Sample records for zk60 magnesium alloy

  1. Superplasticity in a ZK60 magnesium alloy at low temperatures

    SciTech Connect

    Watanabe, Hiroyuki; Mukai, Toshiji [Osaka Municipal Technical Research Inst. (Japan)] [Osaka Municipal Technical Research Inst. (Japan); Higashi, Kenji [Osaka Prefecture Univ., Sakai (Japan)] [Osaka Prefecture Univ., Sakai (Japan)

    1999-01-22

    High tensile ductilities associated with superplasticity occur when the grain size is small and typically less than {approximately}10 {micro}m. The conventional superplasticity in pseudo single phase alloys is observed at relatively low strain rate of <10{sup {minus}3} s{sup {minus}1} and at temperatures of {approximately}0.8T{sub m} where T{sub m} is the melting point of the material. Recently, several method have been developed for extreme grain refinement including mechanical alloying, crystallization from amorphous powders, and/or equal-channel-angular-extrusion. Experimental evidence suggests that a reduction in grain size will increase the strain rate and/or decrease the temperature for optimum superplastic flow. The purpose of this paper is to investigate superplastic deformation mechanism at lower temperatures. In this study, mechanical properties in a pseudo single phase magnesium alloy were examined at relatively low homologous temperatures of {approximately}0.5T{sub m}. Based on the constitutive equation for superplastic flow, deformation mechanism at low temperatures is discussed.

  2. Microstructure characterization of ZK60 magnesium alloys using TEM and HR-EBSD.

    PubMed

    Cho, Jae-Hyung; Kim, Soo-Hyun; Han, Sang-Ho; Kang, Suk-Bong

    2013-08-01

    ZK60 (Mg-Zn-Zr) alloys exhibited a variation in precipitates with aging, and their mechanical properties also changed. Microindentation tests were carried out on two types of ZK60 alloys of solid solution (T4) and peak aging (T6). Microstructure and texture evolution during indentation was investigated using electron backscatter diffraction. Twinning occurred near the indentation marks in most grains. It was found that tensile twinning was dominant, and two twin variants were usually observed. Texture and microstructure evolution by twinning and slip activation was further examined by uniaxial compression test with strain. The initial random orientation gradually changed into basal fibers with strain. Some grains with nonbasal orientations aligned with the loading direction easily underwent twinning followed by slip deformation. Other grains near basal orientations revealed only slip deformation. PMID:23920164

  3. Microstructure, in vitro corrosion and cytotoxicity of Ca-P coatings on ZK60 magnesium alloy prepared by simple chemical conversion and heat treatment.

    PubMed

    Li, Kaikai; Wang, Bing; Yan, Biao; Lu, Wei

    2013-09-01

    Magnesium alloys are potential biodegradable materials for biomedical application. But their poor corrosion resistance may result in premature failure of implants. In this study, to solve this problem, Ca-P coatings were prepared on ZK60 magnesium alloy by a simple chemical conversion process and heat treatment. Surface characterization showed that a flake-like Dicalcium phosphate dihydrate (DCPD) (CaHPO?·2H?O) coating was formed on ZK60 alloy by the chemical conversion process. DCPD transformed into Dicalcium phosphate anhydrous (DCPa) (CaHPO?) and Ca?P?O? after heat treatment. Results of potentiodynamic polarization showed the corrosion potential of ZK60 was increased from -1666?mV to -1566?mV with DCPD coating, while -1515?mV was obtained after heat treatment. The corrosion current density of ZK60 was measured to be reduced from 35?µA/cm² to 3.5?µA/cm² with DCPD coating, while a further reduction to 1?µA/cm² was observed after heat treatment. This indicated that the coatings improved the substrate corrosion resistance significantly, and apparently, the heat-treated coating had a higher corrosion resistance. Immersion test demonstrated that both the coatings could provide protection for the substrate and the heat-treated coating could induce deposition of bone-like apatite. Cytotoxicity evaluation revealed that none of the samples induced toxicity to L-929 cells after 1- and 3-day culture. The cytocompatibility of ZK60 was improved by the coatings, with the following sequence: uncoated ZK60?ZK60?

  4. The in vitro degradation process and biocompatibility of a ZK60 magnesium alloy with a forsterite-containing micro-arc oxidation coating.

    PubMed

    Lin, Xiao; Tan, Lili; Zhang, Qiang; Yang, Ke; Hu, Zhuangqi; Qiu, Jianhong; Cai, Yong

    2013-11-01

    Magnesium has attracted much attention as a class of biodegradable metallic biomaterials. In this study, a silicate electrolyte-based micro-arc oxidation (MAO) treatment was adopted to prepare forsterite-containing MAO coatings on a ZK60 magnesium alloy in order to decrease the degradation rate and increase the biological property of the alloy. Four anodization voltages were chosen to prepare the MAO coatings. The cell experiment showed a cytotoxicity of grade 0 for the MAO-coated alloy to L929 cells and the hemolytic ratio was dramatically decreased for the MAO-coated alloy compared with the bare one. The corrosion resistance and the degradation behavior of the MAO-coated ZK60 alloy were studied using drop tests, electrochemical measurements and immersion tests. The results indicate that the MAO coating could effectively decrease the initial degradation rate of the alloy. The corrosion resistance of MAO coating was increased with the elevation of the preparation voltage. A degradation model for ZK60 alloy with a forsterite-containing MAO coating was proposed. Based on the model, the MAO-coated alloy experiences destruction and restoration simultaneously, and the coating fails in a peeling-off mode. PMID:23261923

  5. Microstructure, texture evolution, mechanical properties and corrosion behavior of ECAP processed ZK60 magnesium alloy for biodegradable applications.

    PubMed

    Mostaed, Ehsan; Hashempour, Mazdak; Fabrizi, Alberto; Dellasega, David; Bestetti, Massimiliano; Bonollo, Franco; Vedani, Maurizio

    2014-09-01

    Ultra-fine grained ZK60 Mg alloy was obtained by multi-pass equal-channel angular pressing at different temperatures of 250°C, 200°C and 150°C. Microstructural observations showed a significant grain refinement after ECAP, leading to an equiaxed and ultrafine grain (UFG) structure with average size of 600nm. The original extrusion fiber texture with planes oriented parallel to extrusion direction was gradually undermined during ECAP process and eventually it was substituted by a newly stronger texture component with considerably higher intensity, coinciding with ECAP shear plane. A combination of texture modification and grain refinement in UFG samples led to a marked reduction in mechanical asymmetric behavior compared to the as-received alloy, as well as adequate mechanical properties with about 100% improvement in elongation to failure while keeping relatively high tensile strength. Open circuit potential, potentiodynamic and weight loss measurements in a phosphate buffer solution electrolyte revealed an improved corrosion resistance of UFG alloy compared to the extruded one, stemming from a shift of corrosion regime from localized pitting in the as-received sample to a more uniform corrosion mode with reduced localized attack in ECAP processed alloy. Compression tests on immersed samples showed that the rate of loss of mechanical integrity in the UFG sample was lower than that in the as-received sample. PMID:24971801

  6. The n-MAO/EPD bio-ceramic composite coating fabricated on ZK60 magnesium alloy using combined micro-arc oxidation with electrophoretic deposition

    NASA Astrophysics Data System (ADS)

    Xiong, Ying; Lu, Chao; Wang, Chao; Song, Renguo

    2014-12-01

    A bio-ceramic composite coating was fabricated on ZK60 magnesium (Mg) alloy using combined micro-arc oxidation (MAO) with electrophoretic deposition (EPD) technique. The MAO coating as the basal layer was produced in alkaline electrolyte with (n-MAO coating) and without (MAO coating) the addition of CeO2 and ZrO2 nano-particles, respectively. A hydroxyapatite (HA) coating as the covering layer was deposited on the n-MAO coating to improve the biological properties of the coating (n-MAO/EPD composite coating). The morphology and phase composition of three treated coatings were investigated by scanning electron microscope (SEM) and X-ray diffraction (XRD). The corrosion resistance of these coatings was evaluated with potentiodynamic polarization tests and immersion tests in simulated body fluid (SBF) at 36.5 ± 0.5 °C. The XRD spectra showed that the CeO2 and ZrO2 peaks can be collected in the n-MAO coating, and HA particles exists in the n-MAO/EPD composite coating. The results of corrosion tests indicated that the n-MAO/EPD composite coating owned increased bioactivity and long-term protective ability compared with the MAO coating and the n-MAO coating. Thus Mg alloy coated with the n-MAO/EPD composite coating should be more suited as biodegradable bone implants.

