at the University of Virginia. This work is funded by the NASA-Langley Research Center under Grant NAG-1-745. Here, the authors report on progress achieved between January 1 and June 30, 1994. These results were presented at the Fifth Annual NASA LA2ST Grant Review Meeting held at the Langley Research Center in July of 1994. The objective of the LA2ST Program is to conduct interdisciplinary graduate student research on the performance of next generation, lightweight aerospace alloys, composites, and thermal gradient structures in collaboration with NASA-Langley researchers. Specific technical objectives are presented for each research project. The authors generally aim to produce relevant data and basic understanding of material mechanical response, environmental/corrosion behavior, and microstructure; new monolithic and composite alloys; advanced processing methods; new solid and fluid mechanics analyses; measurement and modeling advances; and a pool of educated graduate students for aerospace technologies.

  11. Aerospace Industries Association (AIA) work practices report for composites

    NASA Technical Reports Server (NTRS)

    Luca, Jackie

    1994-01-01

    In an effort to gain a better understanding of effective safety and health work practice controls for composite manufacturing operations, the Aerospace Industries Association (AIA) Occupational Safety and Health Committee established a Composites Task Group. The group's task was to provide AIA members with recommendations for minimizing occupational exposure risk and to determine research needs and information gaps. The strategy included a review of toxicological information on composites, a review of member company experience and control methods, and interaction with other professional organizations who share an interest in composite work practices.

  12. Nonlinear analyses of composite aerospace structures in sonic fatigue

    NASA Technical Reports Server (NTRS)

    Mei, Chuh

    1992-01-01

    The primary research effort of this project is the development of analytical methods for the prediction of nonlinear random response of composite aerospace structures subjected to combined acoustic and thermal loads. The progress, accomplishments, and future plans of three random response research topics are discussed, namely acoustics-structure interactions using boundary/finite element methods, nonlinear vibrations of beams and composite plates under harmonic and random excitations, and numerical simulation of the nonlinear response of composite plates under combined thermal and acoustic loading.

  13. Aerogel Composites for Aerospace Thermal Protection

    NASA Technical Reports Server (NTRS)

    White, Susan

    2003-01-01

    Aerogel composites formed by infiltrating organic and/or inorganic aerogels into fiber matrix materials enable us to exploit the low thermal conductivity and low density of aerogels while maintaining the strength, structure and other useful properties of a porous fiber matrix. New materials for extreme heating ranges are needed to insulate future spacecraft against the extreme heat of planetary atmospheric entry, but the insulation mass must be minimized in order to maximize the payload. A reusable system passively insulates to survive heating unchanged for relatively low heating. Ablators, which sacrifice mass to control heating, are used to protect vehicles against more extreme heating for a single use thermal protection system (TPS). Aerogel composites were fabricated and tested for spacecraft thermal protection. The high-temperaturey high heat flux tests described in this paper were performed in NASA Ames arc-jet facilities to simulate spacecraft atmospheric entry, and include heating conditions predicted for the forebody and backshell of the Mars Science Lander (MSL) entry probe. The aerogel composites tested showed excellent thermal performance in the arc-jet tests, functioning both as reusuable insulation under lower heat fluxes, and as ablative aerogels under the extreme heating predicted for the MSL forebody.

  14. VARTM Process Modeling of Aerospace Composite Structures

    NASA Technical Reports Server (NTRS)

    Song, Xiao-Lan; Grimsley, Brian W.; Hubert, Pascal; Cano, Roberto J.; Loos, Alfred C.

    2003-01-01

    A three-dimensional model was developed to simulate the VARTM composite manufacturing process. The model considers the two important mechanisms that occur during the process: resin flow, and compaction and relaxation of the preform. The model was used to simulate infiltration of a carbon preform with an epoxy resin by the VARTM process. The model predicted flow patterns and preform thickness changes agreed qualitatively with the measured values. However, the predicted total infiltration times were much longer than measured most likely due to the inaccurate preform permeability values used in the simulation.

  15. Progress in patch repair of aerospace composite structures

    NASA Astrophysics Data System (ADS)

    Hou, Weiguo; Zhang, Weifang; Tang, Qingyun

    2011-11-01

    With the rapid application of the composite structure in the aerospace industry, more load-bearing structures and components are used with composites instead of conventional engineering materials. However, the composite structures are inevitably suffered damages in the complex environment, the composites structures repair become more important in the airplane maintenance. This paper describes the composites patch repair progress. Firstly, the flaws and damages concerned to composite structures are concluded, and also the repair principles are presented. Secondly, the advantages and disadvantages for different repair methods are analyzed, as well as the different bonded repair and their applicability to different structures is discussed. According the recent research in theory and experiment, the scarf repair effects under different parameters are analyzed. Finally, the failure mechanisms of repair structure are discussed, and some prospects are put forward.

  16. Progress in patch repair of aerospace composite structures

    NASA Astrophysics Data System (ADS)

    Hou, Weiguo; Zhang, Weifang; Tang, Qingyun

    2012-04-01

    With the rapid application of the composite structure in the aerospace industry, more load-bearing structures and components are used with composites instead of conventional engineering materials. However, the composite structures are inevitably suffered damages in the complex environment, the composites structures repair become more important in the airplane maintenance. This paper describes the composites patch repair progress. Firstly, the flaws and damages concerned to composite structures are concluded, and also the repair principles are presented. Secondly, the advantages and disadvantages for different repair methods are analyzed, as well as the different bonded repair and their applicability to different structures is discussed. According the recent research in theory and experiment, the scarf repair effects under different parameters are analyzed. Finally, the failure mechanisms of repair structure are discussed, and some prospects are put forward.

  17. Applications of Materials Selection For Joining Composite/Alloy Piping Systems

    NASA Technical Reports Server (NTRS)

    Crosby, Karen E.; Smith, Brett H.; Mensah, Patrick F.; Stubblefield, Michael A.

    2001-01-01

    A study in collaboration between investigators at Southern University and Louisiana State University in Baton Rouge, Louisiana and NASA/MSFC is examining materials for modeling and analysis of heat-activated thermal coupling for joining composite to composite/alloy structures. The short-term objectives of this research are to develop a method for joining composite or alloy structures, as well as to study the effects of thermal stress on composite-to-alloy joints. This investigation will result in the selection of a suitable metallic alloy. Al-Li alloys have potential for this purpose in aerospace applications due to their excellent strength-to-weight ratio. The study of Al-Li and other alloys is of significant importance to this and other aerospace as well as offshore related interests. Further research will incorporate the use of computer aided design and rapid prototype hardware for conceptual design and verification of a potential composite piping delivery system.

  18. Aerospace Patented High-Strength Aluminum Alloy Used in Commercial Industries

    NASA Technical Reports Server (NTRS)

    2004-01-01

    NASA structural materials engineer, Jonathan Lee, displays blocks and pistons as examples of some of the uses for NASA's patented high-strength aluminum alloy originally developed at Marshall Space Flight Center in Huntsville, Alabama. NASA desired an alloy for aerospace applications with higher strength and wear-resistance at elevated temperatures. The alloy is a solution to reduce costs of aluminum engine pistons and lower engine emissions for the automobile industry. The Boats and Outboard Engines Division at Bombardier Recreational Products of Sturtevant, Wisconsin is using the alloy for pistons in its Evinrude E-Tec outboard engine line.

  19. Evaluation of Sc-Bearing Aluminum Alloy C557 for Aerospace Applications

    NASA Technical Reports Server (NTRS)

    Domack, Marcia S.; Dicus, Dennis L.

    2002-01-01

    The performance of the Al-Mg-Sc alloy C557 was evaluated to assess its potential for a broad range of aerospace applications, including airframe and launch vehicle structures. Of specific interest were mechanical properties at anticipated service temperatures and thermal stability of the alloy. Performance was compared with conventional airframe aluminum alloys and with other emerging aluminum alloys developed for specific service environments. Mechanical properties and metallurgical structure were evaluated for commercially rolled sheet in the as-received H116 condition and after thermal exposures at 107 C. Metallurgical analyses were performed to de.ne grain morphology and texture, strengthening precipitates, and to assess the effect of thermal exposure.

  20. Capacitance-based damage detection sensing for aerospace structural composites

    NASA Astrophysics Data System (ADS)

    Bahrami, P.; Yamamoto, N.; Chen, Y.; Manohara, H.

    2014-04-01

    Damage detection technology needs improvement for aerospace engineering application because detection within complex composite structures is difficult yet critical to avoid catastrophic failure. Damage detection is challenging in aerospace structures because not all the damage detection technology can cover the various defect types (delamination, fiber fracture, matrix crack etc.), or conditions (visibility, crack length size, etc.). These defect states are expected to become even more complex with future introduction of novel composites including nano-/microparticle reinforcement. Currently, non-destructive evaluation (NDE) methods with X-ray, ultrasound, or eddy current have good resolutions (< 0.1 mm), but their detection capabilities is limited by defect locations and orientations and require massive inspection devices. System health monitoring (SHM) methods are often paired with NDE technologies to signal out sensed damage, but their data collection and analysis currently requires excessive wiring and complex signal analysis. Here, we present a capacitance sensor-based, structural defect detection technology with improved sensing capability. Thin dielectric polymer layer is integrated as part of the structure; the defect in the structure directly alters the sensing layer's capacitance, allowing full-coverage sensing capability independent of defect size, orientation or location. In this work, capacitance-based sensing capability was experimentally demonstrated with a 2D sensing layer consisting of a dielectric layer sandwiched by electrodes. These sensing layers were applied on substrate surfaces. Surface indentation damage (~1mm diameter) and its location were detected through measured capacitance changes: 1 to 250 % depending on the substrates. The damage detection sensors are light weight, and they can be conformably coated and can be part of the composite structure. Therefore it is suitable for aerospace structures such as cryogenic tanks and rocket

  1. Health monitoring studies on composite structures for aerospace applications

    SciTech Connect

    James, G.; Roach, D.; Hansche, B.; Meza, R.; Robinson, N.

    1996-02-01

    This paper discusses ongoing work to develop structural health monitoring techniques for composite aerospace structures such as aircraft control surfaces, fuselage sections or repairs, and reusable launch vehicle fuel tanks. The overall project is divided into four tasks: Operational evaluation, diagnostic measurements, information condensation, and damage detection. Five composite plates were constructed to study delaminations, disbonds, and fluid retention issues as the initial step in creating an operational system. These four square feet plates were graphite-epoxy with nomex honeycomb cores. The diagnostic measurements are composed of modal tests with a scanning laser vibrometer at over 500 scan points per plate covering the frequency range up to 2000 Hz. This data has been reduced into experimental dynamics matrices using a generic, software package developed at the University of Colorado at Boulder. The continuing effort will entail performing a series of damage identification studies to detect, localize, and determine the extent of the damage. This work is providing understanding and algorithm development for a global NDE technique for composite aerospace structures.

  2. Mishap risk control for advanced aerospace/composite materials

    NASA Technical Reports Server (NTRS)

    Olson, John M.

    1994-01-01

    Although advanced aerospace materials and advanced composites provide outstanding performance, they also present several unique post-mishap environmental, safety, and health concerns. The purpose of this paper is to provide information on some of the unique hazards and concerns associated with these materials when damaged by fire, explosion, or high-energy impact. Additionally, recommended procedures and precautions are addressed as they pertain to all phases of a composite aircraft mishap response, including fire-fighting, investigation, recovery, clean-up, and guidelines are general in nature and not application-specific. The goal of this project is to provide factual and realistic information which can be used to develop consistent and effective procedures and policies to minimize the potential environmental, safety, and health impacts of a composite aircraft mishap response effort.

  3. Effects of Cryogenic Treatment on the Residual Stress and Mechanical Properties of an Aerospace Aluminum Alloy

    NASA Technical Reports Server (NTRS)

    Chen, Po; Malone, Tina; Bod, Robert; Torres, Pablo

    2000-01-01

    Investigators at Marshall Space Flight Center (MSFC) are studying the potential benefits of cryogenic treatment for aerospace Aluminum (Al) alloys. This paper reports the effects of cryogenic treatment on residual stress, tensile strength, hardness, fatigue life, and stress corrosion cracking (SCC) resistance.

  4. Effects of Cryogenic Treatment on the Residual Stress and Mechanical Properties of an Aerospace Aluminum Alloy

    NASA Technical Reports Server (NTRS)

    Chen, P.; Malone, T.; Bond, R.; Torres, P.

    2001-01-01

    Investigators at Marshall Space Flight Center (MSFC) are studying the potential benefits of cryogenic treatment for aerospace Aluminum (Al) alloys. This paper reports the effects of cryogenic treatment on residual stress, tensile strength, hardness, fatigue life, and stress corrosion cracking (SCC) resistance.

  5. NASA-UVA Light Aerospace Alloy and Structures Technology Program (LA2ST). Research on Materials for the High Speed Civil Transport

    NASA Technical Reports Server (NTRS)

    Gangloff, Richard P.; Starke, Edgar A., Jr.; Kelly, Robert G.; Scully, John R.; Stoner, Glenn E.; Wert, John A.

    1997-01-01

    Since 1986, the NASA-Langley Research Center has sponsored the NASA-UVa Light Alloy and Structures Technology (LA2ST) Program at the University of Virginia (UVa). The fundamental objective of the LA2ST program is to conduct interdisciplinary graduate student research on the performance of next generation, light-weight aerospace alloys, composites and thermal gradient structures. The LA2ST program has aimed to product relevant data and basic understanding of material mechanical response, environmental/corrosion behavior, and microstructure; new monolithic and composite alloys; advanced processing methods; measurement and modeling advances; and a pool of educated graduate students for aerospace technologies. The scope of the LA2ST Program is broad. Research areas include: (1) Mechanical and Environmental Degradation Mechanisms in Advanced Light Metals and Composites, (2) Aerospace Materials Science, (3) Mechanics of materials for Aerospace Structures, and (4) Thermal Gradient Structures. A substantial series of semi-annual progress reports issued since 1987 documents the technical objectives, experimental or analytical procedures, and detailed results of graduate student research in these topical areas.

  6. NASA-UVa light aerospace alloy and structure technology program supplement: Aluminum-based materials for high speed aircraft

    NASA Technical Reports Server (NTRS)

    Starke, E. A., Jr.

    1993-01-01

    This report on the NASA-UVa Light Aerospace Alloy and Structure Technology Program Supplement: Aluminum-Based Materials for High Speed Aircraft covers the period from January 1, 1992 to June 30, 1992. The objective of the research is to develop aluminum alloys and aluminum matrix composites for the airframe which can efficiently perform in the HSCT environment for periods as long as 60,000 hours (certification for 120,000 hours) and, at the same time, meet the cost and weight requirements for an economically viable aircraft. Current industry baselines focus on flight at Mach 2.4. The research covers four major materials systems: (1) ingot metallurgy 2XXX, 6XXX, and 8XXX alloys, (2) powder metallurgy 2XXX alloys, (3) rapidly solidified, dispersion strengthened Al-Fe-X alloys, and (4) discontinuously reinforced metal matrix composites. There are ten major tasks in the program which also include evaluation and trade-off studies by Boeing and Douglas aircraft companies.

  7. The fabricability and corrosion resistance of several Al-Cu-Li aerospace alloys

    SciTech Connect

    Walsh, D.W.; Danford, M.; Sanders, J.

    1996-12-31

    Al-Li-Cu alloys are attractive to the aerospace industry. The high specific strength and stiffness of these alloys will improve lift efficiency, fuel economy, performance and increase payload capabilities. The objectives of this study were to measure the fabricability of Al 2195 (Al-4Cu-1Li) and to assess the effect of welding on corrosion behavior. Al 2219 samples were used in parallel tests to provide a baseline for the data generated. In this study samples were exposed to 3.5% NaCl and mild corrosive water solutions in both the as received and as welded conditions. Fabricability was assessed using Gleeble testing, Varestraint testing and differential scanning calorimetry (DSC). Results indicate that Alloy 2195 is much more susceptible to hot cracking than Al 2219, and that cracking sensitivity is a strong function of chemical composition within specification ranges for Al 2195. Furthermore, for base metal samples, corrosion in mild corrosive water was more severe than corrosion in salt water. In addition, welding increases the corrosion rate in Al 2195 and 2219, and causes severe localization in Al 2195. Furthermore, autogenously welded Al 2195 samples were more susceptible to attack than heterogeneously welded Al 2195 samples and autogenously welded Al2219 samples were less susceptible to corrosion than autogenously welded Al 2195 samples. Heterogeneously welded samples in both materials had high corrosion rates, but only the Al 2195 material was subject to localization of attack. The partially melted zones of Al 2195 samples were subject to severe, focused attack. In all cases, interdendritic constituents in welded areas and intergranular constituents in base material were cathodic to the Al rich matrix materials. Fabricability and corrosion resistance were correlated to material microstructure using optical microscopy, scanning electron microscopy, electron probe microanalysis, polarization resistance and environmental scanning electron microscopy.

  8. Intercalated graphite fiber composites as EMI shields in aerospace structures

    NASA Technical Reports Server (NTRS)

    Gaier, James R.

    1990-01-01

    The requirements for electromagnetic interference (EMI) shielding in aerospace structures are complicated over that of ground structures by their weight limitations. As a result, the best EMI shielding materials must blend low density, high strength, and high elastic modulus with high shielding ability. In addition, fabrication considerations including penetrations and joints play a major role. The EMI shielding properties are calculated for shields formed from pristine and intercalated graphite fiber/epoxy composites and compared to preliminary experimental results and to shields made from aluminum. Calculations indicate that EMI shields could be fabricated from intercalated graphite composites which would have less than 12 percent of the mass of conventional aluminum shields, based on mechanical properties and shielding properties alone.

  9. Intercalated graphite fiber composites as EMI shields in aerospace structures

    NASA Technical Reports Server (NTRS)

    Gaier, James R.

    1992-01-01

    The requirements for electromagnetic interference (EMI) shielding in aerospace structures are more complicated than those for ground structures because of their weight limitations. As a result, the best EMI shielding materials must combine low density, high strength, and high elastic modulus with high shielding ability. EMI shielding characteristics were calculated for shields formed from pristine and intercalated graphite fiber/epoxy composites and compare to preliminary experimental results for these materials and to the characteristics of shields made from aluminum. Calculations indicate that effective EMI shields could be fabricated from intercalated graphite composites which would have less than 12 percent of the mass of conventional aluminum shields, based on mechanical properties and shielding characteristics alone.

  10. MHD technologies for electroslag welding and melting of titanium alloys for aerospace industry

    NASA Astrophysics Data System (ADS)

    Shcherbinin, E.; Kompan, Ya.

    2006-09-01

    The basic tendency in improving titanium alloys is the need to increase the specific strength of structures of the aerospace engineering. Owing to the strength of advanced alloys Ti­10­2­3 (the USA) and VT22 (Russia), reaching 1300­1400 MPA, titanium is used widely in the load­carrying airframes and most loaded parts of engines of the modern airplanes "Boeing", "Airbus", "Antonov", "Ilyushin ", and others. At present, the problem is to develop alloys with a tensile strength of 1600 MPa and higher. Figs 2, Refs 6.

  11. Thermal conductivity, electrical resistivity, and thermopower of aerospace alloys from 4 to 300 K.

    NASA Technical Reports Server (NTRS)

    Hust, J. G.; Weitzel, D. H.; Powell, R. L.

    1971-01-01

    Measurement of thermal conductivity, electrical resistivity, and thermopower for several aerospace alloys: titanium alloy A110-AT, aluminum alloy 7039, Inconel 718, and Hastelloy X. Tables and graphs of the measured properties and Lorenz ratio are presented over the range from 4 to 300 K. Comparisons to other measurements and theoretical analysis of the data are included. The uncertainties of the property data are estimated as 0.7 to 2.5% for thermal conductivity, 0.25% in electrical resistivity, and about 0.1 microvolt/K in thermopower.

  12. Metals Technology for Aerospace Applications in 2020: Development of High Temperature Aluminum Alloys For Aerospace Applications

    NASA Technical Reports Server (NTRS)

    Dicus, Dennis (Technical Monitor); Starke, Edgar A., Jr.

    2003-01-01

    The role of trace additions on the nucleation and stability of the primary strengthening phase, omega, is of paramount importance for the enhancement of mechanical properties for moderate temperature application of Al-Cu-Mg-(Ag) alloys. In order to better understand the competition for solute, which governs the microstructural evolution of these alloys, a series of Al-Cu-Mg-Si quaternary alloys were prepared to investigate the role of trace Si additions on the nucleation of the omega phase. Si additions were found to quell omega nucleation in conjunction with the enhanced matrix precipitation of competing phases. These initial results indicate that it is necessary to overcome a critical Mg/Si ratio for omega precipitation, rather than a particular Si content.

  13. Prediction of residual strength of impact damaged aerospace composite structures

    SciTech Connect

    Garg, A.C.

    1993-12-31

    The importance of composites for aerospace structures is well known and therefore its increased use is being made for such structural components. However, these structures may be damaged as a result of various causes. One of the important causes is the impact damage either during manufacture or service. The amount of damage by impact created in the structure depends on several parameters such as impactor mass and velocity (impact energy), the structure material and support conditions. Since the magnitude of damage depends on impact energy, the residual strength may be expressed as a function of impact energy. Using a three parametric approach, a model is proposed to predict the residual strength behavior of impact damaged structure. The predicted behavior is shown to compare favorably with the available test data.

  14. Nondestructive Damage Evaluation in Ceramic Matrix Composites for Aerospace Applications

    PubMed Central

    Dassios, Konstantinos G.; Kordatos, Evangelos Z.; Aggelis, Dimitrios G.; Matikas, Theodore E.

    2013-01-01

    Infrared thermography (IRT) and acoustic emission (AE) are the two major nondestructive methodologies for evaluating damage in ceramic matrix composites (CMCs) for aerospace applications. The two techniques are applied herein to assess and monitor damage formation and evolution in a SiC-fiber reinforced CMC loaded under cyclic and fatigue loading. The paper explains how IRT and AE can be used for the assessment of the material's performance under fatigue. IRT and AE parameters are specifically used for the characterization of the complex damage mechanisms that occur during CMC fracture, and they enable the identification of the micromechanical processes that control material failure, mainly crack formation and propagation. Additionally, these nondestructive parameters help in early prediction of the residual life of the material and in establishing the fatigue limit of materials rapidly and accurately. PMID:23935428

  15. Experimental process development and aerospace alloy formability studies for hydroforming

    NASA Astrophysics Data System (ADS)

    Mojarad Farimani, Saeed

    In tube hydroforming process, a pressurized liquid is used to expand a thin walled tube inside a closed die in order to fill the die cavity. Tube hydroforming has many advantages that make it interesting for different industries such as automotive and aerospace, but due to the effects of different factors, such as formability of the material, load path (end feeding force and internal pressure during the process), tool geometry and friction, it is a quite complex manufacturing process. Therefore, finite element simulation along with optimization methods can significantly reduce the cost of trial and error approach used in conventional manufacturing methods. In this work, to investigate the effects of different process parameters such as friction condition, tube thickness and end feeding on the final product, tube hydroforming experiments were performed using a round to square-shape die. Experiments were performed on stainless steel 321 tubes with 50.8 mm (2 in) diameter and two different thicknesses; 0.9 mm and 1.2 mm. Experimental load paths were obtained via the data acquisition system of the hydroforming press, which is fully instrumented. An automated deformation measurement system, Argus, was used to measure the strains on the hydroformed tubes. Data collected from the initial experiments were used to simulate and then optimize the process. The process was simulated and optimized using Ls-Dyna and Ls-Opt software, respectively. Strains and thickness variations measured from experiments were compared to FE simulation results at critical sections. The comparison of the results from FE simulations and experiments were in good agreement, indicating that the approach can be used for predicting the final shape and thickness variations of the hydroformed parts for aerospace applications.

  16. Neutron diffraction studies of welds of aerospace aluminum alloys

    SciTech Connect

    Martukanitz, R.P.; Howell, P.R.; Payzant, E.A.; Spooner, S.; Hubbard, C.R.

    1996-10-01

    Neutron diffraction and electron microscopy were done on residual stress in various regions comprising variable polarity plasma arc welds of alloys 2219 (Al-6.3Cu) and 2195 (Al-4.0Cu-1.0Li-0.5Mg-0.5Ag). Results indicate that lattice parameter changes in the various weld regions may be attributed to residual stresses generated during welding, as well as local changes in microstructure. Distribution of longitudinal and transverse stress of welded panels shows peaks of tension and compression, respectively, within the HAZ and corroborate earlier theoretical results. Position of these peaks are related to position of minimum strength within the HAZ, and the magnitude of these peaks are a fraction of the local yield strength in this region. Weldments of alloy 2195-T8 exhibited higher peak residual stress than alloy 2219-T87. Comparison of neutron diffraction and microstructural analysis indicate decreased lattice parameters associated with the solid solution of the near HAZ; this results in decreased apparent tensile residual stress within this region and may significantly alter interpretation of residual stress measurements of these alloys. Considerable relaxation of residual stress occurs during removal of specimens from welded panels and was used to aid in differentiating changes in lattice parameters attributed to residual stress from welding and modifications in microstructure.

  17. Aerospace Patented High-Strength Aluminum Alloy Used in Commercial Industries

    NASA Technical Reports Server (NTRS)

    2004-01-01

    NASA structural materials engineers at Marshall Space Flight Center (MSFC) in Huntsville, Alabama developed a high-strength aluminum alloy for aerospace applications with higher strength and wear-resistance at elevated temperatures. The alloy is a solution to reduce costs of aluminum engine pistons and lower engine emissions for the automobile industry. The Boats and Outboard Engines Division at Bombardier Recreational Products of Sturtevant, Wisconsin is using the alloy for pistons in its Evinrude E-Tec outboard, 40-90 horsepower, engine line. The alloy pistons make the outboard motor quieter and cleaner, while improving fuel mileage and increasing engine durability. The engines comply with California Air resources Board emissions standards, some of the most stringent in the United States. (photo credit: Bombardiier Recreational Products)

  18. Finite element analysis of composites materials for aerospace applications

    NASA Astrophysics Data System (ADS)

    Nurhaniza, M.; Ariffin, M. K. A.; Ali, Aidy; Mustapha, F.; Noraini, A. W.

    2010-05-01

    Composites materials are intended to be used more extensively as an alternative of aluminum structure in aircraft and aerospace applications. This is due to their attractive properties as high strength-to-weight ratio and stiffness-to-weight ratio. Besides that it clarifies the growing interest for composites materials due to advantages of lightweight, high strength, high stiffness, superior fatigue life, tremendous corrosion resistance and low cost manufacturing. In this study, a finite element analysis (FEA) of fiberglass unidirectional E-type was analyzed in the framework of ABAQUS finite element commercial software. The analysis was done to quantify the mechanical properties and response of unidirectional E-glass in term of tensile, compression and thermal responses. From the analysis, the maximum and minimum values of stress and strain for E-glass 21xK43 Gevetex and Silenka E-glass 1200tex were obtained and stress-strain curve is presented. The ultimate load of failure, elastic behavior, tensile strength and other properties for each laminated plates under tensile and thermal-stress are determined from stress-strain curves. The simulation will run twice for each material where the first simulation based on orientation angles of 45° for ply-1, -45° for ply-2 and 90° for ply-3 while the second simulation, the orientation angles is 0° for all plies. The simulation is successfully conducted and verified by experimental data.

  19. Correlating Hardness Retention and Phase Transformations of Al and Mg Cast Alloys for Aerospace Applications

    NASA Astrophysics Data System (ADS)

    Kasprzak, W.; Czerwinski, F.; Niewczas, M.; Chen, D. L.

    2015-03-01

    The methodology based on correlating hardness and phase transformations was developed and applied to determine the maximum temperature of hardness retention of selected Al-based and Mg-based alloys for aerospace applications. The Al alloys: A356, F357, and C355 experienced 34-66% reduction of the initial hardness, in comparison to 4-22% hardness reduction observed in Mg alloys: QE22A, EV31A, ZE41A, and WE43B after the same annealing to 450 °C. For Al alloys the hardness reduction showed a steep transition between 220 and 238 °C. In contrast, Mg alloys showed a gradual hardness decrease occurring at somewhat higher temperatures between 238 and 250 °C. The hardness data were correlated with corresponding phase transformation kinetics examined by dilatometer and electrical resistivity measurements. Although Mg alloys preserved hardness to higher temperatures, their room temperature tensile strength and hardness were lower than Al alloys. The experimental methodology used in the present studies appears to be very useful in evaluating the softening temperature of commercial Al- and Mg-based alloys, permitting to assess their suitability for high-temperature applications.

  20. Molybdenum disilicide alloy matrix composite

    DOEpatents

    Petrovic, John J.; Honnell, Richard E.; Gibbs, W. Scott

    1991-01-01

    Compositions of matter consisting of matrix materials having silicon carbide dispersed throughout them and methods of making the compositions. A matrix material is an alloy of an intermetallic compound, molybdenum disilicide, and at least one secondary component which is a refractory silicide. The silicon carbide dispersant may be in the form of VLS whiskers, VS whiskers, or submicron powder or a mixture of these forms.

  1. Molybdenum disilicide alloy matrix composite

    DOEpatents

    Petrovic, J.J.; Honnell, R.E.; Gibbs, W.S.

    1991-12-03

    Compositions of matter consisting of matrix materials having silicon carbide dispersed throughout them and methods of making the compositions are disclosed. A matrix material is an alloy of an intermetallic compound, molybdenum disilicide, and at least one secondary component which is a refractory silicide. The silicon carbide dispersant may be in the form of VLS whiskers, VS whiskers, or submicron powder or a mixture of these forms. 3 figures.

  2. Molybdenum disilicide alloy matrix composite

    DOEpatents

    Petrovic, John J.; Honnell, Richard E.; Gibbs, W. Scott

    1990-01-01

    Compositions of matter consisting of matrix matrials having silicon carbide dispersed throughout them and methods of making the compositions. A matrix material is an alloy of an intermetallic compound, molybdenum disilicide, and at least one secondary component which is a refractory silicide. The silicon carbide dispersant may be in the form of VLS whiskers, VS whiskers, or submicron powder or a mixture of these forms.

  3. Approaches to hybrid SHM and NDE of composite aerospace structures

    NASA Astrophysics Data System (ADS)

    Michaels, Jennifer E.; Dawson, Alexander J.; Michaels, Thomas E.; Ruzzene, Massimo

    2014-03-01

    Periodic inspection of aerospace structures, while essential for ensuring their safety, incurs significant costs over a structure's life and also can result in significant loss of service. Structural health monitoring (SHM), which is also referred to as in situ nondestructive evaluation (NDE), offers the promise of more frequent assessments of structural integrity with little or no loss of service; however, such systems are not in common use. Here we consider a combined SHM and NDE approach to inspection of composite, plate-like components where the SHM system detects sites of possible damage and the follow-up NDE method utilizes the in situ SHM sensors to facilitate the inspection. The specific SHM approach considered is that of a sparse guided wave array using simple transducers that are spatially distributed on the structure. The NDE approach is non-contact guided wavefield imaging whereby one or more of the SHM transducers is used as a source and full wavefield data are recorded over the area of interest. This method has the advantage over conventional ultrasonic methods of being non-contact and requiring minimal surface preparation. Sparse array and wavefield data from a composite specimen with simulated sites of damage are presented here to illustrate the concept. Damage is simulated via glued-on steel plate pieces at multiple locations, and localization is performed using delay-and-sum imaging. A small, single site of simulated damage is well-localized, whereas larger and multiple sites of damage are not; however, their presence is readily detected. The follow-up wavefield imaging using a single sparse array transducer as a source is able to not only locate the sites of damage, but is able to provide a reasonable estimate of their sizes.

  4. Thermal Decoating of Aerospace Aluminum Alloys for Aircraft Recycling

    NASA Astrophysics Data System (ADS)

    Muñiz Lerma, Jose Alberto; Jung, In-Ho; Brochu, Mathieu

    2016-03-01

    Recycling of aircraft aluminum alloys can be complex due to the presence of their corrosion protection coating that includes inorganic compounds containing Cr(VI). In this study, the characterization and thermal degradation behavior of the coating on aluminum substrates coming from an aircraft destined for recycling are presented. Elements such as Sr, Cr, Si, Ba, Ti, S, C, and O were found in three different layers by EDS elemental mapping corresponding to SrCrO4, Rutile-TiO2, SiO2, and BaSO4 with an overall particle size D 50 = 1.96 µm. The thermal degradation profile analyzed by TGA showed four different stages. The temperature of complete degradation at the fourth stage occurred at 753.15 K (480 °C) at lower heating rates. At higher heating rates and holding an isotherm at the same temperature, the residence time to fully decompose the aircraft coating has been estimated as 4.0 ± 0.2 minutes. The activation energy calculated by the Flynn-Wall-Ozawa and the modified Coats-Redfern methods for multiple fraction of decomposition showed a non-constant behavior indicating the complexity of the reaction. Finally, the concentration of Cr(VI) released to the environment during thermal decoating was obtained by UV-Vis spectroscopy. It was found that 2.6 ± 0.1 µg of Cr(VI)/mm2 of aluminum substrate could be released unless adequate particle controls are used.

  5. Thermal Decoating of Aerospace Aluminum Alloys for Aircraft Recycling

    NASA Astrophysics Data System (ADS)

    Muñiz Lerma, Jose Alberto; Jung, In-Ho; Brochu, Mathieu

    2016-06-01

    Recycling of aircraft aluminum alloys can be complex due to the presence of their corrosion protection coating that includes inorganic compounds containing Cr(VI). In this study, the characterization and thermal degradation behavior of the coating on aluminum substrates coming from an aircraft destined for recycling are presented. Elements such as Sr, Cr, Si, Ba, Ti, S, C, and O were found in three different layers by EDS elemental mapping corresponding to SrCrO4, Rutile-TiO2, SiO2, and BaSO4 with an overall particle size D 50 = 1.96 µm. The thermal degradation profile analyzed by TGA showed four different stages. The temperature of complete degradation at the fourth stage occurred at 753.15 K (480 °C) at lower heating rates. At higher heating rates and holding an isotherm at the same temperature, the residence time to fully decompose the aircraft coating has been estimated as 4.0 ± 0.2 minutes. The activation energy calculated by the Flynn-Wall-Ozawa and the modified Coats-Redfern methods for multiple fraction of decomposition showed a non-constant behavior indicating the complexity of the reaction. Finally, the concentration of Cr(VI) released to the environment during thermal decoating was obtained by UV-Vis spectroscopy. It was found that 2.6 ± 0.1 µg of Cr(VI)/mm2 of aluminum substrate could be released unless adequate particle controls are used.

  6. Environmental, Safety, and Health Considerations: Composite Materials in the Aerospace Industry

    NASA Technical Reports Server (NTRS)

    Chu, Huai-Pu (Compiler)

    1994-01-01

    The Aerospace Industries Association, Suppliers of Advanced Composite Materials Association, and the National Aeronautics and Space Administration co-sponsored a conference on 'Environmental, Safety, and Health Considerations--Composite Materials in the Aerospace Industry.' The conference was held in Mesa, Arizona, on October 20-21, 1994. Seventeen papers were presented in four sessions including general information, safety, waste, and emissions from composites. Topics range from product stewardship, best work practice, biotransformation of uncured composite materials, to hazardous waste determination and offgassing of composite materials.

  7. Research of aluminium alloy aerospace structure aperture measurement based on 3D digital speckle correlation method

    NASA Astrophysics Data System (ADS)

    Bai, Lu; Wang, Hongbo; Zhou, Jiangfan; Yang, Rong; Zhang, Hui

    2014-11-01

    In this paper, the aperture change of the aluminium alloy aerospace structure under real load is researched. Static experiments are carried on which is simulated the load environment of flight course. Compared with the traditional methods, through experiments results, it's proved that 3D digital speckle correlation method has good adaptability and precision on testing aperture change, and it can satisfy measurement on non-contact,real-time 3D deformation or stress concentration. The test results of new method is compared with the traditional method.

  8. Surface Finishing—Chip Arrangement Relationship in the Dry Turning of Aerospace Titanium Alloys

    NASA Astrophysics Data System (ADS)

    Gerez, J. M.; Diaz-Vazquez, J. E.; Gonzalez, J. M.; Batista, M.; Huerta, M.; Marcos, M.

    2009-11-01

    Nowadays, one of the industrial sectors with greater implication in the technological development of Spain is the related one to the aerospace industry that, in some zones of the country, has gotten to become the industrial motor of the same ones, and to replace sectors that, by tradition and geographical strategy, had come occupying this place. Being located within this sector in height, the increasing application of titanium alloys is verified for the different constructions, that is to say, the use in light alloy rise. Along with the aluminium alloys, titanium alloys are widely used in the aeronautical industry. The good relationship hardness/weight and the high corrosion resistance turn them excellent candidates for high performance machining operations. Production requirements force a greater surface quality of the machined pieces. In this work a preliminary analysis of the evolution of the surface quality in the dry turning in of the Ti-6Al-4V is carried out, looking for a possible correlation with the geometry of the chips obtained in the tests. In order to evaluate the surface quality the arithmetical average roughness, Ra, has been used.

  9. Composite growth in hypermonotectic alloys

    NASA Astrophysics Data System (ADS)

    Grugel, R. N.

    1991-06-01

    The feasibility of solidifying uniformly aligned composites from alloys of hypermonotectic composition was investigated through the use of organic analogues and a directional solidification temperature gradient stage. Previously demonstrated macrostructurally detrimental effects due to coalescence and/or preferential wetting (or lack of) by the excess LII phase have been taken advantage of by the inclusion of constrained fibers aligned parallel to the growth direction. Upon passing through the miscibility gap, L II droplets are shown to attach and grow along the fibers prior to the monotectic reaction, resulting in a uniform composite. The results of different fiber materials in combination with “wetting” and “nonwetting” miscibility gap systems are presented and discussed in reference to processing in a microgravity environment.

  10. New ASTM Standards for Nondestructive Testing of Aerospace Composites

    NASA Technical Reports Server (NTRS)

    Waller, Jess M.; Saulsberry, Regor L.

    2010-01-01

    Problem: Lack of consensus standards containing procedural detail for NDE of polymer matrix composite materials: I. Flat panel composites. II. Composite components with more complex geometries a) Pressure vessels: 1) composite overwrapped pressure vessels (COPVs). 2) composite pressure vessels (CPVs). III. Sandwich core constructions. Metal and brittle matrix composites are a possible subject of future effort.

  11. The role of polymer based composites materials in modern and future aerospace structures

    NASA Astrophysics Data System (ADS)

    Cantoni, Stefania; De Nicola, Felice; Mercurio, Umberto; Quaranta, Vincenzo

    2014-05-01

    The need to reduce the overall weight of aeronautical and space structures, while at the same time preserving or even improving their performances, make the research and development in the field of innovative structures and advanced composite materials a crucial step for the advancement of aerospace technologies. Several fields of innovation have been explored in the last decades but the most promising solutions for the future of aerospace structures will be found in the "intelligent" use of polymer based composite materials both in the design and in their "nature like" use.

  12. Trends in aerospace structures

    NASA Technical Reports Server (NTRS)

    Card, M. F.

    1978-01-01

    Recent developments indicate that there may soon be a revolution in aerospace structures. Increases in allowable operational stress levels, utilization of high-strength, high-toughness materials, and new structural concepts will highlight this advancement. Improved titanium and aluminum alloys and high-modulus, high-strength advanced composites, with higher specific properties than aluminum and high-strength nickel alloys, are expected to be the principal materials. Significant advances in computer technology will cause major changes in the preliminary design cycle and permit solutions of otherwise too-complex interactive structural problems and thus the development of vehicles and components of higher performance. The energy crisis will have an impact on material costs and choices and will spur the development of more weight-efficient structures. There will also be significant spinoffs of aerospace structures technology, particularly in composites and design/analysis software.

  13. Braided Composites for Aerospace Applications. (Latest citations from the Aerospace Database)

    NASA Technical Reports Server (NTRS)

    1996-01-01

    The bibliography contains citations concerning the design, fabrication, and testing of structural composites formed by braiding machines. Topics include computer aided design and associated computer aided manufacture of braided tubular and flat forms. Applications include aircraft and spacecraft structures, where high shear strength and stiffness are required.

  14. Polymer-based composites for aerospace: An overview of IMAST results

    NASA Astrophysics Data System (ADS)

    Milella, Eva; Cammarano, Aniello

    2016-05-01

    This paper gives an overview of technological results, achieved by IMAST, the Technological Cluster on Engineering of Polymeric Composite Materials and Structures, in the completed Research Projects in the aerospace field. In this sector, the Cluster developed different solutions: lightweight multifunctional fiber-reinforced polymer composites for aeronautic structures, advanced manufacturing processes (for the optimization of energy consumption and waste reduction) and multifunctional components (e.g., thermal, electrical, acoustic and fire resistance).

  15. Advanced powder metallurgy aluminum alloys and composites

    NASA Technical Reports Server (NTRS)

    Lisagor, W. B.; Stein, B. A.

    1982-01-01

    The differences between powder and ingot metallurgy processing of aluminum alloys are outlined. The potential payoff in the use of advanced powder metallurgy (PM) aluminum alloys in future transport aircraft is indicated. The national program to bring this technology to commercial fruition and the NASA Langley Research Center role in this program are briefly outlined. Some initial results of research in 2000-series PM alloys and composites that highlight the property improvements possible are given.

  16. Materials for aerospace

    SciTech Connect

    Steinberg, M.A.

    1986-10-01

    Early last year the US Office of Science and Technology put forward an agenda for American aerospace activity in the coming decades. The plan established goals for subsonic, supersonic and transatmospheric hypersonic flight. Those goals, together with Reagan Administration's programs for a space station and the Strategic Defense Initiative, serve as a driving force for extensive improvements in the materials that enable airplanes and spacecraft to function efficiently. The development of materials, together with advances in the technology of fabricating parts, will play a key role in aerospace systems of the future. Among the materials developments projected for the year 2000 are new composites and alloys for structural members; superalloys, ceramics and glass composites for propulsion systems, and carbon-carbon composites (carbon fibers in a carbon matrix) for high-temperature applications in places where resistance to heat and ablation is critical. 5 figures.

  17. High Volume Fraction Carbon Nanotube Composites for Aerospace Applications

    NASA Technical Reports Server (NTRS)

    Siochi, E. J.; Kim, J.-W.; Sauti, G.; Cano, R. J.; Wincheski, R. A.; Ratcliffe, J. G.; Czabaj, M.

    2016-01-01

    Reported mechanical properties of carbon nanotubes (CNTs) at the nanoscale suggest their potential to enable significantly lighter structures of interest for space applications. However, their utility depends on the retention of these properties in bulk material formats that permit practical fabrication of large structures. This presentation summarizes recent progress made to produce carbon nanotube composites with specific tensile properties that begin to rival those of carbon fiber reinforced polymer composites. CNT content in these nanocomposites was greater than 70% by weight. Tested nanocomposite specimens were fabricated from kilometers or tens of square meters of CNT, depending on the starting material format. Processing methods to yield these results, and characterization and testing to evaluate the performance of these composites will be discussed. The final objective is the demonstration of a CNT composite overwrapped pressure vessel to be flight tested in the Fall of 2016.

  18. Amorphous metal alloy and composite

    DOEpatents

    Wang, Rong; Merz, Martin D.

    1985-01-01

    Amorphous metal alloys of the iron-chromium and nickel-chromium type have excellent corrosion resistance and high temperature stability and are suitable for use as a protective coating on less corrosion resistant substrates. The alloys are stabilized in the amorphous state by one or more elements of titanium, zirconium, hafnium, niobium, tantalum, molybdenum, and tungsten. The alloy is preferably prepared by sputter deposition.

  19. Standardization of shape memory alloy test methods toward certification of aerospace applications

    NASA Astrophysics Data System (ADS)

    Hartl, D. J.; Mabe, J. H.; Benafan, O.; Coda, A.; Conduit, B.; Padan, R.; Van Doren, B.

    2015-08-01

    The response of shape memory alloy (SMA) components employed as actuators has enabled a number of adaptable aero-structural solutions. However, there are currently no industry or government-accepted standardized test methods for SMA materials when used as actuators and their transition to commercialization and production has been hindered. This brief fast track communication introduces to the community a recently initiated collaborative and pre-competitive SMA specification and standardization effort that is expected to deliver the first ever regulatory agency-accepted material specification and test standards for SMA as employed as actuators for commercial and military aviation applications. In the first phase of this effort, described herein, the team is working to review past efforts and deliver a set of agreed-upon properties to be included in future material certification specifications as well as the associated experiments needed to obtain them in a consistent manner. Essential for the success of this project is the participation and input from a number of organizations and individuals, including engineers and designers working in materials and processing development, application design, SMA component fabrication, and testing at the material, component, and system level. Going forward, strong consensus among this diverse body of participants and the SMA research community at large is needed to advance standardization concepts for universal adoption by the greater aerospace community and especially regulatory bodies. It is expected that the development and release of public standards will be done in collaboration with an established standards development organization.

  20. High temperature resin matrix composites for aerospace structures

    NASA Technical Reports Server (NTRS)

    Davis, J. G., Jr.

    1980-01-01

    Accomplishments and the outlook for graphite-polyimide composite structures are briefly outlined. Laminates, skin-stiffened and honeycomb sandwich panels, chopped fiber moldings, and structural components were fabricated with Celion/LARC-160 and Celion/PMR-15 composite materials. Interlaminar shear and flexure strength data obtained on as-fabricated specimens and specimens that were exposed for 125 hours at 589 K indicate that epoxy sized and polyimide sized Celion graphite fibers exhibit essentially the same behavior in a PMR-15 matrix composite. Analyses and tests of graphite-polyimide compression and shear panels indicate that utilization in moderately loaded applications offers the potential for achieving a 30 to 50 percent reduction in structural mass compared to conventional aluminum panels. Data on effects of moisture, temperature, thermal cycling, and shuttle fluids on mechanical properties indicate that both LARC-160 and PMR-15 are suitable matrix materials for a graphite-polyimide aft body flap. No technical road blocks to building a graphite-polyimide composite aft body flap are identified.

  1. Mechanical Characterization of Composites and Foams for Aerospace Applications

    NASA Technical Reports Server (NTRS)

    Veazie, D. R.; Glinsey, C.; Webb, M. M.; Norman, M.; Meador, Michael A. (Technical Monitor)

    2000-01-01

    Experimental studies to investigate the mechanical properties of ultra-lightweight polyimide foams for space applications, compression after impact (CAI) properties for low velocity impact of sandwich composites, and aspen fiber/polypropylene composites containing an interface adhesive additive, Maleic Anhydride Grafted Polypropylene (MAPP), were performed at Clark Atlanta University. Tensile, compression, flexural, and shear modulus tests were performed on TEEK foams categorized by their densities and relative cost according to ASTM specifications. Results showed that the mechanical properties of the foams increased as a function of higher price and increasing density. The CAI properties of Nomex/phenolic honeycomb core, fiberglass/epoxy facesheet sandwich composites for two damage arrangements were compared using different levels of impact energy ranging from 0 - 452 Joules. Impact on the thin side showed slightly more retention of CAI strength at low impact levels, whereas higher residual compressive strength was observed from impact on the thick side at higher impact levels. The aspen fiber/polypropylene composites studied are composed of various percentages (by weight) of aspen fiber and polypropylene ranging from 30%-60% and 40%-100%, respectively. Results showed that the MAPP increases tensile and flexural strength, while having no significant influence on tensile and flexural modulus.

  2. Laser Surface Preparation and Bonding of Aerospace Structural Composites

    NASA Technical Reports Server (NTRS)

    Belcher, Marcus A.; Wohl, Christopher J.; Connell, John W.

    2009-01-01

    A Nd:YAG laser was used to etch patterns conducive to adhesive bonding onto CFRP surfaces. These were compared to typical pre-bonding surface treatments including grit blasting, manual abrasion, and peel ply. Laser treated composites were then subjected to optical microscopy, contact angle measurements, and post-bonding mechanical testing.

  3. Manufacturing and NDE of Large Composite Aerospace Structures at MSFC

    NASA Technical Reports Server (NTRS)

    Whitaker, Ann

    2000-01-01

    NASA's vision for transportation to orbit calls for new vehicles built with new materials technology. The goals of this new launch system development are to improve safety, dramatically reduce cost to orbit, and improve vehicle turn around time. Planned Space Shuttle upgrades include new reusable liquid propellant boosters to replace the solid propellant boosters. These boosters are to have wings and return to the launch site for a horizontal landing on an airport runway. New single and two stages to orbit concepts are being investigated. To reduce weight and improve performance composite materials are proposed for fuel and oxidizer tanks, fuel feedlines, valve bodies, aerostructures, turbomachinery components. For large composite structures new methods of fabrication are being proposed and developed. Containment of cryogenic fuel or oxidizer requires emphases on composite material densification and chemical compatibility. Ceramic matrix and fiber composites for hot rotating turbomachinery have been developed with new fabrication processes. The new requirements on the materials for launcher components are requiring development of new manufacturing and inspection methods. This talk will examine new and proposed manufacturing methods to fabricate the revolutionary components. New NDE methods under consideration include alternative X-ray methods, X-ray laminagraphy, advanced CT, Thermography, new ultrasonic methods, and imbedded sensors. The sizes, complexity, use environment, and contamination restrictions will challenge the inspection process. In flight self-diagnosis and rapid depot inspection are also goals of the NDE development.

  4. Transient infrared thermography for damage evaluation in aerospace composites

    NASA Astrophysics Data System (ADS)

    Pawar, S.; Peters, K.

    2010-04-01

    In this paper we investigate the performance of defect detection using long duration transient thermography for woven composite laminates subjected to low-velocity impacts. Two types of defects are studied: inclusions represented by foam tabs inserted into the laminate during fabrication and barely visible impact damage due to low-velocity impacts. These defects represent the expected damage states that are necessary for inspection during the service life of a woven composite aircraft component. The long duration transient thermography is demonstrated to successfully detect the embedded inclusions, with a dimension to depth ratio detection capability of approximately 3. It is also demonstrated that the detection of low velocity impact damage with the transient thermography is less successful due to uneven emissivity of the surface. Therefore, processing of the image using a self referencing algorithm is performed which improves the damage detection clarity.

  5. Diffraction-based study of fatigue crack initiation and propagation in aerospace aluminum alloys

    NASA Astrophysics Data System (ADS)

    Gupta, Vipul K.

    The crack initiation sites and microstructure-sensitive growth of small fatigue cracks are experimentally characterized in two precipitation-hardened aluminum alloys, 7075-T651 and 7050-T7451, stressed in ambient temperature moist-air (warm-humid) and -50°C dry N2 (cold-dry) environmental conditions. Backscattered electron imaging (BSE) and energy dispersive spectroscopy (EDS) of the fracture surfaces showed that Fe-Cu rich constituent particle clusters are the most common initiation sites within both alloys stressed in either environment. The crack growth within each alloy, on average, was observed to be slowed in the cold-dry environment than in the warm-humid environment, but only at longer crack lengths. Although no overwhelming effects of grain boundaries and grain orientations on small-crack growth were observed, crack growth data showed local fluctuations within individual grains. These observations are understood as crack propagation through the underlying substructure at the crack surface and frequent interaction with low/high-angle grain and subgrain boundaries, during cyclic loading, and, are further attributed to periodic changes in crack propagation path and multiple occurrences of crack-branching observed in the current study. SEM-based stereology in combination with electron backscattered diffraction (EBSD) established fatigue crack surface crystallography within the region from ˜1 to 50 mum of crack initiating particle clusters. Fatigue crack facets were parallel to a wide variety of crystallographic planes, with pole orientations distributed broadly across the irreducible stereographic triangle between the {001} and {101}-poles within both warm-humid and cold-dry environments. The results indicate environmentally affected fatigue cracking in both cases, given the similarity between the observed morphology and crystallography with that of a variety of aerospace aluminum alloys cracked in the presence of moist-air. There was no evidence of

  6. High Volume Fraction Carbon Nanotube Composites for Aerospace Applications

    NASA Technical Reports Server (NTRS)

    Siochi, Emilie J.; Kim, Jae-Woo; Sauti, Godfrey; Cano, Roberto J.; Wincheski, Russell A.; Ratcliffe, James G.; Czabaj, Michael; Jensen, Benjamin D.; Wise, Kristopher E.

    2015-01-01

    Reported nanoscale mechanical properties of carbon nanotubes (CNTs) suggest that their use may enable the fabrication of significantly lighter structures for use in space applications. To be useful in the fabrication of large structures, however, their attractive nanoscale properties must be retained as they are scaled up to bulk materials and converted into practically useful forms. Advances in CNT production have significantly increased the quantities available for use in manufacturing processes, but challenges remain with the retention of nanoscale properties in larger assemblies of CNTs. This work summarizes recent progress in producing carbon nanotube composites with tensile properties approaching those of carbon fiber reinforced polymer composites. These advances were achieved in nanocomposites with CNT content of 70% by weight. The processing methods explored to yield these CNT composite properties will be discussed, as will the characterization and test methods that were developed to provide insight into the factors that contribute to the enhanced tensile properties. Technology maturation was guided by parallel advancements in computational modeling tools that aided in the interpretation of experimental data.

  7. Advances in Ceramic Matrix Composite Blade Damping Characteristics for Aerospace Turbomachinery Applications

    NASA Technical Reports Server (NTRS)

    Min, James B.; Harris, Donald L.; Ting, J. M.

    2011-01-01

    For advanced aerospace propulsion systems, development of ceramic matrix composite integrally-bladed turbine disk technology is attractive for a number of reasons. The high strength-to-weight ratio of ceramic composites helps to reduce engine weight and the one-piece construction of a blisk will result in fewer parts count, which should translate into reduced operational costs. One shortcoming with blisk construction, however, is that blisks may be prone to high cycle fatigue due to their structural response to high vibration environments. Use of ceramic composites is expected to provide some internal damping to reduce the vibratory stresses encountered due to unsteady flow loads through the bladed turbine regions. A goal of our research was to characterize the vibration viscous damping behavior of C/SiC composites. The vibration damping properties were measured and calculated. Damping appeared to decrease with an increase in the natural frequency. While the critical damping amount of approximately 2% is required for typical aerospace turbomachinery engines, the C/SiC damping at high frequencies was less than 0.2% from our study. The advanced high-performance aerospace propulsion systems almost certainly will require even more damping than what current vehicles require. A purpose of this paper is to review some work on C/SiC vibration damping by the authors for the NASA CMC turbine blisk development program and address an importance of the further investigation of the blade vibration damping characteristics on candidate CMC materials for the NASA s advanced aerospace turbomachinery engine systems.

  8. Ultrasonic and radiographic evaluation of advanced aerospace materials: Ceramic composites

    NASA Technical Reports Server (NTRS)

    Generazio, Edward R.

    1990-01-01

    Two conventional nondestructive evaluation techniques were used to evaluate advanced ceramic composite materials. It was shown that neither ultrasonic C-scan nor radiographic imaging can individually provide sufficient data for an accurate nondestructive evaluation. Both ultrasonic C-scan and conventional radiographic imaging are required for preliminary evaluation of these complex systems. The material variations that were identified by these two techniques are porosity, delaminations, bond quality between laminae, fiber alignment, fiber registration, fiber parallelism, and processing density flaws. The degree of bonding between fiber and matrix cannot be determined by either of these methods. An alternative ultrasonic technique, angular power spectrum scanning (APSS) is recommended for quantification of this interfacial bond.

  9. Solidification processing of monotectic alloy matrix composites

    NASA Technical Reports Server (NTRS)

    Frier, Nancy L.; Shiohara, Yuh; Russell, Kenneth C.

    1989-01-01

    Directionally solidified aluminum-indium alloys of the monotectic composition were found to form an in situ rod composite which obeys a lambda exp 2 R = constant relation. The experimental data shows good agreement with previously reported results. A theoretical boundary between cellular and dendritic growth conditions was derived and compared with experiments. The unique wetting characteristics of the monotectic alloys can be utilized to tailor the interface structure in metal matrix composites. Metal matrix composites with monotectic and hypermonotectic Al-In matrices were made by pressure infiltration, remelted and directionally solidified to observe the wetting characteristics of the alloys as well as the effect on structure of solidification in the constrained field of the fiber interstices. Models for monotectic growth are modified to take into account solidification in these constrained fields.

  10. Composite multilayer insulations for thermal protection of aerospace vehicles

    NASA Technical Reports Server (NTRS)

    Kourtides, Demetrius A.; Pitts, William C.

    1989-01-01

    Composite flexible multilayer insulation systems (MLI), consisting of alternating layers of metal foil and scrim cloth or insulation quilted together using ceramic thread, were evaluated for thermal performance and compared with a silica fibrous (baseline) insulation system. The systems studied included: (1) alternating layers of aluminoborosilicate (ABS) scrim cloth and stainless steel foil, with silica, ABS, or alumina insulation; (2) alternating layers of scrim cloth and aluminum foil, with silica or ABS insulation; (3) alternating layers of aluminum foil and silica or ABS insulation; and (4) alternating layers of aluminum-coated polyimide placed on the bottom of the silica insulation. The MLIs containing aluminum were the most efficient, measuring as little as half the backface temperature increase of the baseline system.

  11. Laser Surface Preparation and Bonding of Aerospace Structural Composites

    NASA Technical Reports Server (NTRS)

    Belcher, M. A.; Wohl, C. J.; Hopkins, J. W.; Connell, J. W.

    2010-01-01

    Adhesive bonds are critical to the integrity of built-up structures. Disbonds can often be detected but the strength of adhesion between surfaces in contact is not obtainable without destructive testing. Typically the number one problem in a bonded structure is surface contamination, and by extension, surface preparation. Standard surface preparation techniques, including grit blasting, manual abrasion, and peel ply, are not ideal because of variations in their application. Etching of carbon fiber reinforced plastic (CFRP) panels using a neodymium-doped yttrium aluminum garnet (Nd:YAG) laser appears to be a highly precise and promising way to both clean a composite surface prior to bonding and provide a bond-promoting patterned surface akin to peel ply without the inherent drawbacks from the same (i.e., debris and curvature). CFRP surfaces prepared using laser patterns conducive to adhesive bonding were compared to typical prebonding surface treatments through optical microscopy, contact angle goniometry, and post-bonding mechanical testing.

  12. Laser Surface Preparation for Adhesive Bonding of Aerospace Structural Composites

    NASA Technical Reports Server (NTRS)

    Belcher, M. A.; Wohl, C. J.; Hopkins, J. W.; Connell, J. W.

    2010-01-01

    Adhesive bonds are critical to the integrity of built-up structures. Disbonds can often be detected but the strength of adhesion between surfaces in contact is not obtainable without destructive testing. Typically the number one problem in a bonded structure is surface contamination, and by extension, surface preparation. Standard surface preparation techniques, including grit blasting, manual abrasion, and peel ply, are not ideal because of variations in their application. Etching of carbon fiber reinforced plastic (CFRP) panels using a neodymium-doped yttrium aluminum garnet (Nd:YAG) laser appears to be a highly precise and promising way to both clean a composite surface prior to bonding and provide a bond-promoting patterned surface akin to peel ply without the inherent drawbacks from the same (i.e., debris and curvature). CFRP surfaces prepared using laser patterns conducive to adhesive bonding were compared to typical pre-bonding surface treatments through optical microscopy, contact angle goniometry, and post-bonding mechanical testing.

  13. Design and Test of Low-Profile Composite Aerospace Tank Dome

    NASA Technical Reports Server (NTRS)

    Ahmed, R.

    1999-01-01

    This report summarizes the design, analysis, manufacture, and test of a subscale, low-profile composite aerospace dome under internal pressure. A low-profile dome has a radius-to-height ratio greater than the square root of two. This effort demonstrated that a low-profile composite dome with a radius-to-height ratio of three was a feasible design and could adequately withstand the varying stress states resulting from internal pressurization. Test data for strain and displacement versus pressure are provided to validate the design.

  14. NDE of Fiber Reinforced Foam Composite Structures for Future Aerospace Vehicles

    NASA Technical Reports Server (NTRS)

    Walker, james; Roth, Don; Hopkins, Dale

    2010-01-01

    This slide presentation reviews the complexities of non-destructive evaluation (NDE) of fiber reinforced foam composite structures to be used for aerospace vehicles in the future.Various views of fiber reinforced foam materials are shown and described. Conventional methods of NDE for composites are reviewed such as Micro-computed X-Ray Tomography, Thermography, Shearography, and Phased Array Ultrasonics (PAUT). These meth0ods appear to work well on the face sheet and face sheet ot core bond, they do not provide adequate coverage for the webs. There is a need for additional methods that will examine the webs and web to foam core bond.