  7. Twinning–detwinning behavior during the strain-controlled low-cycle fatigue testing of a wrought magnesium alloy, ZK60A

    Microsoft Academic Search

    L. Wu; A. Jain; D. W. Brown; G. M. Stoica; S. R. Agnew; B. Clausen; D. E. Fielden; P. K. Liaw

    2008-01-01

    The twinning and detwinning behavior in a strongly textured magnesium alloy was investigated using in situ neutron diffraction during the cyclic deformation along the prior extrusion direction at the fully reversed total constant strain amplitude of 1.2% at room temperature. The initial preferred orientation places the c-axis in most grains perpendicular to the loading axis, and this favors extensive {101¯2}?101¯1?

  8. Corrosion resistance enhancement of magnesium ZK60/SiC composite by Nd:YAG laser cladding

    SciTech Connect

    Yue, T.M.; Wang, A.H.; Man, H.C. [Hong Kong Polytechnic Univ., Kowloon (Hong Kong). Dept. of Mfg. Engineering] [Hong Kong Polytechnic Univ., Kowloon (Hong Kong). Dept. of Mfg. Engineering

    1999-01-08

    Magnesium-based metal matrix composites (MMCs) which possess high specific stiffness and strength are attractive in applications where it is advantageous to employ low density structural materials, such as in aerospace, automotive and sports industries. However, it is well known that magnesium is one of the most active structural metals, and is usually susceptible to galvanic corrosion when in contact with other materials, especially, in wet and salt-laden environments. The corrosion is enhanced when an additional phase is added to magnesium alloys because most of the magnesium/reinforcement systems are electrochemically unstable. Previous investigations have revealed that high power laser surface treatment is an efficient way to improve the corrosion resistance of magnesium alloys and their composite materials, without resulting in significant adverse effects on the properties of the bulk materials. In the present study, laser cladding of an Al-Si eutectic alloy on magnesium ZK60/SiC composite was performed using a multiwave Nd:YAG laser. In order to avoid excessive oxidation, argon shielding gas was blown directly into the laser-generated molten pool instead of using a vacuum condition.

  9. Deformation behavior and microstructure evolution of wrought magnesium alloys

    NASA Astrophysics Data System (ADS)

    Wang, Shouren; Song, Linghui; Kang, Sukbong; Cho, Jaehyung; Wang, Yingzi

    2013-05-01

    There are many researches on the deformation behavior of wrought magnesium alloys, such as AZ31, AZ80, AZ91, and ZK60 magnesium alloys at different temperatures and strain rates, but few of them focuses on the deformation behavior of AZ41M and ZK60M alloys, especially under the twin-roll casting (TRC) state. Meanwhile, the existing researches only focus on the grain refinement law of the magnesium alloys under deformation conditions, the deformation mechanism has not been revealed yet. The hot compression behavior of AZ41M and ZK60M magnesium alloys under the temperature and strain rate ranges of 250-400 °C and 0.001-1 s-1 are studied by thermal simulation methods using Gleeble 1500 machine and virtual simulation using finite element analysis software. Simulation results show that sine hyperbolic law is the most suitable flow stress model for wider deformation conditions. The most reasonable selected deformation conditions of ZK60M alloy is 350 °C/0.1 s-1 for TRC and 350 °C/1 s-1 for conventional casting (CC), while AZ41M alloy is 300 °C/0.01 s-1 for TRC and 350 °C/0.1 s-1 for CC. Deformation behavior and dynamic recrystallization (DRX) mechanism of them are analyzed at the same deformation conditions. The microstructures of AZ41M and ZK60M alloys are observed at different deformed conditions by optical microscopy (OM) and electron back scatter diffraction (EBSD) and it reveals the flow behavior and deformation mechanism of them. Working harden and work soften contribute to the activation of basal, non-basal slip systems which promote DRX. The proposed research reveals the deformation behavior and mechanism of the AZ41M and ZK 60M magnesium alloys and concludes their optimized deformation parameters and processes and provides a theory basis for their manufacturing and application.

  10. Magnesium and magnesium alloys

    SciTech Connect

    Avedesian, M.; Baker, H. [eds.

    1998-12-31

    This new handbook is the most comprehensive publication of engineering information on commercial magnesium alloys under one cover in the last sixty years. Prepared with the cooperation of the International Magnesium Association, it presents the industrial practices currently used throughout the world, as well as the properties of the products critical to their proper application. Contents include: general characteristics; physical metallurgy; melting, refining, alloying, recycling, and powder production; casting; heat treatment; forging, rolling, and extrusion; semisolid processing; forming; joining; cleaning and finishing; selection, application, and properties of grades and alloys; design considerations; mechanical behavior and wear resistance; fatigue and fracture-mechanics; high-temperature strength and creep; corrosion and stress-corrosion cracking; specification.

  11. Sintered magnesium and magnesium-beryllium alloys

    Microsoft Academic Search

    V. E. Ivanov; V. F. Zelenskii; S. I. Faifer; S. M. Zhdanov; V. I. Maksimenko; V. I. Savchenko

    1965-01-01

    The use of powder metallurgy methods for the production of magnesium alloys is highly promising. By employing technological procedures widely known in powder metallurgy practice, it is possible to make magnesium alloys whose production by the methods of melting and casting would be hardly feasible.

  12. Investigation of HVOF spraying on magnesium alloys

    Microsoft Academic Search

    Maria Parco; Lidong Zhao; Jochen Zwick; Kirsten Bobzin; Erich Lugscheider

    2006-01-01

    Magnesium alloys are promising alternatives to other lightweight alloys such as aluminum alloys due to their high specific strength and stiffness. However, the use of magnesium alloys is limited by their poor wear behaviour and corrosion performance. Recent studies have shown an enormous potential of thermal spray techniques for the surface modification of Mg alloys. The high particle velocities and

  13. Electrodeposition of magnesium and magnesium/aluminum alloys

    DOEpatents

    Mayer, Anton (Los Alamos, NM)

    1988-01-01

    Electrolytes and plating solutions for use in processes for electroplating and electroforming pure magnesium and alloys of aluminum and magnesium and also electrodeposition processes. An electrolyte of this invention is comprised of an alkali metal fluoride or a quaternary ammonium halide, dimethyl magnesium and/or diethyl magnesium, and triethyl aluminum and/or triisobutyl aluminum. An electrolyte may be dissolved in an aromatic hydrocarbon solvent to form a plating solution. The proportions of the component compounds in the electrolyte are varied to produce essentially pure magnesium or magnesium/aluminum alloys having varying selected compositions.

  14. Magnesium-lithium casting alloys

    NASA Technical Reports Server (NTRS)

    Latenko, V. P.; Silchenko, T. V.; Tikhonov, V. A.; Maltsev, V. P.; Korablin, V. P.

    1974-01-01

    The strength properties of magnesium-lithium alloys at room, low, and high temperatures are investigated. It is found that the alloys may have practical application at ambient temperatures up to 100 C, that negative temperatures have a favorable influence on the alloy strength, and that cyclic temperature variations have practically no effect on the strength characteristics. The influence of chemical coatings on corrosion resistance of the MgLi alloys is examined. Several facilities based on pressure casting machines, low-pressure casting machines, and magnetodynamic pumps were designed for producing MgLi alloy castings. Results were obtained for MgLi alloys reinforced with fibers having a volumetric content of 15%.

  15. Nondestructive spot test method for magnesium and magnesium alloys

    NASA Technical Reports Server (NTRS)

    Wilson, M. L. (inventor)

    1973-01-01

    A method for spot test identification of magnesium and various magnesium alloys commonly used in aerospace applications is described. The spot test identification involves color codes obtained when several drops of 3 M hydrochloric acid are placed on the surface to be tested. After approximately thirty seconds, two drops of this reacted acid is transferred to each of two depressions in a spot plate for additions of other chemicals with subsequent color changes indicating magnesium or its alloy.

  16. Imparting passivity to vapor deposited magnesium alloys

    NASA Astrophysics Data System (ADS)

    Wolfe, Ryan C.