  15. Friction Stir Welding of Metal Matrix Composites for use in aerospace structures

    NASA Astrophysics Data System (ADS)

    Prater, Tracie

    2014-01-01

    Friction Stir Welding (FSW) is a relatively nascent solid state joining technique developed at The Welding Institute (TWI) in 1991. The process was first used at NASA to weld the super lightweight external tank for the Space Shuttle. Today FSW is used to join structural components of the Delta IV, Atlas V, and Falcon IX rockets as well as the Orion Crew Exploration Vehicle. A current focus of FSW research is to extend the process to new materials which are difficult to weld using conventional fusion techniques. Metal Matrix Composites (MMCs) consist of a metal alloy reinforced with ceramics and have a very high strength to weight ratio, a property which makes them attractive for use in aerospace and defense applications. MMCs have found use in the space shuttle orbiter's structural tubing, the Hubble Space Telescope's antenna mast, control surfaces and propulsion systems for aircraft, and tank armors. The size of MMC components is severely limited by difficulties encountered in joining these materials using fusion welding. Melting of the material results in formation of an undesirable phase (formed when molten Aluminum reacts with the reinforcement) which leaves a strength depleted region along the joint line. Since FSW occurs below the melting point of the workpiece material, this deleterious phase is absent in FSW-ed MMC joints. FSW of MMCs is, however, plagued by rapid wear of the welding tool, a consequence of the large discrepancy in hardness between the steel tool and the reinforcement material. This work characterizes the effect of process parameters (spindle speed, traverse rate, and length of joint) on the wear process. Based on the results of these experiments, a phenomenological model of the wear process was constructed based on the rotating plug model for FSW. The effectiveness of harder tool materials (such as Tungsten Carbide, high speed steel, and tools with diamond coatings) to combat abrasive wear is explored. In-process force, torque, and

  16. Metal- and intermetallic-matrix composites for aerospace propulsion and power systems

    NASA Technical Reports Server (NTRS)

    Doychak, J.

    1992-01-01

    The requirements for high specific strength refractory materials of prospective military, civil, and space propulsion systems are presently addressed in the context of emerging capabilities in metal- and intermetallic-matrix composites. The candidate systems encompass composite matrix compositions of superalloy, Nb-Zr refractory alloy, Cu-base, and Ti-base alloy types, as well as such intermetallics as TiAl, Ti3Al, NiAl, and MoSi2. The brittleness of intermetallic matrices remains a major consideration, as does their general difficulty of fabrication.

  17. Composition control in laser surface alloying

    NASA Astrophysics Data System (ADS)

    Chande, T.; Mazumder, J.

    1983-06-01

    Laser surface alloying, a process of growing interest for local surface modification, relies upon a suitable composition and microstructure for satisfactory on-the-job performance. This paper reports the results of an initial systematic study of laser surface alloying nickel onto AISI 1020 steel substrates using a statistical experimental design technique. The objective was to relate processing conditions to dimensions, solute content, and microstructural refinement of the laser alloyed zones. Solute content was of principal concern as it is the single most important factor affecting the properties of laser surface alloys. The effects of varying the laser power, beam diameter, and speed on the width, depth, nickel content, and fluctuations in nickel content are reported. Interactions between process parameters are discussed, the reproducibility assessed, contour plots for solute content drawn. Dimensionless plots are developed that relate average solute content and microstructural refinement to process parameters. Previously published data for alloying chromium into 1018 steels are shown to contain similar trends. It is felt that such an approach would facilitate selection of processing conditions to obtain reproducibly the compositions and microstructures necessary for gainful utilization of laser surface alloys.

  18. Integrity assessment of preforms and thick textile reinforced composites for aerospace applications

    NASA Astrophysics Data System (ADS)

    Saboktakin Rizi, Abbasali

    Three-dimensional (3D) textile composites containing in-plane fibers and fibers oriented in the thickness direction offer some advantages over two-dimensional (2D) textile composites. These advantages include high delamination resistance and improved damage tolerance. Textile composites containing 3D textile preforms have mostly been developed by the aerospace industry for structural applications such as wing panels, landing gear, rocket nozzles, and the Orion capsule, and so forth. This thesis is devoted to structural integrity assessment of textile composites including 2D and 3D tufted composites by combining destructive and non-destructive techniques. In the first part of the thesis, non-destructive techniques including X-ray computed tomography (CT) and ultrasound-based techniques (UT) were used to detect two significant processinduced defects called fiber breakage and fabric misalignment. The second part focuses on studying of the influence of manufacturing defects introduced during the tufting process on the mechanical properties. Experimental results proved that X-ray CT facilitates the characterization of those two manufacturing defects as well as the architecture of the textile fabrics. Furthermore, mesoscale modeling of a 2D woven composite was successfully performed for the analysis of the fiber breakage defect influence and fiber architecture on wave propagation. Experimental results prove that tufting the preform assists in locking and restricting the yarn's movement in the preform. The threads used for tufting have a major influence on tensile strength, as stronger threads may give higher resistance. Tufting increases the compaction force due locking of fiber bundles, therefore, a higher compaction force is needed to obtain a fiber volume of up to 50 percent in comparison to an untufted preform. The drape behaviour of a tufted preform is influenced by tufting so that high drapability is observed for a tufted preform along with local variation of fiber

  19. Innovative features providing proven solutions for integration of composite pressure vessels into aerospace systems

    NASA Astrophysics Data System (ADS)

    Braun, C. A.

    1993-06-01

    Some specific proven aerospace applications of pressure vessels made of a thin aluminum liner overwrapped with a composite of epoxy resin and high-strength carbon fiber are discussed. The discussion focuses on the safety and reliability of carbon overwrapped vessels. In particular, attention is given to safety with respect to impact damage and exposure to corrosive fluids, safety factor on operating pressure, stress rupture of carbon fiber, and the ability of the aluminum liner to contain the fluid for the life of the mission.

  20. Effects of proof loads and combined mode loadings on fracture and flaw growth characteristics of aerospace alloys

    NASA Technical Reports Server (NTRS)

    Shah, R. C.

    1974-01-01

    This experimental program was undertaken to determine the effects of (1) combined tensile and bending loadings, (2) combined tensile and shear loadings, and (3) proof overloads on fracture and flaw growth characteristics of aerospace alloys. Tests were performed on four alloys: 2219-T87 aluminum, 5Al-2.5Sn (ELl) titanium, 6Al-4V beta STA titanium and high strength 4340 steel. Tests were conducted in room air, gaseous nitrogen at -200F (144K), liquid nitrogen and liquid hydrogen. Flat center cracked and surface flawed specimens, cracked tube specimens, circumferentially notched round bar and surface flawed cylindrical specimens were tested. The three-dimensional photoelastic technique of stress freezing and slicing was used to determine stress intensity factors for surface flawed cylindrical specimens subjected to tension or torsion. Results showed that proof load/temperature histories used in the tests have a small beneficial effect or no effect on subsequent fracture strength and flaw growth rates.

  1. Resilient and Corrosion-Proof Rolling Element Bearings Made from Superelastic Ni-Ti Alloys for Aerospace

    NASA Technical Reports Server (NTRS)

    Dellacorte, Christopher

    2014-01-01

    Mechanical components (bearings, gears, mechanisms) typically utilize hardened construction materials to minimize wear and attain long life. In such components, loaded contact points (e.g., meshing gear teeth, bearing balls-raceway contacts) experience high contact stresses. The combination of high hardness and high elastic modulus often leads to damaging contact stress and denting, particularly during transient overload events such as shock impacts that occur during the launching of space vehicles or the landing of aircraft. In this webinar, Dr. DellaCorte will introduce the results of a research project that employs a superelastic alloy, Ni-Ti for rolling element bearing applications. Bearings and components made from such alloys can alleviate many problems encountered in advanced aerospace applications and may solve many terrestrial applications as well

  2. Real-Time Impact Visualization Inspection of Aerospace Composite Structures with Distributed Sensors.

    PubMed

    Si, Liang; Baier, Horst

    2015-01-01

    For the future design of smart aerospace structures, the development and application of a reliable, real-time and automatic monitoring and diagnostic technique is essential. Thus, with distributed sensor networks, a real-time automatic structural health monitoring (SHM) technique is designed and investigated to monitor and predict the locations and force magnitudes of unforeseen foreign impacts on composite structures and to estimate in real time mode the structural state when impacts occur. The proposed smart impact visualization inspection (IVI) technique mainly consists of five functional modules, which are the signal data preprocessing (SDP), the forward model generator (FMG), the impact positioning calculator (IPC), the inverse model operator (IMO) and structural state estimator (SSE). With regard to the verification of the practicality of the proposed IVI technique, various structure configurations are considered, which are a normal CFRP panel and another CFRP panel with "orange peel" surfaces and a cutout hole. Additionally, since robustness against several background disturbances is also an essential criterion for practical engineering demands, investigations and experimental tests are carried out under random vibration interfering noise (RVIN) conditions. The accuracy of the predictions for unknown impact events on composite structures using the IVI technique is validated under various structure configurations and under changing environmental conditions. The evaluated errors all fall well within a satisfactory limit range. Furthermore, it is concluded that the IVI technique is applicable for impact monitoring, diagnosis and assessment of aerospace composite structures in complex practical engineering environments. PMID:26184196

  3. Real-Time Impact Visualization Inspection of Aerospace Composite Structures with Distributed Sensors

    PubMed Central

    Si, Liang; Baier, Horst

    2015-01-01

    For the future design of smart aerospace structures, the development and application of a reliable, real-time and automatic monitoring and diagnostic technique is essential. Thus, with distributed sensor networks, a real-time automatic structural health monitoring (SHM) technique is designed and investigated to monitor and predict the locations and force magnitudes of unforeseen foreign impacts on composite structures and to estimate in real time mode the structural state when impacts occur. The proposed smart impact visualization inspection (IVI) technique mainly consists of five functional modules, which are the signal data preprocessing (SDP), the forward model generator (FMG), the impact positioning calculator (IPC), the inverse model operator (IMO) and structural state estimator (SSE). With regard to the verification of the practicality of the proposed IVI technique, various structure configurations are considered, which are a normal CFRP panel and another CFRP panel with “orange peel” surfaces and a cutout hole. Additionally, since robustness against several background disturbances is also an essential criterion for practical engineering demands, investigations and experimental tests are carried out under random vibration interfering noise (RVIN) conditions. The accuracy of the predictions for unknown impact events on composite structures using the IVI technique is validated under various structure configurations and under changing environmental conditions. The evaluated errors all fall well within a satisfactory limit range. Furthermore, it is concluded that the IVI technique is applicable for impact monitoring, diagnosis and assessment of aerospace composite structures in complex practical engineering environments. PMID:26184196

  4. Aluminum-Alloy-Matrix/Alumina-Reinforcement Composites

    NASA Technical Reports Server (NTRS)

    Kashalikar, Uday; Rozenoyer, Boris

    2004-01-01

    Isotropic composites of aluminum-alloy matrices reinforced with particulate alumina have been developed as lightweight, high-specific-strength, less-expensive alternatives to nickel-base and ferrous superalloys. These composites feature a specific gravity of about 3.45 grams per cubic centimeter and specific strengths of about 200 MPa/(grams per cubic centimeter). The room-temperature tensile strength is 100 ksi (689 MPa) and stiffness is 30 Msi (206 GPa). At 500 F (260 C), these composites have shown 80 percent retention in strength and 95 percent retention in stiffness. These materials also have excellent fatigue tolerance and tribological properties. They can be fabricated in net (or nearly net) sizes and shapes to make housings, pistons, valves, and ducts in turbomachinery, and to make structural components of such diverse systems as diesel engines, automotive brake systems, and power-generation, mining, and oil-drilling equipment. Separately, incorporation of these metal matrix composites within aluminum gravity castings for localized reinforcement has been demonstrated. A composite part of this type can be fabricated in a pressure infiltration casting process. The process begins with the placement of a mold with alumina particulate preform of net or nearly net size and shape in a crucible in a vacuum furnace. A charge of the alloy is placed in the crucible with the preform. The interior of the furnace is evacuated, then the furnace heaters are turned on to heat the alloy above its liquidus temperature. Next, the interior of the furnace is filled with argon gas at a pressure about 900 psi (approximately equal to 6.2 MPa) to force the molten alloy to infiltrate the preform. Once infiltrated, the entire contents of the crucible can be allowed to cool in place, and the composite part recovered from the mold.

  5. Development and Processing Improvement of Aerospace Aluminum Alloys-Development of AL-Cu-Mg-Ag Alloy (2139)

    NASA Technical Reports Server (NTRS)

    Cho, Alex; Lisagor, W. Barry; Bales, Thomas T.

    2007-01-01

    This final report supplement in presentation format describes a comprehensive multi-tasked contract study to continue the development of the silver bearing alloy now registered as aluminum alloy 2139 by the Aluminum Association. Two commercial scale ingots were processed into nominal plate gauges of two, four and six inches, and were extensively characterized in terms of metallurgical and crystallographic structure, and resulting mechanical properties. This report includes comparisons of the property combinations for this alloy and 2XXX and 7XXX alloys more widely used in high performance applications. Alloy 2139 shows dramatic improvement in all combinations of properties, moreover, the properties of this alloy are retained in all gauge thicknesses, contrary to typical reductions observed in thicker gauges of the other alloys in the comparison. The advancements achieved in this study are expected to result in rapid, widespread use of this alloy in a broad range of ground based, aircraft, and spacecraft applications.

  6. Corrosion characteristics of nickel alloys. Citations from the International Aerospace Abstracts data base

    NASA Technical Reports Server (NTRS)

    Zollars, G. F.

    1979-01-01

    This bibliography cites 118 articles from the international literature concerning corrosion characteristics of nickel alloys. Articles dealing with corrosion resistance, corrosion tests, intergranular corrosion, oxidation resistance, and stress corrosion cracking of nickel alloys are included.

  7. Manufacturing Challenges Associated with the Use of Metal Matrix Composites in Aerospace Structures

    NASA Technical Reports Server (NTRS)

    Prater, Tracie

    2014-01-01

    Metal Matrix Composites (MMCs) consist of a metal alloy reinforced with ceramic particles or fibers. These materials possess a very high strength to weight ratio, good resistance to impact and wear, and a number of other properties which make them attractive for use in aerospace and defense applications. MMCs have found use in the space shuttle orbiter's structural tubing, the Hubble Space Telescope's antenna mast, control surfaces and propulsion systems for aircraft, and tank armors. The size of MMC components is severely limited by difficulties encountered in joining these materials using fusion welding. Melting of the material results in formation of an undesirable phase (formed when molten Aluminum reacts with the reinforcement) which leaves a strength depleted region along the joint line. Friction Stir Welding (FSW) is a relatively nascent solid state joining technique developed at The Welding Institute (TWI) in 1991. The process was first used at NASA to weld the super lightweight external tank for the Space Shuttle. Today FSW is used to join structural components of the Delta IV, Atlas V, and Falcon IX rockets as well as NASA's Orion Crew Exploration Vehicle and Space Launch System. A current focus of FSW research is to extend the process to new materials, such as MMCs, which are difficult to weld using conventional fusion techniques. Since Friction Stir Welding occurs below the melting point of the workpiece material, this deleterious phase is absent in FSW-ed MMC joints. FSW of MMCs is, however, plagued by rapid wear of the welding tool, a consequence of the large discrepancy in hardness between the steel tool and the reinforcement material. This chapter summarizes the challenges encountered when joining MMCs to themselves or to other materials in structures. Specific attention is paid to the influence of process variables in Friction Stir Welding on the wear process characterizes the effect of process parameters (spindle speed, traverse rate, and length

  8. Quality control and health monitoring of aerospace composites via quadrupole resonance

    NASA Astrophysics Data System (ADS)

    Ward, Catherine; Vierkoetter, Stephanie A.

    2005-05-01

    Techniques for quality control and health monitoring of aerospace composite structures must be reliable, nonintrusive and preferably, non-contacting. Quadrupole resonance (QR) spectroscopy can fill this need. Previously, we have demonstrated that Quadrupole Resonance can be used for nondestructive inspection of polymeric fiber-reinforced composites, which can be exploited for both in-service inspection and on-going structural health monitoring.1-6 In this paper we present an extension of this work, applying the QR method to the quality control of composite parts manufactured via pultrusion. In order to use the QR method for quality control of composite parts they must contain a small amount of tiny crystals of a QR active compound. These crystals are embedded in the part during the manufacture by blending it into the uncured resin. The QR active crystals sense any residual strains that may form inside the part during the manufacturing process. The crystals are interrogated via a single-side coil detector head, which transmits radio frequency (RF) pulses into the composite part. The strain-dependent QR response from the crystals is picked up by the same detector head. The results presented in this paper demonstrate that the QR method is very successful at distinguishing composites parts manufactured under optimal conditions from those that were manufactured with a misaligned die or at reduced temperatures. Both QR frequency and line widths were used as a distinguishing parameter.

  9. Shape memory polymers and their composites in aerospace applications: a review

    NASA Astrophysics Data System (ADS)

    Liu, Yanju; Du, Haiyang; Liu, Liwu; Leng, Jinsong

    2014-02-01

    As a new class of smart materials, shape memory polymers and their composites (SMPs and SMPCs) can respond to specific external stimulus and remember the original shape. There are many types of stimulus methods to actuate the deformation of SMPs and SMPCs, of which the thermal- and electro-responsive components and structures are common. In this review, the general mechanism of SMPs and SMPCs are first introduced, the stimulus methods are then discussed to demonstrate the shape recovery effect, and finally, the applications of SMPs and SMPCs that are reinforced with fiber materials in aerospace are reviewed. SMPC hinges and booms are discussed in the part on components; the booms can be divided again into foldable SMPC truss booms, coilable SMPC truss booms and storable tubular extendible member (STEM) booms. In terms of SMPC structures, the solar array and deployable panel, reflector antenna and morphing wing are introduced in detail. Considering the factors of weight, recovery force and shock effect, SMPCs are expected to have great potential applications in aerospace.

  10. A Digital Methodology for the Design Process of Aerospace Assemblies with Sustainable Composite Processes & Manufacture

    NASA Astrophysics Data System (ADS)

    McEwan, W.; Butterfield, J.

    2011-05-01

    The well established benefits of composite materials are driving a significant shift in design and manufacture strategies for original equipment manufacturers (OEMs). Thermoplastic composites have advantages over the traditional thermosetting materials with regards to sustainability and environmental impact, features which are becoming increasingly pertinent in the aerospace arena. However, when sustainability and environmental impact are considered as design drivers, integrated methods for part design and product development must be developed so that any benefits of sustainable composite material systems can be assessed during the design process. These methods must include mechanisms to account for process induced part variation and techniques related to re-forming, recycling and decommissioning, which are in their infancy. It is proposed in this paper that predictive techniques related to material specification, part processing and product cost of thermoplastic composite components, be integrated within a Through Life Management (TLM) product development methodology as part of a larger strategy of product system modeling to improve disciplinary concurrency, realistic part performance, and to place sustainability at the heart of the design process. This paper reports the enhancement of digital manufacturing tools as a means of drawing simulated part manufacturing scenarios, real time costing mechanisms, and broader lifecycle performance data capture into the design cycle. The work demonstrates predictive processes for sustainable composite product manufacture and how a Product-Process-Resource (PPR) structure can be customised and enhanced to include design intent driven by `Real' part geometry and consequent assembly. your paper.

  11. Application of thermal life prediction model to high-temperature aerospace alloys B1900+Hf and Haynes 188

    NASA Technical Reports Server (NTRS)

    Halford, Gary R.; Saltsman, James F.; Verrilli, Michael J.; Arya, Vinod K.

    1990-01-01

    The results of the application of a newly proposed thermomechanical fatigue (TMF) life prediction method to a series of laboratory TMF results on two high-temperature aerospace engine alloys are presented. The method, referred to as TMF/TS-SRP, is based on three relatively recent developments: the total strain version of the method of Strainrange Partitioning (TS-SRP), the bithermal testing technique for characterizing TMF behavior, and advanced viscoplastic constitutive models. The high-temperature data reported in a companion publication are used to evaluate the constants in the model and to provide the TMF verification data to check its accuracy. Predicted lives are in agreement with the experimental lives to within a factor of approximately 2.

  12. Dynamic fiber Bragg gratings based health monitoring system of composite aerospace structures

    NASA Astrophysics Data System (ADS)

    Panopoulou, A.; Loutas, T.; Roulias, D.; Fransen, S.; Kostopoulos, V.

    2011-09-01

    The main purpose of the current work is to develop a new system for structural health monitoring of composite aerospace structures based on real-time dynamic measurements, in order to identify the structural state condition. Long-gauge Fibre Bragg Grating (FBG) optical sensors were used for monitoring the dynamic response of the composite structure. The algorithm that was developed for structural damage detection utilizes the collected dynamic response data, analyzes them in various ways and through an artificial neural network identifies the damage state and its location. Damage was simulated by slightly varying locally the mass of the structure (by adding a known mass) at different zones of the structure. Lumped masses in different locations upon the structure alter the eigen-frequencies in a way similar to actual damage. The structural dynamic behaviour has been numerically simulated and experimentally verified by means of modal testing on two different composite aerospace structures. Advanced digital signal processing techniques, e.g. the wavelet transform (WT), were used for the analysis of the dynamic response for feature extraction. WT's capability of separating the different frequency components in the time domain without loosing frequency information makes it a versatile tool for demanding signal processing applications. The use of WT is also suggested by the no-stationary nature of dynamic response signals and the opportunity of evaluating the temporal evolution of their frequency contents. Feature extraction is the first step of the procedure. The extracted features are effective indices of damage size and location. The classification step comprises of a feed-forward back propagation network, whose output determines the simulated damage location. Finally, dedicated training and validation activities were carried out by means of numerical simulations and experimental procedures. Experimental validation was performed initially on a flat stiffened panel

  13. Guided waves in anisotropic and quasi-isotropic aerospace composites: three-dimensional simulation and experiment.

    PubMed

    Leckey, Cara A C; Rogge, Matthew D; Raymond Parker, F

    2014-01-01

    Three-dimensional (3D) elastic wave simulations can be used to investigate and optimize nondestructive evaluation (NDE) and structural health monitoring (SHM) ultrasonic damage detection techniques for aerospace materials. 3D anisotropic elastodynamic finite integration technique (EFIT) has been implemented for ultrasonic waves in carbon fiber reinforced polymer (CFRP) composite laminates. This paper describes 3D EFIT simulations of guided wave propagation in undamaged and damaged anisotropic and quasi-isotropic composite plates. Comparisons are made between simulations of guided waves in undamaged anisotropic composite plates and both experimental laser Doppler vibrometer (LDV) wavefield data and dispersion curves. Time domain and wavenumber domain comparisons are described. Wave interaction with complex geometry delamination damage is then simulated to investigate how simulation tools incorporating realistic damage geometries can aid in the understanding of wave interaction with CFRP damage. In order to move beyond simplistic assumptions of damage geometry, volumetric delamination data acquired via X-ray microfocus computed tomography is directly incorporated into the simulation. Simulated guided wave interaction with the complex geometry delamination is compared to experimental LDV time domain data and 3D wave interaction with the volumetric damage is discussed. PMID:23769180

  14. The Effects of Chemical Wash Additives on the Corrosion of Aerospace Alloys in Marine Environments

    NASA Technical Reports Server (NTRS)

    MacDowell, Louis; Calle, Luz Marina; Curran, Joseph; Hodge, Tim; Barile, Ronald; Heidersbach, Robert; Steinrock, T. (Technical Monitor)

    2002-01-01

    This paper presents the methodology for comparing the relative effectiveness of four chemical products used for rinsing airplanes and helicopters. The products were applied on a weekly basis to a series of flat alloy panels exposed to an oceanfront marine environment for one year. The results are presented along with comparisons of exposures of the same alloys that were not washed, were washed with seawater, or washed with de-ionized water.

  15. Viscoelastic damping in crystalline composites and alloys

    NASA Astrophysics Data System (ADS)

    Ranganathan, Raghavan; Ozisik, Rahmi; Keblinski, Pawel

    We use molecular dynamics simulations to study viscoelastic behavior of model Lennard-Jones (LJ) crystalline composites subject to an oscillatory shear deformation. The two crystals, namely a soft and a stiff phase, individually show highly elastic behavior and a very small loss modulus. On the other hand, when the stiff phase is included within the soft matrix as a sphere, the composite exhibits significant viscoelastic damping and a large phase shift between stress and strain. In fact, the maximum loss modulus in these model composites was found to be about 20 times greater than that given by the theoretical Hashin-Shtrikman upper bound. We attribute this behavior to the fact that in composites shear strain is highly inhomogeneous and mostly accommodated by the soft phase, corroborated by frequency-dependent Grüneisen parameter analysis. Interestingly, the frequency at which the damping is greatest scales with the microstructural length scale of the composite. Finally, a critical comparison between damping properties of these composites with ordered and disordered alloys and superlattice structures is made.

  16. The relative stress-corrosion-cracking susceptibility of candidate aluminum-lithium alloys for aerospace applications

    NASA Technical Reports Server (NTRS)

    Pizzo, P. P.

    1982-01-01

    Stress corrosion tests of Al-Li-Cu powder metallurgy alloys are described. Alloys investigated were Al-2.6% Li-1.4% and Al-2.6% Li-1.4% Cu-1.6% Mg. The base properties of the alloys were characterized. Process, heat treatment, and size/orientational effects on the tensile and fracture behavior were investigated. Metallurgical and electrochemical conditions are identified which provide reproducible and controlled parameters for stress corrosion evaluation. Preliminary stress corrosion test results are reported. Both Al-Li-Cu alloys appear more susceptible to stress corrosion crack initiation than 7075-T6 aluminum, with the magnesium bearing alloy being the most susceptible. Tests to determine the threshold stress intensity for the base and magnesium bearing alloys are underway. Twelve each, bolt loaded DCB type specimens are under test (120 days) and limited crack growth in these precracked specimens has been observed. General corrosion in the aqueous sodium chloride environment is thought to be obscuring results through crack tip blunting.

  17. Resilient and Corrosion-Proof Rolling Element Bearings Made from Superelastic Ni-Ti Alloys for Aerospace Mechanism Applications

    NASA Technical Reports Server (NTRS)

    DellaCorte, Christopher; Noebe, Ronald D.; Stanford, Malcolm; Padula, Santo A.

    2011-01-01

    Mechanical components (bearings, gears, mechanisms) typically utilize hard materials to minimize wear and attain long life. In such components, heavily loaded contact points (e.g., meshing gear teeth, bearing ball-raceway contacts) experience high contact stresses. The combination of high hardness, heavy loads and high elastic modulus often leads to damaging contact stress. In addition, mechanical component materials, such as tool steel or silicon nitride exhibit limited recoverable strain (typically less than 1 percent). These material attributes can lead to Brinell damage (e.g., denting) particularly during transient overload events such as shock impacts that occur during the launching of space vehicles or the landing of aircraft. In this paper, a superelastic alloy, 60NiTi, is considered for rolling element bearing applications. A series of Rockwell and Brinell hardness, compressive strength, fatigue and tribology tests are conducted and reported. The combination of high hardness, moderate elastic modulus, large recoverable strain, low density, and intrinsic corrosion immunity provide a path to bearings largely impervious to shock load damage. It is anticipated that bearings and components made from alloys with such attributes can alleviate many problems encountered in advanced aerospace applications.

  18. Real-Time Radiographic In-Situ Characterization Of Ply Lift In Composite Aerospace Materials

    NASA Technical Reports Server (NTRS)

    Beshears, Ronald D.; Doering, Edward R.

    2006-01-01

    The problem of ply lifting in composite materials is a significant issue for various aerospace and military applications. A fundamental element in the prevention or mitigation of ply lift is determination of the timing of the ply lifting event during exposure of the composite material to flight conditions. The Marshall Space Flight Center s Nondestructive Evaluation Team developed a real-time radiographic technique for the detection of ply lift in carbon phenolic ablative materials in situ during live firings of subscale test motors in support of NASA s Reusable Solid Rocket Motor program, using amorphous silicon detector panels. The radiographic method has successfully detected ply lifting in seven consecutive carbon phenolic converging cones attached to solid fuel torches, providing the time of ply lift initiation in each test. Post-processing of the radiographic images improved the accuracy of timing measurements and allowed measurement of the ply lifting height as a function of time. Radiographic data correlated well with independent pressure and temperature measurements that indicate the onset of ply lift in the nozzle material.

  19. Thermal Performance of Composite Flexible Blanket Insulations for Hypersonic Aerospace Vehicles

    NASA Technical Reports Server (NTRS)

    Kourtides, Demetrius A.

    1993-01-01

    This paper describes the thermal performance of a Composite Flexible Blanket Insulation (C.F.B.I.) considered for potential use as a thermal protection system or thermal insulation for future hypersonic vehicles such as the National Aerospace Plane (N.A.S.P.). Thermophysical properties for these insulations were also measured including the thermal conductivity at various temperatures and pressures and the emissivity of the fabrics used in the flexible insulations. The thermal response of these materials subjected to aeroconvective heating from a plasma arc is also described. Materials tested included two surface variations of the insulations, and similar insulations coated with a Protective Ceramic Coating (P.C.C.). Surface and backface temperatures were measured in the flexible insulations and on Fibrous Refractory Composite Insulation (F.R.C.I.) used as a calibration model. The uncoated flexible insulations exhibited good thermal performance up to 35 W/sq cm. The use of a P.C.C. to protect these insulations at higher heating rates is described. The results from a computerized thermal analysis model describing thermal response of those materials subjected to the plasma arc conditions are included. Thermal and optical properties were determined including thermal conductivity for the rigid and flexible insulations and emissivity for the insulation fabrics. These properties were utilized to calculate the thermal performance of the rigid and flexible insulations at the maximum heating rate.

  20. Advances in SiC/SiC Composites for Aerospace Applications

    NASA Technical Reports Server (NTRS)

    DiCarlo, James A.

    2006-01-01

    In recent years, supported by a variety of materials development programs, NASA Glenn Research Center has significantly increased the thermostructural capability of SiC/SiC composite materials for high-temperature aerospace applications. These state-of-the-art advances have occurred in every key constituent of the composite: fiber, fiber coating, matrix, and environmental barrier coating, as well as processes for forming the fiber architectures needed for complex-shaped components such as turbine vanes for gas turbine engines. This presentation will briefly elaborate on the nature of these advances in terms of performance data and underlying mechanisms. Based on a list of first-order property goals for typical high-temperature applications, key data from a variety of laboratory tests are presented which demonstrate that the NASA-developed constituent materials and processes do indeed result in SiC/SiC systems with the desired thermal and structural capabilities. Remaining process and microstructural issues for further property enhancement are discussed, as well as on-going approaches at NASA to solve these issues. NASA efforts to develop physics-based property models that can be used not only for component design and life modeling, but also for constituent material and process improvement will also be discussed.

  1. Fiber Bragg Grating Sensor System for Monitoring Smart Composite Aerospace Structures

    NASA Technical Reports Server (NTRS)

    Moslehi, Behzad; Black, Richard J.; Gowayed, Yasser

    2012-01-01

    Lightweight, electromagnetic interference (EMI) immune, fiber-optic, sensor- based structural health monitoring (SHM) will play an increasing role in aerospace structures ranging from aircraft wings to jet engine vanes. Fiber Bragg Grating (FBG) sensors for SHM include advanced signal processing, system and damage identification, and location and quantification algorithms. Potentially, the solution could be developed into an autonomous onboard system to inspect and perform non-destructive evaluation and SHM. A novel method has been developed to massively multiplex FBG sensors, supported by a parallel processing interrogator, which enables high sampling rates combined with highly distributed sensing (up to 96 sensors per system). The interrogation system comprises several subsystems. A broadband optical source subsystem (BOSS) and routing and interface module (RIM) send light from the interrogation system to a composite embedded FBG sensor matrix, which returns measurand-dependent wavelengths back to the interrogation system for measurement with subpicometer resolution. In particular, the returned wavelengths are channeled by the RIM to a photonic signal processing subsystem based on powerful optical chips, then passed through an optoelectronic interface to an analog post-detection electronics subsystem, digital post-detection electronics subsystem, and finally via a data interface to a computer. A range of composite structures has been fabricated with FBGs embedded. Stress tensile, bending, and dynamic strain tests were performed. The experimental work proved that the FBG sensors have a good level of accuracy in measuring the static response of the tested composite coupons (down to submicrostrain levels), the capability to detect and monitor dynamic loads, and the ability to detect defects in composites by a variety of methods including monitoring the decay time under different dynamic loading conditions. In addition to quasi-static and dynamic load monitoring, the

  2. New vistas in the determination of hydrogen in aerospace engine metal alloys

    NASA Technical Reports Server (NTRS)

    Danford, M. D.

    1986-01-01

    The application of diffusion theory to the analysis of hydrogen desorption data has been studied. From these analyses, important information concerning hydrogen solubilities and the nature of the hydrogen distributions in the metal has been obtained. Two nickel base alloys, Rene' 41 and Waspaloy, and one ferrous alloy, 4340 steel, were studied in this work. For the nickel base alloys, it was found that the hydrogen distributions after electrolytic charging conformed closely to those which would be predicted by diffusion theory. The hydrogen distributions in electrolytically charged 4340 steel, on the other hand, were essentially uniform in nature, which would not be predicted by diffusion theory. Finally, it has been found that the hydrogen desorption is completely explained by the nature of the hydrogen distribution in the metal, and that the 'fast' hydrogen is not due to surface and subsurface hydride formation, as was originally proposed.

  3. Fatigue-crack propagation in advanced aerospace materials: Aluminum-lithium alloys

    SciTech Connect

    Venkateswara Rao, K.T.; Ritchie, R.O.

    1988-10-01

    Characteristics of fatigue-crack propagation behavior are reviewed for recently developed commercial aluminum-lithium alloys, with emphasis on the underlying micromechanisms associated with crack advance and their implications to damage-tolerant design. Specifically, crack-growth kinetics in Alcoa 2090-T8E41, Alcan 8090 and 8091, and Pechiney 2091 alloys, and in certain powder-metallurgy alloys, are examined as a function of microstructure, plate orientation, temperature, crack size, load ratio and loading sequence. In general, it is found that growth rates for long (> 10 mm) cracks are nearly 2--3 orders of magnitude slower than in traditional 2000 and 7000 series alloys at comparable stress-intensity levels. In additions, Al-Li alloys shown enhanced crack-growth retardations following the application of tensile overloads and retain superior fatigue properties even after prolonged exposure at overaging temperatures; however, they are less impressive in the presence of compression overloads and further show accelerated crack-growth behavior for microstructurally-small (2--1000 {mu}m) cracks (some three orders of magnitude faster than long cracks). These contrasting observations are attributed to a very prominent role of crack-tip shielding during fatigue-crack growth in Al-Li alloys, promoted largely by the tortuous and zig-zag nature of the crack-path morphologies. Such crack paths result in locally reduced crack-tip stress intensities, due to crack deflection and consequent crack wedging from fracture-surface asperities (roughness-induced crack closure); however, such mechanisms are far less potent in the presence of compressive loads, which act to crush the asperities, and for small cracks, where the limited crack wake severely restricts the shielding effect. 50 refs., 21 figs.

  4. Microstructural and Mechanical Property Characterization of Shear Formed Aerospace Aluminum Alloys

    NASA Technical Reports Server (NTRS)

    Troeger, Lillianne P.; Domack, Marcia S.; Wagner, John A.

    2000-01-01

    Advanced manufacturing processes such as near-net-shape forming can reduce production costs and increase the reliability of launch vehicle and airframe structural components through the reduction of material scrap and part count and the minimization of joints. The current research is an investigation of the processing-microstructure-property relationships for shear formed cylinders of the Al-Cu-Li-Mg-Ag alloy 2195 for space applications and the Al-Cu-Mg-Ag alloy C415 for airframe applications. Cylinders which had undergone various amounts of shear-forming strain were studied to correlate the grain structure, texture, and mechanical properties developed during and after shear forming.

  5. The effect of alloy composition on the mechanism of stress corrosion cracking of titanium alloys in aqueous environments

    NASA Technical Reports Server (NTRS)

    Boyd, J. D.; Williams, D. N.; Wood, R. A.; Jaffee, R. I.

    1972-01-01

    The effects of alloy composition on the aqueous stress corrosion of titanium alloys were studied with emphasis on determining the interrelations among composition, phase structure, and deformation and fracture properties of the alpha phase in alpha-beta alloys. Accomplishments summarized include the effects of alloy composition on susceptibility, and metallurgical mechanisms of stress-corrosion cracking.

  6. Validating finite element models of composite aerospace structures for damage detection applications

    NASA Astrophysics Data System (ADS)

    Oliver, J. A.; Kosmatka, J. B.; Hemez, François M.; Farrar, Charles R.

    2006-03-01

    Carbon-fiber-reinforced-polymer (CFRP) composites represent the future for advanced lightweight aerospace structures. However, reliable and cost-effective techniques for structural health monitoring (SHM) are needed. Modal and vibration-based analysis, when combined with validated finite element (FE) models, can provide a key tool for SHM. Finite element models, however, can easily give spurious and misleading results if not finely tuned and validated. These problems are amplified in complex structures with numerous joints and interfaces. A small series of all-composite test pieces emulating wings from a lightweight all-composite Unmanned Aerial Vehicle (UAV) have been developed to support damage detection and SHM research. Each wing comprises two CFRP prepreg and Nomex honeycomb co-cured skins and two CFRP prepreg spars bonded together in a secondary process using a structural adhesive to form the complete wings. The first of the set is fully healthy while the rest have damage in the form of disbonds built into the main spar-skin bondline. Detailed FE models were created of the four structural components and the assembled structure. Each wing component piece was subjected to modal characterization via vibration testing using a shaker and scanning laser Doppler vibrometer before assembly. These results were then used to correlate the FE model on a component-basis, through fitting and optimization of polynomial meta-models. Assembling and testing the full wing provided subsequent data that was used to validate the numerical model of the entire structure, assembled from the correlated component models. The correlation process led to the following average percent improvement between experimental and FE frequencies of the first 20 modes for each piece: top skin 10.98%, bottom skin 45.62%, main spar 25.56%, aft spar 10.79%. The assembled wing model with no further correlation showed an improvement of 32.60%.

  7. NASA-UVA Light Aerospace Alloy and Structure Technology Program Supplement: Aluminum-Based Materials for High Speed Aircraft

    NASA Technical Reports Server (NTRS)

    Starke, E. A., Jr.

    1997-01-01

    This is the final report of the study "Aluminum-Based Materials for High Speed Aircraft" which had the objectives (1) to identify the most promising aluminum-based materials with respect to major structural use on the HSCT and to further develop those materials and (2) to assess the materials through detailed trade and evaluation studies with respect to their structural efficiency on the HSCT. The research team consisted of ALCOA, Allied-Signal, Boeing, McDonnell Douglas, Reynolds Metals and the University of Virginia. Four classes of aluminum alloys were investigated: (1) I/M 2XXX containing Li and I/M 2XXX without Li, (2) I/M 6XXX, (3) two P/M 2XXX alloys, and (4) two different aluminum-based metal matrix composites (MMC). The I/M alloys were targeted for a Mach 2.0 aircraft and the P/M and MMC alloys were targeted for a Mach 2.4 aircraft. Design studies were conducted using several different concepts including skin/stiffener (baseline), honeycomb sandwich, integrally stiffened and hybrid adaptations (conventionally stiffened thin-sandwich skins). Alloy development included fundamental studies of coarsening behavior, the effect of stress on nucleation and growth of precipitates, and fracture toughness as a function of temperature were an integral part of this program. The details of all phases of the research are described in this final report.

  8. Stress analysis of shape memory alloy composites

    NASA Astrophysics Data System (ADS)

    Wang, Yulong; Zhou, Limin; Wang, Zhenqing; Huang, Haitao; Ye, Lin

    2009-07-01

    Shape memory alloys (SMAs), when in the form of wires or short fibers, can be embedded into a host material to form SMA-composite for satisfying a wide variety of engineering requirements. Due to the weak interface strength between the SMA wire and the matrix, the interface debonding often happens when the SMA composites act by external force or actuation temperature or combination of them. It is, therefore, very important to understand the stress transfers between the SMA fibers and matrix and the distributions of internal stresses in the SMA composite in order to improve its properties. In this paper, a theoretical model incorporated with Brinson's constitutive law of SMA for the prediction of internal stresses has been successfully developed. The assumed stress functions which satisfy equilibrium equations in the fiber and matrix respectively and the principle of minimum complementary energy are utilized to analyze the internal stress distributions during fiber pull-out and/or thermal loading processes. The complete axisymmetric states of stresses in the SMA fiber and matrix have been developed. A finite element analysis has been also conducted to compare with the theoretical results.

  9. AFM study of the effects of laser surface remelting on the morphology of Al-Fe aerospace alloys

    SciTech Connect

    Pariona, Moises Meza; Teleginski, Viviane; Santos, Kelly dos; Leandro Ribeiro dos Santos, Everton; Aparecida de Oliveira Camargo de Lima, Angela; Riva, Rudimar

    2012-12-15

    Laser beam welding has recently been incorporated into the fabrication process of aircraft and automobile structures. Surface roughness is an important parameter of product quality that strongly affects the performance of mechanical parts, as well as production costs. This parameter influences the mechanical properties such as fatigue behavior, corrosion resistance, creep life, etc., and other functional characteristics such as friction, wear, light reflection, heat transmission, lubrification, electrical conductivity, etc. The effects of laser surface remelting (LSR) on the morphology of Al-Fe aerospace alloys were examined before and after surface treatments, using optical microscopy (OM), scanning electron microscopy (SEM), low-angle X-ray diffraction (LA-XRD), atomic force microscopy (AFM), microhardness measurements (Vickers hardness), and cyclic voltammetry. This analysis was performed on both laser-treated and untreated sanded surfaces, revealing significant differences. The LA-XRD analysis revealed the presence of alumina, simple metals and metastable intermetallic phases, which considerably improved the microhardness of laser-remelted surfaces. The morphology produced by laser surface remelting enhanced the microstructure of the Al-Fe alloys by reducing their roughness and increasing their hardness. The treated surfaces showed passivity and stability characteristics in the electrolytic medium employed in this study. - Highlights: Black-Right-Pointing-Pointer The samples laser-treated and untreated showed significant differences. Black-Right-Pointing-Pointer The La-XRD revealed the presence of alumina in Al-1.5 wt.% Fe. Black-Right-Pointing-Pointer The laser-treated reducing the roughness and increasing the hardness. Black-Right-Pointing-Pointer The laser-treated surfaces showed characteristic passive in the electrolytic medium. Black-Right-Pointing-Pointer The laser-treated is a promising technique for applications technological.

  10. Novel Diels-Alder based self-healing epoxies for aerospace composites

    NASA Astrophysics Data System (ADS)

    Coope, T. S.; Turkenburg, D. H.; Fischer, H. R.; Luterbacher, R.; van Bracht, H.; Bond, I. P.

    2016-08-01

    Epoxy resins containing Diels-Alder (DA) furan and maleimide moieties are presented with the capability to self-heal after exposure to an external heat source. A conventional epoxy amine system has been combined with furfuryl and maleimide functional groups in a two-step process, to avoid major side-reactions, and the concentration of a thermo-reversibly binding cross-linker was considered to balance thermoset and thermoplastic behaviours, and the subsequent self-healing performance. In the context of self-repair technologies an inbuilt ‘intrinsic’ self-healing system is deemed favourable as the healing agent can be placed in known ‘hot spot’ regions (i.e. skin-stringer run outs, ply drops and around drilled holes) where operational damage predominately occurs in load bearing aerospace structures. In this study, the mechanical and self-healing performance of furan functionalised epoxy resins containing varying amounts (10, 20, 30 or 40 pph) of bismaleimide were investigated using a bulk epoxy polymer tapered double cantilever beam test specimen geometry. Two forms, a thin film and a bulk material, were evaluated to account for future integration methods into fibre reinforced polymer (FRP) composites. The highest healing efficiency, with respect to the obtained initial load value, was observed from the 20 pph bulk material derivative. The polymers were successful in achieving consistent multiple (three) healing cycles when heated at 150 °C for 5 min. This novel investigated DA material exhibits favourable processing characteristics for FRP composites as preliminary studies have shown successful coextrution with reinforcing fibres to form free standing films and dry fibre impregnation.

  11. Mechanochromic Fluorescent Probe Molecules for Damage Detection in Aerospace Polymers and Composites

    NASA Astrophysics Data System (ADS)

    Toivola, Ryan E.

    The detection of damage in aerospace composites can be improved by incorporation of mechanochromic fluorescent probe molecules into the polymers used in composite parts. This study focuses on a novel series of mechanochromic probes, AJNDE15 and AJNDE17, which are incorporated in structural epoxy resin DGEBA-DETA. Chapter 1 details the characterization of the DGEBA-DETA epoxy system used in this study. The important characteristics of DGEBA-DETA's response to mechanical loading will be discussed within the larger field of glassy amorphous polymer deformation. The mechanical, thermal, and chemical properties of DGEBA-DETA relevant to this work will be measured using standardized techniques and instrumentation. Chapters 2 and 3 focus on the mechanochromic probes AJNDE15 and AJNDE17 in the DGEBA-DETA system. Chapter 2 presents research designed to identify the mechanism through which the probes display mechanochromism. The possible mechanochromic mechanisms are introduced in a literature review. Research on these probes in DGEBA-DETA will be presented and discussed with respect to the possible mechanisms, and the mechanism that best fits the results will be identified as a mechanochemical reaction. Chapter 3 continues the analysis of the mechanochromism of the probes in DGEBA-DETA. The kinetics of the mechanochromic reaction will be studied and compared with the current understanding of glassy polymer deformation. Possible models for the molecular interactions responsible for mechanochromism in this system will be put forward. Research will be presented to evaluate the mechanochromism kinetics and for comparison with the behavior predicted by the models.

  12. Effect of alloying on the phase composition of titanium carbonitride-titanium nickelide alloys

    NASA Astrophysics Data System (ADS)

    Askarova, L. Kh.; Grigorov, I. G.; Ermakov, A. N.; Zainulin, Yu. G.; Nikitina, E. V.

    2015-08-01

    X-ray diffraction, electron microprobe analysis, electron microscopy, and chemical analysis are used to study the effect of alloying with zirconium, niobium, vanadium, and molybdenum on the phase composition of titanium carbonitride-titanium nickel cermets. It is shown that two-phase alloys containing alloyed titanium carbonitride and titanium nickelide can only be produced by alloying with zirconium. The addition of niobium, molybdenum, and vanadium leads to the formation of a third phase, namely, Nb z Ni, Mo(Ti,C), or V4Ni, in the alloy. A correlation between the phase composition of the alloys and the ratio of the energies of formation of titanium carbides and the carbides of alloying elements is found.

  13. Fabrication of tungsten wire reinforced nickel-base alloy composites

    NASA Technical Reports Server (NTRS)

    Brentnall, W. D.; Toth, I. J.

    1974-01-01

    Fabrication methods for tungsten fiber reinforced nickel-base superalloy composites were investigated. Three matrix alloys in pre-alloyed powder or rolled sheet form were evaluated in terms of fabricability into composite monotape and multi-ply forms. The utility of monotapes for fabricating more complex shapes was demonstrated. Preliminary 1093C (2000F) stress rupture tests indicated that efficient utilization of fiber strength was achieved in composites fabricated by diffusion bonding processes. The fabrication of thermal fatigue specimens is also described.

  14. Al-TiH2 Composite Foams Magnesium Alloy

    NASA Astrophysics Data System (ADS)

    Prasada Rao, A. K.; Oh, Y. S.; Ain, W. Q.; A, Azhari; Basri, S. N.; Kim, N. J.

    2016-02-01

    The work presented here in describes the synthesis of aluminum based titanium-hydride particulate composite by casting method and its foaming behavior of magnesium alloy. Results obtained indicate that the Al-10TiH2 composite can be synthesized successfully by casting method. Further, results also reveal that closed-cell magnesium alloy foam can be synthesized by using Al-10TiH2 composite as a foaming agent.

  15. System integration and demonstration of adhesive bonded high temperature aluminum alloys for aerospace structure, phase 2

    NASA Technical Reports Server (NTRS)

    Falcone, Anthony; Laakso, John H.

    1993-01-01

    Adhesive bonding materials and processes were evaluated for assembly of future high-temperature aluminum alloy structural components such as may be used in high-speed civil transport aircraft and space launch vehicles. A number of candidate high-temperature adhesives were selected and screening tests were conducted using single lap shear specimens. The selected adhesives were then used to bond sandwich (titanium core) test specimens, adhesive toughness test specimens, and isothermally aged lap shear specimens. Moderate-to-high lap shear strengths were obtained from bonded high-temperature aluminum and silicon carbide particulate-reinforced (SiC(sub p)) aluminum specimens. Shear strengths typically exceeded 3500 to 4000 lb/in(sup 2) and flatwise tensile strengths exceeded 750 lb/in(sup 2) even at elevated temperatures (300 F) using a bismaleimide adhesive. All faceskin-to-core bonds displayed excellent tear strength. The existing production phosphoric acid anodize surface preparation process developed at Boeing was used, and gave good performance with all of the aluminum and silicon carbide particulate-reinforced aluminum alloys investigated. The results of this program support using bonded assemblies of high-temperature aluminum components in applications where bonding is often used (e.g., secondary structures and tear stoppers).

  16. The effect of alloy composition on radiation-induced segregation in FeCrNi alloys

    NASA Astrophysics Data System (ADS)

    Allen, T. R.; Was, G. S.; Kenik, E. A.

    1997-04-01

    The effect of alloy composition on radiation-induced segregation (RIS) was investigated in austenitic iron-base and nickel-base alloys using proton irradiation. Specifically, RIS was studied by irradiation of Ni18Cr, Ni18Cr9Fe, and Fe20Cr9Ni over a dose range of 0 to 1.0 dpa and a temperature range of 200 to 500°C. Grain boundary composition was measured using Auger electron spectroscopy and scanning transmission electron microscopy with energy dispersive X-ray spectroscopy. Measurements from this study along with measurements from Fe16Cr24Ni, Fe20Cr24Ni, Fe24Cr24Ni, and Fe24Cr19Ni alloys irradiated with protons confirm that RIS is strongly dependent on the alloy composition. Trends in segregation behavior in Fe-base alloys are consistent with high temperature diffusion measurements, indicating that a vacancy mechanism is the most likely primary driving force for RIS in austenitic steels. The migration energy for Cr is shown to be larger than the migration energy of Fe. Segregation measurements in Ni-base alloys are not consistent with high temperature diffusion measurements, indicating that ordering forces may be significant in the segregation process. Comparison of model calculations to measured RIS data indicate that Fe, Cr, and Ni diffusivities are composition dependent. This dependence on alloy composition limits the predictive ability of simple models because of the need for separate diffusion parameters for every alloy composition.

  17. Surface compositional variations of Mo-47Re alloy as a function of temperature

    NASA Technical Reports Server (NTRS)

    Hoekje, S. J.; Outlaw, R. A.; Sankaran, S. N.

    1993-01-01

    Molybdenum-rhenium alloys are candidate materials for the National Aero-Space Plane (NASP) as well as for other applications in generic hypersonics. These materials are expected to be subjected to high-temperature (above 1200 C) casual hydrogen (below 50 torr), which could potentially degrade the material strength. Since the uptake of hydrogen may be controlled by the contaminant surface barriers, a study of Mo-47Re was conducted to examine the variations in surface composition as a function of temperature from 25 C to 1000 C. Pure molybdenum and rhenium were also examined and the results compared with those for the alloy. The analytical techniques employed were Auger electron spectroscopy, electron energy loss spectroscopy, ion scattering spectroscopy, and x ray photoelectron spectroscopy. The native surface was rich in metallic oxides that disappeared at elevated temperatures. As the temperature increased, the carbon and oxygen disappeared by 800 C and the surface was subsequently populated by the segregation of silicon, presumably from the grain boundaries. The alloy readily chemisorbed oxygen, which disappeared with heating. The disappearance temperature progressively increased for successive dosings. When the alloy was exposed to 800 torr of hydrogen at 900 C for 1 hour, no hydrogen interaction was observed.

  18. A Unified Model for Predicting the Open Hole Tensile and Compressive Strengths of Composite Laminates for Aerospace Applications

    NASA Technical Reports Server (NTRS)

    Davidson, Paul; Pineda, Evan J.; Heinrich, Christian; Waas, Anthony M.

    2013-01-01

    The open hole tensile and compressive strengths are important design parameters in qualifying fiber reinforced laminates for a wide variety of structural applications in the aerospace industry. In this paper, we present a unified model that can be used for predicting both these strengths (tensile and compressive) using the same set of coupon level, material property data. As a prelude to the unified computational model that follows, simplified approaches, referred to as "zeroth order", "first order", etc. with increasing levels of fidelity are first presented. The results and methods presented are practical and validated against experimental data. They serve as an introductory step in establishing a virtual building block, bottom-up approach to designing future airframe structures with composite materials. The results are useful for aerospace design engineers, particularly those that deal with airframe design.

  19. Bisphenyl-Polymer/Carbon-Fiber-Reinforced Composite Compared to Titanium Alloy Bone Implant

    PubMed Central

    Petersen, Richard C.

    2014-01-01

    Aerospace/aeronautical thermoset bisphenyl-polymer/carbon-fiber-reinforced composites are considered as new advanced materials to replace metal bone implants. In addition to well-recognized nonpolar chemistry with related bisphenol-polymer estrogenic factors, carbon-fiber-reinforced composites can offer densities and electrical conductivity/resistivity properties close to bone with strengths much higher than metals on a per-weight basis. In vivo bone-marrow tests with Sprague-Dawley rats revealed far-reaching significant osseoconductivity increases from bisphenyl-polymer/carbon-fiber composites when compared to state-of-the-art titanium-6-4 alloy controls. Midtibial percent bone area measured from the implant surface increased when comparing the titanium alloy to the polymer composite from 10.5% to 41.6% at 0.8 mm, P < 10−4, and 19.3% to 77.7% at 0.1 mm, P < 10−8. Carbon-fiber fragments planned to occur in the test designs, instead of producing an inflammation, stimulated bone formation and increased bone integration to the implant. In addition, low-thermal polymer processing allows incorporation of minerals and pharmaceuticals for future major tissue-engineering potential. PMID:25553057

  20. Self-Repairing Fatigue Damage in Metallic Structures for Aerospace Vehicles Using Shape Memory Alloy Self-healing (SMASH) Technology

    NASA Technical Reports Server (NTRS)

    Wright, M. Clara; Manuel, Michele; Wallace, Terryl; Newman, Andy; Brinson, Kate

    2015-01-01

    This DAA is for the Phase II webinar presentation of the ARMD-funded SMASH technology. A self-repairing aluminum-based composite system has been developed using liquid-assisted healing theory in conjunction with the shape memory effect of wire reinforcements. The metal matrix composite was thermodynamically designed to have a matrix with a relatively even dispersion of low-melting phase, allowing for repair of cracks at a pre-determined temperature. Shape memory alloy wire reinforcements were used within the composite to provide crack closure. Investigators focused the research on fatigue cracks propagating through the matrix in order to optimize and computer model the SMASH technology for aeronautical applications.

  1. Processing and response of aluminum-lithium alloy composites reinforced with copper-coated silicon carbide particulates

    SciTech Connect

    Khor, K.A.; Cao, Y.; Boey, F.Y.C.; Hanada, K.; Murakoshi, Y.; Sudarshan, T.S.; Srivatsan, T.S.

    1998-02-01

    Lithium-containing aluminum alloys have shown promise for demanding aerospace applications because of their light weight, high strength, and good damage tolerance characteristics. Additions of ceramic reinforcements to an aluminum-lithium alloy can significantly enhance specific strength, and specific modulus while concurrently offering acceptable performance at elevated temperatures. The processing and fabrication of aluminum-lithium alloy-based composites are hampered by particulate agglomeration or clustering and the existence of poor interfacial relationships between the reinforcing phase and the matrix. The problem of distribution of the reinforcing phase in the metal matrix can be alleviated by mechanical alloying. This article presents the results of a study aimed at addressing and improving the interfacial relationship between the host matrix and the reinforcing phase. Copper-coated silicon carbide particulates are introduced as the particulate reinforcing phase, and the resultant composite mixture is processed by conventional milling followed by hot pressing and hot extrusion. The influence of extrusion ration and extrusion temperature on microstructure and mechanical properties was established. Post extrusion processing by hot isostatic pressing was also examined. Results reveal the increase in elastic modulus of the aluminum-lithium alloy matrix reinforced with copper-coated SiC to be significantly more than the mechanically alloyed Al-Li/SiC counterpart. This suggests the possible contributions of interfacial strengthening on mechanical response in direct comparison with a uniform distribution of the reinforcing ceramic particulates.

  2. Analysis and Evaluation of Novel Al-Mg-Sc-Zr Aerospace Alloy Strip Produced Using the Horizontal Single Belt Casting (HSBC) Process

    NASA Astrophysics Data System (ADS)

    Ge, Sa; Celikin, Mert; Isac, Mihaiela; Guthrie, Roderick I. L.

    2015-04-01

    Horizontal single belt casting (HSBC) is a near net shape casting process in which molten metal is directly cast into thin strips, at high cooling rates (order of several 100 °C/s), with the potential for high volume, friction free, continuous production of metal strips. This casting process was used in the present work to produce strips of Al-Mg alloys in the AA5000 series, with additions of Sc and Zr. Such aluminum alloys show exceptional potential as a structural material for transportation/aerospace applications. To demonstrate the suitability of the HSBC process to manufacture competitive strip products of Al-Mg-Sc-Zr, the mechanical properties and microstructures of the strips produced using the HSBC process were compared with conventionally cast products. The effects of annealing on the mechanical properties of the strip-cast Al-Mg-Sc-Zr alloys were also investigated.

  3. Oxidation resistant coating for titanium alloys and titanium alloy matrix composites

    NASA Technical Reports Server (NTRS)

    Brindley, William J. (Inventor); Smialek, James L. (Inventor); Rouge, Carl J. (Inventor)

    1992-01-01

    An oxidation resistant coating for titanium alloys and titanium alloy matrix composites comprises an MCrAlX material. M is a metal selected from nickel, cobalt, and iron. X is an active element selected from Y, Yb, Zr, and Hf.

  4. Aerospace Community. Aerospace Education I.

    ERIC Educational Resources Information Center

    Mickey, V. V.

    This book, one in the series on Aerospace Education I, emphasizes the two sides of aerospace--military aerospace and civilian aerospace. Chapter 1 includes a brief discussion on the organization of Air Force bases and missile sites in relation to their missions. Chapter 2 examines the community services provided by Air Force bases. The topics…

  5. The aqueous corrosion behavior of technetium - Alloy and composite materials

    SciTech Connect

    Jarvinen, G.; Kolman, D.; Taylor, C.; Goff, G.; Cisneros, M.; Mausolf, E.; Poineau, F.; Koury, D.; Czerwinski, K.

    2013-07-01

    Metal waste forms are under study as possible disposal forms for technetium and other fission products. The alloying of Tc is desirable to reduce the melting point of the Tc-containing metal waste form and potentially improve its corrosion resistance. Technetium-nickel composites were made by mixing the two metal powders and pressing the mixture to make a pellet. The as-pressed composite materials were compared to sintered composites and alloys of identical composition in electrochemical corrosion tests. As-pressed samples were not robust enough for fine polishing and only a limited number of corrosion tests were performed. Alloys and composites with 10 wt% Tc appear to be more corrosion resistant at open circuit than the individual components based on linear polarization resistance and polarization data. The addition of 10 wt% Tc to Ni appears beneficial at open circuit, but detrimental upon anodic polarization. Qualitatively, the polarizations of 10 wt% Tc alloys and composites appear like crude addition of Tc plus Ni. The 1 wt% Tc alloys behave like pure Ni, but some effect of Tc is seen upon polarization. Cathodic polarization of Tc by Ni appears feasible based on open circuit potential measurements, however, zero resistance ammetry and solution measurements are necessary to confirm cathodic protection.