    Magnesium has the lowest density of all structural metals. Utilization of low density materials is advantageous from a design standpoint, because lower weight translates into improved performance of engineered products (i.e., notebook computers are more portable, vehicles achieve better gas mileage, and aircraft can carry more payload). Despite their low density and high strength to weight ratio, however, the widespread implementation of magnesium alloys is currently hindered by their relatively poor corrosion resistance. The objective of this research dissertation is to develop a scientific basis for the creation of a corrosion resistant magnesium alloy. The corrosion resistance of magnesium alloys is affected by several interrelated factors. Among these are alloying, microstructure, impurities, galvanic corrosion effects, and service conditions, among others. Alloying and modification of the microstructure are primary approaches to controlling corrosion. Furthermore, nonequilibrium alloying of magnesium via physical vapor deposition allows for the formation of single-phase magnesium alloys with supersaturated concentrations of passivity-enhancing elements. The microstructure and surface morphology is also modifiable during physical vapor deposition through the variation of evaporation power, pressure, temperature, ion bombardment, and the source-to-substrate distance. Aluminum, titanium, yttrium, and zirconium were initially chosen as candidates likely to impart passivity on vapor deposited magnesium alloys. Prior to this research, alloys of this type have never before been produced, much less studied. All of these metals were observed to afford some degree of corrosion resistance to magnesium. Due to the especially promising results from nonequilibrium alloying of magnesium with yttrium and titanium, the ternary magnesium-yttrium-titanium system was investigated in depth. While all of the alloys are lustrous, surface morphology is observed under the scanning electron microscope. The corrosion rate of the nonequilibrium sputtered alloys, as determined by polarization resistance, is significantly reduced compared to the most corrosion resistant commercial magnesium alloys. The open circuit potentials of the sputter deposited alloys are significantly more noble compared to commercial, equilibrium phase magnesium alloys. Galvanic corrosion susceptibility has also been considerably reduced. Nonequilibrium magnesium-yttrium-titanium alloys have been shown to achieve passivity autonomously by alteration of the composition chemistry of the surface oxide/hydroxide layer. Self-healing properties are also evident, as corrosion propagation can be arrested after initial pitting of the material. A clear relationship exists between the corrosion resistance of sputter vapor deposited magnesium alloys and the amount of ion bombardment incurred by the alloy during deposition. Argon pressure, the distance between the source and the substrate, and alloy morphology play important roles in determining the ability of the alloy to develop a passive film. Thermal effects, both during and after alloy deposition, alter the stress state of the alloys, precipitation of second phases, and the mechanical stability of the passive film. An optimal thermal treatment has been developed in order to maximize the corrosion resistance of the magnesium-yttrium-titanium alloys. The significance of the results includes the acquisition of electrochemical data for these novel materials, as well as expanding the utilization of magnesium alloys by the improvement in their corrosion resistance. The magnesium alloys developed in this work are more corrosion resistant than any commercial magnesium alloy. Structural components comprised of these alloys would therefore exhibit unprecedented corrosion performance. Coatings of these alloys on magnesium components would provide a corrosion resistant yet galvanically-compatible coating. The broad impact of these contributions is that these new low-density, corrosion resistant magnesium alloys can be used to produce engine

  17. LOST FOAM CASTING OF MAGNESIUM ALLOYS

    SciTech Connect

    Han, Qingyou [ORNL; Dinwiddie, Ralph Barton [ORNL; Sklad, Philip S [ORNL; Currie, Kenneth [Tennessee Technological University; Abdelrahman, Mohamed [Tennessee Technological University; Vondra, Fred [Tennessee Technological University; Walford, Graham [Walford Technologies; Nolan, Dennis J [Foseco-Morval

    2007-01-01

    The lost foam casting process has been successfully used for making aluminum and cast iron thin walled castings of complex geometries. Little work has been carried out on cast magnesium alloys using the lost foam process. The article describes the research activities at Oak Ridge National Laboratory and Tennessee Technological University on lost foam casting of magnesium alloys. The work was focused on castings of simple geometries such as plate castings and window castings. The plate castings were designed to investigate the mold filling characteristics of magnesium and aluminum alloys using an infrared camera. The pate castings were then characterized for porosity distribution. The window castings were made to test the castability of the alloys under lost foam conditions. Significant differences between lost foam aluminum casting and lost foam magnesium casting have been observed.

  18. Creep strength of magnesium-based alloys

    Microsoft Academic Search

    Kouichi Maruyama; Mayumi Suzuki; Hiroyuki Sato

    2002-01-01

    The high-temperature creep resistance of magnesium alloys was discussed, with special reference to Mg-Al and Mg-Y alloys.\\u000a Mg-Al solid-solution alloys are superior to Al-Mg solid-solution alloys in terms of creep resistance. This is attributed to\\u000a the high internal stress typical of an hcp structure having only two independent basal slip systems. Although magnesium has\\u000a a smaller shear modulus than aluminum,

  19. 62 FR 13863 - Pure Magnesium and Alloy Magnesium From Canada; Preliminary Results of Countervailing Duty...

    Federal Register 2010, 2011, 2012, 2013, 2014

    1997-03-24

    ...invoiced amounts of its water bills. In the Final...Duty Determinations: Pure Magnesium and Alloy Magnesium...NHCI would have paid for water during the POR by NHCI's...Administrative Reviews: Pure Magnesium and Alloy Magnesium...subsidies according to their characteristics. For example, in...

  20. Anticorrosive magnesium hydroxide coating on AZ31 magnesium alloy by hydrothermal method

    NASA Astrophysics Data System (ADS)

    Zhu, Yanying; Wu, Guangming; Zhao, Qing; Zhang, Yun-Hong; Xing, Guangjian; Li, Donglin

    2009-09-01

    Magnesium alloys are potential biodegradable biomaterials in orthopedic surgery. However, the rapid degradation rate has limited their application in biomedical field. A great deal of studies have been done to improve the resistance of magnesium alloys. In this article, An anticorrosive magnesium hydroxide coating with a thickness of approximately 100?m was formed on an AZ31 magnesium alloy by hydrothermal method. The morphology of the coatings were observed by an optical microscope and SEM. And the samples were soaked in hank's solution (37°C) to investigate the corrosion resistance. Magnesium alloy AZ31 with magnesium hydroxide coatings present superior corrosion resistance than untreated samples.

  1. Impurity control and corrosion resistance of magnesium-aluminum alloy

    SciTech Connect

    Liu, M. [GM China Lab] [GM China Lab; Song, GuangLing [ORNL] [ORNL

    2013-01-01

    The corrosion resistance of magnesium alloys is very sensitive to the contents of impurity elements such as iron. In this study, a series of diecast AXJ530 magnesium alloy samples were prepared with additions of Mn and Fe. Through a comprehensive phase diagram calculation and corrosion evaluation, the mechanisms for the tolerance limit of Fe in magnesium alloy are discussed. This adds a new dimension to control the alloying impurity in terms of alloying composition design and casting conditions.

  2. Magnesium Alloy Precipitate Formation Using Mixed Basis Cluster Expansions

    NASA Astrophysics Data System (ADS)

    Leone, Robert

    2005-03-01

    Unlike steel and aluminum alloys, the basic science of magnesium alloys is poorly understood. The automotive industry is driving demand for lighter structural material, and readily available magnesium alloys have a higher strength-to-weight ratio than their aluminum counterparts. We seek to predict magnesium alloy properties from first principles, particularly the hardening effect of precipitate formation. Mixed basis cluster expansions (MBCE) have successfully modeled precipitate shapes and growth in aluminum alloys. Unfortunately, this methodology has not been extended to hcp-based materials such as magnesium alloys. In order to model binary magnesium alloys using the MBCE, particularly precipitate morphologies, we have constructed a coherency strain model for hcp structures to correctly represent the long range strain fields around precipitates. Coupling this generalized strain model to an Ising-like expansion methodology we have developed a mixed-basis cluster expansion for hexagonal symmetries. Results for several representative magnesium alloys will be presented.

  3. IRRADIATION EFFECTS IN SUPER PURITY ALUMINUM MAGNESIUM ALLOYS

    Microsoft Academic Search

    Piercy

    1959-01-01

    The tensile properties of annealed samples of aluminum -magnesium alloys ; containing 0.001 to 2.8 wt. % magnesium have been determined in the irradiated ; and unirradiated condition. The increase in elastic limit caused by reactor ; irradiation is shown by two effects, an increase proportional to the integrated ; fast-neutron flux that is greater for alloys of lower magnesium

  4. Magnesium

    Microsoft Academic Search

    B. L Mordike; T Ebert

    2001-01-01

    Magnesium is the lightest of all metals used as the basis for constructional alloys. It is this property which entices automobile manufacturers to replace denser materials, not only steels, cast irons and copper base alloys but even aluminium alloys by magnesium based alloys. The requirement to reduce the weight of car components as a result in part of the introduction

  5. Superplastic deformation mechanism in powder metallurgy magnesium alloys and composites

    Microsoft Academic Search

    H. Watanabe; T. Mukai; M. Mabuchi; K. Higashi

    2001-01-01

    The parametric dependencies for superplastic flow in powder metallurgy (PM) magnesium alloys and composites were characterized so as to elucidate the deformation mechanism. The mechanism was proposed to be slip accommodated grain boundary sliding. However, the PM alloys and composites were strengthened at low temperatures below ?550K. This was different from the case in ingot metallurgy (IM) magnesium alloys, that

  6. On the Modeling of Plastic Deformation of Magnesium Alloys

    Microsoft Academic Search

    S. Ertuerk; D. Steglich; J. Bohlen; D. Letzig; W. Brocks

    2007-01-01

    Magnesium alloys are promising materials due to their low density and therefore high specific strength. However, the industrial application is not well established so far, especially for wrought products such as sheets or profiles. Due to its hexagonal crystallographic structure, deformation mechanisms observed in magnesium alloys are rather different from those in face centered cubic metals such as aluminum alloys.

  7. Dry sliding wear behavior of magnesium alloys

    Microsoft Academic Search

    J. An; R. G. Li; Y. Lu; C. M. Chen; Y. Xu; X. Chen; L. M. Wang

    2008-01-01

    Dry sliding tests were performed on as-cast magnesium alloys Mg97Zn1Y2 and AZ91 using a pin-on-disc configuration. Coefficients of friction and wear rates were measured within a load range of 20–380 and 20–240N at a sliding velocity of 0.785m\\/s. X-ray differactometer, scanning electron microscopy, tensile testing machine were used to characterize the microstructures and mechanical properties of Mg97Zn1Y2 alloy and AZ91

  8. Protective coatings on magnesium and its alloys — a critical review

    Microsoft Academic Search

    J. E. Gray; B. Luan

    2002-01-01

    Magnesium and its alloys have excellent physical and mechanical properties for a number of applications. In particular its high strength:weight ratio makes it an ideal metal for automotive and aerospace applications, where weight reduction is of significant concern. Unfortunately, magnesium and its alloys are highly susceptible to corrosion, particularly in salt-spray conditions. This has limited its use in the automotive

  9. Creep deformation in magnesium aluminum calcium-based alloys

    Microsoft Academic Search

    Jessica Renae Terbush

    2010-01-01

    Magnesium alloys, with a lower density than steel or aluminum, have the potential to reduce the mass of automotive components. However, new alloys with improved creep resistance must be developed before Mg can be used for high temperature powertrain applications. Limiting the development of these alloys is the lack of fundamental knowledge of creep deformation in Mg alloys. This dissertation

  10. Application of YAG Laser TIG Arc Hybrid Welding to Thin AZ31B Magnesium Alloy Sheet

    Microsoft Academic Search

    Taewon Kim; Jongcheol Kim; Yu Hasegawa; Yasuo Suga

    2005-01-01

    A magnesium alloy is said to be an ecological material with high ability of recycling and lightweight property. Especially, magnesium alloys are in great demand on account of outstanding material property as a structural material. Under these circumstances, research and development of welding process to join magnesium alloy plates are of great significance for wide industrial application of magnesium. In

  11. Creep and microstructure of magnesium-aluminum-calcium based alloys

    Microsoft Academic Search

    Alan A. Luo; Bob R. Powell; Michael P. Balogh

    2002-01-01

    This article describes the creep and microstructure of Mg-Al-Ca-based magnesium alloys (designated as ACX alloys, where A\\u000a stands for aluminum; C for calcium; and X for strontium or silicon) developed for automotive powertrain applications. Important\\u000a creep parameters, i.e., secondary creep rate and creep strength, for the new alloys are reported. Creep properties of the new alloys are significantly\\u000a better than

  12. Warm Deep Drawing Of Rectangular Cups With Magnesium Alloy AZ31 Sheets

    Microsoft Academic Search

    L. M. Ren; G. Palumbo; S. H. Zhang; L. Tricarico

    2007-01-01

    Recently, magnesium alloys have been widely applied in automotive and electronic industries as the lightest weight structural and functional materials. Warm forming of magnesium alloys has attracted much attention due to the very poor formability of Mg alloys at room temperature. The formability of magnesium alloy sheet at elevated temperature is significantly affected by the processing parameters. Among them the

  13. On the Modeling of Plastic Deformation of Magnesium Alloys

    NASA Astrophysics Data System (ADS)

    Ertürk, S.; Steglich, D.; Bohlen, J.; Letzig, D.; Brocks, W.

    2007-05-01

    Magnesium alloys are promising materials due to their low density and therefore high specific strength. However, the industrial application is not well established so far, especially for wrought products such as sheets or profiles. Due to its hexagonal crystallographic structure, deformation mechanisms observed in magnesium alloys are rather different from those in face centered cubic metals such as aluminum alloys. This leads not only to a mechanical anisotropy, but also to a tension-compression asymmetry, i.e. unequal compressive and tensile yield strength. The resulting complexity in the yielding behavior of such materials cannot be captured by conventional models of J2 plasticity. Cazacu and Barlat, therefore, proposed a phenomenological yield potential which accounts for the respective phenomena by introducing the third invariant of the stress tensor. Simulations based on this model are performed with ABAQUS/Explicit and a user defined routine VUMAT for validating the respective implementation. The application aims at simulating the extrusion process of magnesium alloys.

  14. On the Modeling of Plastic Deformation of Magnesium Alloys

    SciTech Connect

    Ertuerk, S.; Steglich, D.; Bohlen, J.; Letzig, D.; Brocks, W. [GKSS Research Center, Institute of Materials Research, Max-Plank-Str., D-21502 Geesthacht (Germany)

    2007-05-17

    Magnesium alloys are promising materials due to their low density and therefore high specific strength. However, the industrial application is not well established so far, especially for wrought products such as sheets or profiles. Due to its hexagonal crystallographic structure, deformation mechanisms observed in magnesium alloys are rather different from those in face centered cubic metals such as aluminum alloys. This leads not only to a mechanical anisotropy, but also to a tension-compression asymmetry, i.e. unequal compressive and tensile yield strength. The resulting complexity in the yielding behavior of such materials cannot be captured by conventional models of J2 plasticity. Cazacu and Barlat, therefore, proposed a phenomenological yield potential which accounts for the respective phenomena by introducing the third invariant of the stress tensor. Simulations based on this model are performed with ABAQUS/Explicit and a user defined routine VUMAT for validating the respective implementation. The application aims at simulating the extrusion process of magnesium alloys.

  15. Review of warm forming of aluminum–magnesium alloys

    Microsoft Academic Search

    Serkan Toros; Fahrettin Ozturk; Ilyas Kacar

    2008-01-01

    Aluminum–magnesium (Al–Mg) alloys (5000 series) are desirable for the automotive industry due to their excellent high-strength to weight ratio, corrosion resistance, and weldability. However, the formability and the surface quality of the final product of these alloys are not good if processing is performed at room temperature. Numerous studies have been conducted on these alloys to make their use possible

  16. Nondestructive evaluation of an environmentally friendly conversion coating for magnesium alloys using optical measurement techniques

    E-print Network

    Zuniga, David

    2006-10-30

    Magnesium alloys have one of the highest specific strengths of all construction metals used. Specifically, magnesium alloy castings are used in the aerospace industry to reduce the weight of aerospace vehicles. Coating systems must be employed...

  17. Interactions between aggressive ions and the surface of a magnesium-yttrium alloy.

    PubMed

    Johnson, Ian; Perchy, Daniel; Liu, Huinan

    2012-01-01

    Magnesium alloys possess many desirable properties for biodegradable orthopedic implants. Unfortunately, magnesium degrades too rapidly in vivo. This rapid degradation reduces the alloys' mechanical properties and increases the alkalinity of the local environment. Controlling the degradation rate and mode is an essential step in the development of magnesium based biomaterials. Accomplishing this essential step will require an improved understanding of magnesium alloy degradation. Herein, three interacting factors controlling magnesium degradation were investigated; (1) alloy composition, (2) alloy surface, (3) presence of aggressive ions in the immersion media. The magnesium-yttrium alloy was more susceptible to degradation in water than the high purity magnesium alloy. However, the polished surface magnesium-yttrium alloy had the least susceptibility to degradation in phosphate buffered saline (PBS) among all the sample compositions and surfaces. PMID:23367216

  18. Nondestructive evaluation of an environmentally friendly conversion coating for magnesium alloys using optical measurement techniques 

    E-print Network

    Zuniga, David

    2006-10-30

    Magnesium alloys have one of the highest specific strengths of all construction metals used. Specifically, magnesium alloy castings are used in the aerospace industry to reduce the weight of aerospace vehicles. Coating ...