  6. Mechanical Properties of Particulate Reinforced Aluminium Alloy Matrix Composite

    SciTech Connect

    Sayuti, M.; Sulaiman, S.; Baharudin, B. T. H. T.; Arifin, M. K. A.; Suraya, S.; Vijayaram, T. R.

    2011-01-17

    This paper discusses the mechanical properties of Titanium Carbide (TiC) particulate reinforced aluminium-silicon alloy matrix composite. TiC particulate reinforced LM6 alloy matrix composites were fabricated by carbon dioxide sand molding process with different particulate weight fraction. Tensile strength, hardness and microstructure studies were conducted to determine the maximum load, tensile strength, modulus of elasticity and fracture surface analysis have been performed to characterize the morphological aspects of the test samples after tensile testing. Hardness values are measured for the TiC reinforced LM6 alloy composites and it has been found that it gradually increases with increased addition of the reinforcement phase. The tensile strength of the composites increased with the increase percentage of TiC particulate.

  7. NASA-UVA Light Aerospace Alloy and Structures Technology Program (LA2ST). Supplement: Research on Materials for the High Speed Civil Transport

    NASA Technical Reports Server (NTRS)

    Gangloff, Richard P.; Starke, Edgar A., Jr.

    1997-01-01

    This report documents the progress achieved over the past 6 to 12 months on four graduate student projects conducted within the NASA-UVA Light Aerospace Alloy and Structures Technology Program. These studies were aimed specifically at light metallic alloy issues relevant to the High Speed Civil Transport. Research on Hydrogen-Enhanced Fracture of High-Strength Titanium Alloy Sheet refined successfully the high resolution R-curve method necessary to characterize initiation and growth fracture toughnesses. For solution treated and aged Low Cost Beta without hydrogen precharging, fracture is by ductile transgranular processes at 25 C, but standardized initiation toughnesses are somewhat low and crack extension is resolved at still lower K-levels. This fracture resistance is degraded substantially, by between 700 and 1000 wppm of dissolved hydrogen, and a fracture mode change is affected. The surface oxide on P-titanium alloys hinders hydrogen uptake and complicates the electrochemical introduction of low hydrogen concentrations that are critical to applications of these alloys. Ti-15-3 sheet was obtained for study during the next reporting period. Research on Mechanisms of deformation and Fracture in High-Strength Titanium Alloys is examining the microstructure and fatigue resistance of very thin sheet. Aging experiments on 0. 14 mm thick (0.0055 inch) foil show microstructural agility that may be used to enhance fatigue performance. Fatigue testing of Ti-15-3 sheet has begun. The effects of various thermo-mechanical processing regimens on mechanical properties will be examined and deformation modes identified. Research on the Effect of Texture and Precipitates on Mechanical Property Anisotropy of Al-Cu-Mg-X and Al-Cu alloys demonstrated that models predict a minor influence of stress-induced alignment of Phi, caused by the application of a tensile stress during aging, on the yield stress anisotropy of both modified AA2519 and a model Al-Cu binary alloy. This project

  8. Measurement Of Composition In Transparent Model Alloy

    NASA Technical Reports Server (NTRS)

    Kaukler, William F.; Perry, Gretchen L.; Curreri, Peter A.

    1989-01-01

    Variation of FTIR technique developed to enable study of growth of cells of different solid phase in unidirectional solidification of these organic mixtures, which serve as transparent anologs of opaque monotectic metal alloys. Study of organic analogs expected to contribute to understanding of formation of aligned rods and particles in directional solidification of metal alloys. Advantage of technique is redistribution of material caused by solidification determined after fact, to very fine scale.

  9. The effect of in-service aerospace contaminants on X-band dielectric properties of a bismaleimide/quartz composite

    NASA Astrophysics Data System (ADS)

    Rodriguez, Luis A.; García, Carla; Grace, Landon R.

    2015-05-01

    The impact of three common aerospace in-service liquid contaminants on the X-band dielectric properties of a polymer composite radar protecting structure (radome) is investigated and quantified. The dielectric properties of the composite laminate are critical to radar transparency, and thus performance, of the radome structure. Further, polymer composites are highly susceptible to absorption of liquids. As such, the effect of common aerospace contaminants on the dielectric properties of composite laminates is crucial. Measurement of relative permittivity and loss tangent via a split-post dielectric resonant technique at 10 GHz is used to determine the effect of water, deicing fluid, and propylene glycol absorption in a three-ply quartz-reinforced bismaleimide laminate. Additionally, fluid uptake kinetics are investigated as a function of liquid type. An approximately linear relationship between fluid content and relative permittivity is observed for all three contaminant types. A 1% increase in contaminant content by weight results in a 7.8%, 4.5%, and 2.5% increase in relative permittivity of the material due to water, deicing fluid, and propylene glycol, respectively. A more significant impact is seen in material loss tangent, where a 1% increase in contaminant content by weight is responsible for a 378.5%, 593.0%, and 441.5% increase in loss tangent due to the aforementioned fluids, respectively. A fluid uptake weight content of 1.31%, 3.41%, and 4.28% is achieved for water, deicing fluid, and propylene glycol respectively, at approximately 1300 hours exposure. Based on the reported observations, the dielectric property degradation of composite laminates due to these commonly used fluids is of significant concern for in-service aircraft radar systems routinely exposed to these contaminants.

  10. Preparation of cast aluminum alloy-mica particle composites

    NASA Technical Reports Server (NTRS)

    Deonath, MR.; Bhat, R. T.; Rohatgi, P. K.

    1980-01-01

    A method for making aluminum-mica particle composites is presented in which mica particles are stirred in molten aluminum alloys followed by casting in permanent molds. Magnesium is added either as an alloying element or in the form of pieces to the surface of the alloy melts to disperse up to 3 wt% mica powders in the melts and to obtain high recoveries of mica in the castings. The mechanical properties of the aluminum alloy-mica composite decrease with increasing mica content; however, even at 2.2% it has a tensile strength of 14.22 kg/sq mm with 1.1% elongation, a compression strength of 42.61 kg/sq mm, and an impact strength of 0.30 kgm/sq cm. Cryogenic and self-lubricating bearing are mentioned applications.

  11. Aerospace Medicine

    NASA Technical Reports Server (NTRS)

    Michaud, Vince

    2015-01-01

    NASA Aerospace Medicine overview - Aerospace Medicine is that specialty area of medicine concerned with the determination and maintenance of the health, safety, and performance of those who fly in the air or in space.

  12. Progress toward a tungsten alloy wire/high temperature alloy composite turbine blade

    SciTech Connect

    Ritzert, F.J.; Dreshfield, R.L.

    1992-11-01

    A tungsten alloy wire reinforced high temperature alloy composite is being developed for potential application as a hollow turbine blade for advanced rocket engine turbopumps. The W-24Re-HfC alloy wire used for these composite blades provides an excellent balance of strength and wire ductility. Preliminary fabrication, specimen design, and characterization studies were conducted by using commercially available W218 tungsten wire in place of the W-24Re-Hfc wire. Subsequently, two-ply, 50 vol pct composite panels using the W-24Re-HfC wire were fabricated. Tensile tests and metallographic studies were performed to determine the material viability. Tensile strengths of a Waspaloy matrix composite at 870 C were 90 pct of the value expected from rule-of-mixtures calculations. During processing of this Waspaloy matrix composite, a brittle phase was formed at the wire/matrix interface. Circumferential wire cracks were found in this phase. Wire coating and process evaluation efforts were performed in an attempt to solve the reaction problem. Although problems were encountered in this study, wire reinforced high temperature alloy composites continue to show promise for turbopump turbine blade material improvement.

  13. Progress toward a tungsten alloy wire/high temperature alloy composite turbine blade

    NASA Technical Reports Server (NTRS)

    Ritzert, F. J.; Dreshfield, R. L.

    1992-01-01

    A tungsten alloy wire reinforced high temperature alloy composite is being developed for potential application as a hollow turbine blade for advanced rocket engine turbopumps. The W-24Re-HfC alloy wire used for these composite blades provides an excellent balance of strength and wire ductility. Preliminary fabrication, specimen design, and characterization studies were conducted by using commercially available W218 tungsten wire in place of the W-24Re-Hfc wire. Subsequently, two-ply, 50 vol pct composite panels using the W-24Re-HfC wire were fabricated. Tensile tests and metallographic studies were performed to determine the material viability. Tensile strengths of a Waspaloy matrix composite at 870 C were 90 pct of the value expected from rule-of-mixtures calculations. During processing of this Waspaloy matrix composite, a brittle phase was formed at the wire/matrix interface. Circumferential wire cracks were found in this phase. Wire coating and process evaluation efforts were performed in an attempt to solve the reaction problem. Although problems were encountered in this study, wire reinforced high temperature alloy composites continue to show promise for turbopump turbine blade material improvement.

  14. The relative stress-corrosion-cracking susceptibility of candidate aluminum-lithium alloys for aerospace structural applications

    NASA Technical Reports Server (NTRS)

    Pizzo, P. P.

    1980-01-01

    The microstructure and tensile properties of two powder metallurgy processed aluminum-lithium alloys were determined. Strength properties of 480 MPa yield and 550 MPa ultimate tensile strength with 5% strain to fracture were attained. Very little reduction in area was observed and fracture characteristics were brittle. The magnesium bearing alloy exhibited the highest strength and ductility, but fracture was intergranular. Recrystallization and grain growth, as well as coarse grain boundary precipitation, occurred in Alloy 2. The fracture morphology of the two alloys differed. Alloy 1 fractured along a plane of maximum shear stress, while Alloy 2 fractured along a plane of maximum tensile stress. It is found that a fixed orientation relationship exists between the shear fracture plane and the rolling direction which suggests that the PM alloys are strongly textured.

  15. Compressive strength of the mineral reinforced aluminium alloy composite

    NASA Astrophysics Data System (ADS)

    Arora, Rama; Sharma, Anju; Kumar, Suresh; Singh, Gurmel; Pandey, O. P.

    2016-05-01

    This paper presents the results of quasi-static compressive strength of aluminium alloy reinforced with different concentration of rutile mineral particles. The reinforced material shows increase in compressive strength with 5wt% rutile concentration as compared to the base alloy. This increase in compressive strength of composite is attributed to direct strengthening due to transfer of load from lower stiffness matrix (LM13 alloy) to higher stiffness reinforcement (rutile particles). Indirect strengthening mechanisms like increase in dislocation density at the matrix-reinforcement interface, grain size refinement of the matrix and dispersion strengthening are also the contributing factors. The decrease in compressive strength of composite with the increased concentration of rutile concentration beyond 5 wt.% can be attributed to the increase in dislocation density due to the void formation at the matrix-reinforcement interface.

  16. Functionally Graded Al Alloy Matrix In-Situ Composites

    NASA Astrophysics Data System (ADS)

    Kumar, S.; Subramaniya Sarma, V.; Murty, B. S.

    2010-01-01

    In the present work, functionally graded (FG) aluminum alloy matrix in-situ composites (FG-AMCs) with TiB2 and TiC reinforcements were synthesized using the horizontal centrifugal casting process. A commercial Al-Si alloy (A356) and an Al-Cu alloy were used as matrices in the present study. The material parameters (such as matrix and reinforcement type) and process parameters (such as mold temperature, mold speed, and melt stirring) were found to influence the gradient in the FG-AMCs. Detailed microstructural analysis of the composites in different processing conditions revealed that the gradients in the reinforcement modify the microstructure and hardness of the Al alloy. The segregated in-situ formed TiB2 and TiC particles change the morphology of Si particles during the solidification of Al-Si alloy. A maximum of 20 vol pct of reinforcement at the surface was achieved by this process in the Al-4Cu-TiB2 system. The stirring of the melt before pouring causes the reinforcement particles to segregate at the periphery of the casting, while in the absence of such stirring, the particles are segregated at the interior of the casting.

  17. ALLOY COMPOSITION FOR NEUTRONIC REACTOR CONTROL RODS

    DOEpatents

    Lustman, B.; Losco, E.F.; Snyder, H.J.; Eggleston, R.R.

    1963-01-22

    This invention relates to alloy compositons suitable as cortrol rod material consisting of, by weight, from 85% to 85% Ag, from 2% to 20% In, from up to 10% of Cd, from up to 5% Sn, and from up to 1.5% Al, the amount of each element employed being determined by the equation X + 2Y + 3Z + 3W + 4V = 1.4 and less, where X, Y, Z, W, and V represent the atom fractions of the elements Ag, Cd, In, Al and Sn. (AEC)

  18. Tungsten wire-nickel base alloy composite development

    NASA Technical Reports Server (NTRS)

    Brentnall, W. D.; Moracz, D. J.

    1976-01-01

    Further development and evaluation of refractory wire reinforced nickel-base alloy composites is described. Emphasis was placed on evaluating thermal fatigue resistance as a function of matrix alloy composition, fabrication variables and reinforcement level and distribution. Tests for up to 1,000 cycles were performed and the best system identified in this current work was 50v/o W/NiCrAlY. Improved resistance to thermal fatigue damage would be anticipated for specimens fabricated via optimized processing schedules. Other properties investigated included 1,093 C (2,000 F) stress rupture strength, impact resistance and static air oxidation. A composite consisting of 30v/o W-Hf-C alloy fibers in a NiCrAlY alloy matrix was shown to have a 100-hour stress rupture strength at 1,093 C (2,000 F) of 365 MN/square meters (53 ksi) or a specific strength advantage of about 3:1 over typical D.S. eutectics.

  19. Environment enhanced fatigue of advanced aluminum alloys and composites

    NASA Technical Reports Server (NTRS)

    Slavik, Donald C.; Gangloff, Richard P.

    1990-01-01

    The objective is to characterize and understand the environmental fatigue crack propagation behavior of advanced, high stiffness and strength, aluminum alloys and metal matrix composites. Those gases and aqueous electrolytes which are capable of producing atomic hydrogen by reactions on clean crack surfaces are emphasized. Characterizations of the behavior of new materials are sought to provide data for damage tolerant component life prediction. Mechanistic models are sought for crack tip damage processes which are generally applicable to structural aluminum alloys. Such models will enable predictions of cracking behavior outside of the data, metallurgical improvements in material cracking resistance, and insight on hydrogen compatibility.

  20. Wear Behavior of Aluminum Alloy 6061-Based Composites Reinforced with SiC, Al2O3, and Red Mud: A Comparative Study

    NASA Astrophysics Data System (ADS)

    Singla, Yogesh Kumar; Chhibber, Rahul; Bansal, Hitesh; Kalra, Anil

    2015-09-01

    Metal-matrix composites are widely used in shipping, aerospace, automotive, and nuclear applications. Research attempts have been made in the past to reduce the cost of processing of composites, decrease the weight of the composites, and increase the desired performance characteristics. In this research article, an attempt has been made in using red mud obtained as an industrial waste during the production of aluminum from bauxite ore. This article discusses the novel findings of the experimental study on the dry sliding wear behavior of aluminum alloy 6061-based composites reinforced individually with red mud, SiC, and Al2O3. The microstructural characterization of the composites provides the further insight into the structure—wear behavior of the processed composites.

  1. AI-Li/SiCp composites and Ti-AI alloy powders and coatings prepared by a plasma spray atomization (PSA) technique

    NASA Astrophysics Data System (ADS)

    Khor, K. A.; Boey, F. Y. C.; Murakoshi, Y.; Sano, T.

    1994-06-01

    There has been increasing use of Al-Li alloys in the aerospace industry, due mainly to the low density and high elastic modulus of this material. However, the problem of low ductility and fracture toughness of this material has limited its present application to only weight- and stiffness-critical components. Development of Al-Li/ceramic composites is currently being investigated to enhance the service capabilities of this material. The Ti-Al alloy is also of interest to aerospace-type applications, engine components in particular, due to its attractive high-temperature properties. Preparation of fine powders by plasma melting of composite feedstock and coatings formed by plasma spraying was carried out to examine the effect of spray parameters on the microstructure and properties of these materials. Characterization of the powders and coatings was performed using the scanning electron microscope and image analyzer. Examination of the plasma-sprayed powders and coatings has shown that in the Al-Li/SiC composite there is melting of both materials to form a single composite particle. The SiC reinforcement was in the submicron range and contributed to additional strengthening of the composite body, which was formed by a cold isostatic press and consolidated by hot extrusion or hot forging processes. The plasma-sprayed Ti-Al powder showed four categories of microstructures: featureless, dendritic, cellular, and martensite-like.

  2. Metal Alloy Compositions And Process Background Of The Invention

    DOEpatents

    Flemings, Merton C.; Martinez-Ayers, Raul A.; de Figueredo, Anacleto M.; Yurko, James A.

    2003-11-11

    A skinless metal alloy composition free of entrapped gas and comprising primary solid discrete degenerate dendrites homogeneously dispersed within a secondary phase is formed by a process wherein the metal alloy is heated in a vessel to render it a liquid. The liquid is then rapidly cooled while vigorously agitating it under conditions to avoid entrapment of gas while forming solid nuclei homogeneously distributed in the liquid. Agitation then is ceased when the liquid contains a small fraction solid or the liquid-solid alloy is removed from the source of agitation while cooling is continued to form the primary solid discrete degenerate dendrites in liquid secondary phase. The solid-liquid mixture then can be formed such as by casting.

  3. Ceramic Matrix Composites: High Temperature Effects. (Latest Citations from the Aerospace Database)

    NASA Technical Reports Server (NTRS)

    1997-01-01

    The bibliography contains citations concerning the development and testing of ceramic matrix composites for high temperature use. Tests examining effects of the high temperatures on bond strength, thermal degradation, oxidation, thermal stress, thermal fatigue, and thermal expansion properties are referenced. Applications of the composites include space structures, gas turbine and engine components, control surfaces for spacecraft and transatmospheric vehicles, heat shields, and heat exchangers.

  4. Surface characterization of carbon fiber polymer composites and aluminum alloys after laser interference structuring

    DOE PAGESBeta

    Sabau, Adrian S.; Greer, Clayton M.; Chen, Jian; Warren, Charles David; Daniel, Claus

    2016-05-03

    Here, the increasing use of Carbon Fiber-reinforced Polymer matrix Composites (CFPC) and aluminum alloys as lightweight materials in the automotive and aerospace industries demands enhanced surface preparation and control of surface morphology prior to joining. In this study, surfaces of both composite and aluminum were prepared for joining using an Nd:YAG laser in a two-beam interference setup, enabling the (a) structuring of the AL 5182 surface, (b) removal of the resin layer on top of carbon fibers, and (c) structuring of the carbon fibers. CFPC specimens of T700S carbon fiber, Prepreg - T83 epoxy, 5 ply thick, 0/90o plaques weremore » used. The effect of laser fluence, scanning speed, and number of shots-per-spot was investigated on the removal rate of the resin without an excessive damage of the fibers. Optical micrographs, 3D imaging, and scanning electron microscope (SEM) imaging were used to study the effect of the laser processing on surface morphology.« less

  5. Surface Characterization of Carbon Fiber Polymer Composites and Aluminum Alloys After Laser Interference Structuring

    NASA Astrophysics Data System (ADS)

    Sabau, Adrian S.; Greer, Clayton M.; Chen, Jian; Warren, Charles D.; Daniel, Claus

    2016-07-01

    The increasing use of carbon fiber-reinforced polymer matrix composites (CFPC) and aluminum alloys as lightweight materials in the automotive and aerospace industries demands enhanced surface preparation and control of surface morphology prior to joining. In this study, surfaces of both composite and aluminum were prepared for joining using an Nd:YAG laser in a two-beam interference setup, enabling the (1) structuring of the AL 5182 surface, (2) removal of the resin layer on top of carbon fibers, and (3) structuring of the carbon fibers. CFPC specimens of T700S carbon fiber, Prepreg—T83 epoxy, 5 ply thick, 0°/90° plaques were used. The effects of laser fluence, scanning speed, and number of shots-per-spot were investigated on the removal rate of the resin without an excessive damage of the fibers. Optical micrographs, 3D imaging, and scanning electron microscope imaging were used to study the effect of the laser processing on the surface morphology. It was found that an effective resin ablation and a low density of broken fibers for CFPC specimens was attained using laser fluences of 1-2 J/cm2 and number of 2-4 pulses per spot. A relatively large area of periodic line structures due to energy interference were formed on the aluminum surface at laser fluences of 12 J/cm2 and number of 4-6 pulses per spot.

  6. Surface Characterization of Carbon Fiber Polymer Composites and Aluminum Alloys After Laser Interference Structuring

    NASA Astrophysics Data System (ADS)

    Sabau, Adrian S.; Greer, Clayton M.; Chen, Jian; Warren, Charles D.; Daniel, Claus

    2016-05-01

    The increasing use of carbon fiber-reinforced polymer matrix composites (CFPC) and aluminum alloys as lightweight materials in the automotive and aerospace industries demands enhanced surface preparation and control of surface morphology prior to joining. In this study, surfaces of both composite and aluminum were prepared for joining using an Nd:YAG laser in a two-beam interference setup, enabling the (1) structuring of the AL 5182 surface, (2) removal of the resin layer on top of carbon fibers, and (3) structuring of the carbon fibers. CFPC specimens of T700S carbon fiber, Prepreg—T83 epoxy, 5 ply thick, 0°/90° plaques were used. The effects of laser fluence, scanning speed, and number of shots-per-spot were investigated on the removal rate of the resin without an excessive damage of the fibers. Optical micrographs, 3D imaging, and scanning electron microscope imaging were used to study the effect of the laser processing on the surface morphology. It was found that an effective resin ablation and a low density of broken fibers for CFPC specimens was attained using laser fluences of 1-2 J/cm2 and number of 2-4 pulses per spot. A relatively large area of periodic line structures due to energy interference were formed on the aluminum surface at laser fluences of 12 J/cm2 and number of 4-6 pulses per spot.

  7. Composite of coated magnetic alloy particle

    DOEpatents

    Moorhead, Arthur J.; Kim, Hyoun-Ee

    2000-01-01

    A composite structure and method for manufacturing same, the composite structure being comprised of metal particles and an inorganic bonding media. The method comprises the steps of coating particles of a metal powder with a thin layer of an inorganic bonding media selected from the group of powders consisting of a ceramic, glass, and glass-ceramic. The particles are assembled in a cavity and heat, with or without the addition of pressure, is thereafter applied to the particles until the layer of inorganic bonding media forms a strong bond with the particles and with the layer of inorganic bonding media on adjacent particles. The resulting composite structure is strong and remains cohesive at high temperatures.

  8. Thermal and damping behaviour of magnetic shape memory alloy composites

    NASA Astrophysics Data System (ADS)

    Glock, Susanne; Michaud, Véronique

    2015-06-01

    Single crystals of ferromagnetic shape memory alloys (MSMA) exhibit magnetic field and stress induced strains via energy dissipating twinning. Embedding single crystalline MSMA particles into a polymer matrix could thus produce composites with enhanced energy dissipation, suitable for damping applications. Composites of ferromagnetic, martensitic or austenitic Ni-Mn-Ga powders embedded in a standard epoxy matrix were produced by casting. The martensitic powder composites showed a crystal structure dependent damping behaviour that was more dissipative than that of austenitic powder or Cu-Ni reference powder composites and than that of the pure matrix. The loss ratio also increased with increasing strain amplitude and decreasing frequency, respectively. Furthermore, Ni-Mn-Ga powder composites exhibited an increased damping behaviour at the martensite/austenite transformation temperature of the Ni-Mn-Ga particles in addition to that at the glass transition temperature of the epoxy matrix, creating possible synergetic effects.

  9. Military Aerospace. Aerospace Education II.

    ERIC Educational Resources Information Center

    Smith, J. C.

    This book is a revised publication in the series on Aerospace Education II. It describes the employment of aerospace forces, their methods of operation, and some of the weapons and equipment used in combat and combat support activities. The first chapter describes some of the national objectives and policies served by the Air Force in peace and…

  10. Aerospace Environment. Aerospace Education I.

    ERIC Educational Resources Information Center

    Savler, D. S.; Smith, J. C.

    This book is one in the series on Aerospace Education I. It briefly reviews current knowledge of the universe, the earth and its life-supporting atmosphere, and the arrangement of celestial bodies in outer space and their physical characteristics. Chapter 1 includes a brief survey of the aerospace environment. Chapters 2 and 3 examine the…

  11. Metal Matrix Composites: Fatigue and Fracture Testing. (Latest citations from the Aerospace Database)

    NASA Technical Reports Server (NTRS)

    1996-01-01

    The bibliography contains citations concerning techniques and results of testing metal matrix composites for fatigue and fracture. Methods include non-destructive testing techniques, and static and cyclic techniques for assessing compression, tensile, bending, and impact characteristics.

  12. Design and analysis of variable-twist tiltrotor blades using shape memory alloy hybrid composites

    NASA Astrophysics Data System (ADS)

    Park, Jae-Sang; Kim, Seong-Hwan; Jung, Sung Nam; Lee, Myeong-Kyu

    2011-01-01

    The tiltrotor blade, or proprotor, acts as a rotor in the helicopter mode and as a propeller in the airplane mode. For a better performance, the proprotor should have different built-in twist distributions along the blade span, suitable for each operational mode. This paper proposes a new variable-twist proprotor concept that can adjust the built-in twist distribution for given flight modes. For a variable-twist control, the present proprotor adopts shape memory alloy hybrid composites (SMAHC) containing shape memory alloy (SMA) wires embedded in the composite matrix. The proprotor of the Korea Aerospace Research Institute (KARI) Smart Unmanned Aerial Vehicle (SUAV), which is based on the tiltrotor concept, is used as a baseline proprotor model. The cross-sectional properties of the variable-twist proprotor are designed to maintain the cross-sectional properties of the original proprotor as closely as possible. However, the torsion stiffness is significantly reduced to accommodate the variable-twist control. A nonlinear flexible multibody dynamic analysis is employed to investigate the dynamic characteristics of the proprotor such as natural frequency and damping in the whirl flutter mode, the blade structural loads in a transition flight and the rotor performance in hover. The numerical results show that the present proprotor is designed to have a strong similarity to the baseline proprotor in dynamic and load characteristics. It is demonstrated that the present proprotor concept could be used to improve the hover performance adaptively when the variable-twist control using the SMAHC is applied appropriately.

  13. Phase Composition and Microstructure of Ti-Nb Alloy Produced by Selective Laser Melting

    NASA Astrophysics Data System (ADS)

    Sharkeev, Yu P.; Eroshenko, A. Yu; Kovalevskaya, Zh G.; Saprykin, A. A.; Ibragimov, E. A.; Glukhov, I. A.; Chimich, M. A.; Uvarkin, P. V.; Babakova, E. V.

    2016-07-01

    The phase composition and microstructure of Ti-Nb alloy produced from composite titanium and niobium powder by selective laser melting (SLM) was studied. Produced monolayered Ti-Nb alloy enhanced the formation of fine-grained and medium-grained zones with homogeneous element composition of 36-38% Nb mass interval. Alloy phase composition responded to β-alloy substrate phase (grain size was 5-7 pm) and non-equilibrium martensite α"- phase (grain size was 0.1-0.7 µm). α"-phase grains were found along β-phase grain boundaries and inside grains, including decreased niobium content. Alloy microhardness varied within 4200-5500 MPa.

  14. Corrosive wear behavior of 2014 and 6061 aluminum alloy composites

    SciTech Connect

    Varma, S.K.; Andrews, S.; Vasquez, G.

    1999-02-01

    Alloys of 2014 and 6061 aluminum reinforced with 0.1 volume fraction of alumina particles (VFAP) were subjected to impact scratching during a corrosive wear process. The transient currents generated due to the impact were measured in the two composites as well as in their respective monoliths. The effect of solutionizing time on the transient currents was correlated to the near surface microstructures, scratch morphology, concentration of quenched-in vacancies, and changes in grain sizes. It was observed that the transient current values increase with an increase in solutionizing time, indicating that the corrosive wear behavior is not strongly affected by the grain boundaries. However, a combination of pitting and the galvanic corrosion may account for the typical corrosive wear behavior exhibited by the alloys and the composites of this study.

  15. Cermet anode compositions with high content alloy phase

    DOEpatents

    Marschman, S.C.; Davis, N.C.

    1989-10-03

    Cermet electrode compositions comprising NiO-NiFe[sub 2]O[sub 4]-Cu-Ni, and methods for making, are disclosed. Addition of nickel metal prior to formation and densification of a base mixture into the cermet allows for an increase in the total amount of copper and nickel that can be contained in the NiO-NiFe[sub 2]O[sub 4] oxide system. Nickel is present in a base mixture weight concentration of from 0.1% to 10%. Copper is present in the alloy phase in a weight concentration of from 10% to 30% of the densified composition. Such cermet electrodes can be formed to have electrical conductivities well in excess of 100 ohm[sup [minus]1] cm[sup [minus]1]. Other alloy and oxide system cermets having high content metal phases are also expected to be manufacturable in accordance with the invention.

  16. Cermet anode compositions with high content alloy phase

    DOEpatents

    Marschman, Steven C.; Davis, Norman C.

    1989-01-01

    Cermet electrode compositions comprising NiO-NiFe.sub.2 O.sub.4 -Cu-Ni, and methods for making, are disclosed. Addition of nickel metal prior to formation and densification of a base mixture into the cermet allows for an increase in the total amount of copper and nickel that can be contained in the NiO-NiFe.sub.2 O.sub.4 oxide system. Nickel is present in a base mixture weight concentration of from 0.1% to 10%. Copper is present in the alloy phase in a weight concentration of from 10% to 30% of the densified composition. Such cermet electrodes can be formed to have electrical conductivities well in excess of 100 ohm.sup.-1 cm.sup.-1. Other alloy and oxide system cermets having high content metal phases are also expected to be manufacturable in accordance with the invention.

  17. Cracking of Composite Modified Alloy 825 Primary Air Port Tubes

    SciTech Connect

    Kish, Joseph R.; Keiser, James R; Singbeil, Douglas; Willoughby, Adam W; Longmire, Hu Foster

    2007-04-01

    Twenty primary air ports fabricated from modified Alloy 825-based composite tubes underwent a metallurgical examination to document the mode and extent of cracking on the external fireside surface of a kraft recovery boiler. Collectively, the crack features found are most consistent with thermal fatigue, but corrosion fatigue cannot be ruled out. Regardless of the true cracking mechanism, temperature cycling is implicated as a critical factor for crack propagation. on the basis of the relative crack lengths observed, membrane welds and tube weld repairs, and their adjacent heat-affected zones, appear to be more susceptible to cracking than the cladding itself. This work suggests that mills should avoid boiler operating conditions that promote large temperature fluctuations, which can cause Alloy 825-based composite tubes to crack.

  18. Improved Damage Resistant Composite Materials Incorporating Shape Memory Alloys

    NASA Technical Reports Server (NTRS)

    Paine, Jeffrey S. N.; Rogers, Craig A.

    1996-01-01

    Metallic shape memory alloys (SMA) such as nitinol have unique shape recovery behavior and mechanical properties associated with a material phase change that have been used in a variety of sensing and actuation applications. Recent studies have shown that integrating nitinol-SMA actuators into composite materials increases the composite material's functionality. Hybrid composites of conventional graphite/epoxy or glass/epoxy and nitinol-SMA elements can perform functions in applications where monolithic composites perform inadequately. One such application is the use of hybrid composites to function both in load bearing and armor capacities. While monolithic composites with high strength-to-weight ratios function efficiently as loadbearing structures, because of their brittle nature, impact loading can cause significant catastrophic damage. Initial composite failure modes such as delamination and matrix cracking dissipate some impact energy, but when stress exceeds the composite's ultimate strength, fiber fracture and material perforation become dominant. One of the few methods that has been developed to reduce material perforation is hybridizing polymer matrix composites with tough kevlar or high modulus polyethynylene plies. The tough fibers increase the impact resistance and the stiffer and stronger graphite fibers carry the majority of the load. Similarly, by adding nitinol-SMA elements that absorb impact energy through the stress-induced martensitic phase transformation, the composites' impact perforation resistance can be greatly enhanced. The results of drop-weight and high velocity gas-gun impact testing of various composite materials will be presented. The results demonstrate that hybridizing composites with nitinol-SMA elements significantly increases perforation resistance compared to other traditional toughening elements. Inspection of the composite specimens at various stages of perforation by optical microscope illustrates the mechanisms by which

  19. Evolution of and projections for automated composite material placement equipment in the aerospace industry

    NASA Astrophysics Data System (ADS)

    McCarville, Douglas A.

    2009-12-01

    As the commercial aircraft industry attempts to improve airplane fuel efficiency by shifting from aluminum to composites (reinforced plastics), there is a concern that composite processing equipment is not mature enough to meet increasing demand and that delivery delays and loss of high tech jobs could result. The research questions focused on the evolution of composite placement machines, improvement of machine functionality by equipment vendors, and the probability of new inventions helping to avoid production shortfalls. An extensive review of the literature found no studies that addressed these issues. Since the early twentieth century, exploratory case study of pivotal technological advances has been an accepted means of performing historic analysis and furthering understanding of rapidly changing marketplaces and industries. This qualitative case study investigated evolution of automated placement equipment by (a) codifying and mapping patent data (e.g., claims and functionality descriptions), (b) triangulating archival data (i.e., trade literature, vender Web sites, and scholarly texts), and (c) interviewing expert witnesses. An industry-level sensitivity model developed by the author showed that expanding the vendor base and increasing the number of performance enhancing inventions will most likely allow the industry to make the transition from aluminum to composites without schedule delays. This study will promote social change by (a) advancing individual and community knowledge (e.g., teaching modules for students, practitioners, and professional society members) and (b) providing an empirical model that will help in the understanding and projection of next generation composite processing equipment demand and productivity output.

  20. Refractory metal alloys and composites for space nuclear power systems

    SciTech Connect

    Titran, R.H.; Stephens, J.R.; Petrasek, D.W.

    1988-01-01

    Space power requirements for future NASA and other United States missions will range from a few kilowatts to megawatts of electricity. Maximum efficiency is a key goal of any power system in order to minimize weight and size so that the space shuttle may be used a minimum number of times to put the power supply into orbit. Nuclear power has been identified as the primary power source to meet these high levels of electrical demand. One method to achieve maximum efficiency is to operate the power supply, energy conversion system, and related components at relatively high temperatures. For systems now in the planning stages, design temperatures range from 1300 K for the immediate future to as high as 1700 K for the advanced systems. NASA Lewis Research Center has undertaken a research program on advanced technology of refractory metal alloys and composites that will provide base line information for space power systems in the 1900's and the 21st century. Special emphasis is focused on the refractory metal alloys of niobium and on the refractory metal composites which utilize tungsten alloy wire for reinforcement. Basic research on the creep and creep-rupture properties of wires, matrices, and composites will be discussed. 20 refs., 27 figs., 1 tab.

  1. Refractory metal alloys and composites for space nuclear power systems

    NASA Technical Reports Server (NTRS)

    Titran, Robert H.; Stephens, Joseph R.; Petrasek, Donald W.

    1988-01-01

    Space power requirements for future NASA and other U.S. missions will range from a few kilowatts to megawatts of electricity. Maximum efficiency is a key goal of any power system in order to minimize weight and size so that the Space Shuttle may be used a minimum number of times to put the power supply into orbit. Nuclear power has been identified as the primary power source to meet these high levels of electrical demand. One method to achieve maximum efficiency is to operate the power supply, energy conservation system, and related components at relatively high temperatures. For systems now in the planning stages, design temperatures range from 1300 K for the immediate future to as high as 1700 K for the advanced systems. NASA Lewis Research Center has undertaken a research program on advanced technology of refractory metal alloys and composites that will provide baseline information for space power systems in the 1900's and the 21st century. Special emphasis is focused on the refractory metal alloys of niobium and on the refractory metal composites which utilize tungsten alloy wires for reinforcement. Basic research on the creep and creep-rupture properties of wires, matrices, and composites are discussed.

  2. Spectroscopic detection and analysis of atomic emissions during industrial pulsed laser-drilling of structural aerospace alloys

    NASA Astrophysics Data System (ADS)

    Bright, Robin Michael

    The ability to adequately cool internal gas-turbine engine components in next-generation commercial and military aircraft is of extreme importance to the aerospace industry as the demand for high-efficiency engines continues to push operating temperatures higher. Pulsed laser-drilling is rapidly becoming the preferred method of creating cooling holes in high temperature components due a variety of manufacturing advantages of laser-drilling over conventional hole-drilling techniques. As cooling requirements become more demanding, the impact of drilling conditions on material removal behavior and subsequent effects on hole quality becomes critical. In this work, the development of emission spectroscopy as a method to probe the laser-drilling process is presented and subsequently applied to the study of material behavior of various structural aerospace materials during drilling. Specifically, emitted photons associated with energy level transitions within excited neutral atoms in material ejected during drilling were detected and analyzed. Systematic spectroscopic studies indicated that electron energy level populations and calculated electron temperatures within ejected material are dependent on both laser pulse energy and duration. Local thermal conditions detected by the developed method were related to the characteristics of ejected material during drilling and to final hole quality. Finally, methods of utilizing the observed relationships for spectroscopic process monitoring and control were demonstrated.

  3. Experimental Modal Analysis and Dynaic Strain Fiber Bragg Gratings for Structural Health Monitoring of Composite Aerospace Structures

    NASA Astrophysics Data System (ADS)

    Panopoulou, A.; Fransen, S.; Gomez Molinero, V.; Kostopoulos, V.

    2012-07-01

    The objective of this work is to develop a new structural health monitoring system for composite aerospace structures based on dynamic response strain measurements and experimental modal analysis techniques. Fibre Bragg Grating (FBG) optical sensors were used for monitoring the dynamic response of the composite structure. The structural dynamic behaviour has been numerically simulated and experimentally verified by means of vibration testing. The hypothesis of all vibration tests was that actual damage in composites reduces their stiffness and produces the same result as mass increase produces. Thus, damage was simulated by slightly varying locally the mass of the structure at different zones. Experimental modal analysis based on the strain responses was conducted and the extracted strain mode shapes were the input for the damage detection expert system. A feed-forward back propagation neural network was the core of the damage detection system. The features-input to the neural network consisted of the strain mode shapes, extracted from the experimental modal analysis. Dedicated training and validation activities were carried out based on the experimental results. The system showed high reliability, confirmed by the ability of the neural network to recognize the size and the position of damage on the structure. The experiments were performed on a real structure i.e. a lightweight antenna sub- reflector, manufactured and tested at EADS CASA ESPACIO. An integrated FBG sensor network, based on the advantage of multiplexing, was mounted on the structure with optimum topology. Numerical simulation of both structures was used as a support tool at all the steps of the work. Potential applications for the proposed system are during ground qualification extensive tests of space structures and during the mission as modal analysis tool on board, being able via the FBG responses to identify a potential failure.

  4. MoS2-Filled PEEK Composite as a Self-Lubricating Material for Aerospace Applications

    NASA Technical Reports Server (NTRS)

    Theiler, Geraldine; Gradt, Thomas

    2010-01-01

    At BAM, several projects were conducted in the past years dealing with the tribological properties of friction couples at cryogenic temperature and in vacuum environment. Promising candidates for vacuum application are MoS2-filled PEEK/PTFE composites, which showed a friction coefficient as low as 0.03 in high vacuum. To complete the tribological profile of these composites, further tests were performed in ultra-high vacuum (UHV) at room temperature. In this paper, friction and stick slip behavior, as well as outgassing characteristics during the test are presented.

  5. Nano {gamma}'/{gamma}'' composite precipitates in Alloy 718

    SciTech Connect

    Phillips, P. J.; McAllister, D.; Gao, Y.; Lv, D.; Williams, R. E. A.; Wang, Y.; Mills, M. J.; Peterson, B.

    2012-05-21

    Nanoscale composite precipitates of Alloy 718 have been investigated with both high-resolution scanning transmission electron microscopy and phase field modeling. Chemical analysis via energy-dispersive x-ray spectroscopy allowed for the differentiation of {gamma}' and {gamma}'' particles, which is not otherwise possible through traditional Z-contrast methods. Phase field modeling was applied to determine the stress distribution and elastic interaction around and between the particles, respectively, and it was determined that a composite particle (of both {gamma}' and {gamma}'') has an elastic energy that is significantly lower than, for example, single {gamma}' and {gamma}'' precipitates which are non-interacting.

  6. Corrosion performance of a nickel-molybdenum-chromium alloy: Effects of aging, alloying elements, and electrolyte composition

    SciTech Connect

    Rebak, R.B.; Srivastava, S.K.

    1999-04-01

    General and stress corrosion cracking (SCC) behaviors of a Ni-Mo-Cr alloy were assessed in the mill-annealed and aged conditions. Performance of this Ni-25% Mo-8% Cr alloy (alloy 242 [proposed UNS N10242]) was compared to the performance of a Ni-Mo alloy (alloy B-3 [UNS N10675]) and a Ni-Cr-Mo alloy (C-2000 [UNS N06200]). Results showed the general corrosion rate of alloy 242 in reducing acids was slightly higher than that of alloy B-3. However, in mildly oxidizing conditions, the corrosion rate of alloy 242 was lower than that of alloy B-3. Effects of electrolyte and alloy composition on the general corrosion rate were studied. After aging at 650 C (1,200 F) for 24 h, the corrosion rate of alloy 242 increased slightly, particularly in strongly reducing conditions. Alloy 242 was resistant to SCC but was prone to hydrogen-induced cracking, especially in the aged condition.

  7. Applications of laser ultrasound NDT methods on composite structures in aerospace industry

    NASA Astrophysics Data System (ADS)

    Kalms, Michael; Focke, Oliver; v. Kopylow, Christoph

    2008-09-01

    Composite materials are used more and more in aircraft production. Main composite types are Carbon Fiber Reinforced Plastics (CFRP), Glass Fiber Reinforced Plastics (GFRP) and metal-aluminium laminates (e. g. Glass Fiber Aluminium Reinforced GLARE©). Typical parts made of CFRP material are flaps, vertical and horizontal tail planes, center wing boxes, rear pressure bulkheads, ribs and stringers. These composite parts require adequate nondestructive testing (NDT) methods. Flaws to be detected are delaminations and debondings, porosity and foreign body inclusion. Manual ultrasonic testing with single element transducers is still the most applied method for composite parts with small and medium size. The extension of the conventional ultrasound technique for nondestructive testing with the laser ultrasound method brings new possibilities into the production processes for example the inspection of complex CFRP-components and the possibilities of online observation under remote control. In this paper we describe the principle of laser ultrasound with respect to the demands of nondestructive testing especially of small complex CFRP and C/PPS parts. We report applications of laser-based ultrasound options with generated types of guided and bulk waves on modern aircraft materials.

  8. Aerospace Technology.

    ERIC Educational Resources Information Center

    Paschke, Jean; And Others

    1991-01-01

    Describes the Sauk Rapids (Minnesota) High School aviation and aerospace curriculum that was developed by Curtis Olson and the space program developed by Gerald Mayall at Philadelphia's Northeast High School. Both were developed in conjunction with NASA. (JOW)

  9. Pressure-dependent isotopic composition of iron alloys.

    PubMed

    Shahar, A; Schauble, E A; Caracas, R; Gleason, A E; Reagan, M M; Xiao, Y; Shu, J; Mao, W

    2016-04-29

    Our current understanding of Earth's core formation is limited by the fact that this profound event is far removed from us physically and temporally. The composition of the iron metal in the core was a result of the conditions of its formation, which has important implications for our planet's geochemical evolution and physical history. We present experimental and theoretical evidence for the effect of pressure on iron isotopic composition, which we found to vary according to the alloy tested (FeO, FeH(x), or Fe3C versus pure Fe). These results suggest that hydrogen or carbon is not the major light-element component in the core. The pressure dependence of iron isotopic composition provides an independent constraint on Earth's core composition. PMID:27126042

  10. Pressure-dependent isotopic composition of iron alloys

    NASA Astrophysics Data System (ADS)

    Shahar, A.; Schauble, E. A.; Caracas, R.; Gleason, A. E.; Reagan, M. M.; Xiao, Y.; Shu, J.; Mao, W.

    2016-04-01

    Our current understanding of Earth’s core formation is limited by the fact that this profound event is far removed from us physically and temporally. The composition of the iron metal in the core was a result of the conditions of its formation, which has important implications for our planet’s geochemical evolution and physical history. We present experimental and theoretical evidence for the effect of pressure on iron isotopic composition, which we found to vary according to the alloy tested (FeO, FeHx, or Fe3C versus pure Fe). These results suggest that hydrogen or carbon is not the major light-element component in the core. The pressure dependence of iron isotopic composition provides an independent constraint on Earth’s core composition.

  11. Composition maps in self-assembled alloy quantum dots.

    PubMed

    Medhekar, N V; Hegadekatte, V; Shenoy, V B

    2008-03-14

    Nanoscale variations in composition arising from the competition between chemical mixing effects and elastic relaxation can substantially influence the electronic and optical properties of self-assembled alloy quantum dots. Using a combination of finite element and quadratic programming optimization methods, we have developed an efficient technique to compute the equilibrium composition profiles in strained quantum dots. We find that the composition profiles depend strongly on the morphological features such as the slopes and curvatures of their surfaces and the presence of corners and edges as well as the ratio of the strain and chemical mixing energy densities. More generally, our approach provides a means to quantitatively model the interplay among the composition variations, the temperature, the strain, and the shapes of small-scale lattice-mismatched structures. PMID:18352213

  12. Chemical, mechanical and antibacterial properties of silver nanocluster/silica composite coated textiles for safety systems and aerospace applications

    NASA Astrophysics Data System (ADS)

    Ferraris, S.; Perero, S.; Miola, M.; Vernè, E.; Rosiello, A.; Ferrazzo, V.; Valletta, G.; Sanchez, J.; Ohrlander, M.; Tjörnhammar, S.; Fokine, M.; Laurell, F.; Blomberg, E.; Skoglund, S.; Odnevall Wallinder, I.; Ferraris, M.

    2014-10-01

    This work describes the chemical, mechanical and antibacterial properties of a novel silver nanocluster/silica composite coating, obtained by sputtering, on textiles for use in nuclear bacteriological and chemical (NBC) protection suites and for aerospace applications. The properties of the coated textiles were analyzed in terms of surface morphology, silver concentration and silver release in artificial sweat and synthetic tap water, respectively. No release of silver nanoparticles was observed at given conditions. The water repellency, permeability, flammability and mechanical resistance of the textiles before and after sputtering demonstrated that the textile properties were not negatively affected by the coating. The antibacterial effect was evaluated at different experimental conditions using a standard bacterial strain of Staphylococcus aureus and compared with the behavior of uncoated textiles. The coating process conferred all textiles a good antibacterial activity. Optimal deposition conditions were elaborated to obtain sufficient antibacterial action without altering the aesthetical appearance of the textiles. The antibacterial coating retained its antibacterial activity after one cycle in a washing machine only for the Nylon based textile.

  13. A unified formulation for guided-wave propagation in multi-layered mixed anisotropic-isotropic hybrid aerospace composites

    NASA Astrophysics Data System (ADS)

    Barazanchy, Darun; Giurgiutiu, Victor

    2016-04-01

    A unified approach was formulated to predict guided-wave propagation in a material regardless its degree of anisotropy, thereby having one solution method for both isotropic and anisotropic material. The unified approach was based on the coupled eigenvalue problem derived from Chirstoffels equation for a lamina. The eigenvalue problem yielded a set of eigenvalues, and corresponding eigenvectors that were used to obtain the stress-displacement matrix. The dispersion curves were obtained by applying the traction free boundary conditions to the stress-displacement matrix, and searching for sign changes in the complex determinant of the matrix. To search for sign changes, hence the velocity-wavenumber pairs which yielded a solution to the problem, the real and imaginary part of the complex determinant had to change sign simultaneously. A phase angle approach was, therefore, developed and successfully applied. A refinement algorithm was applied to refine the accuracy of the solution without increasing the computational time significantly. A high accuracy was required to calculated the correct partial-wave participation factors. The obtained partial-wave participation factors were used to calculate the modeshape through the thickness for each velocity-wavenumber pair. To identify the different wave types, A0, S0, SHS0, SHA0, a modeshape identification was applied successfully. The unified approach was evaluated for hybrid aerospace composites. In addition, the two most common solution methods: (i) the global matrix method; and (ii) the transfer matrix method were applied, and a comparative study between the different methods was performed.

  14. Study of low-cost fabrication methods for aerospace composite materials

    NASA Technical Reports Server (NTRS)

    Chung, H. H.

    1978-01-01

    Flat and hat section specimens of graphite/epoxy composite materials have been fabricated by the resin bath or wet pultrusion process. This demonstrated the feasibility of incorporating crossplied graphite fiber reinforcements in conjunction with epoxy resin systems in the wet pultrusion process. However, the thickness constraints of the pultrusion process, the lack of dimensional stability of the crossply materials and equipment limitations affect the quality of the hat section pultrusions. The wet pultrusion process shows promise of being a low cost method for producing composite parts with constant cross section along the length. A cost analysis showed at least 80 percent cost reduction for the hat section and 40 percent for flat panel by pultrusion over the conventional manual and automated lay-up.

  15. Role of the micro/macro structure of welds in crack nucleation and propagation in aerospace aluminum-lithium alloy

    NASA Technical Reports Server (NTRS)

    Talia, George E.

    1996-01-01

    Al-Li alloys offer the benefits of increased strength, elastic modulus and lower densities as compared to conventional aluminum alloys. Martin Marietta Laboratories has developed an Al-Li alloy designated 2195 which is designated for use in the cryogenic tanks of the space shuttle. The Variable Polarity Plasma Arc (VPPA) welding process is currently being used to produce these welds [1]. VPPA welding utilizes high temperature ionized gas (plasma) to transfer heat to the workpiece. An inert gas, such as Helium, is used to shield the active welding zone to prevent contamination of the molten base metal with surrounding reactive atmospheric gases. [1] In the Space Shuttle application, two passes of the arc are used to complete a butt-type weld. The pressure of the plasma stream is increased during the first pass to force the arc entirely through the material, a practice commonly referred to as keyholing. Molten metal forms on either side of the arc and surface tension draws this liquid together as the arc passes. 2319 Al alloy filler material may also be fed into the weld zone during this pass. During the second pass, the plasma stream pressure is reduced such that only partial penetration of the base material is obtained. Al 2319 filler material is added during this pass to yield a uniform, fully filled welded joint. This additional pass also acts to alter the grain structure of the weld zone to yield a higher strength joint.

  16. Role of the micro/macro structure of welds in crack nucleation and propagation in aerospace aluminum-lithium alloy

    SciTech Connect

    Talia, G.E.

    1996-02-01

    Al-Li alloys offer the benefits of increased strength, elastic modulus and lower densities as compared to conventional aluminum alloys. Martin Marietta Laboratories has developed an Al-Li alloy designated 2195 which is designated for use in the cryogenic tanks of the space shuttle. The Variable Polarity Plasma Arc (VPPA) welding process is currently being used to produce these welds. VPPA welding utilizes high temperature ionized gas (plasma) to transfer heat to the workpiece. An inert gas, such as Helium, is used to shield the active welding zone to prevent contamination of the molten base metal with surrounding reactive atmospheric gases. (1) In the Space Shuttle application, two passes of the arc are used to complete a butt-type weld. The pressure of the plasma stream is increased during the first pass to force the arc entirely through the material, a practice commonly referred to as keyholing. Molten metal forms on either side of the arc and surface tension draws this liquid together as the arc passes. 2319 Al alloy filler material may also be fed into the weld zone during this pass. During the second pass, the plasma stream pressure is reduced such that only partial penetration of the base material is obtained. Al 2319 filler material is added during this pass to yield a uniform, fully filled welded joint. This additional pass also acts to alter the grain structure of the weld zone to yield a higher strength joint.

  17. Enhanced confinement in compositionally heterogeneous alloy quantum dots

    NASA Astrophysics Data System (ADS)

    Hossain, Zubaer

    While there is a growing need to increase solar cell efficiencies and reduce the cost per watt, reported efficiencies are still well below the thermodynamic limit of photovoltaic energy conversion. The major factor that affects the efficiency (by more than 40%) is the lack of absorption or thermalization of electrons. To improve absorption, existing approaches, till date, are focused on combining multiple materials in the form of heterostructures. This talk will show the application of a physics-based mechanistic approach to engineer absorption by using alloy quantum dots and exploiting its heterogeneous compositional and deformation fields. Using a multiscale computational framework that combines density functional theory, k.p method and the finite element calculations, the work shows that heterogeneous distribution of composition and strain fields can lead to substantial confinement in alloy quantum dots. Subsequently alloy quantum dots that are much larger (on the order of 50 nm) in size - compared to their single crystalline counterparts (which are on the order of 5 nm) - can still provide significant confinement. The findings uncover new fundamental insights for engineering confinement that are unattainable under conventional homogenization approximations.

  18. Welding low thermal expansion alloys for aircraft composite tooling

    SciTech Connect

    Otte, W.H.; O`Donnell, D.B.; Kiser, S.D.; Cox, C.W.

    1996-07-01

    To save weight in commercial aircraft and help military jets evade radar detection, aircraft designers specify the use of composite materials. These new designs have resulted in the use of low-expansion materials for aircraft composite tooling because they keep their dimensions during curing. However, the Fe-Ni low-expansion alloys have long presented problems during welding. When matching composition filler metals were used to match the coefficient of thermal expansion (CTE), cracking problems occurred. Filler metal compositional changes to eliminate cracking disturbed the CTE match of the weld with the base metal. A recently developed welding consumable appears to eliminate those problems. With the development of this new filler metal, high-quality crack-free welds can now be obtained with high deposition rates. Since there is a more closely-matched CTE, weldments and tools should provide longer service because of minimal effects from thermal fatigue. There have been reports of vacuum leaks in tools using the Mn-Ti filler metal, which could be directly attributable to the mismatching CTE. Using Nilo filler metal CF36 eliminates weld hot-cracking problems and provides good thermal fatigue resistance due to its excellent CTE match with the base metal, Nilo alloy 36.

  19. Compressive Strength of Notched Poly(Phenylene Sulfide) Aerospace Composite: Influence of Fatigue and Environment

    NASA Astrophysics Data System (ADS)

    Niitsu, G. T.; Lopes, C. M. A.

    2013-08-01

    The purpose of this work is to evaluate the influences of fatigue and environmental conditions (-55 °C, 23 °C, and 82 °C/Wet) on the ultimate compression strength of notched carbon-fiber-reinforced poly(phenylene sulfide) composites by performing open-hole compression (OHC) tests. Analysis of the fatigue effect showed that at temperatures of -55 and 23 °C, the ultimate OHC strengths were higher for fatigued than for not-fatigued specimens; this could be attributed to fiber splitting and delamination during fatigue cycling, which reduces the stress concentration at the hole edge, thus increasing the composite strength. This effect of increasing strength for fatigued specimens was not observed under the 82 °C/Wet conditions, since the test temperature near the matrix glass transition temperature ( T g) together with moisture content resulted in matrix softening, suggesting a reduction in fiber splitting during cycling; similar OHC strengths were verified for fatigued and not-fatigued specimens tested at 82 °C/Wet. Analysis of the temperature effect showed that the ultimate OHC strengths decreased with increasing temperature. A high temperature together with moisture content (82 °C/Wet condition) reduced the composite compressive strengths, since a temperature close to the matrix T g resulted in matrix softening, which reduced the lateral support provided by the resin to the 0° fibers, leading to fiber instability failure at reduced applied loads. On the other hand, a low temperature (-55 °C) improved the compressive strength because of possible fiber-matrix interfacial strengthening, increasing the fiber contribution to compressive strength.

  20. Measurement and analysis of flow in 3D preforms for aerospace composites

    NASA Astrophysics Data System (ADS)

    Stewart, Andrew Lawrence

    Composite materials have become viable alternatives to traditional engineering materials for many different product categories. Liquid transfer moulding (LTM) processes, specifically resin transfer moulding (RTM), is a cost-effective manufacturing technique for creating high performance composite parts. These parts can be tailor-made to their specific application by optimizing the properties of the textile preform. Preforms which require little or no further assembly work and are close to the shape of the final part are critical to obtaining high quality parts while simultaneously reducing labour and costs associated with other composite manufacturing techniques. One type of fabric which is well suited for near-net- shape preforms is stitched non-crimp fabrics. These fabrics offer very high in-plane strength and stiffness while also having increased resistance to delamination. Manufacturing parts from these dry preforms typically involves long-scale fluid flow through both open channels and porous fibre bundles. This thesis documents and analyzes the flow of fluid through preforms manufactured from non-crimp fabrics featuring through-thickness stitches. The objective of this research is to determine the effect of this type of stitch on the RTM injection process. All of the tests used preforms with fibre volume fractions representative of primary and secondary structural parts. A series of trials was conducted using different fibre materials, flow rates, fibre volumes fractions, and degrees of fibre consolidation. All of the trials were conducted for cases similar to RTM. Consolidation of the fibres showed improvements to both the thoroughness of the filling and to the fibre volume fraction. Experimentally determined permeability data was shown to trend well with simple models and precision of the permeability data was comparable to values presented by other authors who studied fabrics which did not feature the through-thickness stitches.

  1. Ultrasonic characterization of the fiber-matrix interfacial bond in aerospace composites.

    PubMed

    Aggelis, D G; Kleitsa, D; Matikas, T E

    2013-01-01

    The properties of advanced composites rely on the quality of the fiber-matrix bonding. Service-induced damage results in deterioration of bonding quality, seriously compromising the load-bearing capacity of the structure. While traditional methods to assess bonding are destructive, herein a nondestructive methodology based on shear wave reflection is numerically investigated. Reflection relies on the bonding quality and results in discernable changes in the received waveform. The key element is the "interphase" model material with varying stiffness. The study is an example of how computational methods enhance the understanding of delicate features concerning the nondestructive evaluation of materials used in advanced structures. PMID:23935408

  2. Ultrasonic Characterization of the Fiber-Matrix Interfacial Bond in Aerospace Composites

    PubMed Central

    Aggelis, D. G.; Kleitsa, D.; Matikas, T. E.

    2013-01-01

    The properties of advanced composites rely on the quality of the fiber-matrix bonding. Service-induced damage results in deterioration of bonding quality, seriously compromising the load-bearing capacity of the structure. While traditional methods to assess bonding are destructive, herein a nondestructive methodology based on shear wave reflection is numerically investigated. Reflection relies on the bonding quality and results in discernable changes in the received waveform. The key element is the “interphase” model material with varying stiffness. The study is an example of how computational methods enhance the understanding of delicate features concerning the nondestructive evaluation of materials used in advanced structures. PMID:23935408

  3. Ultrasonic guided wave monitoring of composite wing skin-to-spar bonded joints in aerospace structures

    NASA Astrophysics Data System (ADS)

    Matt, Howard; Bartoli, Ivan; Lanza di Scalea, Francesco

    2005-10-01

    The monitoring of adhesively bonded joints by ultrasonic guided waves is the general topic of this paper. Specifically, composite-to-composite joints representative of the wing skin-to-spar bonds of unmanned aerial vehicles (UAVs) are examined. This research is the first step towards the development of an on-board structural health monitoring system for UAV wings based on integrated ultrasonic sensors. The study investigates two different lay-ups for the wing skin and two different types of bond defects, namely poorly cured adhesive and disbonded interfaces. The assessment of bond state is based on monitoring the strength of transmission through the joints of selected guided modes. The wave propagation problem is studied numerically by a semi-analytical finite element method that accounts for viscoelastic damping, and experimentally by ultrasonic testing that uses small PZT disks preferably exciting and detecting the single-plate s0 mode. Both the models and the experiments confirm that the ultrasonic energy transmission through the joint is highly dependent on the bond conditions, with defected bonds resulting in increased transmission strength. Large sensitivity to the bond conditions is found at mode coupling points, as a result of the large interlayer energy transfer.

  4. Investigation on corrosion and wear behaviors of nanoparticles reinforced Ni-based composite alloying layer

    NASA Astrophysics Data System (ADS)

    Xu, Jiang; Tao, Jie; Jiang, Shuyun; Xu, Zhong

    2008-04-01

    In order to investigate the role of amorphous SiO 2 particles in corrosion and wear resistance of Ni-based metal matrix composite alloying layer, the amorphous nano-SiO 2 particles reinforced Ni-based composite alloying layer has been prepared by double glow plasma alloying on AISI 316L stainless steel surface, where Ni/amorphous nano-SiO 2 was firstly predeposited by brush plating. The composition and microstructure of the nano-SiO 2 particles reinforced Ni-based composite alloying layer were analyzed by using SEM, TEM and XRD. The results indicated that the composite alloying layer consisted of γ-phase and amorphous nano-SiO 2 particles, and under alloying temperature (1000 °C) condition, the nano-SiO 2 particles were uniformly distributed in the alloying layer and still kept the amorphous structure. The corrosion resistance of composite alloying layer was investigated by an electrochemical method in 3.5%NaCl solution. Compared with single alloying layer, the amorphous nano-SiO 2 particles slightly decreased the corrosion resistance of the Ni-Cr-Mo-Cu alloying layer. X-ray photoelectron spectroscopy (XPS) revealed that the passive films formed on the composite alloying consisted of Cr 2O 3, MoO 3, SiO 2 and metallic Ni and Mo. The dry wear test results showed that the composite alloying layer had excellent friction-reduced property, and the wear weight loss of composite alloying layer was less than 60% of that of Ni-Cr-Mo-Cu alloying layer.

  5. Design, fabrication and test of graphite/polyimide composite joints and attachments for advanced aerospace vehicles

    NASA Technical Reports Server (NTRS)

    1981-01-01

    The development of several types of graphite/polyimide (GR/PI) bonded and bolted joints is reported. The program consists of two concurrent tasks: (1) design and test of specific built up attachments; and (2) evaluation of standard advanced bonded joint concepts. A data base for the design and analysis of advanced composite joints for use at elevated temperatures (561K (550 deg F)) to design concepts for specific joining applications, and the fundamental parameters controlling the static strength characteristics of such joints are evaluated. Data for design and build GR/PI of lightly loaded flight components for advanced space transportation systems and high speed aircraft are presented. Results for compression and interlaminar shear strengths of Celion 6000/PMR-15 laminates are given. Static discriminator test results for type 3 and type 4 bonded and bolted joints and final joint designs for TASK 1.4 scale up fabrication and testing are presented.

  6. Novel Nanolaminates for Aerospace Applications

    NASA Technical Reports Server (NTRS)

    Volz, Martin; Mazuruk, consty

    2006-01-01

    Nanolaminate manufacturing (NLM) is a new way of developing materials whose properties can far exceed those of homogeneous materials. Traditional alloys, composites and bulk laminates tend to average the properties of the materials from which they were made. With nanostructured materials, the high density of interfaces between dissimilar materials results in novel material properties. For example, materials made -from alternating nanoscale layers of metals and oxides have exhibited thermal conductivities far below those of the oxides themselves. Also, metallic nanolaminates can have peak strengths 100 times lager than the bulk constituent metals. Recent work at MSFC has focused on the development of nickel/aluminum oxide (Ni/Al2O3)) nanolaminates. Ni/Al2O3 nanolaminates are expected to have better strength, creep and fatigue resistance, oxygen compatibility, and corrosion resistance than the traditional metal-matrix composites of this material, which has been used in a variety of aerospace applications. A chemical vapor deposition (CW) system has been developed and optimized for the deposition of nanolaminates. Nanolaminates with layer thicknesses between 10 and 300 nm have been successfully grown and characterization has included scanning electron microscopy (SEM) and atomic force microscopy (AFM) Nanolaminates have a large variety of potential applications. They can be tailored to have both very small and anisotropic thermal conductivities and are promising as thermal coatings for both rock$ engine components and aerobraking structures. They also have the potential to be used in aerospace applications where strength at high temperatures, corrosion resistance or resistance to hydrogen embrittlement is important. Both CVD and magnetron sputtering facilities are available for the deposition of nanolayered materials. Characterization equipment includes SEM, AFM, X-ray diffraction, transmission electron microscopy, optical profilometry, and mechanical tensile pull

  7. and Carbon Fiber Reinforced 2024 Aluminum Alloy Composites

    NASA Astrophysics Data System (ADS)

    Kaczmar, Jacek W.; Naplocha, Krzysztof; Morgiel, Jerzy

    2014-08-01

    The microstructure and mechanical properties of 2024 aluminum alloy composite materials strengthened with Al2O3 Saffil fibers or together with addition of carbon fibers were investigated. The fibers were stabilized in the preform with silica binder strengthened by further heat treatment. The preforms with 80-90% porosity were infiltrated by direct squeeze casting method. The microstructure of the as-cast specimens consisted mainly of α-dendrites with intermetallic compounds precipitated at their boundaries. The homogenization treatment of the composite materials substituted silica binder with a mixture of the Θ phase and silicon precipitates distributed in the remnants of SiO2 amorphous phase. Outside of this area at the binder/matrix interface, fine MgO precipitates were also present. At surface of C fibers, a small amount of fine Al3C4 carbides were formed. During pressure infiltration of preforms containing carbon fibers under oxygen carrying atmosphere, C fibers can burn releasing gasses and causing cracks initiated by thermal stress. The examination of tensile and bending strength showed that reinforcing of aluminum matrix with 10-20% fibers improved investigated properties in the entire temperature range. The largest increase in relation to unreinforced alloy was observed for composite materials examined at the temperature of 300 °C. Substituting Al2O3 Saffil fibers with carbon fibers leads to better wear resistance at dry condition with no relevant effect on strength properties.

  8. Design, fabrication and test of graphite/polyimide composite joints and attachments for advanced aerospace vehicles

    NASA Technical Reports Server (NTRS)

    Barclay, D. L.

    1980-01-01

    Results of an experimental program to develop several types of graphite/polyimide (GR/PI) bonded and bolted joints for lightly loaded flight components for advanced space transportation systems and high speed aircraft are presented. Tasks accomplished include: a literature survey; design of static discriminator specimens; design allowables testing; fabrication of test panels and specimens; small specimen testing; and standard joint testing. Detail designs of static discriminator specimens for each of the four major attachment types are presented. Test results are given for the following: (1) transverse tension of Celion 3000/PMR-15 laminate; (2) net tension of a laminate for both a loaded and unloaded bolt hole; (3) comparative testing of bonded and co-cured doublers along with pull-off tests of single and double bonded angles; (4) single lap shear tests, transverse tension and coefficient of thermal expansion tests of A7F (LARC-13 amide-imide modified) adhesive; and (5) tension tests of standard single lap, double lap, and symmetric step lap bonded joints. Also, included are results of a finite element analysis of a single lap bonded composite joint.

  9. Origins of compositional order in NiPt alloys

    NASA Astrophysics Data System (ADS)

    Pinski, F. J.; Ginatempo, B.; Johnson, D. D.; Staunton, J. B.; Stocks, G. M.; Gyorffy, B. L.

    1991-02-01

    We investigate the cause of compositional ordering in fcc Ni0.50Pt0.50 on the basis of a first-principles theory of electronic structure and finite-temperature concentration fluctuations. We treat the size effect, electronegativity, and band filling on an equal footing and find that the first of these dominates, leading to L10 ordering in agreement with experiment. An electronic origin is given for the metallurgical ``rule of thumb'' that alloys comprised of big atoms and little atoms tend to order into simple stuctures.

  10. Composites

    SciTech Connect

    Chou, T.; McCullough, R.L.; Pipes, R.B.

    1986-10-01

    The degree of control over material properties that is typified by hybrid composites is transforming engineering design. In part because homogeneous materials such as metals and alloys do not offer comparable control, specifying a material and designing a component have traditionally taken place separately. As composites begin to replace traditional materials in fields and such as aerospace, component design and the specification of a material are merging and becoming aspects of a single process. The controllable microstructure of a composite allows it to be tailored to match the distribution of stresses to which it will be subject. At the same time components must come to reflect the distinctive nature of composites: their directional properties and the intricate forms they can be given through processes such as injection molding, filament winding and three-dimensional weaving. The complexity inherent in conceiving components and their materials at the same time suggests engineering design will grow increasingly dependent on computers and multidisciplinary teams. Such an approach will harness the full potential of composites for the technologies of the future. 10 figures.

  11. The effect of water vapor on fatigue crack Growth in 7475-t651 aluminum alloy plate. [for aerospace applications

    NASA Technical Reports Server (NTRS)

    Dicus, D. L.

    1982-01-01

    The effects of water vapor on fatigue crack growth in 7475-T651 aluminum alloy plate at frequencies of 1 Hz and 10 Hz were investigated. Twenty-five mm thick compact specimens were subjected to constant amplitude fatigue testing at a load ratio of 0.2. Fatigue crack growth rates were calculated from effective crack lengths determined using a compliance method. Tests were conducted in hard vacuum and at water vapor partial pressures ranging from 94 Pa to 3.8 kPa. Fatigue crack growth rates were frequency insensitive under all environment conditions tested. For constant stress intensity factor ranges crack growth rate transitions occurred at low and high water vapor pressures. Crack growth rates at intermediate pressures were relatively constant and showed reasonable agreement with published data for two Al-Cu-Mg alloys. The existence of two crack growth rate transitions suggests either a change in rate controlling kinetics or a change in corrosion fatigue mechanism as a function of water vapor pressure. Reduced residual deformation and transverse cracking specimens tested in water vapor versus vacuum may be evidence of embrittlement within the plastic zone due to environmental interaction.

  12. Effect of water vapor on fatigue crack growth in 7475-T651 aluminum alloy plate. [for aerospace applications

    NASA Technical Reports Server (NTRS)

    Dicus, D. L.

    1984-01-01

    The effects of water vapor on fatigue crack growth in 7475-T651 aluminum alloy plate at frequencies of 1 Hz and 10 Hz were investigated. Twenty-five mm thick compact specimens were subjected to constant amplitude fatigue testing at a load ratio of 0.2. Fatigue crack growth rates were calculated from effective crack lengths determined using a compliance method. Tests were conducted in hard vacuum and at water vapor partial pressures ranging from 94 Pa to 3.8 kPa. Fatigue crack growth rates were frequency insensitive under all environment conditions tested. For constant stress intensity factor ranges crack growth rate transitions occurred at low and high water vapor pressures. Crack growth rates at intermediate pressures were relatively constant and showed reasonable agreement with published data for two Al-Cu-Mg alloys. The existence of two crack growth rate transitions suggests either a change in rate controlling kinetics or a change in corrosion fatigue mechanism as a function of water vapor pressure. Reduced residual deformation and transverse cracking specimens tested in water vapor versus vacuum may be evidence of embrittlement within the plastic zone due to environmental interaction.

  13. Refractory metal alloys and composites for space power systems

    SciTech Connect

    Stephens, J.R.; Petrasek, D.W.; Titran, R.H.

    1994-09-01

    Space power requirements for future NASA and other United States missions will range from a few kilowatts to megawatts of electricity. Maximum efficiency is a key goal of any power system in order to minimize weight and size so that the space shuttle may be used a minimum number of times to put the power supply into orbit. Nuclear power has been identified as the primary power source to meet these high levels of electrical demand. One method to achieve maximum efficiency is to operate the power supply, energy conversion system, and related components at relatively high temperatures. NASA Lewis Research Center has undertaken a research program on advanced technology of refractory metal alloys and composites that will provide base line information for space power systems in the 1900`s and the 21st century. Basic research on the tensile and creep properties of fibers, matrices, and composites will be discussed.

  14. Refractory metal alloys and composites for space power systems

    NASA Technical Reports Server (NTRS)

    Stephens, Joseph R.; Petrasek, Donald W.; Titran, Robert H.

    1988-01-01

    Space power requirements for future NASA and other U.S. missions will range from a few kilowatts to megawatts of electricity. Maximum efficiency is a key goal of any power system in order to minimize weight and size so that the space shuttle may be used a minimum number of times to put the power supply into orbit. Nuclear power has been identified as the primary source to meet these high levels of electrical demand. One way to achieve maximum efficiency is to operate the power supply, energy conversion system, and related components at relatively high temperatures. NASA Lewis Research Center has undertaken a research program on advanced technology of refractory metal alloys and composites that will provide baseline information for space power systems in the 1900's and the 21st century. Basic research on the tensile and creep properties of fibers, matrices, and composites is discussed.

  15. Aerospace Medicine

    NASA Technical Reports Server (NTRS)

    Davis, Jeffrey R.

    2006-01-01

    This abstract describes the content of a presentation for ground rounds at Mt. Sinai School of Medicine. The presentation contains three sections. The first describes the history of aerospace medicine beginning with early flights with animals. The second section of the presentation describes current programs and planning for future missions. The third section describes the medical challenges of exploration missions.

  16. Low Cost Al-Si Casting Alloy As In-Situ Composite for High Temperature Applications

    NASA Technical Reports Server (NTRS)

    Lee, Jonathan A.

    2000-01-01

    A new aluminum-silicon (Al-Si) alloy has been successfully developed at NASA- Marshall Space Flight Center (MSFC) that has significant improvement in tensile and fatigue strength at elevated temperatures (500 F-700 F). The alloy offers a number of benefits such as light weight, high hardness, low thermal expansion and high surface wear resistance. In hypereutectic form, this alloy is considered as an in-situ Al-Si composite with tensile strength of about 90% higher than the auto industry 390 alloy at 600 F. This composite is very economically produced by using either conventional permanent steel molds or die casting. The projected material cost is less than $0.90 per pound, and automotive components such as pistons can be cast for high production rate using conventional casting techniques with a low and fully accounted cost. Key Words: Metal matrix composites, In-situ composite, aluminum-silicon alloy, hypereutectic alloy, permanent mold casting, die casting.

  17. Quasicrystalline particulate reinforced aluminum composite

    SciTech Connect

    Anderson, I.E.; Biner, S.B.; Sordelet, D.J.; Unal, O.

    1997-07-01

    Particulate reinforced aluminum and aluminum alloy composites are rapidly emerging as new commercial materials for aerospace, automotive, electronic packaging and other high performance applications. However, their low processing ductility and difficulty in recyclability have been the key concern. In this study, two composite systems having the same aluminum alloy matrix, one reinforced with quasicrystals and the other reinforced with the conventional SiC reinforcements were produced with identical processing routes. Their processing characteristics and tensile mechanical properties were compared.

  18. Aluminum-matrix electrotechnical composite alloys hardened by endogenous nano- and microphases

    NASA Astrophysics Data System (ADS)

    Babkin, V. G.; Terent'ev, N. A.; Cherepanov, A. I.

    2014-09-01

    A method is developed to manufacture aluminum-matrix composite alloys hardened by endogenous nano- and microphases. The formation of the structure and properties of the composite materials is studied. The experimental results demonstrate that the developed alloys are promising to produce electro-technical wire rods and other electrotechnical products.

  19. Physical and Mechanical Properties of Composites and Light Alloys Reinforced with Detonation Nanodiamonds

    NASA Astrophysics Data System (ADS)

    Sakovich, G. V.; Vorozhtsov, S. A.; Vorozhtsov, A. B.; Potekaev, A. I.; Kulkov, S. N.

    2016-07-01

    The influence of introduction of particles of detonation-synthesized nanodiamonds into composites and aluminum-base light alloys on their physical and mechanical properties is analyzed. The data on microstructure and physical and mechanical properties of composites and cast aluminum alloys reinforced with diamond nanoparticles are presented. The introduction of nanoparticles is shown to result in a significant improvement of the material properties.

  20. Laser Cladding of Composite Bioceramic Coatings on Titanium Alloy

    NASA Astrophysics Data System (ADS)

    Xu, Xiang; Han, Jiege; Wang, Chunming; Huang, Anguo

    2016-02-01

    In this study, silicon nitride (Si3N4) and calcium phosphate tribasic (TCP) composite bioceramic coatings were fabricated on a Ti6Al4V (TC4) alloy using Nd:YAG pulsed laser, CO2 CW laser, and Semiconductor CW laser. The surface morphology, cross-sectional microstructure, mechanical properties, and biological behavior were carefully investigated. These investigations were conducted employing scanning electron microscope, energy-dispersive x-ray spectroscopy, and other methodologies. The results showed that both Si3N4 and Si3N4/TCP composite coatings were able to form a compact bonding interface between the coating and the substrate by using appropriate laser parameters. The coating layers were dense, demonstrating a good surface appearance. The bioceramic coatings produced by laser cladding have good mechanical properties. Compared with that of the bulk material, microhardness of composite ceramic coatings on the surface significantly increased. In addition, good biological activity could be obtained by adding TCP into the composite coating.

  1. Understanding Plasticity and Fracture in Aluminum Alloys and their Composites by 3D X-ray Synchrotron Tomography and Microdiffraction

    NASA Astrophysics Data System (ADS)

    Hruby, Peter

    Aluminum alloys and their composites are attractive materials for applications requiring high strength-to-weight ratios and reasonable cost. Many of these applications, such as those in the aerospace industry, undergo fatigue loading. An understanding of the microstructural damage that occurs in these materials is critical in assessing their fatigue resistance. Two distinct experimental studies were performed to further the understanding of fatigue damage mechanisms in aluminum alloys and their composites, specifically fracture and plasticity. Fatigue resistance of metal matrix composites (MMCs) depends on many aspects of composite microstructure. Fatigue crack growth behavior is particularly dependent on the reinforcement characteristics and matrix microstructure. The goal of this work was to obtain a fundamental understanding of fatigue crack growth behavior in SiC particle-reinforced 2080 Al alloy composites. In situ X-ray synchrotron tomography was performed on two samples at low (R=0.1) and at high (R=0.6) R-ratios. The resulting reconstructed images were used to obtain three-dimensional (3D) rendering of the particles and fatigue crack. Behaviors of the particles and crack, as well as their interaction, were analyzed and quantified. Four-dimensional (4D) visual representations were constructed to aid in the overall understanding of damage evolution. During fatigue crack growth in ductile materials, a plastic zone is created in the region surrounding the crack tip. Knowledge of the plastic zone is important for the understanding of fatigue crack formation as well as subsequent growth behavior. The goal of this work was to quantify the 3D size and shape of the plastic zone in 7075 Al alloys. X-ray synchrotron tomography and Laue microdiffraction were used to non-destructively characterize the volume surrounding a fatigue crack tip. The precise 3D crack profile was segmented from the reconstructed tomography data. Depth-resolved Laue patterns were obtained using

  2. Making Thin Laminae Of Frozen Alloy Slurries

    NASA Technical Reports Server (NTRS)

    Ghosh, A. K.; Holmes, L. M.; Houston, R. B.; Ecer, G. M.

    1992-01-01

    In new technique, primary objective to develop method to distribute uniformly-thin powder-metal-alloy layers between alternate fiber layers prior to consolidation. Involves use of sheets of frozen alloy powder. These laminae, interspersed with fiber mats, used to make metal/fiber composites. In addition to aerospace applications, this technique, appropriately modified, has potential in the manufacture of future automobile engines or components including molded ceramics.

  3. Comparison of the Effects of Tool Geometry for Friction Stir Welding Thin Sheet Aluminum Alloys for Aerospace Applications

    NASA Technical Reports Server (NTRS)

    Merry, Josh; Takeshita, Jennifer; Tweedy, Bryan; Burford, Dwight

    2006-01-01

    In this presentation, the results of a recent study on the effect of pin tool design for friction stir welding thin sheets (0.040") of aluminum alloys 2024 and 7075 are provided. The objective of this study was to investigate and document the effect of tool shoulder and pin diameter, as well as the presence of pin flutes, on the resultant microstructure and mechanical properties at both room temperature and cryogenic temperature. Specifically, the comparison between three tools will include: FSW process load analysis (tool forces required to fabricate the welds), Static Mechanical Properties (ultimate tensile strength, yield strength, and elongation), and Process window documenting the range of parameters that can be used with the three pin tools investigated. All samples were naturally aged for a period greater than 10 days. Prior research has shown 7075 may require post weld heat treatment. Therefore, an additional pair of room temperature and cryogenic temperature samples was post-weld aged to the 7075-T7 condition prior to mechanical testing.

  4. Influence of laser surface treated on the characterization and corrosion behavior of Al-Fe aerospace alloys

    NASA Astrophysics Data System (ADS)

    Pariona, Moisés Meza; Teleginski, Viviane; dos Santos, Kelly; de Lima, Angela A. O. C.; Zara, Alfredo J.; Micene, Katieli Tives; Riva, Rudimar

    2013-07-01

    In this research laser surface remelting without protective coating with a 2 kW Yb-fiber laser (IPG YLR-2000S) was applied in the Al-1.5 wt.%Fe alloy in order to investigate the layer treated with different techniques of superficial characterization, thereby, the technique of optical microscopy, atomic force microscopy and low-angle X-ray diffraction were used. The present work mainly focuses on the corrosion study by diverse techniques in aggressive environment of the laser-treated area and the substrate material was carried out, thereby, at open circuit potential testing, the results have shown a displacement to more anodic values in the corrosion potential for the laser-treated specimen when compared to the untreated specimen; in potentiodynamic polarization tests have shown that as a result of the laser treatment, the corrosion current can be reduced by as much as ten times, and a passive region was obtained, which served as an effective barrier for reducing anodic dissolution and finally, the result in cyclic polarization curves of the untreated sample there was a greater area of the hysteresis loop, implying that it is more susceptible to corrosion. This study was complemented by other techniques mentioned above in order to elucidate this study. Laser surface remelting process has definitely modified the surface film, which results in higher corrosion resistance, a large range of passivation and a lower area of the hysteresis loop.

  5. Interfacial stresses in shape memory alloy-reinforced composites

    NASA Astrophysics Data System (ADS)

    Hiremath, S. R.; Prajapati, Maulik; Rakesh, S.; Roy Mahapatra, D.

    2014-03-01

    Debonding of Shape Memory Alloy (SMA) wires in SMA reinforced polymer matrix composites is a complex phenomenon compared to other fabric fiber debonding in similar matrix composites. This paper focuses on experimental study and analytical correlation of stress required for debonding of thermal SMA actuator wire reinforced composites. Fiber pull-out tests are carried out on thermal SMA actuator at parent state to understand the effect of stress induced detwinned martensites. An ASTM standard is followed as benchmark method for fiber pull-out test. Debonding stress is derived with the help of non-local shear-lag theory applied to elasto-plastic interface. Furthermore, experimental investigations are carried out to study the effect of Laser shot peening on SMA surface to improve the interfacial strength. Variation in debonding stress due to length of SMA wire reinforced in epoxy are investigated for non-peened and peened SMA wires. Experimental results of interfacial strength variation due to various L/d ratio for non-peened and peened SMA actuator wires in epoxy matrix are discussed.

  6. Design of fish fin actuators using shape memory alloy composites

    NASA Astrophysics Data System (ADS)

    Ono, Nagato; Kusaka, Masahiro; Taya, Minoru; Wang, Chiyuan

    2004-07-01

    The present paper considers a design of fish fin actuators based on shape memory alloy composites composed of a couple of plates with the opposite functions. Both SMA plates, whose microstructure is either martensite or austenite, are individually arranged in parallel and operated as a bias to each other. The actuation mechanism is based on change in elastic constant, from stiff to soft during austenite to martensite transformation. First, a preliminary model of the elastic and superelastic deformation is proposed for prediction of the optimum curvature of SMA plates, which enable us to control the steering of an underwater object. The analytical model provides the relationship between the bending moment and the curvature for the composite plates in each deformation range. For a given velocity of a moving fish robot, the underwater curvature and bending moment of its plates is successfully obtained. We design such a fish fin actuator made of a set of different types of SMA composite plates which are embedded in an elastometer matrix to form a fish tail fin.

  7. Advances in powder metallurgy - 1991. Vol. 6 - Aerospace, refractory and advanced materials; Proceedings of the Powder Metallurgy Conference and Exhibition, Chicago, IL, June 9-12, 1991

    SciTech Connect

    Pease, L.F. III; Sansoucy, R.J.

    1991-01-01

    Various papers on aerospace, refractory, and advanced materials are presented. Individual topics addressed include: nonequilibrium processing of powder alloys for aerospace applications, chemical conditioning of rapidly solidified aluminum alloy particulate, fabrication of rapidly solidified high temperature aluminum alloys, fatigue and fracture of an advanced PM-aluminum alloy, thermal and mechanical properties of extruded 7075-Al P/M alloys, reactive sintering and reactive hot isostatic pressing of iron aluminides, P/M processing and applications of Fe3Al-based intermetallics, properties of plasma atomized NiAl powders, processing of continuous fiber reinforced NiAl matrix composite. Also discussed are: powder forging process on an alumimum alloy, P/M magnesium particle composites, P/M short-fiber-reinforced magnesium, mechanical properties of a TiAl6V4 alloy processed by powder metallurgy, porous core/Be Ti-6-4 development for aerospace structures, consolidation and plasticity of Bi-Sr-Ca-Cu-O superconductors, development of a new W-Ni-Mn heavy alloy.

  8. Ductile alloy and process for preparing composite superconducting wire

    DOEpatents

    Verhoeven, J.D.; Finnemore, D.K.; Gibson, E.D.; Ostenson, J.E.

    An alloy for the commercial production of ductile superconducting wire is prepared by melting together copper and at least 15 weight percent niobium under non-oxygen-contaminating conditions, and rapidly cooling the melt to form a ductile composite consisting of discrete, randomly distributed and oriented dendritic-shaped particles of niobium in a copper matrix. As the wire is worked, the dendritic particles are realigned parallel to the longitudinal axis and when drawn form a plurality of very fine ductile superconductors in a ductile copper matrix. The drawn wire may be tin coated and wound into magnets or the like before diffusing the tin into the wire to react with the niobium. Impurities such as aluminum or gallium may be added to improve upper critical field characteristics.

  9. Ductile alloy and process for preparing composite superconducting wire

    DOEpatents

    Verhoeven, John D.; Finnemore, Douglas K.; Gibson, Edwin D.; Ostenson, Jerome E.

    1983-03-29

    An alloy for the commercial production of ductile superconducting wire is prepared by melting together copper and at least 15 weight percent niobium under non-oxygen-contaminating conditions, and rapidly cooling the melt to form a ductile composite consisting of discrete, randomly distributed and orientated dendritic-shaped particles of niobium in a copper matrix. As the wire is worked, the dendritric particles are realigned parallel to the longitudinal axis and when drawn form a plurality of very fine ductile superconductors in a ductile copper matrix. The drawn wire may be tin coated and wound into magnets or the like before diffusing the tin into the wire to react with the niobium. Impurities such as aluminum or gallium may be added to improve upper critical field characteristics.

  10. The effect of second-phase on the corrosion and wear behaviors of composite alloying layer

    NASA Astrophysics Data System (ADS)

    Xu, Jiang; Zhuo, Chenzhi; Tao, Jie; Jiang, Shuyun

    2008-12-01

    The present study concerns the effect of second-phase on the corrosion and wear behaviors of composite alloying layer, which is prepared by double glow plasma alloying of AISI316L steel with predeposited Ni/nano-SiC particle interlayer (by electric brush plating). The composition and microstructure of the composite alloying layer are analyzed by means of scanning electron microscopy (SEM), transmission electron microscope (TEM) and X-ray diffraction (XRD). The results indicate that decomposition of nano-SiC particles have occurred under alloying temperature (1000 °C) condition and nano-SiC particles have reacted with Ni and Cr to form Cr 6.5Ni 2.5Si phase and Cr 23C 6 phase. The corrosion resistance of composite alloying layer was investigated by an electrochemical method in 3.5% NaCl and 5% HCl solution. The experimental results show that the corrosion resistance of the composite alloying layer is higher than that of AISI316L stainless steel and Ni/nano-SiC plating coating, but apparently lower than that of single alloying layer, which proves that the precipitated phase is harmful to the corrosion behavior of Ni-based alloying layer. The dry wear test results show that the composite alloying layer has excellent friction-reduced property, and relative wear resistance of composite alloying layer to Ni/nano-SiC plating coating, alloying layer and 316L stainless steel is 2.9, 3.6 and 5.3, respectively.

  11. The effect of alloy composition on the mechanism of stress corrosion cracking of titanium alloys in aqueous environments

    NASA Technical Reports Server (NTRS)

    Williams, D. N.

    1971-01-01

    Emphasis has been placed on determining the interrelations among the composition, phase structure, deformation, and fracture properties of the alpha phase in susceptible alpha-beta alloys. The program is divided into two parts: (1) evaluation of the aqueous stress corrosion susceptibility of a series of alloys that contain various alpha-soluble elements; and (2) investigations of the metallurgical aspects of the mechanism of aqueous stress corrosion cracking.

  12. Aerospace gerontology

    NASA Technical Reports Server (NTRS)

    Comfort, A.

    1982-01-01

    The relevancy of gerontology and geriatrics to the discipline of aerospace medicine is examined. It is noted that since the shuttle program gives the facility to fly passengers, including specially qualified older persons, it is essential to examine response to acceleration, weightlessness, and re-entry over the whole adult lifespan, not only its second quartile. The physiological responses of the older person to weightlessness and the return to Earth gravity are reviewed. The importance of the use of the weightless environment to solve critical problems in the fields of fundamental gerontology and geriatrics is also stressed.

  13. Designation of alloy composition of reduced-activation martensitic steel

    NASA Astrophysics Data System (ADS)

    Kimura, A.; Kayano, H.; Misawa, T.; Matsui, H.

    1994-09-01

    An alloy composition of reduced-activation martensitic steel for fusion reactor is designed on the basis of the experimental results of postirradiation microstructure, mechanical properties, such as creep, fracture toughness and tensile properties, hydrogen effects and corrosion. At present, a desired composition of the steel is 0.1C-0.05Si-0.5Mn-9Cr-2W-0.25V-0.02Ti-0.05Ta- < 0.002S- < 0.002P by weight percent. Effects of the other minor elements such as Al, Zr and B are also inspected. An addition of 0.05 wt% Ta increases the high temperature strength but reduces the fracture toughness. Susceptibility to hydrogen-induced cracking is reduced by an addition of 0.03 wt% Al, though it results in a severe degradation of the fracture toughness. An addition of 30 wppm B together with the addition of 0.02 wt% Ti increases the fracture toughness. Void nucleation at grain boundaries, however, is enhanced by the B addition under the FFTF irradiation at 638 K in 10 dpa.

  14. Transients in the composition of material sputtered from alloy targets

    NASA Astrophysics Data System (ADS)

    Andersen, H. H.; Stenum, B.; Sørensen, T.; Whitlow, H. J.

    1984-03-01

    Material sputtered with 20-320 keV Ar + ions from the binary alloys CuPt, Ni 5Pd and NiPt has been collected sequentially on thin carbon foils. The composition of the collected material was analyzed by Rutherford backscattering to reveal transients in the composition of the sputtered flux. In the beginning Cu and Ni were preferentially ejected. These results, together with earlier data for AgAu and Cu 3Au, where Ag and Cu were preferentially ejected, show the lighter element to be preferentially emitted during the transient, but particularly the results for Cu 3Au and Ni 5Pd suggest that a native oxide layer may play a substantial role, althogh only for the case of Cu 3Au did such an oxide have a sufficient thickness to be revealed by Rutherford backscattering. Measurements have further been carried out for pure copper bombarded with 45 keV Bi + ions. Here, the bismuth re-emission reaches a steady-state a factor of 10 faster than the copper yield, a fact which again may be related to oxygen-driven surface segregation.

  15. Influence of Chemical Composition of Mg Alloys on Surface Alloying by Diffusion Coating

    NASA Astrophysics Data System (ADS)

    Hirmke, J.; Zhang, M.-X.; St John, D. H.

    2012-05-01

    A recently developed technique of surface alloying by diffusion-coating has been used to produce coatings on Mg alloys with various Al and Zn contents. The experimental results show that both Al and Zn solutes in the alloy promote the diffusion of alloying elements through grain refinement of the substrate alloys and through reduction of diffusion active energy because of the reduction of melting temperature of the alloys. Therefore, the efficiency of surface alloying increases by diffusion coating. Thick, dense, uniform, and continuous layers of intermetallic compounds, which consist of a τ-phase layer and a β-phase layer, can be produced on the surface of various Mg alloys. The intermetallic compound layers not only have microhardness values that are 4 to 6 times higher than the substrate but also provide effective protection of the Mg alloys from corrosion in 5 pct NaCl solution at room temperature.

  16. Bond strength of composites to etched and silica-coated porcelain fusing alloys.

    PubMed

    Schneider, W; Powers, J M; Pierpont, H P

    1992-05-01

    In vitro bond strengths of two composite veneering materials to two porcelain fusing alloys were measured utilizing two storage conditions. The alloys were etched or treated with silica applied by blasted, thermal or pyrogenic techniques and then silanated. Bond strengths were higher for the Ni-Cr-Be than the Au-Pd alloy with most values greater than 18 MPa. Bond strengths to etched and silanated Au-Pd alloy were low (less than 6.5 MPa), whereas samples treated with silica and silanated had significantly higher values. Bond strengths to the Ni-Cr-Be alloy were highest with the thermal and pyrogenic silica treatments. After thermocycling, most bond strengths to the Au-Pd alloy decreased, but were the same or higher to the Ni-Cr-Be alloy. Cohesive failures of the opaquers were observed. PMID:1325930

  17. Low energy milling method, low crystallinity alloy, and negative electrode composition

    DOEpatents

    Le, Dihn B; Obrovac, Mark N; Kube, Robert Y; Landucci, James R

    2012-10-16

    A method of making nanostructured alloy particles includes milling a millbase in a pebble mill containing milling media. The millbase comprises: (i) silicon, and (ii) at least one of carbon or a transition metal, and wherein the nanostructured alloy particles are substantially free of crystalline domains greater than 50 nanometers in size. A method of making a negative electrode composition for a lithium ion battery including the nanostructured alloy particles is also disclosed.

  18. Basic Aerospace Education Library

    ERIC Educational Resources Information Center

    Journal of Aerospace Education, 1975

    1975-01-01

    Lists the most significant resource items on aerospace education which are presently available. Includes source books, bibliographies, directories, encyclopedias, dictionaries, audiovisuals, curriculum/planning guides, aerospace statistics, aerospace education statistics and newsletters. (BR)

  19. Aerospace Education - An Overview

    ERIC Educational Resources Information Center

    Journal of Aerospace Education, 1975

    1975-01-01

    Discusses the surge of interest throughout the country in aerospace education and discusses what aerospace education is, the implications in career education and the relevance of aerospace education in the curriculum. (BR)

  20. Advanced Ceramic Materials for Future Aerospace Applications

    NASA Technical Reports Server (NTRS)

    Misra, Ajay

    2015-01-01

    With growing trend toward higher temperature capabilities, lightweight, and multifunctionality, significant advances in ceramic matrix composites (CMCs) will be required for future aerospace applications. The presentation will provide an overview of material requirements for future aerospace missions, and the role of ceramics and CMCs in meeting those requirements. Aerospace applications will include gas turbine engines, aircraft structure, hypersonic and access to space vehicles, space power and propulsion, and space communication.

  1. Thermodynamic method of calculating the effect of alloying additives on interphase interaction in composite materials

    NASA Technical Reports Server (NTRS)

    Tuchinsky, L. I.

    1986-01-01

    The effect of alloying additives to the matrix of a composite on the high temperature solubility rate of a single component fiber was analyzed thermodynamically. With an example of binary Ni alloys, with Group IV-VI transition metals reinforced with W fibers, agreement between the calculated and experimental data was demonstrated.

  2. Ballistic Impact Properties of Zr-Based Amorphous Alloy Composites Reinforced with Woven Continuous Fibers

    NASA Astrophysics Data System (ADS)

    Kim, Gyeong Su; Son, Chang-Young; Lee, Sang-Bok; Lee, Sang-Kwan; Song, Young Buem; Lee, Sunghak

    2012-03-01

    This study aims at investigating ballistic impact properties of Zr-based amorphous alloy (LM1 alloy) matrix composites reinforced with woven stainless steel or glass continuous fibers. The fiber-reinforced composites with excellent fiber/matrix interfaces were fabricated without pores and misinfiltration by liquid pressing process, and contained 35 to 41 vol pct of woven continuous fibers homogeneously distributed in the amorphous matrix. The woven-STS-continuous-fiber-reinforced composite consisted of the LM1 alloy layer of 1.0 mm in thickness in the upper region and the fiber-reinforced composite layer in the lower region. The hard LM1 alloy layer absorbed the ballistic impact energy by forming many cracks, and the fiber-reinforced composite layer interrupted the crack propagation and blocked the impact and traveling of the projectile, thereby resulting in the improvement of ballistic performance by about 20 pct over the LM1 alloy. According to the ballistic impact test data of the woven-glass-continuous-fiber-reinforced composite, glass fibers were preferentially fragmented to form a number of cracks, and the amorphous matrix accelerated the fragmentation of glass fibers and the initiation of cracks. Because of the absorption process of ballistic impact energy by forming very large amounts of cracks, fragments, and debris, the glass-fiber-reinforced composite showed better ballistic performance than the LM1 alloy.

  3. A bio-inspired shape memory alloy composite (BISMAC) actuator

    NASA Astrophysics Data System (ADS)

    Villanueva, A. A.; Joshi, K. B.; Blottman, J. B.; Priya, S.

    2010-02-01

    A beam-shape composite actuator using shape memory alloy (SMA) wires as the active component, termed a Bio-Inspired Shape Memory Alloy Composite (BISMAC), was designed to provide a large deformation profile. The BISMAC design was inspired by contraction of a jellyfish bell, utilizing the rowing mechanism for locomotion. Characterization of maximum deformation in underwater conditions was performed for different actuator configurations to analyze the effect of different design parameters, including silicone thickness, flexible steel thickness and distance between the SMA and flexible steel. A constant cross-section (CC)-BISMAC of length 16 cm was found to achieve deformation with a radius of curvature of 3.5 cm. Under equilibrium conditions, the CC-BISMAC was found to achieve 80% of maximum deformation, consuming 7.9 J/cycle driven at 16.2 V/0.98 A and a frequency of 0.25 Hz. A detailed analytical model was developed using the transfer matrix method and a 1D finite beam element (FE) model to simulate the behavior of the BISMAC incorporating gravity, buoyancy and SMA parameters. The FE and transfer matrix models had a maximum deformation error norm of 1.505 and 1.917 cm in comparison with experimentally observed beam deformation in the CC-BISMAC. The mean curvatures predicted by the FE and transfer matrix methods were 0.292 cm-1 and 0.295 cm-1 compared to a mean experimental curvature of 0.294 cm-1, a percentage error of -5.4% and 2.77%, respectively. Using the developed analytical model, an actuator design was fabricated mimicking the maximum deformation profile of jellyfish of the species Aurelia aurita (AA). The designed AA-BISMAC achieved a maximum curvature of 0.428 cm-1 as compared to 0.438 cm-1 for A. aurita with an average square root error of 0.043 cm-1, 10.2% of maximum A. aurita curvature.

  4. The Aerospace Age. Aerospace Education I.

    ERIC Educational Resources Information Center

    Smith, J. C.

    This book is written for use only in the Air Force ROTC program and cannot be purchased on the open market. The book describes the historical development of aerospace industry. The first chapter contains a brief review of the aerospace environment and the nature of technological changes brought by the aerospace revolution. The following chapter…

  5. Effect of composition on antiphase boundary energy in Ni3Al based alloys: Ab initio calculations

    NASA Astrophysics Data System (ADS)

    Gorbatov, O. I.; Lomaev, I. L.; Gornostyrev, Yu. N.; Ruban, A. V.; Furrer, D.; Venkatesh, V.; Novikov, D. L.; Burlatsky, S. F.

    2016-06-01

    The effect of composition on the antiphase boundary (APB) energy of Ni-based L 12-ordered alloys is investigated by ab initio calculations employing the coherent potential approximation. The calculated APB energies for the {111} and {001} planes reproduce experimental values of the APB energy. The APB energies for the nonstoichiometric γ' phase increase with Al concentration and are in line with the experiment. The magnitude of the alloying effect on the APB energy correlates with the variation of the ordering energy of the alloy according to the alloying element's position in the 3 d row. The elements from the left side of the 3 d row increase the APB energy of the Ni-based L 12-ordered alloys, while the elements from the right side slightly affect it except Ni. The way to predict the effect of an addition on the {111} APB energy in a multicomponent alloy is discussed.

  6. The Microstructure-Processing-Property Relationships in an Al Matrix Composite System Reinforced by Al-Cu-Fe Alloy Particles

    SciTech Connect

    Fei Tang

    2004-12-19

    Metal matrix composites (MMC), especially Al matrix composites, received a lot of attention during many years of research because of their promise for the development of automotive and aerospace materials with improved properties and performance, such as lighter weight and better structural properties, improved thermal conductivity and wear resistance. In order to make the MMC materials more viable in various applications, current research efforts on the MMCs should continue to focus on two important aspects, including improving the properties of MMCs and finding more economical techniques to produce MMCs. Solid state vacuum sintering was studied in tap densified Al powder and in hot quasi-isostatically forged samples composed of commercial inert gas atomized or high purity Al powder, generated by a gas atomization reaction synthesis (GARS) technique. The GARS process results in spherical Al powder with a far thinner surface oxide. The overall results indicated the enhanced ability of GARS-processed Al and Al alloy powders for solid state sintering, which may lead to simplification of current Al powder consolidation processing methods. Elemental Al-based composites reinforced with spherical Al-Cu-Fe alloy powders were produced by quasi-isostatic forging and vacuum hot pressing (VHP) consolidation methods. Microstructures and tensile properties of AYAl-Cu-Fe composites were characterized. It was proved that spherical Al-Cu-Fe alloy powders can serve as an effective reinforcement particulate for elemental Al-based composites, because of their high hardness and a preferred type of matrix/reinforcement interfacial bonding, with reduced strain concentration around the particles. Ultimate tensile strength and yield strength of the composites were increased over the corresponding Al matrix values, far beyond typical observations. This remarkable strengthening was achieved without precipitation hardening and without severe strain hardening during consolidation because of

  7. Aging characteristics of short glass fiber reinforced ZA-27 alloy composite materials

    NASA Astrophysics Data System (ADS)

    Sharma, S. C.; Girish, B. M.; Satish, B. M.; Kamath, R.

    1998-12-01

    Aging characteristics of short glass fiber reinforced ZA-27 alloy composite materials have been evaluated in the present study. The liquid metallurgy technique was used to fabricate the composites, in which preheated short glass fibers were introduced into the ZA-27 alloy melt above its liquidus temperature. The aging temperature employed was 125 °C for 6, 12,18, and 24 h. The aged alloy (no fibers) reached the peak hardness after 18 h, while the composites (regardless of filler content) reached the same hardness in 12 h. It is hypothesized that the aging treatment of a composite improves the strength of the interface between the short fibers and the matrix. This is confirmed by the tensile fractograph analysis, which indicates that at a given aging temperature, the composites aged for 18 h exhibit short fibers that remain attached to the metal matrix, while those aged for 6 h undergo debonding.

  8. Core level shifts in Cu-Pd alloys as a function of bulk composition and structure

    NASA Astrophysics Data System (ADS)

    Boes, Jacob R.; Kondratyuk, Peter; Yin, Chunrong; Miller, James B.; Gellman, Andrew J.; Kitchin, John R.

    2015-10-01

    CuPd alloys are important materials in hydrogen purification, where they are used as dense Pd-based separation membranes. Cu is added to impart sulfur tolerance and improved mechanical properties. At intermediate compositions and T < 873 K, a BCC alloy (B2) phase occurs, which has superior separation characteristics to those of the FCC phases that form at high Cu and high Pd compositions. Identifying the composition and temperature window where the B2 phase forms is a critical need to enable the design of improved alloys. A composition spread alloy film of Cu and Pd was synthesized. The film was characterized by electron back scatter diffraction and X-ray photoelectron spectroscopy, providing the core level shifts as a function of bulk composition and bulk structure. An anomalous deviation in the Cu core level shift was observed in the composition range 0.33 < xPd < 0.55 over which the B2 phase occurs. Density functional theory calculations were used to simulate core level shifts in the FCC and B2 alloy structures. They suggest that the anomalous deviation in core level shift is due to formation of the ordered B2 phase in this composition range.

  9. Long-term thermal degradation and alloying constituent effects on five boron/aluminum composites

    NASA Technical Reports Server (NTRS)

    Olsen, G. C.

    1982-01-01

    Thermal exposure effects on the properties of five boron/aluminum composite systems were experimentally investigated. The composite systems were 49 volume percent boron fibers (203 micron diameter) in aluminum-alloy matrices 1100 Al, 2024 Al, 3003 Al, 5052 Al, and 6061 Al. Specimens were thermally exposed up to 10,000 hours at 500 K and 590 K, up to 500 hours at 730 K, and up to 10,000 hours at 500 K and 590 K, up to 500 hours at 730 K, and up to 2000 thermal cycles between 200 K and 590 K. Composite longitudinal and transverse tensile strengths, longitudinal compression strength, and in-plane shear strength were determined. None of the systems was severely degraded by exposure at 590 K. The best performing system was B-2024 Al. Effects of matrix alloys on degradation mechanisms were experimentally investigated. Composite specimens and individual fibers were metallurgically analyzed with a scanning electron microscope and an electron microprobe to determine failure characteristics, chemical element distribution, and reaction layer morphology. Alloying constituents were found to be affect the composite degradation mechanisms as follows: alloys containing iron, but without manganese as a stabilizer, caused increased low-temperature degradation; alloys containing magnesium, iron, or manganese caused increased degradation; and alloys containing copper caused increased fiber strength.

  10. Size-confined fixed-composition and composition-dependent engineered band gap alloying induces different internal structures in L-cysteine-capped alloyed quaternary CdZnTeS quantum dots.

    PubMed

    Adegoke, Oluwasesan; Park, Enoch Y

    2016-01-01

    The development of alloyed quantum dot (QD) nanocrystals with attractive optical properties for a wide array of chemical and biological applications is a growing research field. In this work, size-tunable engineered band gap composition-dependent alloying and fixed-composition alloying were employed to fabricate new L-cysteine-capped alloyed quaternary CdZnTeS QDs exhibiting different internal structures. Lattice parameters simulated based on powder X-ray diffraction (PXRD) revealed the internal structure of the composition-dependent alloyed CdxZnyTeS QDs to have a gradient nature, whereas the fixed-composition alloyed QDs exhibited a homogenous internal structure. Transmission electron microscopy (TEM) and dynamic light scattering (DLS) analysis confirmed the size-confined nature and monodispersity of the alloyed nanocrystals. The zeta potential values were within the accepted range of colloidal stability. Circular dichroism (CD) analysis showed that the surface-capped L-cysteine ligand induced electronic and conformational chiroptical changes in the alloyed nanocrystals. The photoluminescence (PL) quantum yield (QY) values of the gradient alloyed QDs were 27-61%, whereas for the homogenous alloyed QDs, the PL QY values were spectacularly high (72-93%). Our work demonstrates that engineered fixed alloying produces homogenous QD nanocrystals with higher PL QY than composition-dependent alloying. PMID:27250067

  11. Size-confined fixed-composition and composition-dependent engineered band gap alloying induces different internal structures in L-cysteine-capped alloyed quaternary CdZnTeS quantum dots

    NASA Astrophysics Data System (ADS)

    Adegoke, Oluwasesan; Park, Enoch Y.

    2016-06-01

    The development of alloyed quantum dot (QD) nanocrystals with attractive optical properties for a wide array of chemical and biological applications is a growing research field. In this work, size-tunable engineered band gap composition-dependent alloying and fixed-composition alloying were employed to fabricate new L-cysteine-capped alloyed quaternary CdZnTeS QDs exhibiting different internal structures. Lattice parameters simulated based on powder X-ray diffraction (PXRD) revealed the internal structure of the composition-dependent alloyed CdxZnyTeS QDs to have a gradient nature, whereas the fixed-composition alloyed QDs exhibited a homogenous internal structure. Transmission electron microscopy (TEM) and dynamic light scattering (DLS) analysis confirmed the size-confined nature and monodispersity of the alloyed nanocrystals. The zeta potential values were within the accepted range of colloidal stability. Circular dichroism (CD) analysis showed that the surface-capped L-cysteine ligand induced electronic and conformational chiroptical changes in the alloyed nanocrystals. The photoluminescence (PL) quantum yield (QY) values of the gradient alloyed QDs were 27–61%, whereas for the homogenous alloyed QDs, the PL QY values were spectacularly high (72–93%). Our work demonstrates that engineered fixed alloying produces homogenous QD nanocrystals with higher PL QY than composition-dependent alloying.

  12. Size-confined fixed-composition and composition-dependent engineered band gap alloying induces different internal structures in L-cysteine-capped alloyed quaternary CdZnTeS quantum dots

    PubMed Central

    Adegoke, Oluwasesan; Park, Enoch Y.

    2016-01-01

    The development of alloyed quantum dot (QD) nanocrystals with attractive optical properties for a wide array of chemical and biological applications is a growing research field. In this work, size-tunable engineered band gap composition-dependent alloying and fixed-composition alloying were employed to fabricate new L-cysteine-capped alloyed quaternary CdZnTeS QDs exhibiting different internal structures. Lattice parameters simulated based on powder X-ray diffraction (PXRD) revealed the internal structure of the composition-dependent alloyed CdxZnyTeS QDs to have a gradient nature, whereas the fixed-composition alloyed QDs exhibited a homogenous internal structure. Transmission electron microscopy (TEM) and dynamic light scattering (DLS) analysis confirmed the size-confined nature and monodispersity of the alloyed nanocrystals. The zeta potential values were within the accepted range of colloidal stability. Circular dichroism (CD) analysis showed that the surface-capped L-cysteine ligand induced electronic and conformational chiroptical changes in the alloyed nanocrystals. The photoluminescence (PL) quantum yield (QY) values of the gradient alloyed QDs were 27–61%, whereas for the homogenous alloyed QDs, the PL QY values were spectacularly high (72–93%). Our work demonstrates that engineered fixed alloying produces homogenous QD nanocrystals with higher PL QY than composition-dependent alloying. PMID:27250067

  13. Composition and anisotropy in Al-Cu-Li-Ag-Mg-Zr alloys

    SciTech Connect

    Gayle, F.W. . Metallurgy Div.); Tack, W.T.; Swanson, G. ); Heubaum, F.H.; Pickens, J.R. )

    1994-03-15

    Aluminum-lithium alloys that have been hot worked generally suffer from an anisotropy of mechanical properties, both through thickness (surface to centerline) and in plane (from longitudinal to 45[degree] to transverse). Although such anisotropy is present in all tempers, it is more pronounced in the commercially-important, high strength, artificially aged conditions. Yield strength differences between the longitudinal and long transverse orientations ([Delta]YS) of up to 240 MPa for Al-Cu-Li alloy 2090 have been reported. Since minimum properties in all orientations must be considered in applications design, mechanical property anisotropy can limit the use of an alloy. To investigate the role composition plays in the development of mechanical property anisotropy, the authors have examined a range of compositions in the Weldalite[reg sign] 049 alloy family as well as certain model alloys. This novel approach is in contrast to most attempts to reduce anisotropy which have been based on established alloys of relatively narrow composition ranges. In the present study, a baseline aluminum alloy 2195 (4.0 Cu-0.95 Li-0.4 Ag-0.4 Mg-0.14 Zr, in wt.%) with accompanying experimental variants containing 0 to 1.4% Li and 0.4 and 1.2% Mg, were evaluated for tensile property anisotropy, fracture toughness, and microstructure.

  14. Effect of composition on the high rate dynamic behaviour of tungsten heavy alloys

    NASA Astrophysics Data System (ADS)

    Latif, Kesemen; Kaan, Çalışkan N.; Emrah, Konokman H.; Nuri, Durlu

    2015-09-01

    Tungsten heavy alloys are currently used as kinetic energy penetrators in military applications due to their high density and superior mechanical properties. In the literature, quasi-static properties of different tungsten heavy alloys based on W-Ni-Cu and W-Ni-Fe ternary systems are well documented and presented. However, comparison of the dynamic behaviour of these alloys in terms of the correlation between quasi-static mechanical characterization and dynamical properties is lacking. In the present study, dynamic properties of tungsten heavy alloys having different binder phase compositions (90W-7Ni-3Cu and 90W-8Ni-2Fe) at different projectile velocities were investigated. The examined and tested alloys were produced through the conventional powder metallurgy route of mixing, cold compaction and sintering. Mechanical characterization of these alloys was performed. In the ballistic tests, cylindrical tungsten heavy alloys with L/D ratio of 3 were impacted to hardened steel target at different projectile velocities. After the ballistic tests, deformation characteristics of test specimens during dynamic loading were evaluated by comparing the change of length and diameter of the specimens versus kinetic energy densities. The study concluded that 90W-8Ni-2Fe alloy has better perforation characteristics than 90W-7Ni-3Cu alloy.

  15. On the causes of compositional order in the Ni sub c Pt sub (1-c) alloys

    SciTech Connect

    Gyorffy, B.L. . H.H. Wills Physics Lab.); Pinski, F.J. . Dept. of Physics); Ginatempo, B. . Ist. di Fisica Teorica); Johnson, D.D. ); Staunton, J.B. . Dept. of Physics); Shelton, W.A.; Stocks, G.M.; Nicholson, D.M.

    1991-01-01

    We review, briefly, the arguments which gave rise to the current controversy concerning the origin of compositional order in Ni{sub c}Pt{sub 1-c} alloys. We note that strain fluctuations play an important role in determining the state of compositional order in this system and outline a theoretical framework that takes account of them. 29 refs., 4 figs.

  16. Thermal oxidation induced degradation of carbon fiber reinforced composites and carbon nanotube sheet enhanced fiber/matrix interface for high temperature aerospace structural applications

    NASA Astrophysics Data System (ADS)

    Haque, Mohammad Hamidul

    Recent increase in the use of carbon fiber reinforced polymer matrix composite, especially for high temperature applications in aerospace primary and secondary structures along with wind energy and automotive industries, have generated new challenges to predict its failure mechanisms and service life. This dissertation reports the experimental study of a unidirectional carbon fiber reinforced bismaleimide (BMI) composites (CFRC), an excellent candidate for high temperature aerospace components, undergoing thermal oxidation at 260 °C in air for over 3000 hours. The key focus of the work is to investigate the mechanical properties of the carbon fiber BMI composite subjected to thermal aging in three key aspects - first, studying its bulk flexural properties (in macro scale), second, characterizing the crack propagation along the fiber direction, representing the interfacial bonding strength between fiber and matrix (in micro scale), and third, introducing nano-structured materials to modify the interface (in nano scale) between the carbon fiber and BMI resin and mechanical characterization to study its influence on mitigating the aging effect. Under the first category, weight loss and flexural properties have been monitored as the oxidation propagates through the fiber/matrix interface. Dynamic mechanical analysis and micro-computed tomography analysis have been performed to analyze the aging effects. In the second category, the long-term effects of thermal oxidation on the delamination (between the composite plies) and debonding (between fiber and matrix) type fracture toughness have been characterized by preparing two distinct types of double cantilever beam specimens. Digital image correlation has been used to determine the deformation field and strain distribution around the crack propagation path. Finally the resin system and the fiber/matrix interface have been modified using nanomaterials to mitigate the degradations caused by oxidation. Nanoclay modified

  17. Preparation and optical properties of silica@Ag Cu alloy core-shell composite colloids

    NASA Astrophysics Data System (ADS)

    Zhang, Jianhui; Liu, Huaiyong; Wang, Zhenlin; Ming, Naiben

    2007-04-01

    The silica@Ag-Cu alloy core-shell composite colloids have been successfully synthesized by an electroless plating approach to explore the possibility of modifying the plasmon resonance at the nanoshell surface by varying the metal nanoshell composition for the first time. The surface plasmon resonance of the composite colloids increases in intensity and shifts towards longer, then shorter wavelengths as the Cu/Ag ratio in the alloy shell is increased. The variations in intensity of the surface plasmon resonance with the Cu/Ag ratio obviously affect the Raman bands of the silica colloid core. The report here may supply a new technique to effectively modify the surface plasmon resonance.

  18. The influence of alloy composition on residual stresses in heat treated aluminium alloys

    SciTech Connect

    Robinson, J.S.; Redington, W.

    2015-07-15

    The as quenched properties of eight different heat treatable aluminium alloys are related to residual stress magnitudes with the objective being to establish if there is a relationship between the residual stress and the as quenched alloy hardness and strength. Near surface residual stresses were assessed with X-ray diffraction using both the established sin{sup 2}ψ method and the more recent cos α technique. Through thickness residual stresses were also characterised using neutron diffraction. The alloys were chosen to encompass a wide range of strengths. The low to medium strength alloys were 6060 and 6082, medium to high strength 2618A, 2014A, 7075, 7010 and two variants of 7449, while the very high strength alloy was the powder metallurgy alloy N707. To assess the as quenched strength, dynamic hardness and tensile properties were determined from samples tested immediately after quenching to minimise the influence of precipitation hardening by natural aging. In addition, hot hardness measurements were made in situ on samples cooled to simulate quench paths. Within the experimental constraints of the investigation, the distribution of residual stress through the thickness was found to follow the same pattern for all the alloys investigated, varying from tensile in the interior to surface compression. The influence of alloy strength was manifested as a change in the observed residual stress magnitudes, and surface residual stresses were found to vary linearly with as quenched hardness and strength. - Highlights: • As quenched aluminium alloys contain high magnitude residual stresses. • Surface is compressive balance by a tensile core. • As quenched surface residual stress is linear function of alloy strength. • In situ hot hardness demonstrates rapid change in intrinsic hardness during rapid cooling.

  19. Environmental effects on composite airframes: A study conducted for the ARM UAV Program (Atmospheric Radiation Measurement Unmanned Aerospace Vehicle)

    SciTech Connect

    Noguchi, R.A.

    1994-06-01

    Composite materials are affected by environments differently than conventional airframe structural materials are. This study identifies the environmental conditions which the composite-airframe ARM UAV may encounter, and discusses the potential degradation processes composite materials may undergo when subjected to those environments. This information is intended to be useful in a follow-on program to develop equipment and procedures to prevent, detect, or otherwise mitigate significant degradation with the ultimate goal of preventing catastrophic aircraft failure.

  20. Geometric and Chemical Composition Effects on Healing Kinetics of Voids in Mg-bearing Al Alloys

    NASA Astrophysics Data System (ADS)

    Song, Miao; Du, Kui; Wang, Chunyang; Wen, Shengping; Huang, Hui; Nie, Zuoren; Ye, Hengqiang

    2016-05-01

    The healing kinetics of nanometer-scale voids in Al-Mg-Er and Al-Mg-Zn-Er alloy systems were investigated with a combination of in situ transmission electron microscopy and electron tomography at different temperatures. Mg was observed completely healing the voids, which were then rejuvenated to the alloy composition with further aging, in the Al-Mg-Er alloy. On the contrary, Mg51Zn20 intermetallic compound was formed in voids in the Al-Mg-Zn-Er alloy, which leads to complete filling of the voids but not rejuvenation for the material. For voids with different geometrical aspects, different evolution processes were observed, which are related to the competition between bulk and surface diffusion of the alloys. For voids with a large size difference in their two ends, a viscous flow of surface atoms can be directly observed with in situ electron microscopy, when the size of one end becomes less than tens of nanometers.