  19. The relation between mechanical properties and structure of aluminum and magnesium cast alloys at low temperatures

    Microsoft Academic Search

    R. I. Il'ina; N. G. Sidorov; B. S. Morozov; M. F. Nikitina; P. F. Koshelev

    1970-01-01

    Conclusions 1.The following cast alloys have the best combination of properties in the temperature range 293–20°K: A119 aluminum and VM12 magnesium alloys.2.A satisfactory level of properties is observed down to a temperature of 77°K in the case of alloys VAl5 and Ml10 alloys.3.The use of cast aluminum-magnesium alloys Al27-1 and Al8M and the magnesium alloy M15 is permissible down to

  20. Magnesium and its alloys applications in automotive industry

    Microsoft Academic Search

    Mustafa Kemal Kulekci

    2008-01-01

    The objective of this study is to review and evaluate the applications of magnesium in the automotive industry that can significantly\\u000a contribute to greater fuel economy and environmental conservation. In the study, the current advantages, limitations, technological\\u000a barriers and future prospects of Mg alloys in the automotive industry are given. The usage of magnesium in automotive applications\\u000a is also assessed

  1. Applications of Computer Simulation Methods in Plastic Forming Technologies for Magnesium Alloys

    Microsoft Academic Search

    S. H. Zhang; W. T. Zheng; Y. L. Shang; X. Wu; G. Palumbo; L. Tricarico

    2007-01-01

    Applications of computer simulation methods in plastic forming of magnesium alloy parts are discussed. As magnesium alloys possess very poor plastic formability at room temperature, various methods have been tried to improve the formability, for example, suitable rolling process and annealing procedures should be found to produce qualified magnesium alloy sheets, which have the reduced anisotropy and improved formability. The

  2. A study on factors affecting the degradation of magnesium and a magnesium-yttrium alloy for biomedical applications.

    PubMed

    Johnson, Ian; Liu, Huinan

    2013-01-01

    Controlling degradation of magnesium or its alloys in physiological saline solutions is essential for their potential applications in clinically viable implants. Rapid degradation of magnesium-based materials reduces the mechanical properties of implants prematurely and severely increases alkalinity of the local environment. Therefore, the objective of this study is to investigate the effects of three interactive factors on magnesium degradation, specifically, the addition of yttrium to form a magnesium-yttrium alloy versus pure magnesium, the metallic versus oxide surfaces, and the presence versus absence of physiological salt ions in the immersion solution. In the immersion solution of phosphate buffered saline (PBS), the magnesium-yttrium alloy with metallic surface degraded the slowest, followed by pure magnesium with metallic or oxide surfaces, and the magnesium-yttrium alloy with oxide surface degraded the fastest. However, in deionized (DI) water, the degradation rate showed a different trend. Specifically, pure magnesium with metallic or oxide surfaces degraded the slowest, followed by the magnesium-yttrium alloy with oxide surface, and the magnesium-yttrium alloy with metallic surface degraded the fastest. Interestingly, only magnesium-yttrium alloy with metallic surface degraded slower in PBS than in DI water, while all the other samples degraded faster in PBS than in DI water. Clearly, the results showed that the alloy composition, presence or absence of surface oxide layer, and presence or absence of physiological salt ions in the immersion solution all influenced the degradation rate and mode. Moreover, these three factors showed statistically significant interactions. This study revealed the complex interrelationships among these factors and their respective contributions to degradation for the first time. The results of this study not only improved our understanding of magnesium degradation in physiological environment, but also presented the key factors to consider in order to satisfy the degradation requirements for next-generation biodegradable implants and devices. PMID:23799028

  3. Upsettability and forming limit of magnesium alloys at elevated temperatures

    NASA Astrophysics Data System (ADS)

    Park, Heung Sik; Kim, Si Pom; Park, Young Chul; Park, Joon Hong; Baek, Seung Gul

    2012-11-01

    In recent years, Magnesium (Mg) and its alloys have become a center of special interest in the automotive industry. Due to their high specific mechanical properties, they offer a significant weight saving potential in modern vehicle constructions. Most Mg alloys show very good machinability and processability, and even the most complicated die casting parts can be easily produced. In this study, Microstructure, Vickers hardness and tensile tests were examined and performed for each specimen to verify effects of forming conditions. Also to verify upsettability and forming limit of the specimen at room temperature and elevated temperature, upsetting experiments were performed. For comparison, experiments at elevated temperature were performed for various Mg alloy, such as AZ31, AZ91, and AM50. The experimental results were compared with those of CAE analysis to propose forming limit of Magnesium alloys.

  4. Strain controlled cyclic deformation behavior of an extruded magnesium alloy

    Microsoft Academic Search

    X. Z. Lin; D. L. Chen

    2008-01-01

    Fatigue properties of an extruded AZ31B magnesium alloy were evaluated using strain-controlled push–pull cyclic tests at different total strain amplitudes at room temperature. The alloy exhibited an asymmetric sigmoidal-shaped hysteresis loop due to twinning in compression during the unloading phase and detwinning during the loading phase. As the total strain amplitude increased, the asymmetry of hysteresis loops, plastic strain amplitude,

  5. Corrosion resistance of titanium ion implanted AZ91 magnesium alloy

    SciTech Connect

    Liu Chenglong; Xin Yunchang; Tian Xiubo; Zhao, J.; Chu, Paul K. [Department of Physics and Materials Science, City University of Hong Kong, Tat Chee Avenue, Kowloon, Hong Kong (China); Department of Physics and Materials Science, City University of Hong Kong, Tat Chee Avenue, Kowloon, Hong Kong (China) and Shenzhen Graduate School, Tsinghua University, Shenzhen 518055 (China); Department of Physics and Materials Science, City University of Hong Kong, Tat Chee Avenue, Kowloon, Hong Kong (China) and State Key Laboratory of Welding Production Technology, School of Materials Science and Engineering, Harbin Institute of Technology, Harbin 15001 (China); Department of Physics and Materials Science, City University of Hong Kong, Tat Chee Avenue, Kowloon, Hong Kong (China)

    2007-03-15

    Degradable metal alloys constitute a new class of materials for load-bearing biomedical implants. Owing to their good mechanical properties and biocompatibility, magnesium alloys are promising in degradable prosthetic implants. The objective of this study is to improve the corrosion behavior of surgical AZ91 magnesium alloy by titanium ion implantation. The surface characteristics of the ion implanted layer in the magnesium alloys are examined. The authors' results disclose that an intermixed layer is produced and the surface oxidized films are mainly composed of titanium oxide with a lesser amount of magnesium oxide. X-ray photoelectron spectroscopy reveals that the oxide has three layers. The outer layer which is 10 nm thick is mainly composed of MgO and TiO{sub 2} with some Mg(OH){sub 2}. The middle layer that is 50 nm thick comprises predominantly TiO{sub 2} and MgO with minor contributions from MgAl{sub 2}O{sub 4} and TiO. The third layer from the surface is rich in metallic Mg, Ti, Al, and Ti{sub 3}Al. The effects of Ti ion implantation on the corrosion resistance and electrochemical behavior of the magnesium alloys are investigated in simulated body fluids at 37{+-}1 deg. C using electrochemical impedance spectroscopy and open circuit potential techniques. Compared to the unimplanted AZ91 alloy, titanium ion implantation significantly shifts the open circuit potential (OCP) to a more positive potential and improves the corrosion resistance at OCP. This phenomenon can be ascribed to the more compact surface oxide film, enhanced reoxidation on the implanted surface, as well as the increased {beta}-Mg{sub 12}Al{sub 17} phase.

  6. Fabrication and corrosion resistance of superhydrophobic magnesium alloy

    NASA Astrophysics Data System (ADS)

    Feng, Libang; Zhu, Yali; Fan, Weibo; Wang, Yanping; Qiang, Xiaohu; Liu, Yanhua

    2015-05-01

    A superhydrophobic magnesium alloy (AZ91) is successfully fabricated by sulfuric acid etching, AgNO3 treatment, and dodecyl mercaptan (DM) modification. The effect of the fabrication procedure, the concentration and treatment time of sulfuric acid, AgNO3, and DM on morphology, phase structure, surface wettability, and surface composition of the AZ91 is investigated in detail. Consequently, the optimal treatment parameters are selected, and the superhydrophobic magnesium alloy with a water contact angle of 154° and a sliding angle of 5° is fabricated. The acid etching endows the AZ91 surface with rough structure while the AgNO3 treatment results in more protrusions and grooves. Meanwhile, the long hydrophobic alkyl chains are self-assembled onto the rough AZ91 surface upon DM modification. As a result, the multilayer of netlike surface with protrusions and grooves together with the coral-like structure is obtained. Additionally, the magnesium alloy with higher water contact angle has better corrosion resistance, while the magnesium alloy with the superhydrophobic property has the best corrosion resistance.

  7. Warm incremental forming of magnesium alloy AZ31

    Microsoft Academic Search

    G. Ambrogio; L. Filice; G. L. Manco

    2008-01-01

    Industrial application of magnesium alloy AZ31 is dramatically increasing due to the very competitive mechanical strength vs. weight ratio. On the other hand, AZ31 is very difficult to be formed at room temperature. In this study incremental forming of the above material is taken into account, with particular reference to formability limits. The role of the main process parameters on

  8. Thermal conductivities of nanostructured magnesium oxide coatings deposited on magnesium alloys by plasma electrolytic oxidation.