  1. Shape Memory Alloy Modeling and Applications to Porous and Composite Structures

    NASA Astrophysics Data System (ADS)

    Zhu, Pingping

    There has been a growing concern about an exciting class of advanced material -- shape memory alloys (SMAs) since their discovery several decades ago. SMAs exhibit large reversible stresses and strains owing to a thermoelastic phase transformation. They have been widely used in many engineering fields including aerospace, biomedical, and automotive engineering, especially as sensors, actuators, bone implants and deployable switches. The behavior of SMAs is very complex due to the coupling between thermal and mechanical effects. Theoretical and computational tools are used in this dissertation to investigate the mechanical behavior of SMA and its related structures for seeking better and wider application of this material. In the first part of this dissertation, we proposed an improved macroscopic phenomenological constitutive model of SMA that accounts for all major mechanical behaviors including elasticity, phase transformation, reorientation and plasticity. The model is based on some previous work developed in the Brinson group, and the current efforts are focused on plasticity, the application of a pre-defined strain, unification of notations, and other coding-related work. A user subroutine script VUMAT is developed to implement the constitutive model to the commercial finite element software Abaqus. Typical simulation results based on the model are presented, as well as verification with some experimental results. In the second part, we apply the developed constitutive model to a series of two-dimensional SMA plates with structured arrays of pores to investigate the structural response, especially the stress, strain, phase transformation, and plastic fields. Results are documented about the coupling of the elastic, transformation and plastic fields about the arrays of pores. Theoretical and experimental DIC results are also utilized to validate some simulation results. Conclusions are then drawn to provide understanding in the effect of pores and the

  2. Composite droplets: evolution of InGa and AlGa alloys on GaAs(100).

    PubMed

    Sablon, K A; Wang, Zh M; Salamo, G J

    2008-03-26

    We present a comparative study for the evolution of utilizing indium gallium (InGa) and aluminum gallium (AlGa) alloys fabricated on GaAs(100) by means of simultaneous and sequential droplet formation. The composite alloys reported using the sequential approach lack the ability to precisely determine the final alloy composition as well as consistency in the density of the droplets. Further, the composition of the InGa alloy is not uniform, as seen by the size distribution using an atomic force microscope (AFM). Although this approach may be acceptable for materials with similar surface kinetics, as in the case of AlGa, it is not acceptable for InGa. This investigation reveals that the simultaneous approach for fabricating composite alloys is the optimum approach for producing InGa alloys with better control on composition for plasmonic applications such as plasmonic waveguides. PMID:21817741

  3. Compositional Dependence of Critical Point Transitions in Ge1-xSnx alloys

    NASA Astrophysics Data System (ADS)

    Cook, Candi S.; D'Costa, Vijay; Kouvetakis, John; Zollner, Stefan; Menéndez, José

    2005-06-01

    The compositional dependence of the E1, E1+Δ1, E0', and E2 optical transition energies in Ge1-xSnx alloys has been measured in the 0 < x < 0.18 range. Deviations from linearity are clearly observed and characterized by a bowing parameter b. The value of this parameter is much larger in Ge1-xSnx alloys than in the isoelectronic Si1-xGex system.

  4. Effects of alloy composition in alleviating embrittlement problems associated with the tantalum alloy T-111

    NASA Technical Reports Server (NTRS)

    Stephens, J. R.

    1975-01-01

    The causes of aging embrittlement in T-111 (Ta-8W-2Hf) and the effect of alloy modification were investigated. Results show that T-111 possesses a critical combination of tungsten and hafnium that leads to loss in ductility at -196 C after aging near 1040 C. It was found that this occurs because tungsten enhances hafnium segregation to grain boundaries, which also leads to increased susceptibility to hydrogen embrittlement. Aging embrittlement was not observed in tantalum alloys with reduced tungsten or hafnium contents; most of the alloys studied have lower strengths than T-111 and exhibit susceptibility to hydrogen embrittlement.

  5. Effects of alloy composition in alleviating embrittlement problems associated with the tantalum alloy T-111

    NASA Technical Reports Server (NTRS)

    Stephens, J. R.

    1977-01-01

    The causes of aging embrittlement in T-111 (Ta-8W-2Hf) and the effects of alloy modification were investigated. Results showed that T-111 contains a critical combination of tungsten and hafnium that leads to loss of ductility at -196 C after aging near 1040 C. This appears to occur because tungsten enhances hafnium segregation to grain boundaries and this also leads to increased susceptibility to hydrogen embrittlement. Aging embrittlement was not observed in tantalum alloys with reduced tungsten or hafnium contents; however, most of the alloys studied have lower strengths than T-111 and exhibit susceptibility to hydrogen embrittlement.

  6. Phase composition and distribution of alloying elements in the transition layer

    NASA Astrophysics Data System (ADS)

    Semenov, Ya. S.; Popova, S. K.; Lebedev, M. P.

    2009-11-01

    X-ray spectral and x-ray structural analyses and optical microscopy were used to study the chemical and phase compositions and the structure and morphology of alloying elements of the transition layer produced by gas-flame and plasma spraying on St. 3sp steels. It is shown that the structure and chemical and phase compositions of the transition layer depend significantly on the technological parameters, processing methods, and the chemical composition of the coating.

  7. Compositional dependence of optical critical point parameters in pseudomorphic GeSn alloys

    NASA Astrophysics Data System (ADS)

    D'Costa, Vijay Richard; Wang, Wei; Zhou, Qian; Chan, Taw Kuei; Osipowicz, Thomas; Tok, Eng Soon; Yeo, Yee-Chia

    2014-08-01

    Spectroscopic ellipsometry was used to investigate the optical response of pseudomorphic Ge1-xSnx (0 ≤ x ≤ 0.17) alloys grown directly on Ge (100) by molecular beam epitaxy. A detailed compositional study of amplitudes, broadenings, energies, and phase angles associated with critical points E1, E1 + Δ1, E 0 ', and E2 of GeSn alloys was carried out using a derivative analysis. The results can be understood in terms of the electronic bandstructure of Ge or relaxed GeSn alloys with the following differences. First, broadening parameters in pseudomorphic alloys are found to have lower values compared to relaxed alloys indicating lower dislocation density in our pseudomorphic alloys relative to relaxed alloys. Second, the amplitudes of E1 and E1 + Δ1 are enhanced and reduced, respectively, with respect to relaxed GeSn alloys, and the trends are captured using the k.p method as a biaxial stress induced effect. Third, phase angles are lower than Ge for all the critical points suggesting reduction of excitonic effects in GeSn with respect to Ge.

  8. Alloy composition dependency of plastic deformation behavior in biaxial compressions of Ti-Nb alloys

    NASA Astrophysics Data System (ADS)

    Shimizu, Ichiro; Hisada, Kazuki; Ishikawa, Shinichi; Takemoto, Yoshito; Tada, Naoya

    2015-03-01

    Crystal structure of titanium alloy changes from alpha (hexagonal close-packed) to beta (body centered cubic) with increase of beta stabilizer content. This change of structure strongly influences on the plastic deformation behavior of titanium alloys, because it not only induces changes of slip systems but also activates martensitic transformation and deformation twinning. However, most of past studies on titanium alloys have been focused on the development of specific functionalities induced by alloy designing, and few research works have been reported on metal workability under multi-axial stress conditions, which is key factor to apply titanium alloys for engineering products. In this study, uniaxial and biaxial compression tests of titanium-niobium alloys with various niobium contents have been performed to clarify the influence of beta stabilizer content on the plastic behavior under compressive stress conditions. The titanium-niobium alloys were solution treated and then quenched from beta region to obtain metastable structures. The resultant stress-strain relations together with microscopic observations of texture revealed that the influence of niobium contents on the predominant plastic deformation mechanisms and thus on the hardening phenomena. The equi-plastic work contours obtained by uniaxial and biaxial compression tests also implied the crystal structure dependency of anisotropic hardening, which was evaluated quantitatively by means of Hill's anisotropic yield criterion. The results will provide information on the versatile constitutive relations of titanium alloys containing beta stabilizer elements, that is important to prove the performance of products manufactured by compressive metal working processes such as forging and extrusion.

  9. Properties of High Volume Fraction Fly Ash/Al Alloy Composites Produced by Infiltration Process

    NASA Astrophysics Data System (ADS)

    Kountouras, D. T.; Stergioudi, F.; Tsouknidas, A.; Vogiatzis, C. A.; Skolianos, S. M.

    2015-09-01

    In the present study, pressure infiltration is employed to synthesize aluminum alloy 7075-fly ash composites. The microstructure and chemical composition of the fly ash and the produced composite material was examined using optical and scanning electron microscopy, as well as x-ray diffraction. Several properties of the produced composite material were examined and evaluated including macro-hardness, wear, thermal expansion, and corrosion behavior. The wear characteristics of the composite, in the as-cast conditions, were studied by dry sliding wear tests. The corrosion behavior of composite material was evaluated by means of potentiodynamic corrosion experiments in a 3.5 wt.% NaCl solution. The composite specimens exhibit a homogeneous distribution of fly ash particles and present enhanced hardness values, compared to the matrix material. The high volume fraction of the fly ash reinforcement (>40%) in the composite material led to increased wear rates, attributed to the fragmentation of the fly ash particles. However, the presence of fly ash particles in the Al alloy matrix considerably decreased the coefficiency of thermal expansion, while resulting in an altered corrosion mechanism of the composite material with respect to the matrix alloy.

  10. An Aerospace Workshop

    ERIC Educational Resources Information Center

    Hill, Bill

    1972-01-01

    Describes the 16-day, 10,000 mile national tour of the nation's major aerospace research and development centers by 65 students enrolled in Central Washington State College's Summer Aerospace Workshop. (Author/MB)

  11. Nanostructured Nb reinforced NiTi shape memory alloy composite with high strength and narrow hysteresis

    NASA Astrophysics Data System (ADS)

    Hao, Shijie; Cui, Lishan; Jiang, Daqiang; Yu, Cun; Jiang, Jiang; Shi, Xiaobin; Liu, Zhenyang; Wang, Shan; Wang, Yandong; Brown, Dennis E.; Ren, Yang

    2013-06-01

    An in-situ nanostructured Nb reinforced NiTi shape-memory alloy composite was fabricated by mechanical reduction of an as-cast Nb-NiTi eutectic alloy. The composite exhibits large elastic strain, high strength, narrow hysteresis, and high mechanical energy storage density and efficiency during tensile cycling. In situ synchrotron high-energy X-ray diffraction revealed that these superior properties were attributed to the strong coupling between nanostructured Nb and NiTi matrix during deformation. Furthermore, this study offers a good understanding of the deformation behavior of the nanoscale reinforcement embedded in the metal matrix deformed by stress-induced phase transformation.

  12. Low void content autoclave molded titanium alloy and polyimide graphite composite structures.

    NASA Technical Reports Server (NTRS)

    Vaughan, R. W.; Jones, R. J.; Creedon, J. F.

    1972-01-01

    This paper discusses a resin developed for use in autoclave molding of polyimide graphite composite stiffened, titanium alloy structures. Both primary and secondary bonded structures were evaluated that were produced by autoclave processing. Details of composite processing, adhesive formulary, and bonding processes are provided in this paper, together with mechanical property data for structures. These data include -65 F, room temperature, and 600 F shear strengths; strength retention after aging; and stress rupture properties at 600 F under various stress levels for up to 1000 hours duration. Typically, shear strengths in excess of 16 ksi at room temperature with over 60% strength retention at 600 F were obtained with titanium alloy substrates.

  13. Application of composites to the selective reinforcement of metallic aerospace structures. [application of structural design criteria for weight reduction

    NASA Technical Reports Server (NTRS)

    Brooks, W. A., Jr.; Mathauser, E. E.; Pride, R. A.

    1972-01-01

    The use of composite materials to selectively reinforce metallic structures provides a low-cost way to reduce weight and a means of minimizing the risks usually associated with the introduction of new materials. An overview is presented of the NASA Langley Research Center programs to identify the advantages and to develop the potential of the selective reinforcement approach to the use of composites. These programs have shown that selective reinforcement provides excellent strength and stiffness improvements to metallic structures. Significant weight savings can be obtained in a cost effective manner. Flight service programs which have been initiated to validate further the merits of selective reinforcement are described.

  14. Influence of alloy composition on the hardening of silver-tin dental amalgam.

    PubMed

    Abbott, J R; Miller, D R; Netherway, D J

    1986-01-01

    The objective of the investigation was to examine the reactions of mercury with silver-tin alloys with compositions spanning the phase fields beta, (beta + gamma), gamma, and (gamma + Sn). The experimental methods employed include the application of light microscopy, scanning electron microscopy, and electron probe microanalysis. These techniques were used to investigate the mechanisms of reaction and to identify the nature and morphology of the reaction products formed on bulk specimens of the alloys. The progress and characteristics of the reactions that occur during hardening of amalgams prepared from powders of these alloys were monitored using a high-sensitivity dilatometer. These results were correlated with direct observations on the development of the microstructures. The reaction of mercury with the beta-phase alloy occurred rapidly and resulted in a very marked and rapid expansion during the initial stages of hardening. gamma-Phase alloys, on the other hand, reacted more slowly and contracted markedly during hardening. The behavior of amalgams made from alloys with compositions lying between these two extremes appeared to be explicable in terms of the characteristics of the separate phases from which they were constituted. PMID:3782188

  15. Lattice constant and substitutional composition of GeSn alloys grown by molecular beam epitaxy

    NASA Astrophysics Data System (ADS)

    Bhargava, Nupur; Coppinger, Matthew; Prakash Gupta, Jay; Wielunski, Leszek; Kolodzey, James

    2013-07-01

    Single crystal epitaxial Ge1-xSnx alloys with atomic fractions of tin up to x = 0.145 were grown by solid source molecular beam epitaxy on Ge (001) substrates. The Ge1-xSnx alloys formed high quality, coherent, strained layers at growth temperatures below 250 °C, as shown by high resolution X-ray diffraction. The amount of Sn that was on lattice sites, as determined by Rutherford backscattering spectrometry channeling, was found to be above 90% substitutional in all alloys. The degree of strain and the dependence of the effective unstrained bulk lattice constant of Ge1-xSnx alloys versus the composition of Sn have been determined.

  16. Investigations on the influence of composition in the development of Ni-Ti shape memory alloy using laser based additive manufacturing

    NASA Astrophysics Data System (ADS)

    Shiva, S.; Palani, I. A.; Mishra, S. K.; Paul, C. P.; Kukreja, L. M.

    2015-06-01

    Among the various shaped memory alloys (SMA), nitinol (Ni-Ti alloy) finds applications in automotive, aerospace, biomedical and robotics. The conventional route of fabrication of SMA has several limitations, like formation of stable secondary phases, fabrication of simple geometries, etc. This paper reports a novel method of fabricating SMA using a laser based additive manufacturing technique. Three different compositions of Ni and Ti powders (Ni-45% Ti-55%; Ni-50% Ti-50%; Ni-55% Ti45%) were pre-mixed using ball-milling and laser based additive manufacturing system was employed to fabricate circular rings. The material properties of fabricated rings were evaluated using Scanning Electron Microscopy (SEM), Differential scanning calorimeter (DSC), X-ray diffraction (XRD) system and micro-hardness test. All the characterized results showed that SMA could be manufactured using the laser based additive manufacturing process. The properties of laser additive manufactured SMA (Ni-50% Ti-50%) were found to be close to that of conventionally processed SMA.

  17. Method of preparing copper-dendritic composite alloys for mechanical reduction

    DOEpatents

    Verhoeven, John D.; Gibson, Edwin D.; Schmidt, Frederick A.; Spitzig, William A.

    1988-01-01

    Copper-dendritic composite alloys are prepared for mechanical reduction to increase tensile strength by dispersing molten droplets of the composite alloy into an inert gas; solidifying the droplets in the form of minute spheres or platelets; and compacting a mass of the spheres or platelets into an integrated body. The spheres preferably have diameters of from 50 to 2000 .mu.m, and the platelets thicknesses of 100 to 2000 .mu.m. The resulting spheres or platelets will contain ultra-fine dendrites which produce higher strengths on mechanical reduction of the bodies formed therefrom, or comparable strengths at lower reduction values. The method is applicable to alloys of copper with vanadium, niobium, tantalum, chromium, molybdenum, tungsten, iron and cobalt.

  18. Method of preparing copper-dendritic composite alloys for mechanical reduction

    DOEpatents

    Verhoeven, J.D.; Gibson, E.D.; Schmidt, F.A.; Spitzig, W.A.

    1988-09-13

    Copper-dendritic composite alloys are prepared for mechanical reduction to increase tensile strength by dispersing molten droplets of the composite alloy into an inert gas; solidifying the droplets in the form of minute spheres or platelets; and compacting a mass of the spheres or platelets into an integrated body. The spheres preferably have diameters of from 50 to 2,000 [mu]m, and the platelets thicknesses of 100 to 2,000 [mu]m. The resulting spheres or platelets will contain ultra-fine dendrites which produce higher strengths on mechanical reduction of the bodies formed therefrom, or comparable strengths at lower reduction values. The method is applicable to alloys of copper with vanadium, niobium, tantalum, chromium, molybdenum, tungsten, iron and cobalt. 3 figs.

  19. Computational Optimization of TiO2 Filled A384 Alloy Composites in Erosive Environment

    NASA Astrophysics Data System (ADS)

    Gangwar, Swati; Kukshal, Vikas; Patnaik, Amar; Singh, Tej

    2012-09-01

    In this article, micro and nano titania (TiO2) filled A384 alloy composites are fabricated by stir casting technique with varying filler content from 0-8 wt.% respectively and then we study their physical, mechanical, thermal and erosive wear characteristics respectively. Effect of impact velocity (25-70 m/sec) and impingement angle (30°-90°) on erosion wear behavior of micro and nano TiO2 filled A384 alloy has also been studied. Finally, an optimization technique was implemented in order to develop a correlation between the physical, mechanical and erosion rate of TiO2 filled A384 alloy composites by using technique order preference by similarity to ideal solution (TOPSIS).

  20. One-step brazing process to join CFC composites to copper and copper alloy

    NASA Astrophysics Data System (ADS)

    Salvo, Milena; Casalegno, Valentina; Rizzo, Stefano; Smeacetto, Federico; Ferraris, Monica; Merola, Mario

    2008-02-01

    The aim of this work is to develop a new single-step brazing technique to join carbon fibre reinforced carbon composite (CFC) to pure copper (Cu) and copper alloy (CuCrZr) for nuclear fusion applications. In order to increase the wettability of CFC by a copper-based brazing alloy containing no active metal, the composite surface was modified by direct reaction with chromium, which forms a carbide layer and allows a large reduction of the contact angle. After the CFC surface modification, the commercial Gemco ® alloy (Cu/Ge) was successfully used to braze CFC to pure copper and pure copper to CuCrZr by the same heat treatment. The shear strength of the CFC/Cu joints measured by single lap shear tests at room temperature was (34 ± 4) MPa, comparable to the values obtained by other joining processes and higher than the intrinsic CFC shear strength.

  1. The Magnetic Properties of Metal-Alloy Glass Composites Prepared by Ion Implantation

    SciTech Connect

    Julian Fernandez, Cesar de; Mattei, Giovanni; Sada, Cinzia; Maurizio, Chiara; Padovani, Sara; Mazzoldi, Paolo; Sangregorio, Claudio; Gatteschi, Dante

    2003-08-26

    The structural and magnetic properties of Co-Ni, Co-Fe and Ni-Cu alloy nanoparticles formed in silica matrix by sequential ion implantation are presented. These nanoparticles show crystal structure similar to the corresponding bulk alloys. In the Co-Ni and Co-Fe, magnetization saturation and coercive field depend on the the alloy composition, crystal structure and size effects. Ferromagnetic resonance studies show that collective magnetic processes are present and these are determined by the film-like morphology of the implanted region. The temperature dependence of the magnetization of the NixCu100-x samples indicates that their Curie Temperatures are larger than the corresponding bulk ones. This feature is discussed considering the composition of the nanoparticles and the size effects.

  2. Dry Sliding Wear Behavior of Fly Ash Cenosphere/AZ91D Mg Alloy Composites

    NASA Astrophysics Data System (ADS)

    Yu, S. R.; Huang, Z. Q.

    2014-10-01

    Fly ash cenosphere/AZ91D Mg alloy (FAC/AZ91D) composites were prepared using stir casting method. The effects of the applied load, the wearing time, and the diameter and the content of fly ash cenosphere on the wear behavior of the composites were investigated under dry sliding condition. The results showed the wear resistance of FAC/AZ91D composites is generally better than that of AZ91D Mg alloy. The mass fraction and diameter of FAC have important effects on the wear resistance of the composites, and the wear resistance of the composites is excellent when the mass fraction and diameter of FAC are moderate. When the mass fraction and diameter of FAC are more than the critical values, the wear resistance of the composites lowers again. The wear resistance of the composites decreases with the increase in the applied load. The relationship between the worn mass loss and the applied load is nonlinear. When the applied load is smaller, the worn mass loss of the composites increases rapidly with the increase of the applied load. These research results show that the composites have broad application prospects under dry sliding wear condition, and they can provide guidance for the selection of the raw materials, the structure design, and the application conditions of the composites.

  3. Effect of growth parameters on compositional variations in directionally solidified HgCdTe alloys

    NASA Technical Reports Server (NTRS)

    Szofran, F. R.; Chandra, D.; Wang, J.-C.; Cothran, E. K.; Lehoczky, S. L.

    1984-01-01

    A series of Hg(1-x)Cd(x)Te alloy crystals was grown by directional solidification with compositions ranging from x = 0.2 to x = 0.4. The measured axial compositional profiles were interpreted in terms of an exact numerical solution of the appropriate diffusion equation that takes into account both the variations of the segregation coefficient and solidification rate with composition. The solutions for all growth rates agree generally well with the experimental data, and confirm earlier observations that employed approximate analytical solutions. The effective mass diffusion coefficients showed no significant composition or melt temperature dependence. Slightly higher diffusion coefficients were obtained, however, for the highest growth rates.

  4. Solutal convection induced macrosegregation and the dendrite to composite transition in off-eutectic alloys

    NASA Technical Reports Server (NTRS)

    Boettinger, W. J.; Biancaniello, F. S.; Coriell, S. R.

    1981-01-01

    The effect of solute gradient induced convection during vertical solidification on the macrosegregation of Pb-rich Pb-Sn off-eutectic alloys is determined experimentally as a function of composition and growth rate. In many cases macrosegregation is sufficient to prevent the plane front solidification of the alloy. The transition from dendritic to composite structure is found to occur when the composition of the solid is close enough to the eutectic composition to satisfy a stability criterion based on the ratio of the liquid temperature gradient to growth rate. A vertical or horizontal magnetic field of 0.1 T (1 kilogauss) does not reduce macrosegregation, but downward solidification (liquid below solid) virtually eliminates macrosegregation in small (3 mm) diameter samples.

  5. Preparation, Characterization and Mechanical Properties of Cu-Sn Alloy/Graphite Composites

    NASA Astrophysics Data System (ADS)

    Dong, Ruifeng; Cui, Zhenduo; Zhu, Shengli; Xu, Xu; Yang, Xianjin

    2014-10-01

    Ni-B coating was prepared on the surface of graphite particles using the electroless plating method. The Ni-B coating was composed of spherical grains with average diameter of 80 nm. The phases of Ni-B coating were indexed as nanosized crystal Ni phase and amorphous Ni-B phase. Cu-Sn alloy/graphite composites with 0.5, 1.0, 1.5, and 2.0 wt pct graphite contents were synthesized by the powder metallurgy method. Ni-B coating improved the wettability and bonding strength between the Cu-Sn alloy and graphite. The composite with Ni-B coated graphite exhibited higher density, hardness, and compression strength compared with the composites with bare graphite. The crack propagation mechanism of the composites was also analyzed.

  6. Recent advances and developments in refractory alloys

    SciTech Connect

    Nieh, T.G.; Wadsworth, J.

    1993-11-01

    Refractory metal alloys based on Mo, W, Re, Ta, and Nb (Cb) find applications in a wide range of aerospace applications because of their high melting points and high-temperature strength. This paper, presents recent progress in understanding and applications of these alloys. Recent studies to improve the oxidation and mechanical behavior of refractory metal alloys, and particularly Nb alloys, are also discussed. Some Re structures, for extremely high temperature applications (> 2000C), made by CVD and P/M processes, are also illustrated. Interesting work on the development of new W alloys (W-HfC-X) and the characterization of some commercial refractory metals, e.g., K-doped W, TZM, and Nb-1%Zr, continues. Finally, recent developments in high temperature composites reinforced with refractory metal filaments, and refractory metal-based intermetallics, e.g., Nb{sub 3}Al, Nb{sub 2}Be{sub 17}, and MoSi{sub 2}, are briefly described.

  7. Lattice Structures For Aerospace Applications

    NASA Astrophysics Data System (ADS)

    Del Olmo, E.; Grande, E.; Samartin, C. R.; Bezdenejnykh, M.; Torres, J.; Blanco, N.; Frovel, M.; Canas, J.

    2012-07-01

    The way of mass reduction improving performances in the aerospace structures is a constant and relevant challenge in the space business. The designs, materials and manufacturing processes are permanently in evolution to explore and get mass optimization solutions at low cost. In the framework of ICARO project, EADS CASA ESPACIO (ECE) has designed, manufactured and tested a technology demonstrator which shows that lattice type of grid structures is a promising weight saving solution for replacing some traditional metallic and composite structures for space applications. A virtual testing methodology was used in order to support the design of a high modulus CFRP cylindrical lattice technology demonstrator. The manufacturing process, based on composite Automatic Fiber Placement (AFP) technology developed by ECE, allows obtaining high quality low weight lattice structures potentially applicable to a wide range of aerospace structures. Launcher payload adaptors, satellite platforms, antenna towers or instrument supports are some promising candidates.

  8. Self-biased magnetoelectric responses in magnetostrictive/piezoelectric composites with different high-permeability alloys

    NASA Astrophysics Data System (ADS)

    Lu, Cai-Jiang; Li, Ping; Wen, Yu-Mei; Yang, Ai-Chao; Yang, Chao; Wang, De-Cai; He, Wei; Zhang, Ji-Tao

    2014-11-01

    We comparatively investigate the influence of various high-permeability alloys on the hysteretic and remanent resonant magnetoelectric (ME) response in a composite of magnetostrictive nickel (Ni) and piezoelectric Pb(Zr1-x, Tix)O3 (PZT). In order to implement this comparative research, Co-based amorphous alloy (CoSiB), Fe-based nanocrystalline alloy (FeCuNbSiB) and Fe-based amorphous alloy (FeSiB) are used according to different magnetostriction (λs) and saturation magnetization (μ0Ms) characteristics. The bending and longitudinal resonant ME voltage coefficients (αME,b and αME,l) are observed comparatively for CoSiB/Ni/PZT, FeCuNbSiB/Ni/PZT, and FeSiB/Ni/PZT composites. The experimental data indicate that the FeSiB/Ni/PZT composite has the largest remanent self-biased αME,b and αME,l due to the largest magnetic grading of λs and μ0Ms in the FeSiB/Ni layer. When the number of FeSiB foils is four, the maximum remanent αME,b and αME,l at zero bias magnetic field are 57.8 V/cm·Oe and 107.6 V/cm·Oe, respectively. It is recommended that the high-permeability alloy is supposed to have larger λs and μ0Ms for obtaining a larger remanent self-biased ME responses in ME composite with high-permeability alloy.

  9. High Frequency Properties of Ferrite/Fe-Si-Al Alloy Soft Magnetic Composites

    NASA Astrophysics Data System (ADS)

    Stergiou, Charalampos A.; Zaspalis, Vassilios

    The inclusion of Fe-Si-Al alloy particles in NiCuZn ferrite matrix was investigated with regard to the high frequency electromagnetic properties (complex permeability and permittivity). The resultant composites of relatively low density exhibit a shift of the permeability spectra to higher frequencies and an increase of dielectric polarization, which finally favour the electromagnetic wave attenuation at microwave frequencies. Thus, wider band return loss peaks are attained at frequencies above 6 GHz by thinner composite materials.

  10. Compocasting of an aluminum alloy composite containing B/sub 4/C particulate

    SciTech Connect

    Hosking, F.M.

    1981-07-01

    A description of the compocasting process is given. Processing of metal matrix composites through the additions of nonmetallic particulate into a partially solidified, vigorously agitated metallic slurry is the key feature of the technique. This investigation is specifically directed at the fabrication of an aluminum -4 weight percent magnesium alloy containing uniform dispersions of boron carbide. The boron carbide imparts a dual property to the composite. It has high hardness and the ability to absorb neutrons.

  11. Effect of nano-hydroxyapatite reinforcement in mechanically alloyed NiTi composites for biomedical implant.

    PubMed

    Akmal, Muhammad; Raza, Ahmad; Khan, Muhammad Mudasser; Khan, M Imran; Hussain, Muhammad Asif

    2016-11-01

    Equi-atomic NiTi alloy composites reinforced with 0, 2, 4 and 6vol.% nano-hydroxyapatite (HA) were successfully synthesized using pressureless sintering. Pure Ni and Ti elements were ball milled for 10h in order to produce a mechanically alloyed equi-atomic NiTi alloy (MA-NiTi). Mechanically alloyed NiTi and HA powders were blended, compacted and then sintered for 3h at 1325K. The sintered density varied inversely with volume percent of HA reinforcement. The X-Ray diffraction spectra and SEM images showed the formation of multiple phases like NiTi, NiTi2, Ni3Ti, and Ni4Ti3. The back scattered-SEM image analysis confirmed the presence of Ni-rich and Ti-rich phases with increasing HA content. The 6vol.% HA reinforced composite showed Ni3Ti as the major phase having the highest hardness value which can be attributed to the presence of relatively harder phases along with higher HA content as a reinforcement. The composite of MA-NiTi with 2vol.% HA manifested the most desirable results in the form of better sintering density mainly due to the minute decomposition of NiTi into other phases. Therefore, the 2vol.% reinforced MA-NiTi composite can be exploited as a novel material for manufacturing biomedical implants. PMID:27523992

  12. Analytical study of effects of surface and environmental thermal properties on moisture in composites. [for aerospace application

    NASA Technical Reports Server (NTRS)

    Tompkins, S. S.

    1977-01-01

    The influence of surface and environmental thermal properties on the moisture absorption in fiber-reinforced polymeric-resin-matrix composite materials which have been subjected to convection and solar radiation was studied. Predicted moisture contents based on the conditions at the heated surface and in the ambient air were compared for both short term and long term exposures over a wide range of values for emittance, solar absorptance, convective heat transfer coefficient, solar radiation, ambient temperature, and orientation of the surface with respect to the sun. The calculations showed that absorptance and heat transfer coefficient have significant effects on the moisture content.

  13. Effects of compositional complexity on the ion-irradiation induced swelling and hardening in Ni-containing equiatomic alloys

    DOE PAGESBeta

    Jin, K.; Lu, C.; Wang, L. M.; Qu, J.; Weber, W. J.; Zhang, Y.; Bei, H.

    2016-04-14

    The impact of compositional complexity on the ion-irradiation induced swelling and hardening is studied in Ni and six Ni-containing equiatomic alloys with face-centered cubic structure. The irradiation resistance at the temperature of 500 °C is improved by controlling the number and, especially, the type of alloying elements. Alloying with Fe and Mn has a stronger influence on swelling reduction than does alloying with Co and Cr. Lastly, the quinary alloy NiCoFeCrMn, with known excellent mechanical properties, has shown 40 times higher swelling tolerance than nickel.

  14. Application of Laser Design of Amorphous Feco-Based Alloys for the Formation of Amorphous-Crystalline Composites

    NASA Astrophysics Data System (ADS)

    Permyakova, I. E.; Glezer, A. M.; Ivanov, A. A.; Shelyakov, A. V.

    2016-01-01

    Morphological and fractographic features of change of FeCo-based amorphous alloy surfaces after laser treatment are studied in detail. Regimes of laser treatment that allow various degrees of crystallization of the examined alloys to be obtained, including thin (<1 •m) crystal layers on amorphous alloy surfaces, amorphous-crystalline composites, and completely crystalline alloys are adjusted. The Vickers hardness is estimated in zones of selective laser irradiation. The structure of the examined alloys attendant to the change of their mechanical properties is analyzed.

  15. Characterization and Properties of Micro-arc Composite Ceramic Coatings on Magnesium Alloys

    SciTech Connect

    Zhang, Long; Jiang, Bailing; Ge, Yanfeng; Nyberg, Eric A.; Liu, Ming

    2013-05-21

    Magnesium alloys are of growing interest for many industrial applications due to their favorable strength-to-weight ratio and excellent cast ability. However, one of the limiting factors in the use of magnesium on production vehicles is its poor corrosion resistance. Micro-arc Composite Ceramic (MCC) coatings on AZ91D magnesium alloys were prepared in combination with Micro-arc Oxidation (MAO) and electrophoresis technologies. The microstructure, corrosion resistance, abrasion resistance, stone impact resistance, thermal shock resistance and adhesion of MCC coating were studied, respectively. The surface and cross-section morphologies of MAO and MCC coating showed that the outer organic coating filled the holes on the surface of the MAO coating. It acted as a shelter on the MAO coating surface when the MCC coatings were exposed to corrosive environments. The corrosion resistance of the MCC coating was characterized by a copper-accelerated acetic acid salt spray test. The testing results showed that the creep back from scribe lines was less than 1mm and completely fit the evaluation standard. The composite structure of the MCC coating vastly improved the corrosion resistance of Mg alloys. According to testing standards, the resistance to abrasion, stone impact resistance, thermal shock resistance and adhesion of MCC coatings completely met the evaluation standard requirements. The MCC coated AZ91D magnesium alloys possessed excellent properties; this is a promising corrosion and wear resistance surface treatment technology on magnesium alloys for production vehicles.

  16. A Fatigue Model for Discontinuous Particulate-Reinforced Aluminum Alloy Composite: Influence of Microstructure

    NASA Astrophysics Data System (ADS)

    McCullough, R. R.; Jordon, J. B.; Brammer, A. T.; Manigandan, K.; Srivatsan, T. S.; Allison, P. G.; Rushing, T. W.

    2014-01-01

    In this paper, the use of a microstructure-sensitive fatigue model is put forth for the analysis of discontinuously reinforced aluminum alloy metal matrix composite. The fatigue model was used for a ceramic particle-reinforced aluminum alloy deformed under conditions of fully reversed strain control. Experimental results revealed the aluminum alloy to be strongly influenced by volume fraction of the particulate reinforcement phase under conditions of strain-controlled fatigue. The model safely characterizes the evolution of fatigue damage in this aluminum alloy composite into the distinct stages of crack initiation and crack growth culminating in failure. The model is able to capture the specific influence of particle volume fraction, particle size, and nearest neighbor distance in quantifying fatigue life. The model yields good results for correlation of the predicted results with the experimental test results on the fatigue behavior of the chosen aluminum alloy for two different percentages of the ceramic particle reinforcement. Further, the model illustrates that both particle size and volume fraction are key factors that govern fatigue lifetime. This conclusion is well supported by fractographic observations of the cyclically deformed and failed specimens.

  17. Development of Carbon Fiber Reinforced Stellite Alloy Based Composites for Tribocorrosion Applications

    NASA Astrophysics Data System (ADS)

    Khoddamzadeh, Alireza

    This thesis reports the design and development of two classes of new composite materials, which are low-carbon Stellite alloy matrices, reinforced with either chopped plain carbon fiber or chopped nickel-coated carbon fiber. The focus of this research is on obviating the problems related to the presence of carbides in Stellite alloys by substituting carbides as the main strengthening agent in Stellite alloys with the aforementioned carbon fibers. Stellite 25 was selected as the matrix because of its very low carbon content (0.1 wt%) and thereby relatively carbide free microstructure. The nickel coating was intended to eliminate any chance of carbide formation due to the possible reaction between carbon fibers and the matrix alloying additions. The composite specimens were fabricated using the designed hot isostatic pressing and sintering cycles. The fabricated specimens were microstructurally analyzed in order to identify the main phases present in the specimens and also to determine the possible carbide formation from the carbon fibers. The material characterization of the specimens was achieved through density, hardness, microhardness, corrosion, wear, friction, and thermal conductivity tests. These novel materials exhibit superior properties compared to existing Stellite alloys and are expected to spawn a new generation of materials used for high temperature, severe corrosion, and wear resistant applications in various industries.

  18. Fundamental alloy design of oxide ceramics and their composites

    SciTech Connect

    Chen, I.W.

    1992-01-01

    The main research was on microstructural development of oxide ceramics. Projects were completed and the publications given. Abstracts are given on: Reactive CeO[sub 2]powders by homogeneous precipitation, SiC whisker-reinforced lithium aluminosilicate composite, solute drag on grain boundary in ionic solids (space charge effect), in-situ alumina/aluminate platelet composites, exaggerated texture and grain growth of superplastic silicon nitride (SiAlON), hot extrusion of ceramics, control of grain boundary pinning in Al[sub 2]O[sub 3]/ZrO[sub 2] composites with Ce[sup 3+]/Ce[sup 4+] doping, superplastic forming of ceramic composites, computer simulation of final stage sintering (model, kinetics, microstructure, effect of initial pore size), development of superplastic structural ceramics, and superplastic flow of two-phase ceramics containing rigid inclusions (zirconia/mullite composites). A proposed research program is outlined: materials, solute drag, densification and coarsening, and grain boundary electrical behavior.

  19. One-dimensional shape memory alloy models for use with reinforced composite structures

    NASA Astrophysics Data System (ADS)

    Zak, A. J.; Cartmell, M. P.; Ostachowicz, W. M.; Wiercigroch, M.

    2003-06-01

    In this paper three models of the shape memory alloy behaviour have been presented and re-investigated. The models are attributed to Tanaka, Liang and Rogers, and Brinson, and have been used extensively in the literature for studying the static or dynamic performance of different composite material structures with embedded shape memory alloy components. The major differences and similarities between these models have been emphasised and examined in the paper. A simple experimental rig was designed and manufactured to gain additional insight into the main mechanics governing the shape memory alloy (SMA) mechanical properties. Data obtained from the experimental measurements on Ni-Ti wires have been used in the numerical simulation for validation purposes. It has been found that the three models all agree well in their predictions of the superelastic behaviour at higher temperatures, above the austenite finish temperature when shape memory alloys stay in the fully austenitic phase. However, at low temperatures, when the alloys stay in the fully martensitic phase, some difficulties may be encountered. The model developed by Brinson introduces two new state variables and therefore two different mechanisms for the instigation of stress-induced and temperature-induced martensite. This enables more accurate predictions of the superelastic behaviour. In general, it can be recommended that for investigations of the shape memory and superelastic behaviour of shape memory alloy components the Brinson model, or refinements based on the Brinson model, should be applied.

  20. Work of Adhesion in Al/SiC Composites with Alloying Element Addition

    NASA Astrophysics Data System (ADS)

    Fang, Xin; Fan, Tongxiang; Zhang, Di

    2013-11-01

    In the current work, a general methodology was proposed to demonstrate how to calculate the work of adhesion in a reactive multicomponent alloy/ceramic system. Applying this methodology, the work of adhesion of Al alloy/SiC systems and the influence of different alloying elements were predicted. Based on the thermodynamics of interfacial reaction and calculation models for component activities, the equilibrium compositions of the melts in Al alloy/SiC systems were calculated. Combining the work of adhesion models for reactive metal/ceramic systems, the work of adhesion in Al alloy/SiC systems both before and after the reaction was calculated. The results showed that the addition of most alloying elements, such as Mg, Si, and Mn, could increase the initial work of adhesion, while Fe had a slightly decreasing effect. As for the equilibrium state, the additions of Cu, Fe, Mn, Ni, Ti, and La could increase the equilibrium work of adhesion, but the additions of Mg and Zn had an opposite effect. Si was emphasized due to its suppressing effect on the interfacial reaction.

  1. Manufacturing techniques for titanium aluminide based alloys and metal matrix composites

    NASA Astrophysics Data System (ADS)

    Kothari, Kunal B.

    Dual phase titanium aluminides composed vastly of gamma phase (TiAl) with moderate amount of alpha2 phase (Ti3Al) have been considered for several high temperature aerospace and automobile applications. High specific strength coupled with good high temperature performance in the areas of creep and oxidation resistance makes titanium aluminides "materials of choice" for next generation propulsion systems. Titanium alumnides are primarily being considered as potential replacements for Ni-based superalloys in gas turbine engine components with aim of developing more efficient and leaner engines exhibiting high thrust-to-weight ratio. Thermo-mechanical treatments have shown to enhance the mechanical performance of titanium aluminides. Additionally, small additions of interstitial elements have shown further and significant improvement in the mechanical performance of titanium alumnide alloys. However, titanium aluminides lack considerably in room temperature ductility and as a result manufacturing processes of these aluminides have greatly suffered. Traditional ingot metallurgy and investment casting based methods to produce titanium aluminide parts in addition to being expensive, have also been unsuccessful in producing titanium aluminides with the desired mechanical properties. Hence, the manufacturing costs associated with these methods have completely outweighed the benefits offered by titanium aluminides. Over the last two decades, several powder metallurgy based manufacturing techniques have been studied to produce titanium aluminide parts. These techniques have been successful in producing titanium aluminide parts with a homogeneous and refined microstructure. These powder metallurgy techniques also hold the potential of significant cost reduction depending on the wide market acceptance of titanium aluminides. In the present study, a powder metallurgy based rapid consolidation technique has been used to produce near-net shape parts of titanium aluminides. Micron

  2. Compositional landscape for glass formation in metal alloys

    PubMed Central

    Na, Jong Hyun; Demetriou, Marios D.; Floyd, Michael; Hoff, Andrew; Garrett, Glenn R.; Johnson, William L.

    2014-01-01

    A high-resolution compositional map of glass-forming ability (GFA) in the Ni–Cr–Nb–P–B system is experimentally determined along various compositional planes. GFA is shown to be a piecewise continuous function formed by intersecting compositional subsurfaces, each associated with a nucleation pathway for a specific crystalline phase. Within each subsurface, GFA varies exponentially with composition, wheres exponential cusps in GFA are observed when crossing from one crystallization pathway to another. The overall GFA is shown to peak at multiple exponential hypercusps that are interconnected by ridges. At these compositions, quenching from the high-temperature melt yields glassy rods with diameters exceeding 1 cm, whereas for compositions far from these cusps the critical rod diameter drops precipitously and levels off to 1 to 2 mm. The compositional landscape of GFA is shown to arise primarily from an interplay between the thermodynamics and kinetics of crystal nucleation, or more precisely, from a competition between driving force for crystallization and liquid fragility. PMID:24927600

  3. Characterization of fabricated cobalt-based alloy/nano bioactive glass composites.

    PubMed

    Bafandeh, Mohammad Reza; Gharahkhani, Raziyeh; Fathi, Mohammad Hossein

    2016-12-01

    In this work, cobalt-based alloy/nano bioactive glass (NBG) composites with 10, 15 and 20wt% NBG were prepared and their bioactivity after immersion in simulated body fluid (SBF) for 1 to 4weeks was studied. Scanning electron microscopy images of two- step sintered composites revealed relatively dense microstructure. The results showed that density of composite samples decreased with increase in NBG amount. The microstructure analysis as well as energy dispersive X-ray analysis (EDX) revealed that small amount of calcium phosphate phases precipitates on the surface of composite samples after 1week immersion in SBF. After 2weeks immersion, considerable amounts of cauliflower-like shaped precipitations were seen on the surface of the composites. Based on EDX analysis, these precipitations were composed mainly from Ca, P and Si. The observed bands in the Fourier transform infrared spectroscopy of immersed composites samples for 4weeks in SBF, were characteristic bands of hydroxyapatite. Therefore it is possible to form hydroxyapatite layer on the surface of composite samples during immersion in SBF. The results indicated that prepared composites unlike cobalt-based alloy are bioactive, promising their possibility for implant applications. PMID:27612763

  4. Dry Sliding Wear Behaviour of Flyash Reinforced ZA-27 Alloy Based Metal Matrix Composites

    NASA Astrophysics Data System (ADS)

    Sharma, S. C.; Krishna, M.; Bhattacharyya, D.

    In the present investigation, an attempt has been made to evaluate the wear rate of ZA-27 alloy composites reinforced with fly ash particles from 1 to 3 wt% in steps of 1 wt%. The compo-casting method has been used to fabricate the composites using Raichur fly ash of average size 3-5 microns. The wear specimens are tested under dry conditions using a pin-on-disc sliding wear testing machine with wear loads of 20-120 N in steps of 20 N, and the sliding distances in the range of 0.5 km to 2.5 km. The results indicate that the wear rate of the composites is less than that of the matrix alloy and it further decreases with the increase in fly ash content. However, the material loss in terms of wear rate and wear volume increases with the increase in load and sliding distance, both in the cases of composites and the matrix alloy. An increase in the applied load increases the wear severity by changing the wear mechanism from abrasion to particle-cracking induced delamination wear. It is found that with the increase in fly ash content, the wear resistance increases monotonically. The observations have been explained using scanning electron microscope (SEM) analysis of the worn surfaces of the composites.

  5. P-type InGaN across the entire alloy composition range

    SciTech Connect

    Wang, K.; Araki, T.; Katsuki, T.; Yu, K. M.; Mayer, M. A.; Ager, J. W. III; Walukiewicz, W.; Alarcon-Llado, E.; Nanishi, Y.

    2013-03-11

    A systematic investigation on Mg doped and undoped InGaN epilayers grown by plasma-assisted molecular beam epitaxy has been conducted. Single phase InGaN alloys across the entire composition range were synthesized and Mg was doped into In{sub x}Ga{sub 1-x}N (0.1 {<=} x {<=} 0.88) epilayers up to {approx}10{sup 20}/cm{sup 3}. Hall effect, thermopower, and electrochemical capacitance voltage experimental results demonstrate the realization of p-type InGaN across the entire alloy composition range for properly Mg doped InGaN. Hole densities have been measured or estimated to be in the lower {approx}10{sup 18}/cm{sup 3} range when the net acceptor concentrations are in the lower {approx}10{sup 19}/cm{sup 3} range across the composition range.

  6. Superconducting properties of Nb-Cu nano-composites and nano-alloys

    NASA Astrophysics Data System (ADS)

    Parab, Pradnya; Kumar, Sanjeev; Bhui, Prabhjyot; Bagwe, Vivas; Bose, Sangita

    2016-05-01

    The evolution of the superconducting transition temperature (Tc) in nano-composite and nano-alloys of Nb-Cu, grown by DC magnetron co-sputtering are investigated. Microstructure of these films depends less strongly on the ratio of Nb:Cu but more on the growth temperature. At higher growth temperature, phase separated granular films of Nb and Cu were formed which showed superconducting transition temperatures (Tc) of ~ 7.2±0.5K, irrespective of the composition. Our results show that this is primarily influenced by the microstructure of the films determined during growth which rules out the superconducting proximity effect expected in these systems. At room temperature growth, films with nano-scale alloying were obtained at the optimal compositional range of 45-70 atomic% (At%) of Nb. These were also superconducting with a Tc of 3.2K.

  7. Structure, phase composition, and strengthening of cast Al-Ca-Mg-Sc alloys

    NASA Astrophysics Data System (ADS)

    Belov, N. A.; Naumova, E. A.; Bazlova, T. A.; Alekseeva, E. V.

    2016-02-01

    The structure and phase composition of Al-Ca-Mg-Sc alloys containing 0.3 wt % Sc, up to 10 wt % Ca, and up to 10 wt % Mg have been investigated in the cast state and state after heat treatment. It has been shown that only binary phases Al4Ca, Al3Sc, and Al3Mg2 can be in equilibrium with the aluminum solid solution. It has been found that the maximum strengthening effect caused by the precipitation of Al3Sc nanoparticles for all investigated alloys is attained after annealing at 300-350°C.

  8. Microstructure and wear resistance of Al-SiC composites coatings on ZE41 magnesium alloy

    NASA Astrophysics Data System (ADS)

    Rodrigo, P.; Campo, M.; Torres, B.; Escalera, M. D.; Otero, E.; Rams, J.

    2009-08-01

    Al and Al-SiC composites coatings were prepared by oxyacetylene flame spraying on ZE41 magnesium alloy substrates. Coatings with controlled reinforcement rate of up to 23 vol.% were obtained by spraying mixtures containing aluminium powder with up to 50 vol.% SiC particles. The coatings were sprayed on the magnesium alloy with minor degradation of its microstructure or mechanical properties. The coatings were compacted to improve their microstructure and protective behaviour. The wear behaviour of these coatings has been tested using the pin-on-disk technique and the reinforced coatings provided 85% more wear resistance than uncoated ZE41 and 400% more than pure Al coatings.

  9. Structure, phases, and mechanical response of Ti-alloy bioactive glass composite coatings.

    PubMed

    Nelson, G M; Nychka, J A; McDonald, A G

    2014-03-01

    Porous titanium alloy-bioactive glass composite coatings were manufactured via the flame spray deposition process. The porous coatings, targeted for orthodontic and bone-fixation applications, were made from bioactive glass (45S5) powder blended with either commercially pure titanium (Cp-Ti) or Ti-6Al-4V alloy powder. Two sets of spray conditions, two metallic particle size distributions, and two glass particle size distributions were used for this study. Negative control coatings consisting of pure Ti-6Al-4V alloy or Cp-Ti were sprayed under both conditions. The as-sprayed coatings were characterized through quantitative optical cross-sectional metallography, X-ray diffraction (XRD), and ASTM Standard C633 tensile adhesion testing. Determination of the porosity and glassy phase distribution was achieved by using image analysis in accordance with ASTM Standard E2109. Theoretical thermodynamic and heat transfer modeling was conducted to explain experimental observations. Thermodynamic modeling was performed to estimate the flame temperature and chemical environment for each spray condition and a lumped capacitance heat transfer model was developed to estimate the temperatures attained by each particle. These models were used to establish trends among the choice of alloy, spray condition, and particle size distribution. The deposition parameters, alloy composition, and alteration of the feedstock powder size distribution had a significant effect on the coating microstructure, porosity, phases present, mechanical response, and theoretical particle temperatures that were attained. The most promising coatings were the Ti-6Al-4V-based composite coatings, which had bond strength of 20±2MPa (n=5) and received reinforcement and strengthening from the inclusion of a glassy phase. It was shown that the use of the Ti-6Al-4V-bioactive glass composite coatings may be a superior choice due to the possible osteoproductivity from the bioactive glass, the potential ability to

  10. Comparison of brass alloys composition by laser-induced breakdown spectroscopy and self-organizing maps

    NASA Astrophysics Data System (ADS)

    Pagnotta, Stefano; Grifoni, Emanuela; Legnaioli, Stefano; Lezzerini, Marco; Lorenzetti, Giulia; Palleschi, Vincenzo

    2015-01-01

    In this paper we face the problem of assessing similarities in the composition of different metallic alloys, using the laser-induced breakdown spectroscopy technique. The possibility of determining the degree of similarity through the use of artificial neural networks and self-organizing maps is discussed. As an example, we present a case study involving the comparison of two historical brass samples, very similar in their composition. The results of the paper can be extended to many other situations, not necessarily associated with cultural heritage and archeological studies, where objects with similar composition have to be compared.

  11. Study on the Friction and Wear Behavior of a TA15 Alloy and Its Ni-SiC Composite Coating

    NASA Astrophysics Data System (ADS)

    Guo, Bao-hui; Wang, Zhen-ya; Li, Hai-long

    2016-05-01

    Ni-SiC composite coatings were prepared on TA15 alloy by composite electroplating technology. The friction and wear behavior of TA15 alloy, and the coating were comparatively studied at both room temperature and 600 °C using GCr15 as the counterparts. The results show that the obtained coating is relatively dense and compact, and possesses higher micro-hardness than TA15 alloy. The coating has significant friction reduction effect sliding at 600 °C, but has no obvious friction reduction effect sliding at room temperature. The coating possesses superior wear resistance than TA15 alloy, evidenced by its much lower mass losses than those of TA15 alloy sliding at both room temperature and 600 °C. The TA15 alloy and the coating showed different wear mechanisms under the given sliding conditions.

  12. Supercomputing in Aerospace

    NASA Technical Reports Server (NTRS)

    Kutler, Paul; Yee, Helen

    1987-01-01

    Topics addressed include: numerical aerodynamic simulation; computational mechanics; supercomputers; aerospace propulsion systems; computational modeling in ballistics; turbulence modeling; computational chemistry; computational fluid dynamics; and computational astrophysics.

  13. Aerospace Applications of Microprocessors

    NASA Technical Reports Server (NTRS)

    1980-01-01

    An assessment of the state of microprocessor applications is presented. Current and future requirements and associated technological advances which allow effective exploitation in aerospace applications are discussed.

  14. PALLADIUM/COPPER ALLOY COMPOSITE MEMBRANES FOR HIGH TEMPERATURE HYDROGEN SEPARATION

    SciTech Connect

    J. Douglas Way

    2004-08-31

    This report summarizes progress made during the first year of research funding from DOE Grant No. DE-FG26-03NT41792 at the Colorado School of Mines. The period of performance was September 1, 2003 through August of 2004. Composite membranes, consisting of a thin Pd alloy film supported on a porous substrate have been investigated as a means of reducing the membrane cost and improving H{sub 2} flux. An electroless plating technique was utilized to deposit subsequent layers of palladium and copper over zirconia and alumina-based microfilters. The composite membranes thus made were annealed and tested at temperatures ranging from 250 to 500 C, under very high feed pressures (up to 450 psig) using pure gases and gaseous mixtures containing H{sub 2}, CO, CO{sub 2}, H{sub 2}O and H{sub 2}S, with the purpose of determining the effects these variables had on the H{sub 2} permeation rate, selectivity and percent recovery. The inhibition caused by CO/CO{sub 2} gases on a 7 {micro}m thick Pd-Cu composite membrane was less than 17% over a wide range of compositions at 350 C. H{sub 2}S caused a strong inhibition of the H{sub 2} flux of the same Pd-Cu composite membrane, which is accentuated at levels of 100 ppm or higher. The membrane was exposed to 50 ppm three times without permanent damage. At higher H{sub 2}S levels, above 100 ppm the membrane suffered some physical degradation and its performances was severely affected. The use of sweep gases improved the hydrogen flux and recovery of a Pd-Cu composite membrane. Recently, we have been able to dramatically reduce the thickness of these Pd alloy membranes to approximately one micron. This is significant because at this thickness, it is the cost of the porous support that controls the materials cost of a composite Pd alloy membrane, not the palladium inventory. Very recent results show that the productivity of our membranes is very high, essentially meeting the DOE pure hydrogen flux target value set by the DOE Hydrogen

  15. Processing and microstructural evolution of alumina/aluminum alloy and aluminum nitride/aluminum alloy composites by directed melt oxidation. Ph.D. Thesis

    SciTech Connect

    Crudele, S.D.

    1994-12-31

    An experimental investigation on the directed oxidation of aluminum-zinc alloys to produce alumina/aluminum alloy composites with and without alumina preforms has been conducted. It has been suggested in the literature that Al-Mg alloys grow composites by the dissolution of a magnesia surface layer and reprecipitation of alumina in the composite. The intent of this investigation is to reveal relevant distinctions in the proposed dissolution-reprecipitation process as they apply to a more commercially interesting Zn containing alloy with a reinforcing preform. The TGA behavior and microstructural observations on the oxidation of Al-10Zn-8Si alloys were coupled with a thermodynamic and kinetic analysis to develop a composite growth model. Experiments were carried out in air at 1000-1200 C. At the higher temperatures (greater than 1100 C), Al2O3/Al composites grow by dissolving a ZnAl2O4 (spinel) surface layer. The dissolution process releases oxygen that reprecipitates in the form of Al2O3 on the existing composite, and also releases Zn and Al which migrate upward through the spinel to regenerate the surface oxide. Composite growth may only occur when the surface regenerates at a rate comparable with that of the dissolution process. At the lower temperatures, 1000 C, the composite growth is limited by the spinel regeneration process, and becomes intermittent. The addition of Mg to this alloy allows normal composite growth by the dissolution of a surface (Zn,Mg)Al2O4 layer at the lower temperatures, 980-1060 C, but leads to heterogeneous microstructures with voids as the temperature increases above approximately 1060 C. The directed oxidation of an Al-Zn alloy into porous alumina preforms yields an Al2O3/Al composite matrix which fills the preform interstices. Al-10Zn-8Si-0.25Mg alloys that are oxidized from 960-1100 C, and Al-10Zn-8Si alloys that are oxidized at 800-1000 C climb up the preform particle.

  16. Understanding the Cu-Zn brass alloys using a short-range-order cluster model: significance of specific compositions of industrial alloys.

    PubMed

    Hong, H L; Wang, Q; Dong, C; Liaw, Peter K

    2014-01-01

    Metallic alloys show complex chemistries that are not yet understood so far. It has been widely accepted that behind the composition selection lies a short-range-order mechanism for solid solutions. The present paper addresses this fundamental question by examining the face-centered-cubic Cu-Zn α-brasses. A new structural approach, the cluster-plus-glue-atom model, is introduced, which suits specifically for the description of short-range-order structures in disordered systems. Two types of formulas are pointed out, [Zn-Cu12]Zn(1~6) and [Zn-Cu12](Zn,Cu)6, which explain the α-brasses listed in the American Society for Testing and Materials (ASTM) specifications. In these formulas, the bracketed parts represent the 1(st)-neighbor cluster, and each cluster is matched with one to six 2nd-neighbor Zn atoms or with six mixed (Zn,Cu) atoms. Such a cluster-based formulism describes the 1st- and 2nd-neighbor local atomic units where the solute and solvent interactions are ideally satisfied. The Cu-Ni industrial alloys are also explained, thus proving the universality of the cluster-formula approach in understanding the alloy selections. The revelation of the composition formulas for the Cu-(Zn,Ni) industrial alloys points to the common existence of simple composition rules behind seemingly complex chemistries of industrial alloys, thus offering a fundamental and practical method towards composition interpretations of all kinds of alloys. PMID:25399835

  17. Understanding the Cu-Zn brass alloys using a short-range-order cluster model: significance of specific compositions of industrial alloys

    PubMed Central

    Hong, H. L.; Wang, Q.; Dong, C.; Liaw, Peter K.

    2014-01-01

    Metallic alloys show complex chemistries that are not yet understood so far. It has been widely accepted that behind the composition selection lies a short-range-order mechanism for solid solutions. The present paper addresses this fundamental question by examining the face-centered-cubic Cu-Zn α-brasses. A new structural approach, the cluster-plus-glue-atom model, is introduced, which suits specifically for the description of short-range-order structures in disordered systems. Two types of formulas are pointed out, [Zn-Cu12]Zn1~6 and [Zn-Cu12](Zn,Cu)6, which explain the α-brasses listed in the American Society for Testing and Materials (ASTM) specifications. In these formulas, the bracketed parts represent the 1st-neighbor cluster, and each cluster is matched with one to six 2nd-neighbor Zn atoms or with six mixed (Zn,Cu) atoms. Such a cluster-based formulism describes the 1st- and 2nd-neighbor local atomic units where the solute and solvent interactions are ideally satisfied. The Cu-Ni industrial alloys are also explained, thus proving the universality of the cluster-formula approach in understanding the alloy selections. The revelation of the composition formulas for the Cu-(Zn,Ni) industrial alloys points to the common existence of simple composition rules behind seemingly complex chemistries of industrial alloys, thus offering a fundamental and practical method towards composition interpretations of all kinds of alloys. PMID:25399835

  18. Manufacturing techniques for titanium aluminide based alloys and metal matrix composites

    NASA Astrophysics Data System (ADS)

    Kothari, Kunal B.

    Dual phase titanium aluminides composed vastly of gamma phase (TiAl) with moderate amount of alpha2 phase (Ti3Al) have been considered for several high temperature aerospace and automobile applications. High specific strength coupled with good high temperature performance in the areas of creep and oxidation resistance makes titanium aluminides "materials of choice" for next generation propulsion systems. Titanium alumnides are primarily being considered as potential replacements for Ni-based superalloys in gas turbine engine components with aim of developing more efficient and leaner engines exhibiting high thrust-to-weight ratio. Thermo-mechanical treatments have shown to enhance the mechanical performance of titanium aluminides. Additionally, small additions of interstitial elements have shown further and significant improvement in the mechanical performance of titanium alumnide alloys. However, titanium aluminides lack considerably in room temperature ductility and as a result manufacturing processes of these aluminides have greatly suffered. Traditional ingot metallurgy and investment casting based methods to produce titanium aluminide parts in addition to being expensive, have also been unsuccessful in producing titanium aluminides with the desired mechanical properties. Hence, the manufacturing costs associated with these methods have completely outweighed the benefits offered by titanium aluminides. Over the last two decades, several powder metallurgy based manufacturing techniques have been studied to produce titanium aluminide parts. These techniques have been successful in producing titanium aluminide parts with a homogeneous and refined microstructure. These powder metallurgy techniques also hold the potential of significant cost reduction depending on the wide market acceptance of titanium aluminides. In the present study, a powder metallurgy based rapid consolidation technique has been used to produce near-net shape parts of titanium aluminides. Micron

  19. Effect of gold composition on the orientations of oxide nuclei during the early stage oxidation of Cu-Au alloys

    SciTech Connect

    Luo Langli; Zhou Guangwen; Kang Yihong; Yang, Judith C.

    2012-04-15

    In situ environmental transmission electron microscopy is employed to study the effect of Au composition in Cu-Au alloys on the orientations of oxide islands during the initial-stage oxidation of Cu-Au(100) alloys. An orientation transition from nucleating epitaxial Cu{sub 2}O islands to randomly oriented oxide islands is observed upon increasing the oxygen gas pressure. By increasing the Au composition in the Cu-Au alloys, both the oxide nucleation time and saturation density of oxide islands increase, but the critical oxygen pressure leading to nucleating randomly oriented Cu{sub 2}O islands decreases. It is shown by a kinetic model that such a dependence of the critical oxygen pressure on the alloy composition is related to its effect on two competing processes, the oxide-alloy structure match and the effective collision of oxygen atoms, in determining the overall nucleation rate of oxide islands during the oxidation.

  20. Composition and orientation relationships of constituent particles in 3xxx aluminum alloys

    NASA Astrophysics Data System (ADS)

    Muggerud, Astrid Marie F.; Li, Yanjun; Holmestad, Randi

    2014-02-01

    Constituent and dispersoid phases in two Direct Chill-cast 3xxx aluminum alloys after low-temperature annealing, with different silicon content have been studied. The lattice parameters, chemical composition, morphology and orientations relationships of constituent particles with regard to Al matrix have been addressed. Al?(Fe,Mn) is found to be the most prominent constituent phase in the alloy with a low Si content. The orientation relationship between aluminum matrix and this phase is determined as ?, ?, which is consistent with the orientation relationships of Al?(Fe,Mn) dispersoids. ?-Al(Fe,Mn)Si constituent particles in the Si rich alloy have been found to have various possible orientations. A gradient of Fe content is found in the ?-Al(Fe,Mn)Si dispersoids due to slow diffusion of Fe into dispersoids during annealing.

  1. Corrosion resistance of a composite polymeric coating applied on biodegradable AZ31 magnesium alloy.

    PubMed

    Zomorodian, A; Garcia, M P; Moura e Silva, T; Fernandes, J C S; Fernandes, M H; Montemor, M F

    2013-11-01

    The high corrosion rate of magnesium alloys is the main drawback to their widespread use, especially in biomedical applications. There is a need for developing new coatings that provide simultaneously corrosion resistance and enhanced biocompatibility. In this work, a composite coating containing polyether imide, with several diethylene triamine and hydroxyapatite contents, was applied on AZ31 magnesium alloys pre-treated with hydrofluoric acid by dip coating. The coated samples were immersed in Hank's solution and the coating performance was studied by electrochemical impedance spectroscopy and scanning electron microscopy. In addition, the behavior of MG63 osteoblastic cells on coated samples was investigated. The results confirmed that the new coatings not only slow down the corrosion rate of AZ31 magnesium alloys in Hank's solution, but also enhance the adhesion and proliferation of MG63 osteoblastic cells, especially when hydroxyapatite nanoparticles were introduced in the coating formulation. PMID:23454214

  2. Composite of ceramic-coated magnetic alloy particles

    DOEpatents

    Moorhead, Arthur J.; Kim, Hyoun-Ee

    2000-01-01

    A composite structure and method for manufacturing same, the composite structure being comprised of metal particles and an inorganic bonding media. The method comprises the steps of coating particles of a metal powder with a thin layer of an inorganic bonding media selected from the group of powders consisting of a ceramic, glass, and glass-ceramic. The particles are assembled in a cavity and heat, with or without the addition of pressure, is thereafter applied to the particles until the layer of inorganic bonding media forms a strong bond with the particles and with the layer of inorganic bonding media on adjacent particles. The resulting composite structure is strong and remains cohesive at high temperatures.

  3. Properties of a new type Al/Pb-0.3%Ag alloy composite anode for zinc electrowinning

    NASA Astrophysics Data System (ADS)

    Yang, Hai-tao; Liu, Huan-rong; Zhang, Yong-chun; Chen, Bu-ming; Guo, Zhong-cheng; Xu, Rui-dong

    2013-10-01

    An Al/Pb-0.3%Ag alloy composite anode was produced via composite casting. Its electrocatalytic activity for the oxygen evolution reaction and corrosion resistance was evaluated by anodic polarization curves and accelerated corrosion test, respectively. The microscopic morphologies of the anode section and anodic oxidation layer during accelerated corrosion test were obtained by scanning electron microscopy. It is found that the composite anode (hard anodizing) displays a more compact interfacial combination and a better adhesive strength than plating tin. Compared with industrial Pb-0.3%Ag anodes, the oxygen evolution overpotentials of Al/Pb-0.3%Ag alloy (hard anodizing) and Al/Pb-0.3%Ag alloy (plating tin) at 500 A·m-2 were lower by 57 and 14 mV, respectively. Furthermore, the corrosion rates of Pb-0.3%Ag alloy, Al/Pb-0.3%Ag alloy (hard anodizing), and Al/Pb-0.3%Ag alloy (plating tin) were 13.977, 9.487, and 11.824 g·m-2·h-1, respectively, in accelerated corrosion test for 8 h at 2000 A·m-2. The anodic oxidation layer of Al/Pb-0.3%Ag alloy (hard anodizing) is more compact than Pb-0.3%Ag alloy and Al/Pb-0.3%Ag alloy (plating tin) after the test.

  4. Deformation and fracture behavior of composite structured Ti-Nb-Al-Co(-Ni) alloys

    SciTech Connect

    Okulov, I. V. Marr, T.; Schultz, L.; Eckert, J.; Kühn, U.; Freudenberger, J.; Oertel, C.-G.; Skrotzki, W.

    2014-02-17

    Tensile ductility of the Ti-based composites, which consist of a β-Ti phase surrounded by ultrafine structured intermetallics, is tunable through the control of intermetallics. The two Ti-based alloys studied exhibit similar compressive yield strength (about 1000 MPa) and strain (about 35%–40%) but show a distinct difference in their tensile plasticity. The alloy Ti{sub 71.8}Nb{sub 14.1}Ni{sub 7.4}Al{sub 6.7} fractures at the yield stress while the alloy Ti{sub 71.8}Nb{sub 14.1}Co{sub 7.4}Al{sub 6.7} exhibits about 4.5% of tensile plastic deformation. To clarify the effect of microstructure on the deformation behavior of these alloys, tensile tests were carried out in the scanning electron microscope. It is shown that the distribution as well as the type of intermetallics affects the tensile ductility of the alloys.

  5. NASA technology utilization survey on composite materials

    NASA Technical Reports Server (NTRS)

    Leeds, M. A.; Schwartz, S.; Holm, G. J.; Krainess, A. M.; Wykes, D. M.; Delzell, M. T.; Veazie, W. H., Jr.

    1972-01-01

    NASA and NASA-funded contractor contributions to the field of composite materials are surveyed. Existing and potential non-aerospace applications of the newer composite materials are emphasized. Economic factors for selection of a composite for a particular application are weight savings, performance (high strength, high elastic modulus, low coefficient of expansion, heat resistance, corrosion resistance,), longer service life, and reduced maintenance. Applications for composites in agriculture, chemical and petrochemical industries, construction, consumer goods, machinery, power generation and distribution, transportation, biomedicine, and safety are presented. With the continuing trend toward further cost reductions, composites warrant consideration in a wide range of non-aerospace applications. Composite materials discussed include filamentary reinforced materials, laminates, multiphase alloys, solid multiphase lubricants, and multiphase ceramics. New processes developed to aid in fabrication of composites are given.

  6. Transmutations of elements under irradiation and its impact on alloys composition

    SciTech Connect

    Gomes, I.C.; Smith, D.L.

    1994-09-01

    This study presents a comparison of nuclear transmutation rates for candidate fusion first wall/blanket structural materials in available fission test reactors with those produced in a typical fusion spectrum. The materials analyzed in this study include a vanadium alloy (V-4Cr-4Ti), a reduced activation martensitic steel (Fe-9Cr-2WVTa), a high conductivity copper alloy (Cu-Cr-Zr), and the SiC compound. The fission irradiation facilities considered include the EBR-II (Experimental Breeder Reactor) fast reactor, and two high flux mixed spectrum reactors, HFIR (High Flux Irradiation Reactor) and SM-3 (Russian reactor). The transmutation and dpa rates that occur in these test reactors are compared with the calculated transmutation and dpa rates characteristic of a D-T fusion first wall spectrum. In general, past work has shown that the displacement damage produced in these fission reactors can be correlated to displacement damage in a fusion spectrum; however, the generation of helium and hydrogen through threshold reactions [(n,x{alpha}) and (n,xp)] are much higher in a fusion spectrum. As shown in this study, the compositional changes for several candidate structural materials exposed to a fast fission reactor spectrum are very low, similar to those for a characteristic fusion spectrum. However, the relatively high thermalized spectrum of a mixed spectrum reactor produces transmutation rates quite different from the ones predicted for a fusion reactor, resulting in substantial differences in the final composition of several candidate alloys after relatively short irradiation time. As examples, the transmutation rates of W, Ta, V, Cu, among others, differ considerably when the irradiation is performed under a mixed spectrum reactor`s and fusion first wall`s spectrum. Fast reactors (EBR-II) provide the only possibility for obtaining high damage rates without producing significant compositional effects in vanadium alloys, ferritic steels and copper alloys.

  7. Design of energy absorbing materials and composite structures based on porous shape memory alloys (SE)

    NASA Astrophysics Data System (ADS)

    Zhao, Ying

    Recently, attention has been paid to porous shape memory alloys. This is because the alloys show large and recoverable deformation, i.e. superelasticity and shape memory effect. Due to their light weight and potential large deformations, porous shape memory alloys have been considered as excellent candidates for energy absorption materials. In the present study, porous NiTi alloy with several different porosities are processed by spark plasma sintering (SPS). The compression behavior of the porous NiTi is examined with an aim of using it for a possible high energy absorbing material. Two models for the macroscopic compression behavior of porous shape memory alloy (SMA) are presented in this work, where Eshelby's inhomogeneous inclusion method is used to predict the effective elastic and superelastic behavior of a porous SMA based on the assumption of stress-strain curve. The analytical results are compared with experimental data for porous NiTi with 13% porosity, resulting in a reasonably good agreement. Based on the study upon porous NiTi, an energy absorbing composite structure made of a concentric NiTi spring and a porous NiTi rod is presented in this PhD dissertation. Both NiTi spring and porous NiTi rod are of superelastic grade. Ductile porous NiTi cylindrical specimens are fabricated by spark plasma sintering. The composite structure exhibits not only high reversible force-displacement behavior for small to intermediate loading but also high energy absorbing property when subjected to large compressive loads. A model for the compressive force-displacement curve of the composite structure is presented. The predicted curve is compared to the experimental data, resulting in a reasonably good agreement.

  8. Reactive spark plasma sintering (SPS) of nitride reinforced titanium alloy composites

    SciTech Connect

    Borkar, Tushar; Nag, Soumya; Ren, Yang; Tiley, Jaimie; Banerjee, Rajarshi

    2014-12-25

    Coupled in situ alloying and nitridation of titanium–vanadium alloys, has been achieved by introducing reactive nitrogen gas during the spark plasma sintering (SPS) of blended titanium and vanadium elemental powders, leading to a new class of nitride reinforced titanium alloy composites. The resulting microstructure includes precipitates of the d-TiN phase with the NaCl structure, equiaxed (or globular) precipitates of a nitrogen enriched hcp a(Ti,N) phase with a c/a ratio more than what is expected for pure hcp Ti, and fine scale plate-shaped precipitates of hcp a-Ti, distributed within a bcc b matrix. During SPS processing, the d-TiN phase appears to form at a temperature of 1400 C, while only hcp a(Ti,N) and a-Ti phases form at lower processing temperatures. Consequently, the highest microhardness is exhibited by the composite processed at 1400 C while those processed at 1300 C or below exhibit lower values. Processing at temperatures below 1300 C, resulted in an incomplete alloying of the blend of titanium and vanadium powders. These d-TiN precipitates act as heterogeneous nucleation sites for the a(Ti,N) precipitates that appear to engulf and exhibit an orientation relationship with the nitride phase at the center. Furthermore, fine scale a-Ti plates are precipitated within the nitride precipitates, presumably resulting from the retrograde solubility of nitrogen in titanium.

  9. Subtask 12A3: Fabrication and properties of compositional variants of vanadium alloys

    SciTech Connect

    Grossbeck, M.L.; Alexander, D.J.; Gubbi, A.N.

    1995-03-01

    Procurement of five 15 kg heats of V-Cr-Ti alloys with variations in Cr and Ti concentrations from the primary V-4Cr-4Ti composition. Fabrication into sheet product, determination of the tensile and Charpy impact properties, and preparation of specimens for reactor irradiation experiments. Data obtained from these alloys will be used to define the allowable ranges of Cr and Ti within which consistent properties may be obtained. Four 15 kg heats with variations in Cr and Ti concentration have been procured in various plate and sheet thicknesses. Measurements of recovery and recrystallization kinetics, precipitation behavior, and Charpy impact properties are in progress to compare properties with the behavior of the primary alloy composition V-4Cr-4Ti. In the fully recrystallized condition, the impact properties of the V-6Cr-3Ti alloy are inferior to those of the 500 kg heat of V-4Cr-4Ti. However, properties comparable to those of the V-4Cr-4Ti can be obtained of the V-6Cr-3Ti as tested in a partially-recrystallized condition. 5 figs., 4 tabs.

  10. Optimization of Wear Behavior of Magnesium Alloy AZ91 Hybrid Composites Using Taguchi Experimental Design

    NASA Astrophysics Data System (ADS)

    Girish, B. M.; Satish, B. M.; Sarapure, Sadanand; Basawaraj

    2016-06-01

    In the present paper, the statistical investigation on wear behavior of magnesium alloy (AZ91) hybrid metal matrix composites using Taguchi technique has been reported. The composites were reinforced with SiC and graphite particles of average size 37 μm. The specimens were processed by stir casting route. Dry sliding wear of the hybrid composites were tested on a pin-on-disk tribometer under dry conditions at different normal loads (20, 40, and 60 N), sliding speeds (1.047, 1.57, and 2.09 m/s), and composition (1, 2, and 3 wt pct of each of SiC and graphite). The design of experiments approach using Taguchi technique was employed to statistically analyze the wear behavior of hybrid composites. Signal-to-noise ratio and analysis of variance were used to investigate the influence of the parameters on the wear rate.

  11. Preparation of Composite Coating on AZ91D Magnesium Alloy by Silica Sol-Micro Oxidation

    NASA Astrophysics Data System (ADS)

    Shao, Zhongcai; Zhang, Feifei; Zhao, Ruiqiang; Shen, Xiaoyi

    2016-03-01

    Composite coating was prepared on AZ91D magnesium alloy with a new method which combined silica sol with micro-arc oxidation (MAO). The MAO coating was prepared on the basis of MAO solution, and then coated by sol-gel process. The composite coating was obtained after second MAO treatment. Scanning electron microscopy coupled with X-ray diffraction (XRD), energy spectrum analysis and electrochemical testing was applied to characterize the properties of MAO coating and composite coating. The experimental test results indicated that the Si element derived from SiO2 gel particle embedded into the MAO coating by second MAO treatment. The surface of composite coating became dense and the holes were smaller with silica sol sealing process. The corrosion resistance of composite coating was improved than the MAO coating.

  12. Aerospace - Aviation Education.

    ERIC Educational Resources Information Center

    Martin, Arthur I.; Jones, K. K.

    This document outlines the aerospace-aviation education program of the State of Texas. In this publication the course structures have been revised to fit the quarter system format of secondary schools in Texas. The four courses outlined here have been designed for students who will be consumers of aerospace products, spinoffs, and services or who…

  13. Magnetic viscosity in Ni/Cu compositionally-modulated alloys

    SciTech Connect

    Bennett, L.H.; Swartzendruber, L.J.; Ettedgui, H.; Atzmony, U.; Lashmore, D.S; Watson, R.E.; Brookhaven National Lab., Upton, NY )

    1989-01-01

    The existence of a magnetic aftereffect ( magnetic viscosity'') in Ni/Cu multilayered alloys was established using a vibrating sample magnetometer at room temperature and at 86 K. It was shown that the effect is strongly dependent on the step field, H{sub 2} (i.e., the value the field is reduced to after the magnetic moment has been aligned in high field) and exhibits a maximum relaxation rate for values of H{sub 2} around the reverse coercive field, {minus}H{sub c}. Aftereffect behavior of this type has been observed in other materials, though most often for systems composed of superparamagnetic particles, where the relaxation freezes out at low temperatures. In contrast, the relaxation in the CMA was shown to be enhanced at 86 K over its value at room temperature. New measurements over a wider temperature range show that the enhancement in this sample reaches a maximum near 120 K, but below that temperature the relaxation does freeze out. The temperature of maximum enhancement varies from sample to sample. 6 refs.

  14. Micromechanics of composites with shape memory alloy fibers in uniform thermal fields

    NASA Technical Reports Server (NTRS)

    Birman, Victor; Saravanos, Dimitris A.; Hopkins, Dale A.

    1995-01-01

    Analytical procedures are developed for a composite system consisting of shape memory alloy fibers within an elastic matrix subject to uniform temperature fluctuations. Micromechanics for the calculation of the equivalent properties of the composite are presented by extending the multi-cell model to incorporate shape memory alloy fibers. A three phase concentric cylinder model is developed for the analysis of local stresses which includes the fiber, the matrix, and the surrounding homogenized composite. The solution addresses the complexities induced by the nonlinear dependence of the in-situ martensite fraction of the fibers to the local stresses and temperature, and the local stresses developed from interactions between the fibers and matrix during the martensitic and reverse phase transformations. Results are presented for a nitinol/epoxy composite. The applications illustrate the response of the composite in isothermal longitudinal loading and unloading, and in temperature induced actuation. The local stresses developed in the composite under various stages of the martensitic and reverse phase transformation are also shown.

  15. Micromechanics of composites with shape memory alloy fibers in uniform thermal fields

    SciTech Connect

    Birman, V.; Saravanos, D.A.; Hopkins, D.A.

    1995-08-01

    Analytical procedures are developed for a composite system consisting of shape memory alloy fibers within an elastic matrix subject to uniform temperature fluctuations. Micromechanics for the calculation of the equivalent properties of the composite are presented by extending the multi-cell model to incorporate shape memory alloy fibers. A three phase concentric cylinder model is developed for the analysis of local stresses which includes the fiber, the matrix, and the surrounding homogenized composite. The solution addresses the complexities induced by the nonlinear dependence of the in-situ martensite fraction of the fibers to the local stresses and temperature, and the local stresses developed from interactions between the fibers and matrix during the martensitic and reverse phase transformations. Results are presented for a nitinol/epoxy composite. The applications illustrate the response of the composite in isothermal longitudinal loading and unloading, and in temperature induced actuation. The local stresses developed in the composite under various stages of the martensitic and reverse phase transformation are also shown.

  16. Shock response of boron carbide based composites infiltrated with magnesium alloys

    NASA Astrophysics Data System (ADS)

    Kafri, Mathan; Dariel, Moshe; Frage, Nahum; Zaretsky, Eugene

    2011-06-01

    The fully dense composites were obtained by vacuum infiltrating the boron carbide compacts (80% green density) with liquid AZ91 magnesium alloy (850 °C) and with the melt of 50/50 AZ91-silicon mixture (1050 °C). The densities, the elastic moduli and the Vickers hardness values of the obtained composites were, respectively, 2.44 g/cm3 and 2.54 g/cm3, 300 and 350 GPa, and 1200 and 1800 HV. The impact response of the composites was studied in a series of VISAR-instrumented planar impact experiments with velocities of W and Cu impactors ranged from 100 to 1000 m/s. It was found that velocity histories recorded for the composites produced by infiltration with Mg-Si alloy contain a distinct elastic precursor front followed by a plastic ramp. On the contrary, the velocity histories of the composites infiltrated with AZ91 do not display any step-like front; the amplitude of the elastic wave grows gradually from zero level and transforms smoothly into the plastic front. The influence of the composites microstructure on the compressive elastic-plastic behavior and on the dynamic tensile (spall) strength is discussed.

  17. Facile preparation and thermoelectric properties of Bi₂Te₃ based alloy nanosheet/PEDOT:PSS composite films.

    PubMed

    Du, Yong; Cai, K F; Chen, Song; Cizek, Pavel; Lin, Tong

    2014-04-23

    Bi2Te3 based alloy nanosheet (NS)/poly(3,4-ethylenedioxythiophene):poly(4-styrenesulfonate) (PEDOT:PSS) composite films were prepared separately by spin coating and drop casting techniques. The drop cast composite film containing 4.10 wt % Bi2Te3 based alloy NSs showed electrical conductivity as high as 1295.21 S/cm, which is higher than that (753.8 S/cm) of a dimethyl sulfoxide doped PEDOT:PSS film prepared under the same condition and that (850-1250 S/cm) of the Bi2Te3 based alloy bulk material. The composite film also showed a very high power factor value, ∼32.26 μWm(-1) K(-2). With the content of Bi2Te3 based alloy NSs increasing from 0 to 4.10 wt %, the electrical conductivity and Seebeck coefficient of the composite films increase simultaneously. PMID:24666341

  18. Investigation of the Thermomechanical Response of Shape Memory Alloy Hybrid Composite Beams

    NASA Technical Reports Server (NTRS)

    Davis, Brian A.

    2005-01-01

    Previous work at NASA Langley Research Center (LaRC) involved fabrication and testing of composite beams with embedded, pre-strained shape memory alloy (SMA) ribbons. That study also provided comparison of experimental results with numerical predictions from a research code making use of a new thermoelastic model for shape memory alloy hybrid composite (SMAHC) structures. The previous work showed qualitative validation of the numerical model. However, deficiencies in the experimental-numerical correlation were noted and hypotheses for the discrepancies were given for further investigation. The goal of this work is to refine the experimental measurement and numerical modeling approaches in order to better understand the discrepancies, improve the correlation between prediction and measurement, and provide rigorous quantitative validation of the numerical model. Thermal buckling, post-buckling, and random responses to thermal and inertial (base acceleration) loads are studied. Excellent agreement is achieved between the predicted and measured results, thereby quantitatively validating the numerical tool.

  19. Effect of corrosion on the composition of pulse-plated Cu-Ni alloys

    SciTech Connect

    Roy, S.; Matlosz, M.; Landolt, D. . Dept. des materiaux)

    1994-06-01

    Copper and nickel are codeposited by pulse and reverse-pulse plating on a rotating cylinder cathode from a citrate bath. Polarization data for copper and nickel as well as potential transients during pulse and reverse-pulse current experiments show that displacement reactions may occur during the pulse off-time or pulse-reversal time. A mathematical model which includes this effect is developed to predict the composition of electrodeposited alloys. The model shows that copper deposits at the mass-transfer limiting current throughout-the pulse-cycle while nickel is alternately deposited and dissolved during the pulse on-time and off-time (or reversal time). The alloy composition is governed by pulse parameters and the diffusion limiting current for copper deposition.

  20. Materials Design for Joinable, High Performance Aluminum Alloys

    NASA Astrophysics Data System (ADS)

    Glamm, Ryan James

    An aluminum alloy compatible with friction stir welding is designed for automotive and aerospace structural applications. Current weldable automotive aluminum alloys do not possess the necessary strength to meet safety standards and therefore are not able to replace steel in the automotive body. Significant weight savings could be achieved if steel components are replaced with aluminum. Current aerospace alloys are not weldable, requiring machining of large pieces that are then riveted together. If an aerospace alloy could be friction stir welded, smaller pieces could be welded, reducing material waste. Using a systems approach for materials design, property goals are set from performance objectives. From previous research and computational predictions, a structure is designed for a prototype alloy containing dynamic precipitates to readily dissolve and re-precipitate and high stability precipitates to resist dissolution and coarsening in the weld region. It is found that a Ag modified Al-3.9Mg-0.04Cu (at. %) alloy enhanced the rate and magnitude of hardening during ageing, both beneficial effects for dynamic precipitation. In the same alloy, ageing at 350°C results in hardening from Al 3(Sc,Zr) precipitates. Efforts to effectively precipitate both populations simultaneously are unsuccessful. The Al3(Sc,Zr) precipitation hardened prototype is friction stir processed and no weak zones are found in the weld hardness profile. An aerospace alloy design is proposed, utilizing the dual precipitate structure shown in the prototype. The automotive alloy is designed using a basic strength model with parameters determined from the initial prototype alloy analysis. After ageing to different conditions, the alloy is put through a simulated heat affected zone thermal cycle with a computer controlled induction heater. The aged samples lose hardness from the weld cycle but recover hardness from a post weld heat treatment. Atom probe tomography and transmission electron

  1. Phase composition and structure of aluminum Al-Cu-Si-Sn-Pb alloys

    NASA Astrophysics Data System (ADS)

    Belov, N. A.; Stolyarova, O. O.; Murav'eva, T. I.; Zagorskii, D. L.

    2016-06-01

    The structure and phase composition of cast and heat treated Al-Cu-Si-Sn-Pb alloys containing 6 wt % Sn, 2 wt % Pb, 0-4 wt % Cu, 0-10 wt % Si have been studied using calculations and experimental methods. Polythermal and isothermal sections are reported, which indicate the existence of two liquid phases. It was found that the low-melting phase is inhomogeneous and consists of individual leadand tin-based particles.

  2. Design of torque actuator based on ferromagnetic shape memory alloy composite

    NASA Astrophysics Data System (ADS)

    Cheng, Victor J.; Taya, Minoru; Lee, Jae Kon; Kusaka, Masahiro; Wada, Taishi

    2004-07-01

    Experimental tests were conducted on a torque actuator based on ferromagnetic shape memory alloy composite and performance data obtained. Based on experimental results of the initial design, several design changes were made to the actuator that resulted in improved torque capability and maximum angle of twist compared to the original design. A full 3-D finite element method model was undertaken to optimize magnetic flux lines generated by the hybrid magnet.

  3. Improving the corrosion wear resistance of AISI 316L stainless steel by particulate reinforced Ni matrix composite alloying layer

    NASA Astrophysics Data System (ADS)

    Xu, Jiang; Zhuo, Chengzhi; Tao, Jie; Jiang, Shuyun; Liu, Linlin

    2009-01-01

    In order to overcome the problem of corrosion wear of AISI 316L stainless steel (SS), two kinds of composite alloying layers were prepared by a duplex treatment, consisting of Ni/nano-SiC and Ni/nano-SiO2 predeposited by brush plating, respectively, and subsequent surface alloying with Ni-Cr-Mo-Cu by a double glow process. The microstructure of the two kinds of nanoparticle reinforced Ni-based composite alloying layers was investigated by means of SEM and TEM. The electrochemical corrosion behaviour of composite alloying layers compared with the Ni-based alloying layer and 316L SS under different conditions was characterized by potentiodynamic polarization test and electrochemical impedance spectroscopy. Results showed that under alloying temperature (1000 °C) conditions, amorphous nano-SiO2 particles still retained the amorphous structure, whereas nano-SiC particles were decomposed and Ni, Cr reacted with SiC to form Cr6.5Ni2.5Si and Cr23C6. In static acidic solution, the corrosion resistance of the composite alloying layer with the brush plating Ni/nano-SiO2 particles interlayer is lower than that of the Ni-based alloying layer. However, the corrosion resistance of the composite alloying layer with the brush plating Ni/nano-SiO2 particles interlayer is prominently superior to that of the Ni-based alloying layer under acidic flow medium condition and acidic slurry flow condition. The corrosion resistance of the composite alloying layer with the brush plating Ni/nano-SiC particles interlayer is evidently lower than that of the Ni-based alloying layer, but higher than that of 316L SS under all test conditions. The results show that the highly dispersive nano-SiO2 particles are helpful in improving the corrosion wear resistance of the Ni-based alloying layer, whereas carbides and silicide phase are deleterious to that of the Ni-based alloying layer due to the fact that the preferential removal of the matrix around the precipitated phase takes place by the chemical

  4. Controllable synthesis of molybdenum tungsten disulfide alloy for vertically composition-controlled multilayer

    PubMed Central

    Song, Jeong-Gyu; Ryu, Gyeong Hee; Lee, Su Jeong; Sim, Sangwan; Lee, Chang Wan; Choi, Taejin; Jung, Hanearl; Kim, Youngjun; Lee, Zonghoon; Myoung, Jae-Min; Dussarrat, Christian; Lansalot-Matras, Clement; Park, Jusang; Choi, Hyunyong; Kim, Hyungjun

    2015-01-01

    The effective synthesis of two-dimensional transition metal dichalcogenides alloy is essential for successful application in electronic and optical devices based on a tunable band gap. Here we show a synthesis process for Mo1−xWxS2 alloy using sulfurization of super-cycle atomic layer deposition Mo1−xWxOy. Various spectroscopic and microscopic results indicate that the synthesized Mo1−xWxS2 alloys have complete mixing of Mo and W atoms and tunable band gap by systematically controlled composition and layer number. Based on this, we synthesize a vertically composition-controlled (VCC) Mo1−xWxS2 multilayer using five continuous super-cycles with different cycle ratios for each super-cycle. Angle-resolved X-ray photoemission spectroscopy, Raman and ultraviolet–visible spectrophotometer results reveal that a VCC Mo1−xWxS2 multilayer has different vertical composition and broadband light absorption with strong interlayer coupling within a VCC Mo1−xWxS2 multilayer. Further, we demonstrate that a VCC Mo1−xWxS2 multilayer photodetector generates three to four times greater photocurrent than MoS2- and WS2-based devices, owing to the broadband light absorption. PMID:26204328

  5. Preparation and Characterization of Binder Less Mg/Mg Alloy Infiltrated SiCp Reinforced Composites

    NASA Astrophysics Data System (ADS)

    Muthu Kumar, S.; Dhindaw, B. K.

    2007-10-01

    SiCp-reinforced commercial pure magnesium and AZ91 alloy MMCs’ were prepared through infiltration route without the use of any special atmospheres. The preform was prepared using a mixture of reinforcement particles and the matrix metal particles. The composites were prepared with various volume percentage of the reinforcement and their properties with the variation of SiCp were analyzed. The interfacial properties of the composites were analyzed using microstructure, microhardness, and wear studies. Calculation of thermal conditions during infiltration was done to study the effect of adding matrix metal particles on the infiltration behavior and its effect on the uniformity distribution of the reinforcements.

  6. Review on laser powder injection additive manufacturing of novel alloys and composites

    NASA Astrophysics Data System (ADS)

    Zheng, B.; Yang, N.; Yee, J.; Gaiser, K.; Lu, W. Y.; Clemon, L.; Zhou, Y.; Lavernia, E. J.; Schoenung, J. M.

    2016-04-01

    In this paper, recent research and progress associated with development of alloys and composites using LENS are reviewed. The microstructure of novel materials can be tailored by controlling both composition and process parameters. For process control, closed-loop diagnostics and controls such as in-situ molten pool sensor and Z-height control subsystems are utilized, while the thermal behavior measurement with thermal imaging methods and numerical simulation are also investigated. The existing problems with residual stress and porosity in deposited materials are discussed.

  7. Effects of chemical composition on the corrosion behavior of A7N01S-T5 Al alloys

    NASA Astrophysics Data System (ADS)

    Wang, Xiaomin; Liao, Xiaoyao; Ma, Chuanping; Zhang, Shufang; Liu, Yan; Chen, Hui

    2015-03-01

    Corrosion behavior of 7N01 Al alloy is sensitive to chemical composition. In this paper, stress corrosion cracking (SCC) and electrochemical behaviors of A7N01S-T5 Al alloys with three different chemical compositions were investigated. The corrosion weight loss and corrosion pits depth statistics showed that Alloy #3 (4.53wt.%Zn, 1.27%Mg, < 0.001%Cu, 0.24%Cr, 0.15%Zr) possesses the best anti-SCC property, while Alloy #1 (4.54%Zn, 1.09%Mg, 0.102%Cu, 0.25%Cr, 0.15%Zr) was the weakest one. The different SCC susceptibility was mainly related to the Cu content as Alloy #3 contains higher Cu than Alloys #1 and #2. Electrochemical test result showed that Alloy #3 has higher corrosion potential and lower corrosion current density than Alloys #1 and #2. It is believed that a trace Cu can significantly improve the SC resistance of Al alloy, mainly because that Cu element can reduce the potential difference between grain inside and grain boundaries.

  8. The effect of interface properties on nickel base alloy composites

    NASA Technical Reports Server (NTRS)

    Groves, M.; Grossman, T.; Senemeier, M.; Wright, K.

    1995-01-01

    This program was performed to assess the extent to which mechanical behavior models can predict the properties of sapphire fiber/nickel aluminide matrix composites and help guide their development by defining improved combinations of matrix and interface coating. The program consisted of four tasks: 1) selection of the matrices and interface coating constituents using a modeling-based approach; 2) fabrication of the selected materials; 3) testing and evaluation of the materials; and 4) evaluation of the behavior models to develop recommendations. Ni-50Al and Ni-20AI-30Fe (a/o) matrices were selected which gave brittle and ductile behavior, respectively, and an interface coating of PVD YSZ was selected which provided strong bonding to the sapphire fiber. Significant fiber damage and strength loss was observed in the composites which made straightforward comparison of properties with models difficult. Nevertheless, the models selected generally provided property predictions which agreed well with results when fiber degradation was incorporated. The presence of a strong interface bond was felt to be detrimental in the NiAI MMC system where low toughness and low strength were observed.

  9. 3D Simulation of the Growth of Alloy Semiconductor Quantum Dots Considering Morphological and Compositional Coupling

    NASA Astrophysics Data System (ADS)

    Guo, Junyan; Zhang, Yong-Wei; Narayanaswamy, Sridhar

    2012-02-01

    Fabrication of quantum dots (QDs) with high density may be realized by self-assembly via heteroepitaxial growth of thin films. Since the electronic and optoelectronic properties of QDs are sensitive to size, morphology, strain and especially composition, it is of great importance to control their composition profiles and morphology, and engineer the strain in them. Since the growth is a dynamic process, which carries out via surface diffusion driven primarily by strain relaxation and entropy change due to chemical intermixing, a strong coupling between morphological and composition evolutions during this process leads to a rather complex dynamics, which has not been fully understood. In this work, a 3-D finite element model is developed, which is capable of modeling the formation, self-assembly and coarsening of hetero-epitaxial alloy islands by considering the coupling of morphological and compositional evolution. Several interesting experimental observations, such as fast coarsening kinetics; asymmetries in composition profile and island shape; lateral motion of alloy islands have been observed in our simulations. Our model predictions have painted a rather complete picture for the entire dynamic evolution during the growth of nanoscale heteroepitaxial islands.

  10. Mechanical properties of Al-60 Pct SiC p composites alloyed with Mg

    NASA Astrophysics Data System (ADS)

    Ahlatci, H.; Çimenoğlu, H.; Candan, E.

    2004-07-01

    In the present work, the effect of an Mg addition on the mechanical properties of the Al-60 vol pct SiC p composites were investigated by uniaxial compression, three-point bending, impact and wear tests (composite-metal and composite-abrasive types). The composites were produced by the pressure-infiltration technique. The composition of the Al matrix was varied between 0 and 8 pct Mg. The mean diameter of the SiC particles was 23 µm. Upon addition of Mg, Mg2Si precipitated in the matrix and the amount of the porosity dramatically decreased. Mg-alloyed-matrix composites exhibited higher strength, lower toughness, and higher wear resistance than pure-Al-matrix composites. During composite-metal wear testing, wear progressed in two sequential periods (running-in and steady state). Weight loss during wear testing decreased with increasing Mg content of the matrix. The degree of improvement of abrasive resistance depended on the abrasive-grain size. Above 200 °C, the composite-abrasive wear resistance decreased with increasing test temperature for all materials.

  11. Theoretical investigations of compositional inhomogeneity around threading dislocations in III–nitride semiconductor alloys

    NASA Astrophysics Data System (ADS)

    Sakaguchi, Ryohei; Akiyama, Toru; Nakamura, Kohji; Ito, Tomonori

    2016-05-01

    The compositional inhomogeneity of group III elements around threading dislocations in III–nitride semiconductors are theoretically investigated using empirical interatomic potentials and Monte Carlo simulations. We find that the calculated atomic arrangements around threading dislocations in Al0.3Ga0.7N and In0.2Ga0.8N depend on the lattice strain around dislocation cores. Consequently, compositional inhomogeneity arises around edge dislocation cores to release the strain induced by dislocation cores. In contrast, the compositional inhomogeneity in screw dislocation is negligible owing to relatively small strain induced by dislocation cores compared with edge dislocation. These results indicate that the strain relief around dislocation cores is decisive in determining the atomic arrangements and resultant compositional inhomogeneity around threading dislocations in III–nitride semiconductor alloys.

  12. Mechanically Stretchable and Electrically Insulating Thermal Elastomer Composite by Liquid Alloy Droplet Embedment

    PubMed Central

    Jeong, Seung Hee; Chen, Si; Huo, Jinxing; Gamstedt, Erik Kristofer; Liu, Johan; Zhang, Shi-Li; Zhang, Zhi-Bin; Hjort, Klas; Wu, Zhigang

    2015-01-01

    Stretchable electronics and soft robotics have shown unsurpassed features, inheriting remarkable functions from stretchable and soft materials. Electrically conductive and mechanically stretchable materials based on composites have been widely studied for stretchable electronics as electrical conductors using various combinations of materials. However, thermally tunable and stretchable materials, which have high potential in soft and stretchable thermal devices as interface or packaging materials, have not been sufficiently studied. Here, a mechanically stretchable and electrically insulating thermal elastomer composite is demonstrated, which can be easily processed for device fabrication. A liquid alloy is embedded as liquid droplet fillers in an elastomer matrix to achieve softness and stretchability. This new elastomer composite is expected useful to enhance thermal response or efficiency of soft and stretchable thermal devices or systems. The thermal elastomer composites demonstrate advantages such as thermal interface and packaging layers with thermal shrink films in transient and steady-state cases and a stretchable temperature sensor. PMID:26671673

  13. Mechanically Stretchable and Electrically Insulating Thermal Elastomer Composite by Liquid Alloy Droplet Embedment.

    PubMed

    Jeong, Seung Hee; Chen, Si; Huo, Jinxing; Gamstedt, Erik Kristofer; Liu, Johan; Zhang, Shi-Li; Zhang, Zhi-Bin; Hjort, Klas; Wu, Zhigang

    2015-01-01

    Stretchable electronics and soft robotics have shown unsurpassed features, inheriting remarkable functions from stretchable and soft materials. Electrically conductive and mechanically stretchable materials based on composites have been widely studied for stretchable electronics as electrical conductors using various combinations of materials. However, thermally tunable and stretchable materials, which have high potential in soft and stretchable thermal devices as interface or packaging materials, have not been sufficiently studied. Here, a mechanically stretchable and electrically insulating thermal elastomer composite is demonstrated, which can be easily processed for device fabrication. A liquid alloy is embedded as liquid droplet fillers in an elastomer matrix to achieve softness and stretchability. This new elastomer composite is expected useful to enhance thermal response or efficiency of soft and stretchable thermal devices or systems. The thermal elastomer composites demonstrate advantages such as thermal interface and packaging layers with thermal shrink films in transient and steady-state cases and a stretchable temperature sensor. PMID:26671673

  14. Mechanically Stretchable and Electrically Insulating Thermal Elastomer Composite by Liquid Alloy Droplet Embedment

    NASA Astrophysics Data System (ADS)

    Jeong, Seung Hee; Chen, Si; Huo, Jinxing; Gamstedt, Erik Kristofer; Liu, Johan; Zhang, Shi-Li; Zhang, Zhi-Bin; Hjort, Klas; Wu, Zhigang

    2015-12-01

    Stretchable electronics and soft robotics have shown unsurpassed features, inheriting remarkable functions from stretchable and soft materials. Electrically conductive and mechanically stretchable materials based on composites have been widely studied for stretchable electronics as electrical conductors using various combinations of materials. However, thermally tunable and stretchable materials, which have high potential in soft and stretchable thermal devices as interface or packaging materials, have not been sufficiently studied. Here, a mechanically stretchable and electrically insulating thermal elastomer composite is demonstrated, which can be easily processed for device fabrication. A liquid alloy is embedded as liquid droplet fillers in an elastomer matrix to achieve softness and stretchability. This new elastomer composite is expected useful to enhance thermal response or efficiency of soft and stretchable thermal devices or systems. The thermal elastomer composites demonstrate advantages such as thermal interface and packaging layers with thermal shrink films in transient and steady-state cases and a stretchable temperature sensor.

  15. SISGR: Theoretically relating the surface composition of Pt alloys to their performance as the electrocatalysts of low-temperature fuel cells

    SciTech Connect

    Wang, Guofeng

    2010-12-31

    The main goal of this project is to gain fundamental knowledge about the relation between surface composition and catalytic performance of Pt alloy catalysts for oxygen reduction reaction (ORR). Specific objectives are: to develop and improve a first-principles based multiscale computation approach to simulating surface segregation phenomena in Pt alloy surfaces; to evaluate the surface electronic structure and catalytic activity of Pt alloy catalysts and; to relate the surface composition to the catalytic performance of Pt alloy catalysts.

  16. Highly mismatched crystalline and amorphous GaN(1-x)As(x) alloys in the whole composition range

    SciTech Connect

    Yu, K. M.; Novikov, S. V.; Broesler, R.; Demchenko, I. N.; Denlinger, J. D.; Liliental-Weber, Z.; Luckert, F.; Martin, R. W.; Walukiewicz, W.; Foxon, C. T.

    2009-08-29

    Alloying is a commonly accepted method to tailor properties of semiconductor materials for specific applications. Only a limited number of semiconductor alloys can be easily synthesized in the full composition range. Such alloys are, in general, formed of component elements that are well matched in terms of ionicity, atom size, and electronegativity. In contrast there is a broad class of potential semiconductor alloys formed of component materials with distinctly different properties. In most instances these mismatched alloys are immiscible under standard growth conditions. Here we report on the properties of GaN1-xAsx, a highly mismatched, immiscible alloy system that was successfully synthesized in the whole composition range using a nonequilibrium low temperature molecular beam epitaxy technique. The alloys are amorphous in the composition range of 0.17composition, and sharp, well defined optical absorption edges. The band gap energy varies in a broad energy range from ~;;3.4 eV in GaN to ~;;0.8 eV at x~;;0.85. The reduction in the band gap can be attributed primarily to the downward movement of the conduction band for alloys with x>0.2, and to the upward movement of the valence band for alloys with x<0.2. The unique features of the band structure offer an opportunity of using GaN1-xAsx alloys for various types of solar power conversion devices.

  17. 5th Conference on Aerospace Materials, Processes, and Environmental Technology

    NASA Technical Reports Server (NTRS)

    Cook, M. B. (Editor); Stanley, D. Cross (Editor)

    2003-01-01

    Records are presented from the 5th Conference on Aerospace Materials, Processes, and Environmental Technology. Topics included pollution prevention, inspection methods, advanced materials, aerospace materials and technical standards,materials testing and evaluation, advanced manufacturing,development in metallic processes, synthesis of nanomaterials, composite cryotank processing, environmentally friendly cleaning, and poster sessions.

  18. Microbiologically-Facilitated Effects on the Surface Composition of Alloy 22, A Candidate Nuclear Waste Packaging Material

    SciTech Connect

    Horn, J; Lian, T; Martin, S I

    2001-12-07

    The effects of microbiological activities on the surface composition of Alloy 22 was investigated. Prior studies suggesting microbially-generated selective dissolution of chromium from Alloy 22 were based solely on analyzing solubilized Alloy 22 elements. These and other investigations point to the insufficiencies of analyzing solubilized (or solubilized and reprecipitated) alloying elements to discern between homogeneous/stoichiometric dissolution and selective/non-stoichiometric dissolution of alloying elements. Therefore, an approach using X-ray Photoelectron Spectroscopy (XPS) to interrogate the surface layers of treated Alloy 22 specimens was taken to resolve this issue. Sputtering into the surface of the samples, coupled with XPS analysis at given intervals, allowed a high resolution quantitative elemental evaluation of the alloy as a function of depth. Biotically-incubated Alloy 22 show a region that could be depleted of chromium. Surfacial XPS analysis of these same coupons did not detect the presence of re-precipitated Alloy 22 component elements, also supporting the possible occurrence of non-stoichiometric dissolution. Thus, these preliminary data do not exclude the possibility of selective dissolution. It also appears that this experimental approach shows promise to unequivocally resolve this issue. Further tests using smoother-surface, more highly polished coupons should allow for better resolution between surface layers to permit a decisive determination of the mode of Alloy 22 dissolution using sputtering XPS analysis.

  19. Simulation and optimization of Al-Fe aerospace alloy processed by laser surface remelting using geometric Multigrid solver and experimental validation

    NASA Astrophysics Data System (ADS)

    Pariona, Moisés Meza; de Oliveira, Fabiane; Teleginski, Viviane; Machado, Siliane; Pinto, Marcio Augusto Villela

    2016-05-01

    Al-1.5 wt% Fe alloy was irradiate by Yb-fiber laser beam using the laser surface remelting (LSR) technique, generating weld fillets that covered the whole surface of the sample. The laser-treatment showed to be an efficient technology for corrosion resistance improvements. In this study, the finite element method was used to simulate the solidification processes by LSR technique. The method Multigrid was employed in order to reduce the CPU time, which is important to the viability for industrial applications. Multigrid method is a technique very promising of optimization that reduced drastically the CPU time. The result was highly satisfactory, because the CPU time has fallen dramatically in comparison when it was not used Multigrid method. To validate the result of numerical simulation with the experimental result was done the microstructural characterization of laser-treated layer by the optical microscopy and SEM techniques and however, that both results showing be consistent.

  20. Structural and Phase State of Ti-Nb Alloy at Selective Laser Melting of the Composite Powder

    NASA Astrophysics Data System (ADS)

    Sharkeev, Yu. P.; Eroshenko, A. Yu.; Kovalevskaya, Zh. G.; Saprykin, A. A.; Ibragimov, E. A.; Glukhov, I. A.; Khimich, M. A.; Uvarkin, P. V.; Babakova, E. V.

    2016-07-01

    Phase composition and microstructure of Ti-Nb alloy produced from the composite titanium and niobium powder by selective laser melting (SLM) method were studied in the present research. Ti-Nb alloy produced by SLM is a monolayer and has zones of fine-grained and medium-grained structure with homogenous elemental composition within the range of 36-38 wt.% Nb. Phase state of the alloy corresponds to the main phase of β- solid solution (grain size of 5-7 μm) and non-equilibrium martensite α″-phase (grain size of 0.1-0.7 μm). Grains of the α″-phase are localized along the boundaries of β-phase grains and have a reduced content of niobium. Microhardness of the alloy varies within the range of 4200-5500 MPa.

  1. Influence of the chemical composition of Al-based amorphous alloys on thermally induced embrittlement

    NASA Astrophysics Data System (ADS)

    Sviridova, E. A.; Maksimov, V. V.; Rassolov, S. G.; Nosenko, V. K.; Tkach, V. I.

    2014-07-01

    Structural changes of rapidly cooled ribbons of the amorphous alloys Al88-86(Ni,Co,Fe)6-8(Y,Gd,Nd,La)5-6, which occur during heating at a rate of 10 K/min and lead to a loss of ductility, have been investigated experimentally. It has been shown that samples of the studied alloys are divided into two groups, in the first of which the loss of ductility is due to the formation of a nanocomposite structure, whereas the embrittlement of samples in the second group is caused by processes of structural relaxation in the amorphous phase (decrease in the concentration of a free volume). It has been established for the first time that there is an empirical correlation between the dynamic temperature, after heating to which the alloys lose their ductility at room temperature, and the ratio of the shear modulus to the elastic modulus of the alloys, which is calculated from the nominal chemical composition.

  2. Microstructure and mechanical behavior of metallic glass fiber-reinforced Al alloy matrix composites

    PubMed Central

    Wang, Z.; Georgarakis, K.; Nakayama, K. S.; Li, Y.; Tsarkov, A. A.; Xie, G.; Dudina, D.; Louzguine-Luzgin, D. V.; Yavari, A. R.

    2016-01-01

    Metallic glass-reinforced metal matrix composites are an emerging class of composite materials. The metallic nature and the high mechanical strength of the reinforcing phase offers unique possibilities for improving the engineering performance of composites. Understanding the structure at the amorphous/crystalline interfaces and the deformation behavior of these composites is of vital importance for their further development and potential application. In the present work, Zr-based metallic glass fibers have been introduced in Al7075 alloy (Al-Zn-Mg-Cu) matrices using spark plasma sintering (SPS) producing composites with low porosity. The addition of metallic glass reinforcements in the Al-based matrix significantly improves the mechanical behavior of the composites in compression. High-resolution TEM observations at the interface reveal the formation of a thin interdiffusion layer able to provide good bonding between the reinforcing phase and the Al-based matrix. The deformation behavior of the composites was studied, indicating that local plastic deformation occurred in the matrix near the glassy reinforcements followed by the initiation and propagation of cracks mainly through the matrix. The reinforcing phase is seen to inhibit the plastic deformation and retard the crack propagation. The findings offer new insights into the mechanical behavior of metal matrix composites reinforced with metallic glasses. PMID:27067824

  3. Microstructure and mechanical behavior of metallic glass fiber-reinforced Al alloy matrix composites.

    PubMed

    Wang, Z; Georgarakis, K; Nakayama, K S; Li, Y; Tsarkov, A A; Xie, G; Dudina, D; Louzguine-Luzgin, D V; Yavari, A R

    2016-01-01

    Metallic glass-reinforced metal matrix composites are an emerging class of composite materials. The metallic nature and the high mechanical strength of the reinforcing phase offers unique possibilities for improving the engineering performance of composites. Understanding the structure at the amorphous/crystalline interfaces and the deformation behavior of these composites is of vital importance for their further development and potential application. In the present work, Zr-based metallic glass fibers have been introduced in Al7075 alloy (Al-Zn-Mg-Cu) matrices using spark plasma sintering (SPS) producing composites with low porosity. The addition of metallic glass reinforcements in the Al-based matrix significantly improves the mechanical behavior of the composites in compression. High-resolution TEM observations at the interface reveal the formation of a thin interdiffusion layer able to provide good bonding between the reinforcing phase and the Al-based matrix. The deformation behavior of the composites was studied, indicating that local plastic deformation occurred in the matrix near the glassy reinforcements followed by the initiation and propagation of cracks mainly through the matrix. The reinforcing phase is seen to inhibit the plastic deformation and retard the crack propagation. The findings offer new insights into the mechanical behavior of metal matrix composites reinforced with metallic glasses. PMID:27067824

  4. Microstructure and mechanical behavior of metallic glass fiber-reinforced Al alloy matrix composites

    NASA Astrophysics Data System (ADS)

    Wang, Z.; Georgarakis, K.; Nakayama, K. S.; Li, Y.; Tsarkov, A. A.; Xie, G.; Dudina, D.; Louzguine-Luzgin, D. V.; Yavari, A. R.

    2016-04-01

    Metallic glass-reinforced metal matrix composites are an emerging class of composite materials. The metallic nature and the high mechanical strength of the reinforcing phase offers unique possibilities for improving the engineering performance of composites. Understanding the structure at the amorphous/crystalline interfaces and the deformation behavior of these composites is of vital importance for their further development and potential application. In the present work, Zr-based metallic glass fibers have been introduced in Al7075 alloy (Al-Zn-Mg-Cu) matrices using spark plasma sintering (SPS) producing composites with low porosity. The addition of metallic glass reinforcements in the Al-based matrix significantly improves the mechanical behavior of the composites in compression. High-resolution TEM observations at the interface reveal the formation of a thin interdiffusion layer able to provide good bonding between the reinforcing phase and the Al-based matrix. The deformation behavior of the composites was studied, indicating that local plastic deformation occurred in the matrix near the glassy reinforcements followed by the initiation and propagation of cracks mainly through the matrix. The reinforcing phase is seen to inhibit the plastic deformation and retard the crack propagation. The findings offer new insights into the mechanical behavior of metal matrix composites reinforced with metallic glasses.

  5. Elaboration of metal matrix composites from thixotropic alloy slurries using a new magnetohydrodynamic caster

    NASA Astrophysics Data System (ADS)

    Vivès, Charles

    1993-06-01

    The working principle and the peculiarities of a new electromagnetic rheocaster, which is based on the use of rotating permanent magnets and which allows the production of intense three-dimensional (3-D) multiphase flows in solidifying semisolid alloy slurries and metal matrix composites, are described. This process can be applied to the direct continuous casting of billets, tubes, and slabs and is characterized by very low electric power consumption. Local measurement techniques are applied to the study of the evolution of non-Newtonian magnetohydrodynamic multiphase flow phenomena with the rotational speed of the inductor, the solid fraction of the aluminum alloy matrix, and the size and volume percent of SiC particles. An order of magnitude analysis of the various forces acting on the suspended crystals and SiC particles is given. The Theological behavior of electromagnetically rheocast ferrous metals, simulated by a lead-tin alloy, is also investigated. Satisfactory results concerning the microstructure of solidified aluminum slurries and aluminum matrix composites (homogeneity, crystal shape, grain size, fraction of primary solid, and distribution of SiC particles) were obtained. A discussion is presented relating the metallurgical findings to the heat and three-phase flow measurements.

  6. Surface composition determination of Pt--Sn alloys by chemical titration with carbon monoxide

    SciTech Connect

    Haner, A.H.; Ross, P.N. ); Bardi, U.; Atrei, A. )

    1992-07-01

    The use of chemical titration with carbon monoxide to determine the surface composition of Pt--Sn alloys was studied using Pt{sub 3}Sn single crystals of known surface composition. The surface composition of the (111) and (100) faces were determined independently by the combination of low-energy electron diffraction (LEED) crystallography and low-energy ion scattering (LEIS). CO was adsorbed on these surfaces to saturation at 250 K and thermally desorbed into a mass spectrometer. The area under the thermal desorption spectroscopy curve for the alloy surface was compared to the area under the curve for the pure Pt surface of the same orientation. The ratios were 0.5{plus minus}0.05 for Pt{sub 3}Sn(100) and 0.7{plus minus}0.05 for Pt{sub 3}Sn(111), in excellent agreement with the 50% Pt and 75% Pt surface compositions derived from LEED and LEIS. The success of the titration method in this case appears to be due to (a) selective adsorption of CO on Pt atoms and (b) the relatively weak effect of the Pt--Sn intermetallic bond on the Pt--CO bonding.

  7. Evaluating Aerospace Workshops.

    ERIC Educational Resources Information Center

    Leonard, Rex L.

    1978-01-01

    Declining enrollments in aerospace teacher workshops suggest the need for evaluation and cost effectiveness measurements. A major purpose of this article is to illustrate some typical evaluation methodologies, including the semantic differential. (MA)

  8. Aerospace bibliography, seventh edition

    NASA Technical Reports Server (NTRS)

    Blashfield, J. F. (Compiler)

    1983-01-01

    Space travel, planetary probes, applications satellites, manned spaceflight, the impacts of space exploration, future space activities, astronomy, exobiology, aeronautics, energy, space and the humanities, and aerospace education are covered.

  9. Ninteenth Aerospace Mechanisms Symposium

    NASA Technical Reports Server (NTRS)

    1985-01-01

    The proceedings of the 19th Aerospace Mechanisms Symposium are reported. Technological areas covered include space lubrication, bearings, aerodynamic devices, spacecraft/Shuttle latches, deployment, positioning, and pointing. Devices for spacecraft docking and manipulator and teleoperator mechanisms are also described.

  10. Synthesis of WS2xSe2-2x Alloy Nanosheets with Composition-Tunable Electronic Properties.

    PubMed

    Duan, Xidong; Wang, Chen; Fan, Zheng; Hao, Guolin; Kou, Liangzhi; Halim, Udayabagya; Li, Honglai; Wu, Xueping; Wang, Yicheng; Jiang, Jianhui; Pan, Anlian; Huang, Yu; Yu, Ruqin; Duan, Xiangfeng

    2016-01-13

    Two-dimensional (2D) layered transition metal dichalcogenides (TMDs) have recently emerged as a new class of atomically thin semiconductors for diverse electronic, optoelectronic, and valleytronic applications. To explore the full potential of these 2D semiconductors requires a precise control of their band gap and electronic properties, which represents a significant challenge in 2D material systems. Here we demonstrate a systematic control of the electronic properties of 2D-TMDs by creating mixed alloys of the intrinsically p-type WSe2 and intrinsically n-type WS2 with variable alloy compositions. We show that a series of WS2xSe2-2x alloy nanosheets can be synthesized with fully tunable chemical compositions and optical properties. Electrical transport studies using back-gated field effect transistors demonstrate that charge carrier types and threshold voltages of the alloy nanosheet transistors can be systematically tuned by adjusting the alloy composition. A highly p-type behavior is observed in selenium-rich alloy, which gradually shifts to lightly p-type, and then switches to lightly n-type characteristics with the increasing sulfur atomic ratio, and eventually evolves into highly n-doped semiconductors in sulfur-rich alloys. The synthesis of WS2xSe2-2x nanosheets with tunable optical and electronic properties represents a critical step toward rational design of 2D electronics with tailored spectral responses and device characteristics. PMID:26633760

  11. Aluminum alloy

    NASA Technical Reports Server (NTRS)

    Blackburn, Linda B. (Inventor); Starke, Edgar A., Jr. (Inventor)

    1989-01-01

    This invention relates to aluminum alloys, particularly to aluminum-copper-lithium alloys containing at least about 0.1 percent by weight of indium as an essential component, which are suitable for applications in aircraft and aerospace vehicles. At least about 0.1 percent by weight of indium is added as an essential component to an alloy which precipitates a T1 phase (Al2CuLi). This addition enhances the nucleation of the precipitate T1 phase, producing a microstructure which provides excellent strength as indicated by Rockwell hardness values and confirmed by standard tensile tests.

  12. Characterizing the Use of Ultrasonic Energy in Promoting Uniform Composite Growth in Immiscible Alloys

    NASA Technical Reports Server (NTRS)

    Grugel, Richard N.; Fedoseyev, A. I.

    2000-01-01

    The results of experimental investigation and mathematical modeling for immiscible alloys subjected to ultrasonic influence are presented. It is known that in inoculated light alloy melts, ultrasonic treatment creates a new type of cast structure with extremely fine grains of uniform composition. This effect is produced across a wide range of freezing rates and technologies. However, it has not been demonstrated that the process can be successfully applied during controlled directional solidification processing. In this work we present the results from a set of directional solidification experiments and suggest describing the droplet size versus ultrasonic frequency and amplitude using an energy approach, followed with a more detailed analysis through numerical modeling of the ultrasonic field.

  13. Oxidation and corrosion behavior of modified-composition, low-chromium 304 stainless steel alloys

    NASA Technical Reports Server (NTRS)

    Stephens, J. R.; Barrett, C. A.

    1977-01-01

    The effects of substituting less strategic elements than Cr on the oxidation and corrosion resistance of AISI 304 stainless steel were investigated. Cyclic oxidation resistance was evaluated at 870 C. Corrosion resistance was determined by exposure of specimens to a boiling copper-rich solution of copper sulfate and sulfuric acid. Alloy substitutes for Cr included Al, Mn, Mo, Si, Ti, V, Y, and misch metal. A level of about 12% Cr was the minimum amount of Cr required for adequate oxidation and corrosion resistance in the modified composition 304 stainless steels. This represents a Cr saving of at least 33%. Two alloys containing 12% Cr and 2% Al plus 2% Mo and 12% Cr plus 2.65% Si were identified as most promising for more detailed evaluation.

  14. Composite Ni-Co-fly ash coatings on 5083 aluminium alloy

    NASA Astrophysics Data System (ADS)

    Panagopoulos, C. N.; Georgiou, E. P.; Tsopani, A.; Piperi, L.

    2011-03-01

    Ni-Co-fly ash coatings were deposited on zincate treated 5083 wrought aluminium alloy substrates with the aid of the electrodeposition technique. Structural and chemical characterization of the produced composite coatings was performed with the aid of X-ray diffraction (XRD), scanning electron microscopy (SEM) and electron dispersive X-ray analysis (EDS) techniques. The Ni-Co-fly ash coatings were found to consist of a crystalline Ni-Co solid solution with dispersed fly ash particles. In addition, chemical analysis of the Ni-Co matrix showed that it consisted of 80 wt.% Ni and 20 wt.% Co. The co-deposition of fly ash particles leads to a significant increase of the microhardness of the coating. The corrosion behaviour of the Ni-Co-fly ash/zincate coated aluminium alloy, in a 0.3 M NaCl solution (pH = 3.5), was studied by means of potentiodynamic corrosion experiments.