    PubMed

    Shen, Xinwei; Nie, Xueyuan; Hu, Henry

    2014-10-01

    The resistances of magnesium alloys to wear, friction and corrosion can be effectively improved by depositing coatings on their surfaces. However, the coatings can also reduce the heat transfer from the coated components to the surroundings (e.g., coated cylinder bores for internal combustion of engine blocks). In this paper, nanostructured magnesium oxides were produced by plasma electrolytic oxidation (PEO) process on the magnesium alloy AJ62 under different current densities. The guarded comparative heat flow method was adopted to measure the thermal conductivities of such coatings which possess gradient nanoscale grain sizes. The aim of the paper is to explore how the current density in the PEO process affects the thermal conductivity of the nanostructured magnesium coatings. The experimental results show that, as the current density rises from 4 to 20 A/mm2, the thermal conductivity has a slight increase from 0.94 to 1.21 W/m x K, which is significantly smaller than that of the corresponding bulk magnesium oxide materials (29.4 W/m x K). This mostly attributed to the variation of the nanoscale grain sizes of the PEO coatings. PMID:25942897

  9. Improvement of hydrogen storage properties of magnesium alloys by cold rolling and forging

    NASA Astrophysics Data System (ADS)

    Huot, Jacques; Amira, Sofiene; Lang, Julien; Skryabina, Nataliya; Fruchart, Daniel

    2014-08-01

    In this talk we show that cold rolling (CR) could be used to enhance hydrogen sorption properties of magnesium and magnesium alloys. In particular, cold rolling could reduce the first hydrogenation time, the so-called activation. Pure magnesium, commercial AZ91D alloy, and an experimental creep resistant magnesium alloy MRI153 in the as-cast and die-cast states were investigated. We found that both MRI and AZ91 alloys present faster activation kinetic than pure magnesium. This could be explained by the texture, higher number of defects, and nanostructure in CR materials but also precipitates at the grain boundaries. The effect of filing was also investigated.

  10. Formation of defect bands in high pressure die cast magnesium alloys

    Microsoft Academic Search

    A. K Dahle; S Sannes; D. H St. John; H Westengen

    2001-01-01

    Die cast magnesium components are being increasingly used worldwide because of the excellent castability and properties that magnesium alloys offer. High pressure die casting of thin-walled components is particularly suitable because of the excellent flow characteristics of molten magnesium alloys. Typical automotive applications for thin-walled castings include components such as instrument panels, steering wheels, door frames and seat frames. These

  11. PITTING CORROSION ON MAGNESIUM ALLOYS : A COMPARATIVE STUDY OF FIELD DATA USING EXTREME VALUE

    E-print Network

    Maume-Deschamps, Véronique

    was investigated in field corrosion tests carried out by Volvo Car Corporation. Light metals like magnesiumPITTING CORROSION ON MAGNESIUM ALLOYS : A COMPARATIVE STUDY OF FIELD DATA USING EXTREME VALUE corrosion of the magnesium alloys AZ91D and AM60B combined with different coatings on steel bolts

  12. Imparting passivity to vapor deposited magnesium alloys

    Microsoft Academic Search

    Ryan C. Wolfe

    2005-01-01

    Magnesium has the lowest density of all structural metals. Utilization of low density materials is advantageous from a design standpoint, because lower weight translates into improved performance of engineered products (i.e., notebook computers are more portable, vehicles achieve better gas mileage, and aircraft can carry more payload). Despite their low density and high strength to weight ratio, however, the widespread

  13. SPECTRAL ANALYSIS OF MAGNESIUM-BERYLLIUM ALLOYS

    Microsoft Academic Search

    V. F. Ercko; E. V. Lifshitz; V. G. Konovalov; I. G. Dubinsky; N. I. Bugayeva

    1961-01-01

    The methods of spectral analysis of magnesiumberyllium alloys are ; considered. Beryllium (basic addition), aluminium, zirconium, and calcium were ; alloying additions. Copper, iron, and nickel were determined as noxious ; impurities. The determination of the impurities was carried out both by method ; of solution of a sample and by direct analysis of metal specimens. The ; determined concentration

  14. Mechanical alloys of magnesium - new materials for hydrogen energy

    SciTech Connect

    Ivanov, E.Yu.

    1986-07-01

    One of the possible paths for improving the kinetic characteristics of magnesium hydriding is addition of catalytic doses of metals or intermetallic compounds (IMC). The authors added four types of catalysts to magnesium: Ni, which forms with magnesium the intermetallide Mg/sub 2/Ni; Ce, Nb, and Ti, which form the hydrides CeH/sub 3/, NbH/sub 2/, and TiH/sub 2/; Fe and Co, and Si and C which form compounds having covalent bonds. It was shown that mechanical alloying is a promising method for obtaining hydrogen-storing materials, which while retaining a fairly high hydrogen absorption capacity, possess better kinetic characteristics as compared to Mg, especially in the case of hydriding.

  15. Cold Spray Al5% Mg Coatings for the Corrosion Protection of Magnesium Alloys

    Microsoft Academic Search

    Brian S. DeForce; Timothy J. Eden; John K. Potter

    Poor corrosion resistance is a significant limitation of magnesium alloys as structural materials. To address this problem,\\u000a the objective of this study was to apply to a magnesium alloy a corrosion-resistant barrier coating that has galvanic compatibility\\u000a with magnesium and a hardness value no less than that of magnesium. Aluminum coatings were applied to ZE41A-T5 Mg by the cold\\u000a spray

  16. SIMULATION OF STRESSES DURING CASTING OF BINARY MAGNESIUM-ALUMINUM ALLOYS M.G. Pokorny1

    E-print Network

    Beckermann, Christoph

    SIMULATION OF STRESSES DURING CASTING OF BINARY MAGNESIUM-ALUMINUM ALLOYS M.G. Pokorny1 , C, Geesthacht, Germany Keywords: Magnesium Alloys, Casting, Stress Simulation Abstract A visco-plastic deformation model is used to predict thermal stresses during casting of binary Mg-Al alloys. The predictions

  17. Low-Power Laser\\/TIG Hybrid Welding Process of Magnesium Alloy with Filler Wire

    Microsoft Academic Search

    Liming Liu; Xinfeng Hao

    2010-01-01

    In the welding process of magnesium alloy, evaporative loss of alloying elements will induce welding defects and reduce the mechanical properties of weld joint. In this article, low-power laser\\/arc hybrid welding process of magnesium alloy with filler metal is studied to resolve this problem. Under the optimal welding parameters, weld joint with good formation and high quality can be obtained.

  18. The effect of cooling rate on thermophysical properties of magnesium alloys

    E-print Network

    Medraj, Mamoun

    ARTICLES The effect of cooling rate on thermophysical properties of magnesium alloys M.N. Khan magnesium alloys (AZ91D, AM60B, and AE44) have been studied. Phase-transformation temperatures and enthalpy of solidification of these alloys have been measured using differential scanning calorimetry. Solidification curves

  19. In vivo corrosion of four magnesium alloys and the associated bone response

    Microsoft Academic Search

    F. Witte; V. Kaese; H. Haferkamp; E. Switzer; A. Meyer-Lindenberg; C. J. Wirth; H. Windhagen

    2005-01-01

    Degrading metal alloys are a new class of implant materials suitable for bone surgery. The aim of this study was to investigate the degradation mechanism at the bone–implant interface of different degrading magnesium alloys in bone and to determine their effect on the surrounding bone. Sample rods of four different magnesium alloys and a degradable polymer as a control were

  20. Numerical simulation on warm deep drawing of magnesium alloy AZ31 sheets

    Microsoft Academic Search

    L. M. Ren; S. H. Zhang; G. Palumbo; D. Sorgente; L. Tricarico

    2009-01-01

    Warm forming of magnesium alloys has attracted much attention due to the very poor formability of Mg alloys at room temperature. In the present paper, the warm deep drawing of magnesium alloy AZ31 (3wt.% Al, 1wt.% Zn) sheets was studied by both the experimental approach and the finite element analysis. The results indicated that the formability of the AZ31 sheets

  1. The Corrosion Protection of Magnesium Alloy AZ31B

    NASA Technical Reports Server (NTRS)

    Danford, M. D.; Mendrek, M. J.; Mitchell, M. L.; Torres, P. D.

    1997-01-01

    Corrosion rates for bare and coated Magnesium alloy AZ31B have been measured. Two coatings, Dow-23(Trademark) and Tagnite(Trademark), have been tested by electrochemical methods and their effectiveness determined. Electrochemical methods employed were the scanning reference electrode technique (SRET), the polarization resistance technique (PR) and the electrochemical impedance spectroscopy technique (EIS). In addition, general corrosion and stress corrosion methods were employed to examine the effectiveness of the above coatings in 90 percent humidity. Results from these studies are presented.

  2. Corrosion protection of DLC coatings on magnesium alloy

    Microsoft Academic Search

    J. Choi; S. Nakao; J. Kim; M. Ikeyama; T. Kato

    2007-01-01

    Anti-corrosion properties of DLC films deposited on magnesium alloy, AZ31 (Mg–3%Al–1%Zn) were investigated. The DLC and Si-incorporated DLC (Si–DLC) films were prepared on sputter-deposited AZ31 films using a bi-polar type plasma based ion implantation and deposition (PBII&D). The AZ31 films were prepared on glass plates using an ECR-type ion beam sputter with an AZ31 target. The potentiodynamic polarization curves were

  3. Thermomechanical modelling of indirect extrusion process for magnesium alloys

    Microsoft Academic Search

    S. Ertürk; D. Steglich; J. Bohlen; D. Letzig; W. Brocks

    2009-01-01

    The complexity of deformation phenomena observed in magnesium and its alloys originates from its hexagonal closed packed crystallographic\\u000a structure. Mechanical anisotropy and asymmetry in tension-compression are hence observed. A phenomenological model derived\\u000a by Cazacu and Barlat accounts for the respective phenomena. However, the capabilities of this model for simulation of extrusion\\u000a are limited since strain rate and temperature dependency on

  4. Modelling and Simulation of Extrusion of Magnesium Alloys

    Microsoft Academic Search

    S. Ertürk; D. Steglich; J. Bohlen; D. Letzig; W. Brocks

    2008-01-01

    Extrusion, as one of the bulk-metal forming processes, is of significant importance for the production of semi-finished components.\\u000a For magnesium and its alloys, the technology for processing is available today, but there is still a fundamental lack in understanding\\u000a the factors that determine the development of microstructure and mechanical properties during the process. Due to its hexagonal\\u000a crystallographic structure, deformation

  5. Crystallography of directionally solidified magnesium alloy AZ91

    Microsoft Academic Search

    Ketil Pettersen; Nils Ryum

    1989-01-01

    The crystallographic direction of growth in directionally solidified magnesium alloy AZ91 has been studied by TEM and EBSP\\u000a techniques in SEM. The main direction of growth is found to be\\u000a $$\\\\left\\\\langle {11\\\\bar 20} \\\\right\\\\rangle $$\\u000a . The dendrites have sixfold symmetry around the main direction, with secondary arms lying along the traces of the (0001),\\u000a $$\\\\left( {1\\\\bar 101} \\\\right)$$\\u000a ,

  6. Experimental and numerical study of warm deep drawing of AZ31 magnesium alloy sheet

    Microsoft Academic Search

    Qun-Feng Chang; Da-Yong Li; Ying-Hong Peng; Xiao-Qin Zeng

    2007-01-01

    Warm forming of magnesium alloy sheet has attracted more and more attention in recent years. The formability of magnesium alloy sheet at elevated temperature depends on appropriate processes, and the fabrication of high-performance sheet. In this research, an AZ31 magnesium alloy sheet with excellent performances is fabricated by the cross-rolling and the uniform annealing treatments. The uniaxial tensile tests are

  7. Potential applications of wrought magnesium alloys for passenger vehicles

    SciTech Connect

    Gaines, L.; Cuenca, R.; Stodolsky, F.; Wu, S.

    1995-12-31

    Vehicle weight reduction is one of the major means available for improving automotive fuel efficiency. Although high-strength steels, aluminum (Al), and polymers are already being used to achieve significant weight reductions, substantial additional weight reductions could be achieved by increased use of magnesium (Mg) and its alloys, which have very low density. Magnesium alloys are currently used in relatively small quantities for auto parts; use is generally limited to die castings, such as housings. The Center for Transportation Research at Argonne National Laboratory has performed a study for the Lightweight Materials Program within DOE`s Office of Transportation Materials to evaluate the suitability of wrought Mg and its alloys to replace steel or aluminum for automotive structural and sheet applications. This study identifies technical and economic barriers to this replacement and suggests R&D areas to enable economical large-volume use. Detailed results of the study will be published at a later date. Magnesium sheet could be used in body nonstructural and semi-structural applications, while extrusions could be used in such structural applications as spaceframes. Currently, Mg sheet has found limited use in the aerospace industry, where costs are not a major concern. The major barrier to greatly increased automotive use is high cost; two technical R&D areas are identified that could enable major reductions in costs. These are novel reduction technology and better hot-forming technology, possibly operating at lower temperatures and involving superplastic behavior.

  8. High-strain-rate nanoindentation behavior of fine-grained magnesium alloys

    E-print Network

    Somekawa, Hidetoshi

    The effects of temperature and alloying elements on deformation in the high-strain-rate regime were investigated by testing fine-grained magnesium alloys with an average grain size of 2 ? 3 ?m by a nanoindentation technique. ...

  9. On the shock response of the magnesium alloy Elektron 675

    NASA Astrophysics Data System (ADS)

    Hazell, Paul; Appleby-Thomas, Gareth; Siviour, Clive; Wielewski, Euan

    2011-06-01

    Alloying elements such as aluminium, zinc or rare-earths allow precipitation hardening of magnesium (Mg). The low densities of such strengthened Mg alloys have led to their adoption as aerospace materials and (more recently) they are being considered as armour materials. Consequently, understanding their response to high-strain rate loading is becoming increasingly important. Here, the plate-impact technique was employed to measure longitudinal stress evolution in armour-grade wrought Mg-alloy Elektron 675 under 1D shock loading. The strength and spall behaviour was interrogated, with an estimate made of the material's Hugoniot elastic limit. Finally, electron backscatter diffraction (EBSD) techniques were employed to investigate post-shock microstructural changes.

  10. On the shock response of the magnesium alloy elektron 675

    NASA Astrophysics Data System (ADS)

    Hazell, Paul; Appleby-Thomas, Gareth James; Wielewski, Euan; Siviour, Clive Richard; Stennett, Chris

    2012-03-01

    Alloying elements such as aluminum, zinc or rare-earths allow precipitation hardening of magnesium (Mg). The low densities of such strengthened Mg alloys have led to their adoption as aerospace materials and (more recently) they are being considered as armor materials. Consequently, understanding their response to high strain-rate loading is becoming increasingly important. Here, the plate-impact technique was employed to measure longitudinal stress evolution in armor-grade wrought Mg-alloy Elektron 675 under 1D shock loading. The spall behavior was interrogated using a Heterodyne velocimeter (Het-v) system, with an estimate made of the material's Hugoniot elastic limit for both aged and un-aged materials.

  11. Numerical optimization of gating system parameters for a magnesium alloy casting with multiple performance characteristics

    Microsoft Academic Search

    Zhizhong Sun; Henry Hu; Xiang Chen

    2008-01-01

    An optimization technique for design of gating system parameters of a cylindrical magnesium casting based on the Taguchi method with multiple performance characteristics was proposed in this paper. The various gating systems for a casting model of magnesium alloy were designed. Mold filling and solidification processes of the magnesium casting were simulated with the MAGMASOFT®. The simulation results indicated that

  12. Endurance limit and threshold stress intensity of die cast magnesium and aluminium alloys at elevated temperatures

    Microsoft Academic Search

    H. Mayer; M. Papakyriacou; B. Zettl; S. Vacic

    2005-01-01

    High cycle fatigue properties of the high-pressure die-cast magnesium alloys AZ91 hp, AS21 hp and AE42 hp and of the aluminium alloy AlSi9Cu3 are investigated at elevated temperatures. Fatigue tests are performed at ultrasonic cyclic frequency and load ratio R=?1. Compared with ambient air environment, the S–N curves determined in warm air of 125°C (magnesium alloys) and 150°C (aluminium alloy)

  13. In vitro degradation behavior and cytocompatibility of Mg–Zn–Zr alloys

    PubMed Central

    Huan, Z. G.; Leeflang, M. A.; Fratila-Apachitei, L. E.; Duszczyk, J.

    2010-01-01

    Zinc and zirconium were selected as the alloying elements in biodegradable magnesium alloys, considering their strengthening effect and good biocompatibility. The degradation rate, hydrogen evolution, ion release, surface layer and in vitro cytotoxicity of two Mg–Zn–Zr alloys, i.e. ZK30 and ZK60, and a WE-type alloy (Mg–Y–RE–Zr) were investigated by means of long-term static immersion testing in Hank’s solution, non-static immersion testing in Hank’s solution and cell-material interaction analysis. It was found that, among these three magnesium alloys, ZK30 had the lowest degradation rate and the least hydrogen evolution. A magnesium calcium phosphate layer was formed on the surface of ZK30 sample during non-static immersion and its degradation caused minute changes in the ion concentrations and pH value of Hank’s solution. In addition, the ZK30 alloy showed insignificant cytotoxicity against bone marrow stromal cells as compared with biocompatible hydroxyapatite (HA) and the WE-type alloy. After prolonged incubation for 7 days, a stimulatory effect on cell proliferation was observed. The results of the present study suggested that ZK30 could be a promising material for biodegradable orthopedic implants and worth further investigation to evaluate its in vitro and in vivo degradation behavior. PMID:20532960

  14. A Model for Gas Microporosity in Aluminum and Magnesium Alloys

    NASA Astrophysics Data System (ADS)

    Felicelli, Sergio D.; Wang, Liang; Pita, Claudio M.; Escobar de Obaldia, Enrique

    2009-04-01

    A quantitative prediction of the amount of gas microporosity in aluminum and magnesium-alloy castings is performed with a continuum model of dendritic solidification. The distribution of the pore volume fraction and pore size is calculated from a set of conservation equations that solves the transport phenomena during solidification at the macroscale and the hydrogen diffusion into the pores at the microscale. A technique based on a pseudo-alloy solute that is transported by the melt is used to determine the potential sites of pore growth, subject to considerations of mechanical and thermodynamic equilibrium. The modeling results for aluminum alloy A356 are found to agree well with published studies. In view of the limited availability of experimental data for Mg-alloy gravity-poured castings, the formation of porosity in AZ91 is studied qualitatively, assuming that casting conditions are similar to A356. In particular, the minimum initial hydrogen content that leads to the formation of gas porosity was compared for both alloys. It is found that the initial hydrogen content necessary for forming porosity is much higher in AZ91 than in A356. This is attributed to significant differences in the solubility of the hydrogen in both alloys.