  15. Compositional dependence of the band-gap of Ge1-x-ySixSny alloys

    NASA Astrophysics Data System (ADS)

    Wendav, Torsten; Fischer, Inga A.; Montanari, Michele; Zoellner, Marvin Hartwig; Klesse, Wolfgang; Capellini, Giovanni; von den Driesch, Nils; Oehme, Michael; Buca, Dan; Busch, Kurt; Schulze, Jörg

    2016-06-01

    The group-IV semiconductor alloy Ge1-x-ySixSny has recently attracted great interest due to its prospective potential for use in optoelectronics, electronics, and photovoltaics. Here, we investigate molecular beam epitaxy grown Ge1-x-ySixSny alloys lattice-matched to Ge with large Si and Sn concentrations of up to 42% and 10%, respectively. The samples were characterized in detail by Rutherford backscattering/channeling spectroscopy for composition and crystal quality, x-ray diffraction for strain determination, and photoluminescence spectroscopy for the assessment of band-gap energies. Moreover, the experimentally extracted material parameters were used to determine the SiSn bowing and to make predictions about the optical transition energy.

  16. Composition-dependent metallic glass alloys correlate atomic mobility with collective glass surface dynamics.

    PubMed

    Nguyen, Duc; Zhu, Zhi-Guang; Pringle, Brian; Lyding, Joseph; Wang, Wei-Hua; Gruebele, Martin

    2016-06-22

    Glassy metallic alloys are richly tunable model systems for surface glassy dynamics. Here we study the correlation between atomic mobility, and the hopping rate of surface regions (clusters) that rearrange collectively on a minute to hour time scale. Increasing the proportion of low-mobility copper atoms in La-Ni-Al-Cu alloys reduces the cluster hopping rate, thus establishing a microscopic connection between atomic mobility and dynamics of collective rearrangements at a glass surface made from freshly exposed bulk glass. One composition, La60Ni15Al15Cu10, has a surface resistant to re-crystallization after three heating cycles. When thermally cycled, surface clusters grow in size from about 5 glass-forming units to about 8 glass-forming units, evidence of surface aging without crystal formation, although its bulk clearly forms larger crystalline domains. Such kinetically stable glass surfaces may be of use in applications where glassy coatings stable against heating are needed. PMID:27283239

  17. Thermo-mechanical Response and Damping Behavior of Shape Memory Alloy-MAX Phase Composites

    NASA Astrophysics Data System (ADS)

    Kothalkar, Ankush Dilip; Benitez, Rogelio; Hu, Liangfa; Radovic, Miladin; Karaman, Ibrahim

    2014-05-01

    NiTi/Ti3SiC2 interpenetrating composites that combine two unique material systems—a shape memory alloy (SMA) and a MAX phase—demonstrating two different pseudoelastic mechanisms, were processed using spark plasma sintering. The goal of mixing these two material systems was to enhance the damping behavior and thermo-mechanical response of the composite by combining two pseudoelastic mechanisms, i.e., reversible stress-induced martensitic transformation in SMA and reversible incipient kink band formation in MAX phase. Equal volume fractions of equiatomic NiTi and Ti3SiC2 were used. Microstructural characterization was conducted using scanning electron microscopy to study the distribution of NiTi, Ti3SiC2, and remnant porosity in the composite. Thermo-mechanical testing in the form of thermal cycles under constant stress levels was performed in order to characterize shape memory behavior and thereby introducing residual stresses in the composites. Evolution of two-way shape memory effect was studied and related to the presence of residual stresses in the composites. Damping behavior, implying the energy dissipation per loading-unloading cycle under increasing compressive stresses, of pure NiTi, pure Ti3SiC2, as-sintered, and thermo-mechanically cycled (TC) NiTi/Ti3SiC2 composites, was investigated and compared to the literature data. In this study, the highest energy dissipation was observed for the TC composite followed by the as-sintered (AS) composite, pure NiTi, and pure Ti3SiC2 when compared at the same applied stress levels. Both the AS and TC composites showed higher damping up to 200 MPa stress than any of the metal—MAX phase composites reported in the literature to date. The ability to enhance the performance of the composite by controlling the thermo-mechanical loading paths was further discussed.

  18. Understanding the Cu-Zn brass alloys using a short-range-order cluster model: Significance of specific compositions of industrial alloys

    DOE PAGESBeta

    Hong, H. L.; Wang, Q.; Dong, C.; Liaw, Peter K.

    2014-11-17

    Metallic alloys show complex chemistries that are not yet understood so far. It has been widely accepted that behind the composition selection lies a short-range-order mechanism for solid solutions. The present paper addresses this fundamental question by examining the face-centered-cubic Cu-Zn a-brasses. A new structural approach, the cluster-plus-glue-atom model, is introduced, which suits specifically for the description of short-range-order structures in disordered systems. Two types of formulas are pointed out, [Zn-Cu12]Zn1,6 and [Zn-Cu12](Zn,Cu)6, which explain the a-brasses listed in the American Society for Testing and Materials (ASTM) specifications. In these formulas, the bracketed parts represent the 1st-neighbor cluster, and eachmore » cluster is matched with one to six 2nd-neighbor Zn atoms or with six mixed (Zn,Cu) atoms. Such a cluster-based formulism describes the 1st- and 2nd-neighbor local atomic units where the solute and solvent interactions are ideally satisfied. The Cu-Ni industrial alloys are also explained, thus proving the universality of the cluster-formula approach in understanding the alloy selections. The revelation of the composition formulas for the Cu-(Zn,Ni) industrial alloys points to the common existence of simple composition rules behind seemingly complex chemistries of industrial alloys, therefore offering a fundamental and practical method towards composition interpretations of all kinds of alloys.« less

  19. Understanding the Cu-Zn brass alloys using a short-range-order cluster model: Significance of specific compositions of industrial alloys

    SciTech Connect

    Hong, H. L.; Wang, Q.; Dong, C.; Liaw, Peter K.

    2014-11-17

    Metallic alloys show complex chemistries that are not yet understood so far. It has been widely accepted that behind the composition selection lies a short-range-order mechanism for solid solutions. The present paper addresses this fundamental question by examining the face-centered-cubic Cu-Zn a-brasses. A new structural approach, the cluster-plus-glue-atom model, is introduced, which suits specifically for the description of short-range-order structures in disordered systems. Two types of formulas are pointed out, [Zn-Cu12]Zn1,6 and [Zn-Cu12](Zn,Cu)6, which explain the a-brasses listed in the American Society for Testing and Materials (ASTM) specifications. In these formulas, the bracketed parts represent the 1st-neighbor cluster, and each cluster is matched with one to six 2nd-neighbor Zn atoms or with six mixed (Zn,Cu) atoms. Such a cluster-based formulism describes the 1st- and 2nd-neighbor local atomic units where the solute and solvent interactions are ideally satisfied. The Cu-Ni industrial alloys are also explained, thus proving the universality of the cluster-formula approach in understanding the alloy selections. The revelation of the composition formulas for the Cu-(Zn,Ni) industrial alloys points to the common existence of simple composition rules behind seemingly complex chemistries of industrial alloys, therefore offering a fundamental and practical method towards composition interpretations of all kinds of alloys.

  20. Rearrangement of twin variants in ferromagnetic shape memory alloy polyurethane composites studied by stroboscopic neutron diffraction

    NASA Astrophysics Data System (ADS)

    Feuchtwanger, J.; Lázpita, P.; Vidal, N.; Barandiaran, J. M.; Gutiérrez, J.; Hansen, T.; Peel, M.; Mondelli, C.; O'Handley, R. C.; Allen, S. M.

    2008-03-01

    The use of ferromagnetic shape memory alloy (FSMA) particles as fillers in polymeric matrix composites has been proposed for vibration damping. The large pseudo-plastic recoverable deformation of the FSMA particles due to the rearrangement of twin variants can dissipate a large amount of energy, both under compression and tension. The composites studied are made by mixing particles of NiMnGa with a polyurethane matrix. A magnetic field is applied to the composite while the matrix sets, to achieve a strong [112] texture in the field direction. In situ strobed neutron diffraction measurements were carried out while the composites were subjected to a cyclic deformation. They show that the intensity of certain peaks varies during the deformation cycle. All the peaks that show this behavior can be grouped into pairs that stem from a single austenitic peak. The (020) and (112) martensite peaks correspond to the splitting of the (220) austenite peak, and the intensity of one increases as that of the other decreases. The neutron measurements show directly that there is a change in the texture of the composite during the stress cycle applied to the composite and confirm that the large mechanical loss observed in the stress-strain cycles is in good part due to the rearrangement of twin variants in the FSMA filler used in the composites.

  1. Compositional grading of CZTSSe alloy using exponential and uniform grading laws in SCAPS-ID simulation

    NASA Astrophysics Data System (ADS)

    Simya, O. K.; Mahaboobbatcha, A.; Balachander, K.

    2016-04-01

    The SCAPS (Solar cell capacitance simulation) program were employed to analyze the compositional dependence of CZTSSe (Copper Zinc Tin Sulphur Selenium) absorber layers with Cadmium Sulphide (CdS) as buffer layer and Zinc Oxide (ZnO) as window layer for thin film solar cells applications. The primary motivation of this simulation work is to optimize the composition for Se/(S + Se) ratio, which would yield higher efficiency. The exponential and uniform grading law in SCAPS were set for the composition grading y(x) over a layer, as well as to set the composition dependence P(y) of a property. By varying the different compositions with exponential law and by using uniform law for the same composition, best efficiency of 14.97% were achieved for 0.4-0.1 composition of sulphur and selenium with Se/(S + Se) ratio of 0.80. Higher efficiency were obtained with higher Se content. The influences of the band gap of the CZTSSe alloys, which decreases linearly with an increase in its Se content, were further analyzed. The corresponding open circuit voltage, short circuit voltage, fill factor and efficiency of the simulated values on a photovoltaic cell with Mo back contact were studied in detail.

  2. NASA's Software Bank (Heath Tecna Aerospace)

    NASA Technical Reports Server (NTRS)

    1991-01-01

    Heath Tecna Aerospace used a COSMIC program, "Analysis of Filament Reinforced Metal Shell Pressure Vessels," to predict stresses in motorcase walls in a composite hybrid rocket and calculate the ideal geometry for the domes at either end of the filament-wound pressure vessel. The COSMIC program predictions were confirmed in testing.

  3. Using Aerospace Technology To Design Orthopedic Implants

    NASA Technical Reports Server (NTRS)

    Saravanos, D. A.; Mraz, P. J.; Davy, D. T.

    1996-01-01

    Technology originally developed to optimize designs of composite-material aerospace structural components used to develop method for optimizing designs of orthopedic implants. Development effort focused on designing knee implants, long-term goal to develop method for optimizing designs of orthopedic implants in general.

  4. Design and performance of a shape memory alloy-reinforced composite aerodynamic profile

    NASA Astrophysics Data System (ADS)

    Simpson, J. C.; Boller, C.

    2008-04-01

    Based on a shape memory alloy (SMA)-reinforced composite developed separately, the applicability of the composite has been demonstrated through realization of a realistically scaled aerodynamic profile of around 0.5 m span by 0.5 m root chord whose skins had been made from this composite. The design, manufacturing and assembly of the profile are described. The curved skins were manufactured with two layers of SMA wires integrated into the layup of aramid fibre prepregs. All SMA wires were connected such that they can be operated as individual sets of wires and at low voltages, similar to the conditions for electrical energy generation in a real aircraft. The profile was then mounted on a vibration test rig and excited by a shaker at its tip which allowed the dynamic performance of the profile to be validated under internal actuation conditions generated through the SMA wires.

  5. Compressive behavior of titanium alloy skin-stiffener specimens selectively reinforced with boron-aluminum composite

    NASA Technical Reports Server (NTRS)

    Herring, H. W.; Carri, R. L.; Webster, R. C.

    1971-01-01

    A method of selectively reinforcing a conventional titanium airframe structure with unidirectional boron-aluminum composite attached by brazing was successfully demonstrated in compression tests of short skin-stiffener specimens. In a comparison with all-titanium specimens, improvements in structural performance recorded for the composite-reinforced specimens exceeded 25 percent on an equivalent-weight basis over the range from room temperature to 700 K (800 F) in terms of both initial buckling and maximum strengths. Performance at room temperature was not affected by prior exposure at 588 K (600 F) for 1000 hours in air or by 400 thermal cycles between 219 K and 588 K (-65 F and 600 F). The experimental results were generally predictable from existing analytical procedures. No evidence of failure was observed in the braze between the boron-aluminum composite and the titanium alloy.

  6. Composition of sputtered material from CuNi alloy during Xe + ion sputtering at elevated temperatures

    NASA Astrophysics Data System (ADS)

    Sekine, Shigeyuki; Shimizu, Hazime; Ichimura, Singo

    1995-04-01

    Polycrystalline CuNi alloys were sputtered by 3 kV Xe + ions at elevated temperatures to analyze the ion-beam-induced diffusion. The time evolution of the composition of the sputtered materials from the start of the sputtering was measured by TOF-SNMS (time-of-flight sputtered neutral mass spectrometry). During removal of the Gibbsian segregation layer of copper, the sputtered flux consisted of almost only copper atoms. Then, the copper content gradually decreased due to the formation of a sputter-induced copper-depleted surface layer, and reached an almost steady state with still higher copper content than the bulk composition. From the temperature dependence of the composition at the quasi-steady state the activation energy of copper transportation through a high diffusivity path was derived to be 54 kJ mol -1 (0.56 eV). The high diffusivity path was assigned to copper diffusion through grain boundaries.

  7. Deep ultraviolet distributed Bragg reflectors based on graded composition AlGaN alloys

    SciTech Connect

    Brummer, Gordie; Nothern, Denis; Nikiforov, A. Yu.; Moustakas, T. D.

    2015-06-01

    Distributed Bragg reflectors (DBRs) with peak reflectivity at approximately 280 nm, based on compositionally graded Al{sub x}Ga{sub 1−x}N alloys, were grown on 6H-SiC substrates by plasma-assisted molecular beam epitaxy. DBRs with square, sinusoidal, triangular, and sawtooth composition profiles were designed with the transfer matrix method. The crystal structure of these DBRs was studied with high-resolution x-ray diffraction of the (1{sup ¯}015) reciprocal lattice point. The periodicity of the DBR profiles was confirmed with cross-sectional Z-contrast scanning transmission electron microscopy. The peak reflectance of these DBRs with 15.5 periods varies from 77% to 56% with corresponding full width at half maximum of 17–14 nm. Coupled mode analysis was used to explain the dependence of the reflectivity characteristics on the profile of the graded composition.

  8. Laminated composite of magnetic alloy powder and ceramic powder and process for making same

    DOEpatents

    Moorhead, A.J.; Kim, H.

    1999-08-10

    A laminated composite structure of alternating metal powder layers, and layers formed of an inorganic bonding media powder, and a method for manufacturing same are disclosed. The method includes the steps of assembling in a cavity alternating layers of a metal powder and an inorganic bonding media of a ceramic, glass, and glass-ceramic. Heat, with or without pressure, is applied to the alternating layers until the particles of the metal powder are sintered together and bonded into the laminated composite structure by the layers of sintered inorganic bonding media to form a strong composite structure. The method finds particular application in the manufacture of high performance magnets wherein the metal powder is a magnetic alloy powder. 9 figs.

  9. Laminated composite of magnetic alloy powder and ceramic powder and process for making same

    DOEpatents

    Moorhead, Arthur J.; Kim, Hyoun-Ee

    1999-01-01

    A laminated composite structure of alternating metal powder layers, and layers formed of an inorganic bonding media powder, and a method for manufacturing same are discosed. The method includes the steps of assembling in a cavity alternating layers of a metal powder and an inorganic bonding media of a ceramic, glass, and glass-ceramic. Heat, with or without pressure, is applied to the alternating layers until the particles of the metal powder are sintered together and bonded into the laminated composite structure by the layers of sintered inorganic bonding media to form a strong composite structure. The method finds particular application in the manufacture of high performance magnets wherein the metal powder is a magnetic alloy powder.

  10. Shear strain mediated magneto-electric effects in composites of piezoelectric lanthanum gallium silicate or tantalate and ferromagnetic alloys

    SciTech Connect

    Sreenivasulu, G.; Piskulich, E.; Srinivasan, G.; Qu, P.; Qu, Hongwei; Petrov, V. M.; Fetisov, Y. K.; Nosov, A. P.

    2014-07-21

    Shear strain mediated magneto-electric (ME) coupling is studied in composites of piezoelectric Y-cut lanthanum gallium silicate (LGS) or tantalate (LGT) and ferromagnetic Fe-Co-V alloys. It is shown that extensional strain does not result in ME effects in these layered composites. Under shear strain generated by an ac and dc bias magnetic fields along the length and width of the sample, respectively, strong ME coupling is measured at low-frequencies and at mechanical resonance. A model is discussed for the ME effects. These composites of Y-cut piezoelectrics and ferromagnetic alloys are of importance for shear strain based magnetic field sensors.

  11. Shear strain mediated magneto-electric effects in composites of piezoelectric lanthanum gallium silicate or tantalate and ferromagnetic alloys

    NASA Astrophysics Data System (ADS)

    Sreenivasulu, G.; Qu, P.; Piskulich, E.; Petrov, V. M.; Fetisov, Y. K.; Nosov, A. P.; Qu, Hongwei; Srinivasan, G.

    2014-07-01

    Shear strain mediated magneto-electric (ME) coupling is studied in composites of piezoelectric Y-cut lanthanum gallium silicate (LGS) or tantalate (LGT) and ferromagnetic Fe-Co-V alloys. It is shown that extensional strain does not result in ME effects in these layered composites. Under shear strain generated by an ac and dc bias magnetic fields along the length and width of the sample, respectively, strong ME coupling is measured at low-frequencies and at mechanical resonance. A model is discussed for the ME effects. These composites of Y-cut piezoelectrics and ferromagnetic alloys are of importance for shear strain based magnetic field sensors.

  12. The effect of Co alloying content on the kinetics of reaction zone growth in tungsten fiber reinforced superalloy composites

    NASA Technical Reports Server (NTRS)

    Rodriguez, A.; Tien, J. K.; Caulfield, T.; Petrasek, D. W.

    1988-01-01

    A Co-free modified superalloy similar in composition to Waspaloy is investigated in an effort to understand the effect of Co on reaction zone growth kinetics and verify the chemistry dependence of reaction zone growth in the matrix of tungsten fiber reinforced superalloy composites. The values of the parabolic rate constant, characterizing the kinetics of reaction zone growth, for the Waspaloy matrix and the C-free alloy as well as five other alloys from a previous study confirm the dependence of reaction zone growth kinetics on cobalt content of the matrix. The Co-free alloy composite exhibits the slowest reaction zone growth among all tungsten fiber reinforced composites studied to date.

  13. Characterization of tribological behaviour of graphitic aluminum matrix composites, grey cast iron, and aluminum silicon alloys

    NASA Astrophysics Data System (ADS)

    Riahi, Ahmad Reza

    In recent years a number of aluminum-silicon alloys and some graphitic aluminum matrix composites have been fabricated for potential tribological applications in the automotive industry, in particular for lightweight high efficiency internal combustion engines to replace conventional uses of cast iron. This study provides a systematic investigation for wear mechanisms in dry sliding of the graphitic aluminum-matrix composites (A356 Al-10%SiC-4%Gr and A356 Al-5%Al2O3-3%Gr) developed for cylinder liner applications. Two eutectic Al-Si alloys (modified with rare earth elements) developed for wear resistant engine blocks were also studied. The tribological behavior of grey cast iron (ASTM A30), which is a traditional material for engine components, was also investigated as reference. For graphitic aluminum matrix composites, a wear mapping approach has been adopted. Three main regimes: ultra mild, mild and severe wear regions were determined in the maps; additionally, a scuffing region was observed. In the ultra mild wear regime the wear resistance was primarily due to the hard particles supporting the load. It was shown that the onset of severe wear in graphitic composites occurred at considerably higher loads compared to A356 aluminum alloy and A356 Al-20% SiC composite. At the onset of severe wear, the surface temperatures and coefficient of friction of the graphitic composites was lower than that of A356 Al-20% SiC. At all testing conditions in the mild wear regime, a protective tribo-layer was formed, which by increasing the speed and load became more continuous, more compact, smoother, and harder. The tribo-layers were removed at the onset of severe wear. An experimental wear map of grey cast iron was constructed; it consisted of three wear regimes: ultra mild, mild and severe wear. In the ultra mild regime a compacted fine iron oxide powder formed on the contact. The onset of severe wear was started with local material transfer to the steel counterface, and

  14. Preparation and characterization of Ni-P/Ni3.1B composite alloy coatings

    NASA Astrophysics Data System (ADS)

    Wang, Yurong; He, Jiawei; Wang, Wenchang; Shi, Jianhua; Mitsuzaki, Naotoshi; Chen, Zhidong

    2014-02-01

    The preparation of Ni-P/Ni3.1B composite alloy coating on the surface of copper was achieved by co-deposition of Ni3.1B nanoparticles with Ni-P coating during electroless plating. Ni-P-B alloy coating was obtained by heat-treating the as-plated Ni-P/Ni3.1B composite coating. The effect of the concentration of sodium alginate, borax, thiourea, Ni3.1B, temperature, and pH value on the deposition rate and B content were investigated and determined to be: 30 g L-1, 10 g L-1, 2 mg L-1, 20 mg L-1, 70 °C and 9.0 , respectively. Sodium alginate and thiourea were played as surfactant for coating Ni3.1B nanoparticles and stabilizer for the plating bath, respectively. Ni-P/Ni3.1B composite coating had good performance such as corrosion resistance and solderability.

  15. A composition and size controllable approach for Au-Ag alloy nanoparticles

    PubMed Central

    2012-01-01

    A capillary micro-reaction was established for the synthesis of Au-Ag alloy nanoparticles (NPs) with a flexible and controllable composition and grain size by tuning the synthesis temperature, the residence time, or the mole ratio of Au3+:Ag+. By extending the residence time from 5 to 900 s, enhancing the temperature from 120°C to 160°C, or decreasing the mole ratio of Au3+:Ag+ from 1:1 to 1:20, the composition of samples was changed continuously from Au-rich to Ag-rich. The particles became large with the increase of the residence time; however, synthesis temperatures showed less effect on the particle size change. The particle size of the Au-Ag alloy NPs with various composition could be kept by adjusting the mole ratio of Au3+:Ag+. TEM observation displayed that the as-obtained NPs were sphere-like with the smallest average size of 4.0 nm, which is half of those obtained by the traditional flask method. PMID:22513005

  16. Environmentally regulated aerospace coatings

    NASA Technical Reports Server (NTRS)

    Morris, Virginia L.

    1995-01-01

    Aerospace coatings represent a complex technology which must meet stringent performance requirements in the protection of aerospace vehicles. Topcoats and primers are used, primarily, to protect the structural elements of the air vehicle from exposure to and subsequent degradation by environmental elements. There are also many coatings which perform special functions, i.e., chafing resistance, rain erosion resistance, radiation and electric effects, fuel tank coatings, maskants, wire and fastener coatings. The scheduled promulgation of federal environmental regulations for aerospace manufacture and rework materials and processes will regulate the emissions of photochemically reactive precursors to smog and air toxics. Aerospace organizations will be required to identify, qualify and implement less polluting materials. The elimination of ozone depleting chemicals (ODC's) and implementation of pollution prevention requirements are added constraints which must be addressed concurrently. The broad categories of operations affected are the manufacture, operation, maintenance, and repair of military, commercial, general aviation, and space vehicles. The federal aerospace regulations were developed around the precept that technology had to be available to support the reduction of organic and air toxic emissions, i.e., the regulations cannot be technology forcing. In many cases, the regulations which are currently in effect in the South Coast Air Quality Management District (SCAQMD), located in Southern California, were used as the baseline for the federal regulations. This paper addresses strategies used by Southern California aerospace organizations to cope with these regulatory impacts on aerospace productions programs. All of these regulatory changes are scheduled for implementation in 1993 and 1994, with varying compliance dates established.

  17. Quantification of oxide particle composition in model oxide dispersion strengthened steel alloys.

    PubMed

    London, A J; Lozano-Perez, S; Moody, M P; Amirthapandian, S; Panigrahi, B K; Sundar, C S; Grovenor, C R M

    2015-12-01

    Oxide dispersion strengthened ferritic steels (ODS) are being considered for structural components of future designs of fission and fusion reactors because of their impressive high-temperature mechanical properties and resistance to radiation damage, both of which arise from the nanoscale oxide particles they contain. Because of the critical importance of these nanoscale phases, significant research activity has been dedicated to analysing their precise size, shape and composition (Odette et al., Annu. Rev. Mater. Res. 38 (2008) 471-503 [1]; Miller et al., Mater. Sci. Technol. 29(10) (2013) 1174-1178 [2]). As part of a project to develop new fuel cladding alloys in India, model ODS alloys have been produced with the compositions, Fe-0.3Y2O3, Fe-0.2Ti-0.3Y2O3 and Fe-14Cr-0.2Ti-0.3Y2O3. The oxide particles in these three model alloys have been studied by APT in their as-received state and following ion irradiation (as a proxy for neutron irradiation) at various temperatures. In order to adequately quantify the composition of the oxide clusters, several difficulties must be managed, including issues relating to the chemical identification (ranging and variable peak-overlaps); trajectory aberrations and chemical structure; and particle sizing. This paper presents how these issues can be addressed by the application of bespoke data analysis tools and correlative microscopy. A discussion follows concerning the achievable precision in these measurements, with reference to the fundamental limiting factors. PMID:25754233

  18. Palladium/Copper Alloy Composite Membranes for High Temperature Hydrogen Separation

    SciTech Connect

    J. Douglas Way; Paul M. Thoen

    2006-08-31

    This report summarizes progress made during the a three year University Coal Research grant (DEFG26-03NT41792) at the Colorado School of Mines. The period of performance was September 1, 2003 through August of 2006. We made excellent progress toward our goal of contributing to the development of high productivity, sulfur tolerant composite metal membranes for hydrogen production and membrane reactors. Composite Pd and Pd alloy metal membranes with thin metal films (1-7 {micro}m) were prepared on porous stainless steel and ceramic supports that meet or exceed the DOE 2010 and 2015 pure hydrogen flux targets at differential pressure of only 20 psi. For example, a 2 {micro}m pure Pd membrane on a Pall AccuSep{reg_sign} substrate achieved an ideal H{sub 2}/N{sub 2} separation factor of over 6000, with a pure hydrogen flux of 210 SCFH/ft{sup 2} at only 20 psig feed pressure. Similar performance was achieved with a Pd{sub 80}Au{sub 20} composite membrane on a similar stainless steel substrate. Extrapolating the pure hydrogen flux of this PdAu membrane to the DOE Fossil Energy target conditions of 150 psia feed pressure and 50 psia permeate pressure gives a value of 508 SCFH/ft{sup 2}, exceeding the 2015 target. At these thicknesses, it is the support cost that will dominate the cost of a large scale module. In a direct comparison of FCC phase PdCu and PdAu alloys on identical supports, we showed that a Pd{sub 85}Au{sub 15} (mass %) alloy membrane is not inhibited by CO, CO{sub 2}, or steam present in a water-gas shift feed mixture at 400 C, has better resistance to sulfur than a Pd{sub 94}Cu{sub 6} membrane, and has over twice the hydrogen permeance.

  19. Effects of scandium composition on the structural, electronic, and thermodynamic properties of SCxY1-x metallic alloys

    NASA Astrophysics Data System (ADS)

    López-Pérez, W.; Castro-Diago, P.; Ramírez-Montes, L.; González-García, A.; González-Hernández, R.

    2016-02-01

    The aim of this work is to analyse the compositional dependence of the structural, electronic and thermodynamic properties of ? alloys. Density functional calculations have been carried out to reveal compositional dependence of the structural, electronic and thermodynamic properties of ? alloys. The lattice constants of the binary compounds are in fairly good agreement with the available experimental data. The variation of calculated lattice constant with scandium concentration is almost linear, and shows a slight deviation from Vegard's law. The effect of scandium composition on bulk modulus gives nonlinear dependence on concentration x. A small deviation of the bulk modulus from linear concentration dependence was observed. The metallic nature of binary precursor compounds ScP and YP was confirmed. Our findings indicate that the ? alloys are metallic for ? 0.25, 0.5, 0.75. The calculated excess mixing enthalpy is positive over the entire scandium composition range. The positive mixing enthalpies indicate meta-stability of the ? alloys at high temperatures. The effect of temperature on the volume, bulk modulus, Debye temperature and the heat capacity for ? alloys were analysed using the quasi-harmonic Debye model. Results show that the heat capacity is slightly sensitive to composition as temperature increases.

  20. SeZnSb alloy and its nano tubes, graphene composites properties

    SciTech Connect

    Singh, Abhay Kumar

    2013-04-15

    Composite can alter the individual element physical property, could be useful to define the specific use of the material. Therefore, work demonstrates the synthesis of a new composition Se{sub 96}-Zn{sub 2}-Sb{sub 2} and its composites with 0.05% multi-walled carbon nano tubes and 0.05% bilayer graphene, in the glassy form. The diffused amorphous structure of the multi walled carbon nano tubes and bilayer gaphene in the Se{sub 96}-Zn{sub 2}-Sb{sub 2} alloy have been analyzed by using the Raman, X-ray photoluminescence spectroscopy, Furrier transmission infrared spectra, photoluminescence, UV/visible absorption spectroscopic measurements. The diffused prime Raman bands (G and D) have been appeared for the multi walled carbon nano tubes and graphene composites, while the X-ray photoluminescence core energy levels peak shifts have been observed for the composite materials. Subsequently the photoluminescence property at room temperature and a drastic enhancement (upto 80%) in infrared transmission percentage has been obtained for the bilayer graphene composite, along with optical energy band gaps for these materials have been evaluated 1.37, 1.39 and 1.41 eV.

  1. Environment enhanced fatigue of advanced aluminum alloys and metal matrix composites

    NASA Technical Reports Server (NTRS)

    Slavik, Donald C.; Gangloff, Richard P.

    1991-01-01

    The environmental fatigue crack propagation behavior of advanced Al-Li-Cu based alloys and metal matrix composites is being characterized. Aqueous NaCl and water vapor, which produce atomic hydrogen by reactions on clean crack surfaces, are emphasized. The effects of environment sensitive crack closure, stress ratio, and precipitate microstructure are assessed. Mechanistic models are sought for intrinsic crack tip damage processes to enable predictions of cracking behavior outside of the data, metallurgical improvements in material cracking resistance, and insight on hydrogen compatibility.

  2. The effects of composition on the environmental embrittlement of Fe{sub 3}Al alloys

    SciTech Connect

    Alven, D.A.; Stoloff, N.S.

    1997-12-01

    This paper reviews recent research on embrittlement of iron aluminides at room temperature brought about by exposure to moisture or hydrogen. The tensile and fatigue crack growth behavior of several Fe-28Al-5Cr alloys with small additions of Zr and C are described. It will be shown that fatigue crack growth behavior is dependent on composition, environment, humidity level, and frequency. Environments studied include vacuum, oxygen, hydrogen gas, and moist air. All cases of embrittlement are ultimately traceable to the interaction of hydrogen with the crack tip.

  3. Phase composition and structure of femtosecond laser-produced oxide layer on VT6 alloy surface

    NASA Astrophysics Data System (ADS)

    Kolobov, Yu R.; Zhidkov, M. V.; Golosov, E. V.; Vershinina, T. N.; Kudryashov, S. I.; Makarov, S. V.; Ionin, A. A.; Ligachev, A. E.

    2016-07-01

    The influence of femtosecond laser irradiation on the formation of an oxide layer on the surface of VT6 titanium alloy (Ti–6Al–4V) is studied. The structure, chemical and phase composition have been studied by x-ray diffraction, and scanning and transmission electron microscopy. The formation features of an oxide layer, which contains TiO2-rutile, TiO2-anatase Al2TiO5-aluminum titanate, Ti3O5-titanium oxide and TiO-titanium monoxide on the femtosecond laser-irradiation modified surface have been analyzed.

  4. Spray-forming monolithic aluminum alloy and metal matrix composite strip

    SciTech Connect

    McHugh, K.M.

    1995-10-01

    Spray forming with de Laval nozzles is an advanced materials processing technology that converts a bulk liquid metal to a near-net-shape solid by depositing atomized droplets onto a suitably shaped substrate. Using this approach, aluminum alloys have been spray formed as strip, with technoeconomic advantages over conventional hot mill processing and continuous casting. The spray-formed strip had a flat profile, minimal porosity, high yield, and refined microstructure. In an adaptation to the technique, 6061 Al/SiC particulate-reinforced metal matrix composite strip was produced by codeposition of the phases.

  5. Mechanical properties of as-cast and heat-treated ZA-27 alloy/short glass fiber composites

    SciTech Connect

    Sharma, S.C.; Girish, B.M.; Satish, B.M.; Kamath, R.

    1998-02-01

    This paper reports on the mechanical properties of as-cast and heat-treated ZA-27 alloy composites reinforced with glass fibers from 1 to 5 wt%. The composites were fabricated using the Compocasting method, in which short glass fibers were introduced into the vortex created in the molten alloy through an impeller rotated at 500 rpm. The molten mass was thoroughly stirred and poured into permanent molds and squeezed under pressure. The specimens were heat treated at 320 C for 1, 2, 3, and 4 h. The tests on the as-cast composites revealed that as the glass content in the composites was increased, the ultimate tensile strength (UTS), compressive strength, and hardness of the composite increased, while the ductility and impact strength were decreased. Heat treatment was found to improve significantly the ductility, compressive strength, and impact strength, while the hardness and UTS were reduced. This paper discusses the behavior of these composites.

  6. Preparation and properties of Al-alloy coconut shell char particulate composites

    NASA Astrophysics Data System (ADS)

    Murali, T. P.; Surappa, M. K.; Rohatgi, P. K.

    1982-09-01

    A technique to produce cast Al-11.8 pct Si alloy composites containing up to 40 vol pct (15 pct by weight) dispersions of 125 μm size coconut shell char particles is described. The technique consists of stirring shell char particles into the vortex created by mechanical stirring of melts and subsequent casting of composite melts in suitable molds. The composite melts were also pressure die cast at a pressure of 100 MPa into cylindrical castings. The incorporation of large volume fraction of shell char particles is aided by (a) preheating of the particles to about 500 ° to 600 ° for two hours before introduction into the melts, and (b) alloying of Al-11.8 pct Si melts with 3 to 6 pct Mg. Electron Probe Micro Analysis (EPMA) analysis indicated an Mg enriched region around dispersed char particles in the composite indicating that prealloying with Mg probably improves wetting between char particles and the melt. Dispersions of 15 pct wt of char particles lead to decreases in hardness (from 85 BHN to 55 BHN), compression strength (from 542.30 MPa to 218.68 MPa), U. T. S., (from 164.16 MPa to 63.75 MPa), and electrical conductivity (from 27.8 pct IACS to 11 pct IACS). However, since these decreases are accompanied by a decrease in density, specific strength values of Al-11.8 pct-shell char composites are adequate for a variety of applications. Adhesive wear rates and friction coefficient values at low sliding speeds (0.56 m per second, and at loads of 10 N and 60 N) decrease with increase in wt pct of char particles under dry conditions.

  7. Preparation and properties of Al-alloy coconut shell char particulate composites

    NASA Astrophysics Data System (ADS)

    Murali, T. P.; Surappa, M. K.; Rohatgi, P. K.

    1991-12-01

    A technique to produce cast Al-11.8 pct Si alloy composites containing up to 40 vol pct (15 pct by weight) dispersions of 125 µm size coconut shell char particles is described. The technique consists of stirring shell char particles into the vortex created by mechanical stirring of melts and subsequent casting of composite melts in suitable molds. The composite melts were also pressure die cast at a pressure of 100 MPa into cylindrical castings. The incorporation of large volume fraction of shell char particles is aided by (a) preheating of the particles to about 500 ‡C to 600 ‡C for two hours before introduction into the melts, and (b) alloying of Al-11.8 pct Si melts with 3 to 6 pct Mg. Electron Probe Micro Analysis (EPMA) analysis indicated an Mg enriched region around dispersed char particles in the composite indicating that prealloying with Mg probably improves wetting between char particles and the melt. Dispersions of 15 pct wt of char particles lead to decreases in hardness (from 85 BHN to 55 BHN), compression strength (from 542.30 MPa to 218.68 MPa), U. T. S., (from 164.16 MPa to 63.75 MPa), and electrical conductivity (from 27.8 pct I ACS to 11 pct I ACS). However, since these decreases are accompanied by a decrease in density, specific strength values of Al-11.8 pct-shell char composites are adequate for a variety of applications. Adhesive wear rates and friction coefficient values at low sliding speeds (0.56 m per second, and at loads of 10 N and 60 N) decrease with increase in wt pct of char particles under dry conditions.

  8. Electrochemical synthesis of mesoporous Pt-Au binary alloys with tunable compositions for enhancement of electrochemical performance.

    PubMed

    Yamauchi, Yusuke; Tonegawa, Akihisa; Komatsu, Masaki; Wang, Hongjing; Wang, Liang; Nemoto, Yoshihiro; Suzuki, Norihiro; Kuroda, Kazuyuki

    2012-03-21

    Mesoporous Pt-Au binary alloys were electrochemically synthesized from lyotropic liquid crystals (LLCs) containing corresponding metal species. Two-dimensional exagonally ordered LLC templates were prepared on conductive substrates from diluted surfactant solutions including water, a nonionic surfactant, ethanol, and metal species by drop-coating. Electrochemical synthesis using such LLC templates enabled the preparation of ordered mesoporous Pt-Au binary alloys without phase segregation. The framework composition in the mesoporous Pt-Au alloy was controlled simply by changing the compositional ratios in the precursor solution. Mesoporous Pt-Au alloys with low Au content exhibited well-ordered 2D hexagonal mesostructures, reflecting those of the original templates. With increasing Au content, however, the mesostructural order gradually decreased, thereby reducing the electrochemically active surface area. Wide-angle X-ray diffraction profiles, X-ray photoelectron spectra, and elemental mapping showed that both Pt and Au were atomically distributed in the frameworks. The electrochemical stability of mesoporous Pt-Au alloys toward methanol oxidation was highly improved relative to that of nonporous Pt and mesoporous Pt films, suggesting that mesoporous Pt-Au alloy films are potentially applicable as electrocatalysts for direct methanol fuel cells. Also, mesoporous Pt-Au alloy electrodes showed a highly sensitive amperometric response for glucose molecules, which will be useful in next-generation enzyme-free glucose sensors. PMID:22352760

  9. Aerospace engineering educational program

    NASA Technical Reports Server (NTRS)

    Craft, William; Klett, David; Lai, Steven

    1992-01-01

    The principle goal of the educational component of NASA CORE is the creation of aerospace engineering options in the mechanical engineering program at both the undergraduate and graduate levels. To accomplish this goal, a concerted effort during the past year has resulted in detailed plans for the initiation of aerospace options in both the BSME and MSME programs in the fall of 1993. All proposed new courses and the BSME aerospace option curriculum must undergo a lengthy approval process involving two cirriculum oversight committees (School of Engineering and University level) and three levels of general faculty approval. Assuming approval is obtained from all levels, the options will officially take effect in Fall '93. In anticipation of this, certain courses in the proposed curriculum are being offered during the current academic year under special topics headings so that current junior level students may graduate in May '94 under the BSME aerospace option. The proposed undergraduate aerospace option curriculum (along with the regular mechanical engineering curriculum for reference) is attached at the end of this report, and course outlines for the new courses are included in the appendix.

  10. Determination of a brass alloy concentration composition using calibration-free laser-induced breakdown spectroscopy

    NASA Astrophysics Data System (ADS)

    Achouri, M.; Baba-Hamed, T.; Beldjilali, S. A.; Belasri, A.

    2015-09-01

    Laser-induced breakdown spectroscopy (LIBS) is a technique that can provide qualitative and quantitative measurements of the characteristics of irradiated metals. In the present work, we have calculated the parameters of the plasma produced from a brass alloy sample under the action of a pulsed Nd: YAG laser operating at 1064 nm. The emission lines of copper atoms (Cu I), zinc atoms (Zn I), and lead atoms (Pb I), which are elements of a brass alloy composition, were used to investigate the parameters of the brass plasma. The spectral profiles of Cu, Zn, and Pb lines have been used to extract the electron temperature and density of the brass alloy plasma. The characteristics of Cu, Zn, and Pb were determined quantatively by the calibration-free LIBS (CF-LIBS) method considering for accurate analysis that the laser-induced ablated plasma is optically thin in local thermodynamic equilibrium conditions and the plasma ablation is stoichiometric. The Boltzmann plot method was used to evaluate the plasma temperature, and the Stark broadened profiles were used to determine the electron density. An algorithm based on the experimentally measured values of the intensity of spectral lines and the basic laws of plasma physics was developed for the determination of Cu, Zn, and Pb concentrations in the brass sample. The concentrations C CF-LIBS calculated by CF-LIBS and the certified concentrations C certified were very close.

  11. Determination of a brass alloy concentration composition using calibration-free laser-induced breakdown spectroscopy

    SciTech Connect

    Achouri, M.; Baba-Hamed, T.; Beldjilali, S. A. Belasri, A.

    2015-09-15

    Laser-induced breakdown spectroscopy (LIBS) is a technique that can provide qualitative and quantitative measurements of the characteristics of irradiated metals. In the present work, we have calculated the parameters of the plasma produced from a brass alloy sample under the action of a pulsed Nd: YAG laser operating at 1064 nm. The emission lines of copper atoms (Cu I), zinc atoms (Zn I), and lead atoms (Pb I), which are elements of a brass alloy composition, were used to investigate the parameters of the brass plasma. The spectral profiles of Cu, Zn, and Pb lines have been used to extract the electron temperature and density of the brass alloy plasma. The characteristics of Cu, Zn, and Pb were determined quantatively by the calibration-free LIBS (CF-LIBS) method considering for accurate analysis that the laser-induced ablated plasma is optically thin in local thermodynamic equilibrium conditions and the plasma ablation is stoichiometric. The Boltzmann plot method was used to evaluate the plasma temperature, and the Stark broadened profiles were used to determine the electron density. An algorithm based on the experimentally measured values of the intensity of spectral lines and the basic laws of plasma physics was developed for the determination of Cu, Zn, and Pb concentrations in the brass sample. The concentrations C{sub CF-LIBS} calculated by CF-LIBS and the certified concentrations C{sub certified} were very close.

  12. Structure and composition of nanometer-sized nitrides in a creep resistant cast austenitic alloy

    SciTech Connect

    Evans, Neal D; Maziasz, Philip J; Shingledecker, John P.; Pollard, Michael J

    2010-01-01

    The microstructure of a new and improved high-temperature creep-resistant cast austenitic alloy, CF8C-Plus, was characterized after creep-rupture testing at 1023 K (750 C) and 100 MPa. Microstructures were investigated by detailed scanning electron microscopy, transmission electron microscopy, and energy-dispersive X-ray spectroscopy (EDS). Principal component analysis of EDS spectrum images was used to examine the complex precipitate morphology. Thermodynamic modeling was performed to predict equilibrium phases in this alloy as well as the compositions of these phases at relevant temperatures. The improved high-temperature creep strength of CF8C-Plus over its predecessor CF8C is suggested to be due to the modified microstructure and phase stability in the alloy, including the absence of {delta}-ferrite in the as-cast condition and the development of a stable, slow-growing precipitation hardening nitride phase - the tetragonal Z-phase - which has not been observed before in cast austenitic stainless steels.

  13. In-situ processing of aluminum nitride particle reinforced aluminum alloy composites

    NASA Astrophysics Data System (ADS)

    Zheng, Qingjun

    Discontinuously reinforced aluminum alloy composites (DRACs) have potential applications in automotive, electronic packaging, and recreation industries. Conventional processing of DRACs is by incorporation of ceramic particles/whiskers/fibers into matrix alloys. Because of the high cost of ceramic particles, DRACs are expensive. The goal of this work was to develop a low-cost route of AlN-Al DRACs processing through bubbling and reacting nitrogen and ammonia gases with aluminum alloy melt in the temperature range of 1373--1523 K. Thermodynamic analysis of AlN-Al alloy system was performed based on Gibbs energy minimization theory. AlN is stable in aluminum, Al-Mg, Al-Si, Al-Zn, and Al-Li alloys over the whole temperature range for application and processing of DRACs. Experiments were carried out to form AlN by bubbling nitrogen and ammonia gases through aluminum, Al-Mg, and Al-Si alloy melts. Products were characterized with XRD, SEM, and EDX. The results showed that in-situ processing of AlN reinforced DRACs is technically feasible. Significant AlN was synthesized by bubbling deoxidized nitrogen and ammonia gases. When nitrogen gas was used as the nitrogen precursor, the AlN particles formed in-situ are small in size, (<10 mum). The formation of AlN is strongly affected by the trace oxygen impurities in the nitrogen gas. The deleterious effect of oxygen impurities is due to their inhibition to the chemisorption of nitrogen gas at the interface. In comparison with nitrogen gas, bubbling ammonia led to formation of AlN particles in smaller size (about 2 mum or less) at a significantly higher rate. Ammonia is not stable and dissociated into nitrogen and hydrogen at reaction temperatures. The hydrogen functions as oxygen-getter at the interface and benefits chemisorption of nitrogen, thereby promoting the formation of AlN. The overall process of AlN formation was modeled using two-film model. For nitrogen bubbling gas, the whole process is controlled by chemisorption

  14. NASA's activities in the conservation of strategic aerospace materials

    NASA Technical Reports Server (NTRS)

    Stephens, J. R.

    1980-01-01

    The primary objective of the Conservation of Strategic Aerospace Materials (COSAM) Program is to help reduce the dependence of the United States aerospace industry on strategic metals by providing the materials technology needed to minimize the strategic metal content of critical aerospace components with prime emphasis on components for gas turbine engines. Initial emphasis was placed in the area of strategic element substinction. Specifically, the role of cobalt in nickel base and cobalt base superalloys vital to the aerospace industry is being examined in great detail by means of cooperative university-industry-government research efforts. Investigations are underway in the area of "new classes" of alloys. Specifically, a study was undertaken to investigate the mechanical and physical properties of intermetallics that contain a minimum of the strategic metals. Current plans for the much larger COSAM Program are also presented.

  15. Laser Controllable Growth of Graphene via Ni-Cu Alloy Composition Modulation

    NASA Astrophysics Data System (ADS)

    Ye, Xiaohui; Lin, Zhe; Zhang, Hongjun; Zhu, Hongwei; Zhong, Minlin

    2015-12-01

    Graphene has many unique properties, most of them strongly depend on the number of layers. It is significant to develop a facile approach to realize the controllable growth of graphene with specific number of layers. We ever reported an efficient approach to grow graphene rapidly and locally by laser irradiation. In this work, we offers yet another important feature, to control the number of layers of graphene. Ni-Cu alloy has been reported to be used successfully as the catalyst for graphene growth with controllable number of layers. In that case, the Ni-Cu alloys with different compositions were normally formed by thermal evaporation. Here we provide an efficient way to fabricate the Ni-Cu alloy catalysts by laser cladding. Then the high power laser was employed to melt the Ni and Cu mixed powders. Different Ni-Cu alloy catalysts were formed in a high rate of 720 mm2/min with a thickness of 1.2 mm. Then the graphene with controllable layers was rapidly and locally grown on the Ni-Cu catalysts by laser irradiation at a high rate (18 cm2/min) at room temperature. We found that the Ni-Cu catalyst with 15 % Cu could be helpful to grow single layer graphene, which occupied 92.4 % of the entire film. Higher Cu content didn't promote the growth due to the oxygen involved during the growth process. The controllable growth mechanism of graphene by laser processing was discussed. Combining the rapid catalyst fabrication and graphene synthesis make it a cost- and time-efficient method to produce the controllable graphene films.

  16. Palladium/Copper Alloy Composite Membranes for High Temperature Hydrogen Separation

    SciTech Connect

    J. Douglas Way; Paul M. Thoen

    2005-08-31

    This report summarizes progress made during the second year of research funding from DOE Grant DE-FG26-03NT41792 at the Colorado School of Mines. The period of performance was September 1, 2004 through August of 2005. We have reformulated our Pd plating process to minimize the presence of carbon contamination in our membranes. This has improved durability and increased permeability. We have developed techniques for plating the outside diameter of ceramic and metal substrate tubes. This configuration has numerous advantages including a 40% increase in specific surface area, the ability to assay the alloy composition non-destructively, the ability to potentially repair defects in the plated surface, and the ability to visually examine the plated surfaces. These improvements have allowed us to already meet the 2007 DOE Fossil Energy pure H{sub 2} flux target of 100 SCFH/ft{sup 2} for a hydrogen partial pressure difference of 100 psi with several Pd-Cu alloy membranes on ceramic microfilter supports. Our highest pure H{sub 2} flux on inexpensive, porous alumina support tubes at the DOE target conditions is 215 SCFH/ft{sup 2}. Progress toward meeting the other DOE Fossil Energy performance targets is also summarized. Additionally, we have adapted our membrane fabrication procedure to apply Pd and Pd alloy films to commercially available porous stainless steel substrates. Stable performance of Pd-Cu films on stainless steel substrates was demonstrated over a three week period at 400 C. Finally, we have fabricated and tested Pd-Au alloy membranes. These membranes also exceed both the 2007 and 2010 DOE pure H{sub 2} flux targets and exhibit ideal H{sub 2}/N{sub 2} selectivities of over 1000 at partial pressure difference of 100 psi.

  17. Formation of the properties of antimony matrix alloys for frame-type composite materials

    NASA Astrophysics Data System (ADS)

    Gulevskii, V. A.; Antipov, V. I.; Vinogradov, L. V.; Kolmakov, A. G.; Lazarev, E. M.; Samarina, A. M.; Mukhina, Yu. E.

    2009-12-01

    A frame-type composite material (CM) produced upon impregnation represents a system consisting of a rigid porous frame and a matrix material filling its voids. When metals are used as a matrix material, they bring up specific problems related to melting of a metal, such as the thermal effect of the metal on the frame and the chemical interaction of the matrix and frame with the formation of brittle compounds. A CM that combines the best characteristics of its components can be produced. Since impregnation is, as a rule, performed under vacuum, melting of a matrix metal is accompanied by an increase in the evaporation rate. The evaporation of a matrix metal can be decreased by controlling its chemical composition, decreasing the melting temperature of the melt, and controlling the cooling rate. In this work, antimony alloys are used as a matrix material and their properties are studied.

  18. Measurement and Prediction of the Thermomechanical Response of Shape Memory Alloy Hybrid Composite Beams

    NASA Technical Reports Server (NTRS)

    Davis, Brian; Turner, Travis L.; Seelecke, Stefan

    2008-01-01

    An experimental and numerical investigation into the static and dynamic responses of shape memory alloy hybrid composite (SMAHC) beams is performed to provide quantitative validation of a recently commercialized numerical analysis/design tool for SMAHC structures. The SMAHC beam specimens consist of a composite matrix with embedded pre-strained SMA actuators, which act against the mechanical boundaries of the structure when thermally activated to adaptively stiffen the structure. Numerical results are produced from the numerical model as implemented into the commercial finite element code ABAQUS. A rigorous experimental investigation is undertaken to acquire high fidelity measurements including infrared thermography and projection moire interferometry for full-field temperature and displacement measurements, respectively. High fidelity numerical results are also obtained from the numerical model and include measured parameters, such as geometric imperfection and thermal load. Excellent agreement is achieved between the predicted and measured results of the static and dynamic thermomechanical response, thereby providing quantitative validation of the numerical tool.

  19. Compressive strength of titanium alloy skin-stringer panels selectively reinforced with boron-aluminum composite.

    NASA Technical Reports Server (NTRS)

    Herring, H. W.; Carri, R. L.

    1972-01-01

    Description of a method of selectively reinforcing conventional titanium airframe structure with unidirectional boron-aluminum composite attached by brazing which has been successfully demonstrated based on compression tests of short skin-stringer panels. Improvements in structural performance exceeded 25% on an equivalent weight basis over the range from room temperature to 800 F, both in terms of initial buckling and maximum strengths. Room-temperature performance was not affected by prior exposure at 600 F for 1000 hours in air, or by 400 cycles between -65 and 600 F. The experimental results were generally predictable on the basis of existing analytical procedures. No evidence of failure was observed in the braze bond between the boron-aluminum composite and the titanium alloy.

  20. Precise AuxPt1-x Alloy Nanoparticle Array of Tunable Composition for Catalytic Applications

    NASA Astrophysics Data System (ADS)

    Jahn, Sarah; Lechner, Sebastian J.; Freichels, Helene; Möller, Martin; Spatz, Joachim P.

    2016-02-01

    A 3-dimensional Block Copolymer Micellar nanoLithography (BCML) process was used to prepare AuxPt1-x alloy nanoparticles (NPs) monodisperse in size and composition, strongly anchored onto SiO2-particles (0.2 wt.% AuxPt1-x/SiO2). The particles possess a face-centered cubic (fcc) crystal structure and their size could be varied from 3-12 nm. We demonstrate the uniformity of the Au/Pt composition by analyzing individual NPs by energy-dispersive X-ray spectroscopy. The strongly bound AuxPt1-x NPs catalyzed the oxidation of CO with high activity. Thermal ageing experiments in pure CO2 as well as in ambient atmosphere demonstrated stability of the size distribution for times as long as 22 h.

  1. Soft Magnetic Alloy-Polymer Composite for High-Frequency Power Electronics Application

    NASA Astrophysics Data System (ADS)

    Calata, Jesus N.; Lu, Guo-Quan; Ngo, Khai

    2014-01-01

    Soft magnetic alloys are limited to lower frequencies because of increased eddy-current losses at higher frequencies. A simple low-temperature solvent-based process was developed to coat permalloy powder with a benzocyclobutene insulating layer to reduce interparticle eddy-current loss. Low-signal measurements show that the permeability of the cured composite exhibits a bandwidth beyond 10 MHz. In contrast, the permeability of the pure powder rolled off well below 1 MHz with a corresponding increase in the imaginary permeability. Measurements of the core loss density at 5 MHz on pressed composite cores show a core loss of 300 mW/cm3 at more than 90 gauss, while the pure powder core achieved the same core loss density at just over 10 gauss. The results demonstrate that the polymer coating process is an effective way of reducing the interparticle eddy-current loss in powdered magnetic cores at high frequencies.

  2. Ti-Mo alloys employed as biomaterials: effects of composition and aging heat treatment on microstructure and mechanical behavior.

    PubMed

    Cardoso, Flavia F; Ferrandini, Peterson L; Lopes, Eder S N; Cremasco, Alessandra; Caram, Rubens

    2014-04-01

    The correlation between the composition, aging heat treatments, microstructural features and mechanical properties of β Ti alloys is of primary significance because it is the foundation for developing and improving new Ti alloys for orthopedic biomaterials. However, in the case of Ti-Mo alloys, this correlation is not fully described in the literature. Therefore, the purpose of this study was to experimentally investigate the effect of composition and aging heat treatments on the microstructure, Vickers hardness and elastic modulus of Ti-Mo alloys. These alloys were solution heat-treated and water-quenched, after which their response to aging heat treatments was investigated. Their microstructure, Vickers hardness and elastic modulus were evaluated, and the results allow us to conclude that stabilization of the β phase is achieved with nearly 10% Mo when a very high cooling rate is applied. Young's modulus was found to be more sensitive to phase variations than hardness. In all of the compositions, the highest hardness values were achieved by aging at 723K, which was attributed to the precipitation of α and ω phases. All of the compositions aged at 573K, 623K and 723K showed overaging within 80h. PMID:24394773

  3. Precipitation Hardening and Statistical Modeling of the Aging Parameters and Alloy Compositions in Al-Cu-Mg-Ag Alloys

    NASA Astrophysics Data System (ADS)

    Al-Obaisi, A. M.; El-Danaf, E. A.; Ragab, A. E.; Soliman, M. S.

    2016-04-01

    The addition of Ag to Al-Cu-Mg systems has been proposed to replace the existing high-strength 2xxx and 7xxx Al alloys. The aged Al-Cu-Mg-Ag alloys exhibited promising properties, due to special type of precipitates named Ω, which cooperate with other precipitates to enhance the mechanical properties significantly. In the present investigation, the effect of changing percentages of alloying elements, aging time, and aging temperature on the hardness values was studied based on a factorial design. According to this design of experiments (DOE)—23 factorial design, eight alloys were cast and hot rolled, where (Cu, Mg, and Ag) were added to aluminum with two different levels for each alloying element. These alloys were aged at different temperatures (160, 190, and 220 °C) over a wide range of time intervals from 10 min. to 64 h. The resulting hardness data were used as an input for Minitab software to model and relate the process variables with hardness through a regression analysis. Modifying the alloying elements' weight percentages to the high level enhanced the hardness of the alloy with about 40% as compared to the alloy containing the low level of all alloying elements. Through analysis of variance (ANOVA), it was figured out that altering the fraction of Cu had the greatest effect on the hardness values with a contribution of about 49%. Also, second-level interaction terms had about 21% of impact on the hardness values. Aging time, quadratic terms, and third-level interaction terms had almost the same level of influence on hardness values (about 10% contribution). Furthermore, the results have shown that small addition of Mg and Ag was enough to improve the mechanical properties of the alloy significantly. The statistical model formulated interpreted about 80% of the variation in hardness values.

  4. Precipitation Hardening and Statistical Modeling of the Aging Parameters and Alloy Compositions in Al-Cu-Mg-Ag Alloys

    NASA Astrophysics Data System (ADS)

    Al-Obaisi, A. M.; El-Danaf, E. A.; Ragab, A. E.; Soliman, M. S.

    2016-06-01

    The addition of Ag to Al-Cu-Mg systems has been proposed to replace the existing high-strength 2xxx and 7xxx Al alloys. The aged Al-Cu-Mg-Ag alloys exhibited promising properties, due to special type of precipitates named Ω, which cooperate with other precipitates to enhance the mechanical properties significantly. In the present investigation, the effect of changing percentages of alloying elements, aging time, and aging temperature on the hardness values was studied based on a factorial design. According to this design of experiments (DOE)—23 factorial design, eight alloys were cast and hot rolled, where (Cu, Mg, and Ag) were added to aluminum with two different levels for each alloying element. These alloys were aged at different temperatures (160, 190, and 220 °C) over a wide range of time intervals from 10 min. to 64 h. The resulting hardness data were used as an input for Minitab software to model and relate the process variables with hardness through a regression analysis. Modifying the alloying elements' weight percentages to the high level enhanced the hardness of the alloy with about 40% as compared to the alloy containing the low level of all alloying elements. Through analysis of variance (ANOVA), it was figured out that altering the fraction of Cu had the greatest effect on the hardness values with a contribution of about 49%. Also, second-level interaction terms had about 21% of impact on the hardness values. Aging time, quadratic terms, and third-level interaction terms had almost the same level of influence on hardness values (about 10% contribution). Furthermore, the results have shown that small addition of Mg and Ag was enough to improve the mechanical properties of the alloy significantly. The statistical model formulated interpreted about 80% of the variation in hardness values.

  5. Frontier Aerospace Opportunities

    NASA Technical Reports Server (NTRS)

    Bushnell, Dennis M.

    2014-01-01

    Discussion and suggested applications of the many ongoing technology opportunities for aerospace products and missions, resulting in often revolutionary capabilities. The, at this point largely unexamined, plethora of possibilities going forward, a subset of which is discussed, could literally reinvent aerospace but requires triage of many possibilities. Such initial upfront homework would lengthen the Research and Development (R&D) time frame but could greatly enhance the affordability and performance of the evolved products and capabilities. Structural nanotubes and exotic energetics along with some unique systems approaches are particularly compelling.

  6. Aerospace Environmental Technology Conference

    NASA Technical Reports Server (NTRS)

    Whitaker, A. F. (Editor)

    1995-01-01

    The mandated elimination of CFC's, Halons, TCA, and other ozone depleting chemicals and specific hazardous materials has required changes and new developments in aerospace materials and processes. The aerospace industry has been involved for several years in providing product substitutions, redesigning entire production processes, and developing new materials that minimize or eliminate damage to the environment. These activities emphasize replacement cleaning solvents and their application verifications, compliant coatings including corrosion protection systems, and removal techniques, chemical propulsion effects on the environment, and the initiation of modifications to relevant processing and manufacturing specifications and standards. The Executive Summary of this Conference is published as NASA CP-3297.

  7. Measurement and Prediction of the Thermomechanical Response of Shape Memory Alloy Hybrid Composite Beams

    NASA Technical Reports Server (NTRS)

    Davis, Brian; Turner, Travis L.; Seelecke, Stefan

    2005-01-01

    Previous work at NASA Langley Research Center (LaRC) involved fabrication and testing of composite beams with embedded, pre-strained shape memory alloy (SMA) ribbons within the beam structures. That study also provided comparison of experimental results with numerical predictions from a research code making use of a new thermoelastic model for shape memory alloy hybrid composite (SMAHC) structures. The previous work showed qualitative validation of the numerical model. However, deficiencies in the experimental-numerical correlation were noted and hypotheses for the discrepancies were given for further investigation. The goal of this work is to refine the experimental measurement and numerical modeling approaches in order to better understand the discrepancies, improve the correlation between prediction and measurement, and provide rigorous quantitative validation of the numerical analysis/design tool. The experimental investigation is refined by a more thorough test procedure and incorporation of higher fidelity measurements such as infrared thermography and projection moire interferometry. The numerical results are produced by a recently commercialized version of the constitutive model as implemented in ABAQUS and are refined by incorporation of additional measured parameters such as geometric imperfection. Thermal buckling, post-buckling, and random responses to thermal and inertial (base acceleration) loads are studied. The results demonstrate the effectiveness of SMAHC structures in controlling static and dynamic responses by adaptive stiffening. Excellent agreement is achieved between the predicted and measured results of the static and dynamic thermomechanical response, thereby providing quantitative validation of the numerical tool.

  8. Aero-thermo-mechanical characteristics of imperfect shape memory alloy hybrid composite panels

    NASA Astrophysics Data System (ADS)

    Ibrahim, Hesham Hamed; Yoo, Hong Hee; Lee, Kwan-Soo

    2009-08-01

    A nonlinear finite element model is provided to predict the static aero-thermal deflection and the vibration behavior of geometrically imperfect shape memory alloy hybrid composite panels under the combined effect of thermal and aerodynamic loads. The nonlinear governing equations are obtained using Marguerre curved plate theory and the principle of virtual work taking into account the temperature-dependence of material properties. The effect of large deflection is included in the formulation through the von Karman nonlinear strain-displacement relations. The thermal load is assumed to be a steady-state constant-temperature distribution, whereas the aerodynamic pressure is modeled using the quasi-steady first-order piston theory. The Newton-Raphson iteration method is employed to obtain the nonlinear aero-thermal deflections, while an eigenvalue problem is solved at each temperature step and static aerodynamic load to predict the free vibration frequencies about the deflected equilibrium position. Finally, the nonlinear deflection and free vibration characteristics of a composite panel are presented, illustrating the effects of geometric imperfection, temperature rise, aerodynamic pressure, boundary conditions and shape memory alloy fiber embeddings on the panel response.

  9. Containerless processing and rapid solidification of Nb-Si alloys of hypereutectic composition

    NASA Technical Reports Server (NTRS)

    Hofmeister, W. H.; Bayuzick, R. J.; Robinson, M. B.; Bertero, G. A.

    1991-01-01

    A combination of bulk undercooling in an electromagnetic levitation apparatus and splat quenching between two copper plates is used to process Nb-Si alloys in order to maximize rapid solidification conditions and minimize the effects of recalescence, with emphasis on the solidification of characteristics of alloys in the 21 to 27 at. pct Si range of composition. SEM and TEM as well as X-ray diffraction are used to characterize the microstructures of the processed samples. In the range of compositions studied, the splat-quenched drops always formed the tetragonal Nb3Si phase directly from the liquid. Drops solidified in the coil were characterized by the presence of the primary intermetallic Nb5Si3 and the absence of both peritectic Nb3Si and the equilibrium eutectic. In these cases, a metastable alpha-Nb + beta-Nb5Si3 eutectic formed. The results are discussed in terms of possible metastable configurations of the Nb-Si phase diagram as well as concepts of nucleation and growth kinetics applied to the Nb3Si and Nb5Si3 intermetallics.

  10. The solidification microstructure of Al-Cu-Si alloys metal matrix composites

    SciTech Connect

    Garbellini, O.; Palacio, H.; Biloni, H.

    1998-12-31

    The relationship between solidification microstructure and fluidity in MMC was studied. The composites were fabricated by infiltration of liquid metal into a alumina SAFFIL fibers preform under a gas pressure, using alloys of the AlCuSi system as matrices. The fluidity was measured in terms of classic foundry practice (i.e., the distance of flow liquid metal into the preform, while solidifying). The characterization of solidification microstructure in the cast composite was analyzed and correlated with the results of fluidity. The attention was particularly focused on such effects as the presence or absence of selective nucleation, the refinement of certain solidifying phases in the presence of fibers and their influence on microstructure formation and segregation of certain elements present in the liquid at the fiber matrix interface. By comparing reinforced and non reinforced zones, it was shown that the presence of fibers resulted in a refinement of the dendritic arm spacing of the {alpha}Al phase, with nucleation of Si on the fibers and without nucleation of primary Al dendrites. The results were discussed and compared with the microstructures and fluidity test of the unreinforced Al-Cu-Si alloys.

  11. Three-dimensional nanometer scale analyses of precipitate structures and local compositions in titanium aluminide engineering alloys

    NASA Astrophysics Data System (ADS)

    Gerstl, Stephan S. A.

    Titanium aluminide (TiAl) alloys are among the fastest developing class of materials for use in high temperature structural applications. Their low density and high strength make them excellent candidates for both engine and airframe applications. Creep properties of TiAl alloys, however, have been a limiting factor in applying the material to a larger commercial market. In this research, nanometer scale compositional and structural analyses of several TiAl alloys, ranging from model Ti-Al-C ternary alloys to putative commercial alloys with 10 components are investigated utilizing three dimensional atom probe (3DAP) and transmission electron microscopies. Nanometer sized borides, silicides, and carbide precipitates are involved in strengthening TiAl alloys, however, chemical partitioning measurements reveal oxygen concentrations up to 14 at. % within the precipitate phases, resulting in the realization of oxycarbide formation contributing to the precipitation strengthening of TiAl alloys. The local compositions of lamellar microstructures and a variety of precipitates in the TiAl system, including boride, silicide, binary carbides, and intermetallic carbides are investigated. Chemical partitioning of the microalloying elements between the alpha2/gamma lamellar phases, and the precipitate/gamma-matrix phases are determined. Both W and Hf have been shown to exhibit a near interfacial excess of 0.26 and 0.35 atoms nm-2 respectively within ca. 7 nm of lamellar interfaces in a complex TiAl alloy. In the case of needle-shaped perovskite Ti3AlC carbide precipitates, periodic domain boundaries are observed 5.3+/-0.8 nm apart along their growth axis parallel to the TiAl[001] crystallographic direction with concomitant composition variations after 24 hrs. at 800°C.

  12. Corrosion studies on construction materials for flue-gas-desulfurization systems. [Effects of Ph, chloride content, and alloy composition

    SciTech Connect

    Maiya, P.S.

    1982-08-01

    Several Mo- and Cr-bearing alloys of interest to flue-gas desulfurization (FGD) systems have been examined for corrosion in simulated FGD environments at 85/sup 0/C. To evaluate the importance of hydrogen and chloride ion concentrations, Type 316L stainless steel was exposed for varying times at different pH levels (0.5 to 3.0) and chloride content (0.03 to 5.0 wt% Cl/sup -/). To determine the effects of pH and composition in acid solution that contains a fixed amount of chloride (approx. 0.34 wt% Cl/sup -/), a number of alloys were used in which the composition parameter (defined as the sum of Cr and Mo) varied from 19.5 to 33.5 wt%. In all cases, the general corrosion or dissolution as determined from weight loss measurements (mg mm/sup -2/) varied linearly with time. The corrosion rate (mg mm/sup -2/ h/sup -1/) for the alloys decreased with an increase in pH in a consistent manner regardless of the alloy crystal structure. The composition effects on corrosion rate were most significant at pH = 0.5. The dependence of corrosion rate on pH, chloride ion concentration, and alloy composition is discussed in a quantitative manner. The relationships developed from the kinetic data provide useful guidance in the selection of appropriate alloys for more comprehensive studies under more realistic FGD testing environments that include environmental and stress cycling. Also, the materials evaluation approach adopted in the present study enables predictions of the life of components subjected to different environments and is relevant to alloy development work in progress elsewhere. In addition, testing and evaluation procedures have been developed for two alternative materials, namely, a fiber-reinforced plastic (Atlac 4010-A from ICI Americas, Inc.) and an epoxy coating on mild steel (Markote 300 System from Martek Engineering, Inc.); preliminary results are presented.

  13. Overview of nickel metal hydride battery technology for aerospace applications. Technical report

    SciTech Connect

    Wasz, M.L.

    1996-08-22

    For thirty years, the scientific community has investigated using intermetallic metal hydrides as hydrogen reservoirs and electrodes for secondary batteries. They are now replacing nickel-cadmium batteries in small electronics and may become attractive for aerospace applications. Metal hydride batteries do not require high-pressure containers, and prismatic cell designs are possible. With alloying, a wide range of operational temperatures can be achieved; however, large batteries require thermal control to dissipate and supply heat during high-rate charging and discharging. Recent investigations have concentrated on optimizing electrode capacity and cycle life by manipulating alloy compositions, microstructures, particle sizes, crystallinity, and surface chemistry. Despite intensive efforts, the discharge capacity of the metal hydrides has not improved beyond 250-400 mAh/g, and inherent deterioration processes apparently related to the formation of the hydride phase make metal hydrides unreliable choices for satellite applications demanding more than 500-2000 cycles. Additionally, the long-term effects of exposure of these materials to the potassium-hydroxide electrolyte during low-cycle, long-life missions is not known. This review surveys the status of research and commercial development of metal-hydride cells and evaluates the potential advantages and applications of metal-hydride batteries for aerospace use.

  14. Nanotechnology research for aerospace applications

    NASA Astrophysics Data System (ADS)

    Agee, Forrest J.; Lozano, Karen; Gutierrez, Jose M.; Chipara, Mircea; Thapa, Ram; Chow, Alice

    2009-04-01

    Nanotechnology is impacting the future of the military and aerospace. The increasing demands for high performance and property-specific applications are forcing the scientific world to take novel approaches in developing programs and accelerating output. CONTACT or Consortium for Nanomaterials for Aerospace Commerce and Technology is a cooperative nanotechnology research program in Texas building on an infrastructure that promotes collaboration between universities and transitioning to industry. The participants of the program include the US Air Force Research Laboratory (AFRL), five campuses of the University of Texas (Brownsville, Pan American, Arlington, Austin, and Dallas), the University of Houston, and Rice University. Through the various partnerships between the intellectual centers and the interactions with AFRL and CONTACT's industrial associates, the program represents a model that addresses the needs of the changing and competitive technological world. Into the second year, CONTACT has expanded to twelve projects that cover four areas of research: Adaptive Coatings and Surface Engineering, Nano Energetics, Electromagnetic Sensors, and Power Generation and Storage. This paper provides an overview of the CONTACT program and its projects including the research and development of new electrorheological fluids with nanoladen suspensions and composites and the potential applications.

  15. Effect of gallium alloying on the structure, the phase composition, and the thermoelastic martensitic transformations in ternary Ni-Mn-Ga alloys

    NASA Astrophysics Data System (ADS)

    Belosludtseva, E. S.; Kuranova, N. N.; Marchenkova, E. B.; Popov, A. G.; Pushin, V. G.

    2016-04-01

    The effect of gallium alloying on the structure, the phase composition, and the properties of quasibinary Ni50Mn50- z Ga z (0 ⩽ z ⩽ 25 at %) alloys is studied over a wide temperature range. The influence of the alloy composition on the type of crystal structure in high-temperature austenite and martensite and the critical martensitic transformation temperatures is analyzed. A general phase diagram of the magnetic and structural transformations in the alloys is plotted. The temperature-concentration boundaries of the B2 and L21 superstructures in the austenite field, the tetragonal L10 (2 M) martensite, and the 10 M and 14 M martensite phases with complex multilayer crystal lattices are found. The predominant morphology of martensite is shown to be determined by the hierarchy of the packets of thin coherent lamellae of nano- and submicrocrystalline crystals with planar habit plane boundaries close to {011} B2. Martensite crystals are twinned along one of the 24 24{ {011} }{< {01bar 1} rangle _{B2}} "soft" twinning shear systems, which provides coherent accommodation of the martensitic transformation-induced elastic stresses.

  16. Aerospace Education. NSTA Position Statement

    ERIC Educational Resources Information Center

    National Science Teachers Association (NJ1), 2008

    2008-01-01

    National Science Teachers Association (NSTA) has developed a new position statement, "Aerospace Education." NSTA believes that aerospace education is an important component of comprehensive preK-12 science education programs. This statement highlights key considerations that should be addressed when implementing a high quality aerospace education…

  17. Fabrication and characterization of bioactive composite coatings on Mg-Zn-Ca alloy by MAO/sol-gel.

    PubMed

    Gao, J H; Shi, X Y; Yang, B; Hou, S S; Meng, E C; Guan, F X; Guan, S K

    2011-07-01

    High corrosion rate and accumulation of hydrogen gas upon degradation impede magnesium alloys' clinical application as implants. In this work, micro-arc oxidation (MAO) was used to fabricate a porous coating on magnesium alloys as an intermediate layer to enhance the bonding strength of propolis layer. Then the composite coatings were fabricated using sol-gel method by dipping sample into the solution containing propolis and polylactic acid at 40 °C. The corrosion resistance of the samples was determined based on potentiodynamic polarization experiments and immersion tests. Biocompatibility was designed by observing the attachment and growth of wharton's jelly-derived mesenchymal stem cells (WJCs) on substrates with MAO coating and substrates with composite coatings. The results showed that, compared with that of Mg-Zn-Ca alloy, the corrosion current density of the samples with composite coatings decreased from 5.37 × 10⁻⁵ to 1.10 × 10⁻⁶ A/cm² and the corrosion potential increased by 240 mV. Composite coatings exhibit homogeneous corrosion behavior and can promote WJCs cell adhesion and proliferation. In the meantime, pH value was relatively stable during the immersion tests, which may be significant for cellular survival. In conclusion, our results indicate that composite coatings on Mg-Zn-Ca alloy fabricated by MAO/sol-gel method provide a new type bioactive material. PMID:21656033

  18. Aerospace Safety Advisory Panel

    NASA Technical Reports Server (NTRS)

    1985-01-01

    The following areas of NASA's responsibilities are examined: (1) the Space Transportation System (STS) operations and evolving program elements; (2) establishment of the Space Station program organization and issuance of requests for proposals to the aerospace industry; and (3) NASA's aircraft operations, including research and development flight programs for two advanced X-type aircraft.

  19. Aerospace Bibliography. Seventh Edition.

    ERIC Educational Resources Information Center

    Blashfield, Jean F., Comp.

    Provided for teachers and the general adult reader is an annotated and graded list of books and reference materials dealing with aerospace subjects. Only non-fiction books and pamphlets that need to be purchased from commercial or government sources are included. Free industrial materials and educational aids are not included because they tend to…

  20. Aerospace at Saint Francis.

    ERIC Educational Resources Information Center

    Aviation/Space, 1980

    1980-01-01

    Discusses an aviation/aerospace program as a science elective for 11th and 12th year students. This program is multi-faceted and addresses the needs of a wide variety of students. Its main objective is to present aviation and space sciences which will provide a good base for higher education in these areas. (SK)

  1. Aerospace Safety Advisory Panel

    NASA Technical Reports Server (NTRS)

    1998-01-01

    During 1997, the Aerospace Safety Advisory Panel (ASAP) continued its safety reviews of NASA's human space flight and aeronautics programs. Efforts were focused on those areas that the Panel believed held the greatest potential to impact safety. Continuing safe Space Shuttle operations and progress in the manufacture and testing of primary components for the International Space Station (ISS) were noteworthy. The Panel has continued to monitor the safety implications of the transition of Space Shuttle operations to the United Space Alliance (USA). One area being watched closely relates to the staffing levels and skill mix in both NASA and USA. Therefore, a section of this report is devoted to personnel and other related issues that are a result of this change in NASA's way of doing business for the Space Shuttle. Attention will continue to be paid to this important topic in subsequent reports. Even though the Panel's activities for 1997 were extensive, fewer specific recommendations were formulated than has been the case in recent years. This is indicative of the current generally good state of safety of NASA programs. The Panel does, however, have several longer term concerns that have yet to develop to the level of a specific recommendation. These are covered in the introductory material for each topic area in Section 11. In another departure from past submissions, this report does not contain individual findings and recommendations for the aeronautics programs. While the Panel devoted its usual efforts to examining NASA's aeronautic centers and programs, no specific recommendations were identified for inclusion in this report. In lieu of recommendations, a summary of the Panel's observations of NASA's safety efforts in aeronautics and future Panel areas of emphasis is provided. With profound sadness the Panel notes the passing of our Chairman, Paul M. Johnstone, on December 17, 1997, and our Staff Assistant, Ms. Patricia M. Harman, on October 5, 1997. Other

  2. Magnetoelectric interactions in layered composites of piezoelectric quartz and magnetostrictive alloys

    NASA Astrophysics Data System (ADS)

    Sreenivasulu, G.; Petrov, V. M.; Fetisov, L. Y.; Fetisov, Y. K.; Srinivasan, G.

    2012-12-01

    Mechanical strain mediated magnetoelectric effects are studied in bilayers and trilayers of piezoelectric quartz and magnetostrictive permendur (P), an alloy of Fe-Co-V. It is shown that the magnetoelectric voltage coefficient (MEVC), proportional to the ratio of the piezoelectric coupling coefficient to the permittivity, is higher in quartz-based composites than for traditional ferroelectrics-based ME composites. In bilayers of X-cut single crystal quartz and permendur, the MEVC varies from 1.5 V/cm Oe at 20 Hz to ˜185 V/cm Oe at bending resonance or electromechanical resonance corresponding to longitudinal acoustic modes. In symmetric X-cut quartz-P trilayers, the MEVC ˜4.8 V/cm Oe at 20 Hz and ˜175 V/cm Oe at longitudinal acoustic resonance. Trilayers of Y-cut quartz and permendur show ME coupling under a shear strain with an MEVC that is an order of magnitude smaller than for longitudinal strain in samples with X-cut quartz. A model for low-frequency and resonance ME effects which allows for explicit expressions of MEVC and resonance frequencies is provided and calculated. MEVCs are in general agreement with measured values. Magnetoelectric composites with quartz have the desired characteristics such as the absence of ferroelectric hysteresis and pyroelectric losses and could potentially replace ferroelectrics in composite-based magnetic sensors, transducers, and high-frequency devices.

  3. 1991 P/M in aerospace and defense technologies; Proceedings of the Symposium, Tampa, FL, Mar. 4-6, 1991

    SciTech Connect

    Not Available

    1991-01-01

    The present conference discusses high-performance injection-molded metal components, the importance of phosphorus in P/M alloys, particle-metallurgy steels for antifriction bearings, P/M processing of metal-matrix composites (MMCs), SiC- and B4C-reinforced Mg MMCs for satellite applications, N13Al-based intermetallic MMCs, the synthesis and properties of nanophase ceramics, MMC spray-forming, the microstructure and properties of spray-cast Cu alloys, and the spray casting of hypoeutectic Cu-Cr alloy. Also discussed are the application of the Osprey preform process to light alloys and MMCs, P/M in lightweight aircraft engine components, the fabrication of oriented single-crystal wafer stock from Ni-Al-Mo-X alloy powders, higher-performance P/M Be materials for aerospace applications, the characteristics of electrodischarge compaction, and fatigue crack propagation in dispersion-strengthened P/M Al alloys at elevated and room temperatures.

  4. Influence of composition and heat treatment on damping and magnetostrictive properties of Fe–18%(Ga + Al) alloys

    SciTech Connect

    Golovin, I. S.; Palacheva, V. V.; Zadorozhnyy, V. Yu.; Zhu, J.; Jiang, H.; Cifre, J.; Lograsso, T. A.

    2014-07-16

    The structure, magnetostriction and damping properties of Fe82Ga(18–x)Alx (x = 0, 5, 8, 12) alloys were analyzed. The anelastic response of Fe–18(Ga + Al) alloys was studied as a function of temperature (from 0 to 600 °C), frequency (from 0.01 to 200 Hz) and amplitude (from 0.0004% to 0.2%) of forced vibrations. The origin of the relatively high damping capacity of Fe–Ga–Al alloy at room temperature was determined by applying a magnetic field and different heat treatment regimes. The substitution of Ga by Al in Fe–18% Ga alloys was found to decrease magnetostriction and damping. The heat treatment of alloys influences the damping capacity of alloys more than variations of their chemical compositions. Thermally activated frequency and temperature-dependent anelastic effects in Fe–Ga–Al alloys were analyzed and the corresponding activation parameters for relaxation processes were evaluated. Internal friction effects caused by structural transformations were recorded and were found to be consistent with the A2 → D03 → L12 reaction. Thus, the physical mechanisms for all anelastic effects are discussed.

  5. Processing and Composition Effects on the Fracture Behavior of Spray-Formed 7XXX Series Al Alloys

    NASA Astrophysics Data System (ADS)

    Sharma, M. M.; Ziemian, C. W.; Eden, T. J.

    2010-12-01

    The fracture properties of high-strength spray-formed Al alloys were investigated, with consideration of the effects of elemental additions such as zinc, manganese, and chromium and the influence of the addition of SiC particulate. Fracture resistance values between 13.6 and 25.6 MPa (m)1/2 were obtained for the monolithic alloys in the T6 and T7 conditions, respectively. The alloys with SiC particulate compared well and achieved fracture resistance values between 18.7 and 25.6 MPa (m)1/2. The spray-formed materials exhibited a loss in fracture resistance ( K I) compared to ingot metallurgy 7075 alloys but had an improved performance compared to high-solute powder metallurgy alloys of similar composition. Characterization of the fracture surfaces indicated a predominantly intergranular decohesion, possibly facilitated by the presence of incoherent particles at the grain boundary regions and by the large strength differential between the matrix and precipitate zone. It is believed that at the slip band-grain boundary intersection, particularly in the presence of large dispersoids and/or inclusions, microvoid nucleation would be significantly enhanced. Differences in fracture surfaces between the alloys in the T6 and T7 condition were observed and are attributed to inhomogeneous slip distribution, which results in strain localization at grain boundaries. The best overall combination of fracture resistance properties were obtained for alloys with minimum amounts of chromium and manganese additions.

  6. Influence of composition and heat treatment on damping and magnetostrictive properties of Fe-18%(Ga+Al) alloys

    SciTech Connect

    Golovin, I S; Palacheva, V V; Zadorozhnyy, V Yu; Zhu, J; Jiang, H; Cifre, J; Lograsso, Thomas A

    2014-10-01

    The structure, magnetostriction and damping properties of Fe82Ga(18?x)Alx(x = 0, 5, 8, 12) alloys were analyzed. The anelastic response of Fe–18(Ga + Al) alloys was studied as a function of temperature (from 0 to 600 ?C), frequency (from 0.01 to 200 Hz) and amplitude (from 0.0004% to 0.2%) of forced vibrations. The origin of the relatively high damping capacity of Fe–Ga–Al alloy at room temperature was determined by applying a magnetic field and different heat treatment regimes. The substitution of Ga by Al in Fe–18% Ga alloys was found to decrease magnetostriction and damping. The heat treatment of alloys influences the damping capacity of alloys more than variations of their chemical compositions. Thermally activated frequency and temperature-dependent anelastic effects in Fe– Ga–Al alloys were analyzed and the corresponding activation parameters for relaxation processes were evaluated. Internal friction effects caused by structural transformations were recorded and were found to be consistent with the A2 ! D03! L12reaction. The physical mechanisms for all anelastic effects are discussed

  7. Technical Seminar "Shape Memory Alloys"

    NASA Video Gallery

    Shape memory alloys are a unique group of materials that remember their original shape and return to that shape after being strained. How could the aerospace, automotive, and energy exploration ind...

  8. Assessment of the compositional influences on the toughness of TiCr{sub 2}-base Laves phase alloys

    SciTech Connect

    Chen, K.C.; Allen, S.M.; Livingston, J.D.

    1997-12-31

    Systematic studies of alloys based on TiCr{sub 2} have been performed in order to improve the toughness of Laves phase intermetallics. The extent to which alloy compositions and annealing treatments influence the toughness was quantified by Vickers indentation. The single-phase Laves behavior was first established by studying stoichiometric and nonstoichiometric TiCr{sub 2}. Next, alloying effects were investigated with ternary Laves phases based on TiCr{sub 2}. Different microstructures of two-phase alloys consisting of (Ti,Cr)-bcc + TiCr{sub 2} were also examined. Various toughening theories based on vacancies, site-substitutions, crystal structure (C14, C36, or C15) stabilization, and the presence of a second phase were evaluated. The most effective factors improving the toughness of TiCr{sub 2} were determined, and toughening mechanisms are suggested.

  9. Rheological Behavior and Microstructure of Ceramic Particulate/Aluminum Alloy Composites. Ph.D. Thesis Final Technical Report

    NASA Technical Reports Server (NTRS)

    Moon, Hee-Kyung

    1990-01-01

    The rheological behavior and microstructure were investigated using a concentric cylinder viscometer for three different slurries: semi-solid alloy slurries of a matrix alloy, Al-6.5wt percent Si: composite slurries, SiC (sub p) (8.5 microns)/Al-6.5wt percent Si, with the same matrix alloy in the molten state, and composite slurries of the same composition with the matrix alloy in the semi-solid state. The pseudoplasticity of these slurries was obtained by step changes of the shear rate from a given initial shear rate. To study the thixotropic behavior of the system, a slurry was allowed to rest for different periods of time, prior to shearing at a given initial shear rate. In the continuous cooling experiments, the viscosities of these slurries were dependent on the shear rate, cooling rate, volume fraction of the primary solid of the matrix alloy, and volume fraction of silicon carbide. In the isothermal experiments, all three kinds of slurries exhibited non-Newtonian behavior, depending on the volume fraction of solid particles.

  10. Effect of current density and bath composition on crystalline structure and magnetic properties of electrodeposited FeCoW alloy

    NASA Astrophysics Data System (ADS)

    Ghaferi, Z.; Sharafi, S.; Bahrololoom, M. E.

    2015-11-01

    In this research, FeCoW alloy coatings were prepared by galvanostatic method. The influence of current density and bath composition on microstructure and magnetic properties of electrodeposited FeCoW alloys were also studied. All coatings showed (2 2 0) preferred orientation with a two phase structure at higher current densities. Grain size of the coatings deposited from 0.01 and 0.03 M tungsten content electrolytes was in the range of 29-126 and 10-42 nm, respectively. Microhardness of the coatings deposited from the former electrolyte changed by chemical composition of the alloys, while this parameter changed by grain-size reduction for the coatings deposited from the latter one. The coercivity was controlled by grain-size reduction and surface morphology. It could be stated that the high-tungsten content electrolyte produced coatings with superior magnetic behaviour and microhardness compared with the electrolyte with low -tungsten content.

  11. Optimization of Weld Conditions and Alloy Composition for Welding of Single-Crystal Nickel-Based Superalloys

    SciTech Connect

    Vitek, John Michael; David, Stan A; Babu, Sudarsanam S

    2007-01-01

    Calculations were carried out to identify optimum welding conditions and weld alloy compositions to avoid stray grain formation during welding of single-crystal nickel-based superalloys. The calculations were performed using a combination of three models: a thermal model to describe the weld pool shape and the local thermal gradient and solidification front velocity; a geometric model to identify the local active dendrite growth variant, and a nucleation and growth model to describe the extent of stray grain formation ahead of the advancing solidification front. Optimum welding conditions (low weld power, high weld speed) were identified from the model calculations. Additional calculations were made to determine potential alloy modifications that reduce the solidification temperature range while maintaining high gamma prime content. The combination of optimum weld conditions and alloy compositions should allow for weld repair of single-crystal nickel-based superalloys without sacrificing properties or performance.

  12. The isothermal fatigue behavior of a unidirectional SiC/Ti composite and the Ti alloy matrix

    NASA Technical Reports Server (NTRS)

    Gayda, John, Jr.; Gabb, Timothy P.; Freed, Alan D.

    1989-01-01

    The high temperature fatigue behavior of a metal matrix composite (MMC) consisting of Ti-15V-3Cr-3Al-3Sn (Ti-15-3) matrix reinforced by 33 vol percent of continuous unidirectional SiC fibers was experimentally and analytically evaluated. Isothermal MMC fatigue tests with constant amplitude loading parallel to the fiber direction were performed at 300 and 550 C. Comparative fatigue tests of the Ti-15-3 matrix alloy were also conducted. Composite fatigue behavior and the in-situ stress state of the fiber and matrix were analyzed with a micromechanical model, the Concentric Cylinder Model (CCM). The cyclic stress-strain response of the composite was stable at 300 C. However, an increase in cyclic mean strain foreshortened MMC fatigue life at high strain ranges at 550 C. Fatigue tests of the matrix alloy and CCM analyses indicated this response was associated with stress relaxation of the matrix in the composite.

  13. Development of an oxidation resistant glass-ceramic composite coating on Ti-47Al-2Cr-2Nb alloy

    NASA Astrophysics Data System (ADS)

    Li, Wenbo; Zhu, Shenglong; Chen, Minghui; Wang, Cheng; Wang, Fuhui

    2014-02-01

    Three glass-ceramic composite coatings were prepared on Ti-47Al-2Cr-2Nb alloy by air spraying technique and subsequent firing. The aim of this work is to study the reactions between glass matrix and inclusions and their effects on the oxidation resistance of the glass-ceramic composite coating. The powders of alumina, quartz, or both were added into the aqueous solution of potassium silicate (ASPS) to form slurries used as the starting materials for the composite coatings. The coating formed from an ASPS-alumina slurry was porous, because the reaction between alumina and potassium silicate glass resulted in the formation of leucite (KAlSi2O6), consuming substantive glass phase and hindering the densification of the composite coating. Cracks were observed in the coating prepared from an ASPS-quartz slurry due to the larger volume shrinkage of the coating than that of the alloy. In contrast, an intact and dense SiO2-Al2O3-glass coating was successfully prepared from an ASPS-alumina-silica slurry. The oxidation behavior of the SiO2-Al2O3-glass composite coating on Ti-47Al-2Cr-2Nb alloy was studied at 900 °C. The SiO2-Al2O3-glass composite coating acted as an oxygen diffusion barrier, and prevented the inward diffusion of the oxygen from the air to the coating/alloy interface, therefore, decreasing the oxidation rate of the Ti-47Al-2Cr-2Nb alloy significantly.

  14. Effect of milling time and CNT concentration on hardness of CNT/Al{sub 2024} composites produced by mechanical alloying

    SciTech Connect

    Perez-Bustamante, R.; Perez-Bustamante, F.; Estrada-Guel, I.; Licea-Jimenez, L.; Miki-Yoshida, M.; Martinez-Sanchez, R.

    2013-01-15

    Carbon nanotube/2024 aluminum alloy (CNT/Al{sub 2024}) composites were fabricated with a combination of mechanical alloying (MA) and powder metallurgy routes. Composites were microstructurally and mechanically evaluated at sintering condition. A homogeneous dispersion of CNTs in the Al matrix was observed by a field emission scanning electron microscopy. High-resolution transmission electron microscopy confirmed not only the presence of well dispersed CNTs but also needle-like shape aluminum carbide (Al{sub 4}C{sub 3}) crystals in the Al matrix. The formation of Al{sub 4}C{sub 3} was suggested as the interaction between the outer shells of CNTs and the Al matrix during MA process in which crystallization took place after the sintering process. The mechanical behavior of composites was evaluated by Vickers microhardness measurements indicating a significant improvement in hardness as function of the CNT content. This improvement was associated to a homogeneous dispersion of CNTs and the presence of Al{sub 4}C{sub 3} in the aluminum alloy matrix. - Highlights: Black-Right-Pointing-Pointer The 2024 aluminum alloy was reinforced by CNTs by mechanical alloying process. Black-Right-Pointing-Pointer Composites were microstructural and mechanically evaluated after sintering condition. Black-Right-Pointing-Pointer The greater the CNT concentration, the greater the hardness of the composites. Black-Right-Pointing-Pointer Higher hardness in composites is achieved at 20 h of milling. Black-Right-Pointing-Pointer The formation of Al{sub 4}C{sub 3} does not present a direct relationship with the milling time.

  15. The Role of Alloy Composition and T7 Heat Treatment in Enhancing Thermal Conductivity of Aluminum High Pressure Diecastings

    NASA Astrophysics Data System (ADS)

    Lumley, Roger N.; Deeva, Natalia; Larsen, Robert; Gembarovic, Jozef; Freeman, Joe

    2013-02-01

    The thermal conductivity of some common and experimental high pressure diecasting (HPDC) Al-Si-Cu alloys is evaluated. It is shown that the thermal conductivity of some compositions may be increased by more than 60 pct by utilizing T7 heat treatments. This may have substantial performance and cost benefits for applications where thermal management is a key design parameter.

  16. AN INVESTIGATION OF THE IMPACT OF ALLOY COMPOSITION AND PH ON THE CORROSION OF BRASS IN DRINKING WATER

    EPA Science Inventory

    A better understanding of brass corrosion may provide information and guidance on the use of the safest materials for the production of plumbing fixtures, and optimization of corrosion control treatments. The effect of alloy composition and pH on the metal leached from six differ...

  17. Determination of surface oxide compositions on Alloy 600 using Rutherford backscattering

    SciTech Connect

    Hanson, A.L.; Isaacs, H.S.; Kraner, H.W.

    1984-01-01

    The surface composition of oxides formed on Alloy 600 under conditions similar to those in the primary side of PWR heat exchangers has been studied as a function of potential using Rutherford backscattering and proton inelastic scattering. Electropolished samples of Alloy 600 were exposed at several potentials to a solution of 0.18M H/sub 3/BO/sub 3/(2000 ppM B) with 0.28M LiOH (1.4 ppM Li) at 300/sup 0/C for 450 hours. The potentials relative to an internal hydrogen electrode ranged from -.09 to 750 mV. RBS analysis showed little or no oxide formation on samples exposed at 0 mV. Above 0 mV oxide layers formed whose thicknesses increased with potential. In addition the RBS showed a significantly enhanced concentration of aluminum and silicon in oxide. Both the oxygen and the sum of the aluminum and silicon content appeared to maintain a fixed surface concentration independent of the oxide thickness. Boron and lithium concentration were analyzed with proton inelastic scattering. No lithium was found in any sample. The boron concentration was found to follow the thickness of the oxide.

  18. Surface composite nanostructures of AZ91 magnesium alloy induced by high current pulsed electron beam treatment

    NASA Astrophysics Data System (ADS)

    Li, M. C.; Hao, S. Z.; Wen, H.; Huang, R. F.

    2014-06-01

    High current pulsed electron beam (HCPEB) treatment was conducted on an AZ91 cast magnesium alloy with accelerating voltage 27 kV, energy density 3 J/cm2 and pulse duration 2.5 μs. The surface microstructure was characterized by optical microscope (OM), X-ray diffraction (XRD), scanning electron microscope (SEM) equipped with energy dispersive spectrometer (EDS), and transmission electron microscope (TEM). The surface corrosion property was tested with electrochemical method in 3.5 wt.% NaCl solution. It is found that after 1 pulse of HCPEB treatment, the initial eutectic α phase and Mg17Al12 particles started to dissolve in the surface modified layer of depth ˜15 μm. When using 15 HCPEB pulses, the Al content in surface layer increased noticeably, and the phase structure was modified as composite nanostructures consisted of nano-grained Mg3.1Al0.9 domains surrounded by network of Mg17Al12 phase. The HCPEB treated samples showed an improved corrosion resistance with cathodic current density decreased by two orders of magnitude as compared to the initial AZ91 alloy.

  19. Analysis of interfacial debonding in shape memory alloy wire-reinforced composites

    NASA Astrophysics Data System (ADS)

    Miramini, A.; Kadkhodaei, M.; Alipour, A.; Mashayekhi, M.

    2016-01-01

    One of the common types of failure in shape memory alloy (SMA) wire-reinforced composites is interfacial debonding between the fiber and the matrix. In this paper, a three dimensional finite element model for an SMA wire-reinforced composite is developed based on cohesive zone modeling to predict interfacial debonding between the SMA wire and the surrounding matrix. The interfacial debonding is also experimentally investigated by conducting a number of pull-out tests on steel as well as Nitinol wires embedded in an epoxy matrix. To evaluate the presented method, the developed finite element analysis is employed to simulate a single wire pull-out test for ordinary (e.g. steel) wires. In order to simulate SMA wire pull-out, a 3D SMA constitutive model is implemented into the commercial finite element software ABAQUS using a user material subroutine (UMAT). An acceptable agreement is shown to exist between the theoretical results and the experimental data, indicating the efficiency of the proposed approach to model interfacial debonding in SMA wire-reinforced composites.

  20. Investigation of compositional segregation during unidirectional solidification of solid solution semiconducting alloys

    NASA Technical Reports Server (NTRS)

    Wang, J. C.

    1982-01-01

    Compositional segregation of solid solution semiconducting alloys in the radial direction during unidirectional solidification was investigated by calculating the effect of a curved solid liquid interface on solute concentration at the interface on the solid. The formulation is similar to that given by Coriell, Boisvert, Rehm, and Sekerka except that a more realistic cylindrical coordinate system which is moving with the interface is used. Analytical results were obtained for very small and very large values of beta with beta = VR/D, where V is the velocity of solidification, R the radius of the specimen, and D the diffusivity of solute in the liquid. For both very small and very large beta, the solute concentration at the interface in the solid C(si) approaches C(o) (original solute concentration) i.e., the deviation is minimal. The maximum deviation of C(si) from C(o) occurs for some intermediate value of beta.

  1. Role of Laser Cladding Parameters in Composite Coating (Al-SiC) on Aluminum Alloy

    NASA Astrophysics Data System (ADS)

    Riquelme, Ainhoa; Escalera-Rodriguez, María Dolores; Rodrigo, Pilar; Rams, Joaquin

    2016-08-01

    The effect of the different control parameters on the laser cladding fabrication of Al/SiCp composite coatings on AA6082 aluminum alloy was analyzed. A high-power diode laser was used, and the laser control parameters were optimized to maximize the size (height and width) of the coating and the substrate-coating interface quality, as well as to minimize the melted zone depth. The Taguchi DOE method was applied using a L18 to reduce the number of experiments from 81 to only 18 experiments. Main effects, signal-noise ratio and analysis of variance were used to evaluate the effect of these parameters in the characteristics of the coating and to determine their optimum values. The influence of four control parameters was evaluated: (1) laser power, (2) scanning speed, (3) focal condition, and (4) powder feed ratio. Confirmation test with the optimal control parameters was carried out to evaluate the Taguchi method's effectivity.

  2. Optimal control of AlAs oxidation via digital alloy heterostructure compositions

    NASA Astrophysics Data System (ADS)

    Suárez, I.; Almuneau, G.; Condé, M.; Arnoult, A.; Fontaine, C.

    2009-09-01

    A thorough study of wet thermal oxidation in AlAs/AlxGa1-xAs superlattices is presented. The results shown here demonstrate that the final oxidation depth can be finely tuned via the composition and thickness of AlxGa1-xAs into the digital alloy. A complete model of oxidation in these structures is proposed, relying on diffusion through the AlAs layer, its oxidation and an additional effect due to the AlxGa1-xAs intermediate barriers. This barrier contribution is shown to further improve the control of the oxidation rate, and thereby fabrication of sophisticated AlOx/GaAs integrated optoelectronic devices.

  3. Structural Acoustic Response of a Shape Memory Alloy Hybrid Composite Panel (Lessons Learned)

    NASA Technical Reports Server (NTRS)

    Turner, Travis L.

    2002-01-01

    This study presents results from an effort to fabricate a shape memory alloy hybrid composite (SMAHC) panel specimen and test the structure for dynamic response and noise transmission characteristics under the action of thermal and random acoustic loads. A method for fabricating a SMAHC laminate with bi-directional SMA reinforcement is described. Glass-epoxy unidirectional prepreg tape and Nitinol ribbon comprise the material system. Thermal activation of the Nitinol actuators was achieved through resistive heating. The experimental hardware required for mechanical support of the panel/actuators and for establishing convenient electrical connectivity to the actuators is presented. Other experimental apparatus necessary for controlling the panel temperature and acquiring structural acoustic data are also described. Deficiency in the thermal control system was discovered in the process of performing the elevated temperature tests. Discussion of the experimental results focuses on determining the causes for the deficiency and establishing means for rectifying the problem.

  4. Metal alloy identifier

    DOEpatents

    Riley, William D.; Brown, Jr., Robert D.

    1987-01-01

    To identify the composition of a metal alloy, sparks generated from the alloy are optically observed and spectrographically analyzed. The spectrographic data, in the form of a full-spectrum plot of intensity versus wavelength, provide the "signature" of the metal alloy. This signature can be compared with similar plots for alloys of known composition to establish the unknown composition by a positive match with a known alloy. An alternative method is to form intensity ratios for pairs of predetermined wavelengths within the observed spectrum and to then compare the values of such ratios with similar values for known alloy compositions, thereby to positively identify the unknown alloy composition.

  5. Deformation behavior and microstructural evolution of nanocrystalline aluminum alloys and composites

    NASA Astrophysics Data System (ADS)

    Ahn, Byungmin

    routes. Strain rate sensitivity in room temperature deformation was examined as a function of grain size using nanoindentation. Negative strain rate sensitivity was observed in nanocrystalline and ultrafine-grained materials, while a conventional alloy was strain rate insensitive. For multi-scale materials, local displacements in bimodal materials during tensile deformation were measured by digital image correlation. Inhomogeneous strain behavior was observed between nanocrystalline and coarse-grained regions and attributed to differences in dislocation plasticity. In the Al matrix nanocomposite with hybrid microstructures, microstructural evolution of the composite powder with boron-carbide reinforcements was investigated as a function of milling time.

  6. Shape and Composition Effects on Photocatalytic Hydrogen Production for Pt-Pd Alloy Cocatalysts.

    PubMed

    Luo, Muhua; Lu, Pan; Yao, Weifeng; Huang, Cunping; Xu, Qunjie; Wu, Qiang; Kuwahara, Yasutaka; Yamashita, Hiromi

    2016-08-17

    The shape and composition effects of platinum-palladium (Pt-Pd) alloy nanoparticle cocatalysts on visible-light photocatalytic hydrogen evolution from an aqueous ammonium sulphite solution have been reported and discussed. The activity of Pt-Pd nanoparticles loaded Pt-Pd/CdS photocatalysts are affected based on both the Pt-Pd alloy nanoparticles' shape and their compositions. In this research, two shapes of Pt-Pd nanoparticles have been studied. One is Pt-Pd nanocubes enclosed by {100} crystal planes and the other is nano-octahedra covered with {111} crystal facets. Results show that the photocatalytic turnover frequency (TOF), defined as moles of hydrogen produced per surface mole of Pt-Pd metal atom per second, for Pt-Pd nanocubes/CdS (Pt-Pd NCs/CdS) photocatalyst can be 3.4 times more effective than Pt-Pd nano-octahedra/CdS (Pt-Pd NOTa/CdS) nanocomposite photocatalyst. Along with the shape effect, the atomic ratio of Pt to Pd can also impact the efficiency of Pt-Pd/CdS photocatalysts. When the Pt to Pd atomic ratio changes from 1:0 to about 2:1, the rate of hydrogen production increases from 900 μmol/h for Pt NCs/CdS catalyst to 1837 μmol/h for Pt-Pd (2:1) NCs/CdS photocatalyst-a 104% rate increase. This result suggests that the 33 mol % of more expensive Pt can be replaced with less costly Pd, resulting in a more than 100% hydrogen production rate increase. The finding of this research will lead to the research and development of highly effective catalysts for photocatalytic hydrogen production using solar photonic energy. PMID:27439590

  7. Adhesives for Aerospace

    NASA Technical Reports Server (NTRS)

    Meade, L. E.

    1985-01-01

    The industry is hereby challenged to integrate adhesive technology with the total structure requirements in light of today's drive into automation/mechanization. The state of the art of adhesive technology is fairly well meeting the needs of the structural designers, the processing engineer, and the inspector, each on an individual basis. The total integration of these needs into the factory of the future is the next collective hurdle to be achieved. Improved processing parameters to fit the needs of automation/mechanization will necessitate some changes in the adhesive forms, formulations, and chemistries. Adhesives have, for the most part, kept up with the needs of the aerospace industry, normally leading the rest of the industry in developments. The wants of the aerospace industry still present a challenge to encompass all elements, achieving a totally integrated joined and sealed structural system. Better toughness with hot-wet strength improvements is desired. Lower cure temperatures, longer out times, and improved corrosion inhibition are desired.

  8. Applications of aerospace technology

    NASA Technical Reports Server (NTRS)

    Rouse, Doris J.

    1984-01-01

    The objective of the Research Triangle Institute Technology Transfer Team is to assist NASA in achieving widespread utilization of aerospace technology in terrestrial applications. Widespread utilization implies that the application of NASA technology is to benefit a significant sector of the economy and population of the Nation. This objective is best attained by stimulating the introduction of new or improved commercially available devices incorporating aerospace technology. A methodology is presented for the team's activities as an active transfer agent linking NASA Field Centers, industry associations, user groups, and the medical community. This methodology is designed to: (1) identify priority technology requirements in industry and medicine, (2) identify applicable NASA technology that represents an opportunity for a successful solution and commercial product, (3) obtain the early participation of industry in the transfer process, and (4) successfully develop a new product based on NASA technology.

  9. Evaluation on the Effect of Composition on Radiation Hardening and Embrittlement in Model FeCrAl Alloys

    SciTech Connect

    Field, Kevin G.; Briggs, Samuel A.; Edmondson, Philip; Hu, Xunxiang; Littrell, Kenneth C.; Howard, Richard; Parish, Chad M.; Yamamoto, Yukinori

    2015-09-18

    This report details the findings of post-radiation mechanical testing and microstructural characterization performed on a series of model and commercial FeCrAl alloys to assist with the development of a cladding technology with enhanced accident tolerance. The samples investigated include model alloys with simple ferritic grain structure and two commercial alloys with minor solute additions. These samples were irradiated in the High Flux Isotope Reactor (HFIR) at Oak Ridge National Laboratory (ORNL) up to nominal doses of 7.0 dpa near or at Light Water Reactor (LWR) relevant temperatures (300-400 C). Characterization included a suite of techniques including small angle neutron scattering (SANS), atom probe tomography (APT), and transmission based electron microscopy techniques. Mechanical testing included tensile tests at room temperature on sub-sized tensile specimens. The goal of this work was to conduct detailed characterization and mechanical testing to begin establishing empirical and/or theoretical structure-property relationships for radiation-induced hardening and embrittlement in the FeCrAl alloy class. Development of such relationships will provide insight on the performance of FeCrAl alloys in an irradiation environment and will enable further development of the alloy class for applications within a LWR environment. A particular focus was made on establishing trends, including composition and radiation dose. The report highlights in detail the pertinent findings based on this work. This report shows that radiation hardening in the alloys is primarily composition dependent due to the phase separation in the high-Cr FeCrAl alloys. Other radiation induced/enhanced microstructural features were less dependent on composition and when observed at low number densities, were not a significant contributor to the observed mechanical responses. Pre-existing microstructure in the alloys was found to be important, with grain boundaries and pre-existing dislocation

  10. Surface composition analysis of failed cementless CoCr- and Ti-base-alloy total hip implants.

    PubMed

    Decking, R; Reuter, P; Hüttner, M; Puhl, W; Claes, L E; Scharf, H P

    2003-02-15

    The surfaces of retrieved failed cementless total hip implants made of cobalt-chromium-molybdenum casting alloy and of wrought titanium 6-aluminum 4-vanadium alloy were studied with the use of scanning-electron microscopy (SEM), energy-dispersive X-ray analysis (EDX) and X-ray photoelectron spectroscopy (XPS). New implants of the same make served as controls. The XPS scans revealed a dense carbon layer on the entire analyzed specimen. The relative composition of the titanium alloy implants showed an overall agreement with the international standards for implants for surgery, and the overall surface composition did not change over the period of the implantation. However, an inhomogeneous distribution of the constituents could be demonstrated in the retrieved as well as in the new MEC-screw rings made of TiAl6V4 alloy, an implant that has been linked to a high early failure rate. In the CoCr-alloy components (Lord-screw rings) a high percentage of aluminum, mainly organized in aluminum inclusions, was found in the retrieved as well as in the new implants. PMID:12516084

  11. Comparative study between laser sintering and casting for retention of resin composite veneers to cobalt-chromium alloy.

    PubMed

    Muratomi, Ryuta; Kamada, Kohji; Taira, Yohsuke; Higuchi, Shizuo; Watanabe, Ikuya; Sawase, Takashi

    2013-01-01

    The purpose of this study was to evaluate and compare the bond strengths between resin composite veneer and laser-sintered cobalt-chromium (Co-Cr) alloy with and without retention devices (Laser-R and Laser-N respectively). Cast Co-Cr alloy with and without retention devices (Cast-R and Cast-N respectively) were also prepared for fabrication technique comparison. Disk-shaped Co-Cr alloy specimens were air-abraded with alumina and veneered with a veneering system, Estenia C&B (ES) or Ceramage (CE). After 20,000 thermocycles, tensile testing was performed. Data were analyzed by ANOVA and multiple comparison test. When no retention devices were present, no significant differences were observed between Laser-N/ES and Cast-N/ES, or between Laser- N/CE and Cast-N/CE, but ES exhibited significantly higher bond strength than CE. With retention devices, Laser-R/ES, Cast- R/ES and Laser-R/CE showed no significant differences, and their retention strengths were significantly higher than that of Cast- R/CE. Compared to cast Co-Cr alloy, laser-sintered Co-Cr alloy with retention devices provided better retention durability for resin composite-veneered prostheses. PMID:24240892

  12. Wiring for aerospace applications

    NASA Technical Reports Server (NTRS)

    Christian, J. L., Jr.; Dickman, J. E.; Bercaw, R. W.; Myers, I. T.; Hammoud, A. N.; Stavnes, M.; Evans, J.

    1992-01-01

    In this paper, the authors summarize the current state of knowledge of arc propagation in aerospace power wiring and efforts by the National Aeronautics and Space Administration (NASA) towards the understanding of the arc tracking phenomena in space environments. Recommendations will be made for additional testing. A database of the performance of commonly used insulating materials will be developed to support the design of advanced high power missions, such as Space Station Freedom and Lunar/Mars Exploration.

  13. AI aerospace components

    SciTech Connect

    Heindel, T.A.; Murphy, T.B.; Rasmussen, A.N.; Mcfarland, R.Z.; Montgomery, R.E.; Pohle, G.E.; Heard, A.E.; Atkinson, D.J.; Wedlake, W.E.; Anderson, J.M. Mitre Corp., Houston, TX Unisys Corp., Houston, TX Rockwell International Corp., El Segundo, CA NASA, Kennedy Space Center, Cocoa Beach, FL JPL, Pasadena, CA Lockheed Missiles and Space Co., Inc., Austin, TX McDonnell Douglas Electronic Systems Co., McLean, VA )

    1991-10-01

    An evaluation is made of the application of novel, AI-capabilities-related technologies to aerospace systems. Attention is given to expert-system shells for Space Shuttle Orbiter mission control, manpower and processing cost reductions at the NASA Kennedy Space Center's 'firing rooms' for liftoff monitoring, the automation of planetary exploration systems such as semiautonomous mobile robots, and AI for battlefield staff-related functions.

  14. Aerospace safety advisory panel

    NASA Technical Reports Server (NTRS)

    1994-01-01

    This report from the Aerospace Safety Advisory Panel (ASAP) contains findings, recommendations, and supporting material concerning safety issues with the space station program, the space shuttle program, aeronautics research, and other NASA programs. Section two presents findings and recommendations, section three presents supporting information, and appendices contain data about the panel membership, the NASA response to the March 1993 ASAP report, and a chronology of the panel's activities during the past year.

  15. Unmanned Aerospace Vehicle Workshop

    SciTech Connect

    Vitko, J. Jr.

    1995-04-01

    The Unmanned Aerospace Vehicle (UAV) Workshop concentrated on reviewing and refining the science experiments planned for the UAV Demonstration Flights (UDF) scheduled at the Oklahoma Cloud and Radiation Testbed (CART) in April 1994. These experiments were focused around the following sets of parameters: Clear sky, daylight; Clear-sky, night-to-day transition; Clear sky - improve/validate the accuracy of radiative fluxes derived from satellite-based measurements; Daylight, clouds of opportunity; and, Daylight, broken clouds.

  16. Influence of composition and heat treatment on damping and magnetostrictive properties of Fe–18%(Ga + Al) alloys

    DOE PAGESBeta

    Golovin, I. S.; Palacheva, V. V.; Zadorozhnyy, V. Yu.; Zhu, J.; Jiang, H.; Cifre, J.; Lograsso, T. A.

    2014-07-16

    The structure, magnetostriction and damping properties of Fe82Ga(18–x)Alx (x = 0, 5, 8, 12) alloys were analyzed. The anelastic response of Fe–18(Ga + Al) alloys was studied as a function of temperature (from 0 to 600 °C), frequency (from 0.01 to 200 Hz) and amplitude (from 0.0004% to 0.2%) of forced vibrations. The origin of the relatively high damping capacity of Fe–Ga–Al alloy at room temperature was determined by applying a magnetic field and different heat treatment regimes. The substitution of Ga by Al in Fe–18% Ga alloys was found to decrease magnetostriction and damping. The heat treatment of alloysmore » influences the damping capacity of alloys more than variations of their chemical compositions. Thermally activated frequency and temperature-dependent anelastic effects in Fe–Ga–Al alloys were analyzed and the corresponding activation parameters for relaxation processes were evaluated. Internal friction effects caused by structural transformations were recorded and were found to be consistent with the A2 → D03 → L12 reaction. Thus, the physical mechanisms for all anelastic effects are discussed.« less

  17. Growth and characterization of ZnO1-xSx highly mismatched alloys over the entire composition

    NASA Astrophysics Data System (ADS)

    Jaquez, M.; Yu, K. M.; Ting, M.; Hettick, M.; Sánchez-Royo, J. F.; Wełna, M.; Javey, A.; Dubon, O. D.; Walukiewicz, W.

    2015-12-01

    Alloys from ZnO and ZnS have been synthesized by radio-frequency magnetron sputtering over the entire alloying range. The ZnO1-xSx films are crystalline for all compositions. The optical absorption edge of these alloys decreases rapidly with small amount of added sulfur (x ˜ 0.02) and continues to red shift to a minimum of 2.6 eV at x = 0.45. At higher sulfur concentrations (x > 0.45), the absorption edge shows a continuous blue shift. The strong reduction in the band gap for O-rich alloys is the result of the upward shift of the valence-band edge with x as observed by x-ray photoelectron spectroscopy. As a result, the room temperature bandgap of ZnO1-xSx alloys can be tuned from 3.7 eV to 2.6 eV. The observed large bowing in the composition dependence of the energy bandgap arises from the anticrossing interactions between (1) the valence-band of ZnO and the localized sulfur level at 0.30 eV above the ZnO valence-band maximum for O-rich alloys and (2) the conduction-band of ZnS and the localized oxygen level at 0.20 eV below the ZnS conduction band minimum for the S-rich alloys. The ability to tune the bandgap and knowledge of the location of the valence and conduction-band can be advantageous in applications, such as heterojunction solar cells, where band alignment is crucial.

  18. Microstructures and mechanical properties of compositionally complex Co-free FeNiMnCr18 FCC solid solution alloy

    DOE PAGESBeta

    Wu, Z.; Bei, H.

    2015-07-01

    Recently, a structurally-simple but compositionally-complex FeNiCoMnCr high entropy alloy was found to have excellent mechanical properties (e.g., high strength and ductility). To understand the potential of using high entropy alloys as structural materials for advanced nuclear reactor and power plants, it is necessary to have a thorough understanding of their structural stability and mechanical properties degradation under neutron irradiation. Furthermore, this requires us to develop a similar model alloy without Co because material with Co will make post-neutron-irradiation testing difficult due to the production of the 60Co radioisotope. In order to achieve this goal, a FCC-structured single-phase alloy with amore » composition of FeNiMnCr18 was successfully developed. This near-equiatomic FeNiMnCr18 alloy has good malleability and its microstructure can be controlled by thermomechanical processing. By rolling and annealing, the as-cast elongated-grained-microstructure is replaced by homogeneous equiaxed grains. The mechanical properties (e.g., strength and ductility) of the FeNiMnCr18 alloy are comparable to those of the equiatomic FeNiCoMnCr high entropy alloy. Both strength and ductility increase with decreasing deformation temperature, with the largest difference occurring between 293 and 77 K. Extensive twin-bands which are bundles of numerous individual twins are observed when it is tensile-fractured at 77 K. No twin bands are detected by EBSD for materials deformed at 293 K and higher. Ultimately the unusual temperature-dependencies of UTS and uniform elongation could be caused by the development of the dense twin substructure, twin-dislocation interactions and the interactions between primary and secondary twinning systems which result in a microstructure refinement and hence cause enhanced strain hardening and postponed necking.« less

  19. Roles of Alloy Composition and Grain Refinement on Hot Tearing Susceptibility of 7××× Aluminum Alloys

    NASA Astrophysics Data System (ADS)

    Bai, Q. L.; Li, Y.; Li, H. X.; Du, Q.; Zhang, J. S.; Zhuang, L. Z.

    2016-06-01

    During the production of high-strength 7××× aluminum alloys, hot tearing has set up serious obstacles for attaining a sound billet/slab. In this research, some typical 7××× alloys were studied using constrained rod casting together with the measurement of thermal contraction and load development in the freezing range, aiming at investigating their hot tearing susceptibility. The results showed that the hot tearing susceptibility of an alloy depends not only on the thermal contraction in freezing range, which can decide the accumulated thermal strain during solidification, but also on the amount of nonequilibrium eutectics, which can effectively accommodate the thermally induced deformation. Our investigations reveal that Zn content has very profound effect on hot tearing susceptibility. The Zn/Mg ratio of the alloys also plays a remarkable role though it is not as pronounced as Zn content. The effect of Zn/Mg ratio is mainly associated with the amount of nonequilibrium eutectics. Grain refinement will considerably reduce the hot tearing susceptibility. However, excessive addition of grain refiner may promote hot tearing susceptibility of semi-solid alloy due to deteriorated permeability which is very likely to be caused by the heavy grain refinement and the formation of more intermetallic phases.

  20. Roles of Alloy Composition and Grain Refinement on Hot Tearing Susceptibility of 7××× Aluminum Alloys

    NASA Astrophysics Data System (ADS)

    Bai, Q. L.; Li, Y.; Li, H. X.; Du, Q.; Zhang, J. S.; Zhuang, L. Z.

    2016-08-01

    During the production of high-strength 7××× aluminum alloys, hot tearing has set up serious obstacles for attaining a sound billet/slab. In this research, some typical 7××× alloys were studied using constrained rod casting together with the measurement of thermal contraction and load development in the freezing range, aiming at investigating their hot tearing susceptibility. The results showed that the hot tearing susceptibility of an alloy depends not only on the thermal contraction in freezing range, which can decide the accumulated thermal strain during solidification, but also on the amount of nonequilibrium eutectics, which can effectively accommodate the thermally induced deformation. Our investigations reveal that Zn content has very profound effect on hot tearing susceptibility. The Zn/Mg ratio of the alloys also plays a remarkable role though it is not as pronounced as Zn content. The effect of Zn/Mg ratio is mainly associated with the amount of nonequilibrium eutectics. Grain refinement will considerably reduce the hot tearing susceptibility. However, excessive addition of grain refiner may promote hot tearing susceptibility of semi-solid alloy due to deteriorated permeability which is very likely to be caused by the heavy grain refinement and the formation of more intermetallic phases.