  15. Fracture properties of a fiber-metal laminates based on magnesium alloy

    Microsoft Academic Search

    P. Cortés; W. J. Cantwell

    2004-01-01

    marizes the stacking configurations investigated in this study. The composite volume fraction within the FMLs wa sv aried by increasing the number of composite plies between the two outermost magnesium alloy skins from two to eight. The tensile properties of the FMLs and the magnesium alloy were evaluated using 20 mm wide rectangular samples at a crosshead displacement rate of

  16. The microstructure, mechanical and friction properties of protective diamond like carbon films on magnesium alloy

    Microsoft Academic Search

    Y. S. Zou; Y. F. Wu; H. Yang; K. Cang; G. H. Song; Z. X. Li; K. Zhou

    Protective hard coatings deposited on magnesium alloys are believed to be effective for overcoming their poor wear properties. In this work, diamond-like carbon (DLC) films as hard protective films were deposited on AZ91 magnesium alloy by arc ion plating under negative pulse bias voltages ranging from 0 to ?200V. The microstructure, composition and mechanical properties of the DLC films were

  17. Investigation of particle flattening behaviour and bonding mechanisms of APS sprayed coatings on magnesium alloys

    Microsoft Academic Search

    Maria Parco; Lidong Zhao; Jochen Zwick; Kirsten Bobzin; Erich Lugscheider

    2007-01-01

    Magnesium alloys are promising alternatives to other lightweight materials due to their high specific strength and stiffness. However, the use of magnesium alloys is limited by their poor wear behaviour and low corrosion resistance for many industrial applications. The thermal spray technology offers a wide range of possibilities to improve the surface properties of Mg-based components. In this study, three

  18. Hot cracking in tungsten inert gas welding of magnesium alloy AZ91D

    E-print Network

    Zhou, Wei

    of porosity in the welds. The welding was conducted using alternating current at a voltage of 20­22 V,2 Magnesium alloy AZ91D is widely used because of its relatively higher corrosion resistance and mechanical,4 corrosion resistance5­8 and mechanical properties9 of AZ91D magnesium alloys. Effort has also been made

  19. Effects of process parameters on warm and electromagnetic hybrid forming of magnesium alloy sheets

    Microsoft Academic Search

    Zhenghua Meng; Shangyu Huang; Jianhua Hu; Wei Huang; Zhilin Xia

    2011-01-01

    As the lightest structural metal, magnesium (Mg) is attracting increasing interest from both the industrial and academic fields. Magnesium alloy parts are mainly processed by die casting due to their poor sheet formability at room temperature. Warm forming is a popular method of forming; Mg alloy sheets produced in this manner show excellent formability around 200–400°C. Electromagnetic forming (EMF) can

  20. 62 FR 13857 - Pure and Alloy Magnesium From Canada: Final Results of the First (1992) Countervailing Duty...

    Federal Register 2010, 2011, 2012, 2013, 2014

    1997-03-24

    ...countervailing duty orders on pure and alloy magnesium from...merchandise which exported pure and alloy magnesium to...Exemption from Payment of Water Bills, Article 7 Grants...Less Than Fair Value: Pure and Alloy Magnesium from...Exemption From Payment of Water Bills In the...

  1. The Improvement of Tribological and Fatigue Properties of Casting Magnesium Alloy AZ91 Performed Diamond Like Carbon Coating

    Microsoft Academic Search

    Hiroyuki Akebono; Hideto Suzuki

    2008-01-01

    In recent years, magnesium alloy has been widely used because of its low weight and ease of recycling. However, because magnesium alloys provide inferior wear resistance, it is necessary to improve this property to use magnesium alloy for more machine parts. For this study, we produced a diamond like carbon (DLC) coating that has high hardness, low friction, and excellent

  2. Microstructure and texture studies on magnesium sheet alloys

    NASA Astrophysics Data System (ADS)

    Masoumi, Mohsen

    The AZ3, the most common Mg sheet alloy, is currently produced by hot rolling of the DC cast ingot. Mg wrought alloys, in general have limited formability due to hexagonal close-packed structure and preferred orientation (texture). In order to improve magnesium sheet formability, a good understanding of microstructure and texture evolution in twin-roll casting is necessary. The objectives of this research are to study the microstructural and texture evolution in twin-roll cast AZ31 Mg sheet alloy and to develop/modify alloy compositions with improved mechanical properties (weakened texture). In the first part of study, the influence of cooling rate (CR) on the casting structure of AZ31 magnesium alloy has been investigated, as a background to understand microstructural development in TRC AZ31, using different moulds to obtain slow to moderate cooling rates. It was found that grain size and secondary dendrite arm spacing (SDAS) reduces as the cooling rate increases. Moreover, it was observed that with an increase in cooling rate the fraction of second phase particles increases and the second phase particles become finer. The second part focused on the microstructure and texture study of the twin-roll cast (TRC) AZ31 (Mg-3wt.%Al-1wt.%Zn) sheet. The results indicate that TRC AZ31 exhibits a dendritic microstructure with columnar and equiaxed grains. It was noted that the amount of these second phases in the TRC alloy is greater than the conventionally cast AZ31. Recrystallization at 420 °C leads to a bimodal grain-size distribution, while a fine-grain structure is obtained after rolling and annealing. The TRC AZ31 sheet exhibits basal textures in the (i) as-received, (ii) rolled and (iii) rolled-annealed conditions. However, post-annealing of the TRC AZ31 at 420 °C produces a relatively random texture that has not been previously observed in the conventional AZ31 sheet. The texture randomization is attributed to the particle-stimulated nucleation (PSN) of new grains in the TRC structure. The preliminary evaluation of mechanical properties indicates that such annealing treatment slightly increases the ultimate tensile strength (UTS), but significantly improves elongation. In the final of part of the study, the microstructures and textures of rolled and rolled/annealed Mg-1wt.%Mn-based and Mg-1wt.%Zn-Based alloys containing different levels of Ce and Sr were examined. The Ce addition refines the as-cast and rolled/annealed grain structure of Mg-1wt.%Mn (M1) alloy. Moreover, the overall texture intensity of basal pole was weakened for rolled as well as rolled/annealed Mg-Mn-Ce alloys compared to the M1 alloy. The texture weakening was attributed to the solid solubility of Ce in Mg rather than PSN or c/a ratio alteration. The Sr addition refined the as-cast and rolled/annealed grain structure of Mg-1wt.%Mn-Sr (MJ) and Mg-1wt.%Zn (Z1) alloy. Moreover, the overall texture intensity of basal pole was weakened for rolled as well as rolled/annealed Mg-Zn-Sr (ZJ) alloys compared to the Z1 alloy. The texture weakening is attributed to the PSN of new grains with random orientations.

  3. Investigation of Deformation Dynamics in a Wrought Magnesium Alloy

    SciTech Connect

    Wu, Wei [ORNL; Qiao, Hua [McMaster University; An, Ke [ORNL; Wu, Peidong [McMaster University; Liaw, Peter K [University of Tennessee, Knoxville (UTK)

    2014-11-01

    In the present research, the deformation dynamics and the effect of the deformation history on plastic deformation in a wrought magnesium alloy have been studied using real-time in-situ neutron diffraction measurements under a continuous loading condition and elastic-viscoplastic self-consistent (EVPSC) polycrystal modeling. The experimental results reveal that the pre-deformation delayed the activation of the tensile twinning during subsequent compression, mainly resulting from the residual strain. No apparent detwinning occurred during unloading and even in the elastic region during reverse loading. It is believed that the grain rotation played an important role in the elastic region during reverse loading. The EVPSC model, which has been recently updated by implementing the twinning and detwinning model, was employed to characterize the deformation mechanism during the strain-path changes. The simulation result predicts well the experimental observation from the real-time in-situ neutron diffraction measurements. The present study provides a deep insight of the nature of deformation mechanisms in a hexagonal close-packed structured polycrystalline wrought magnesium alloy, which might lead to a new era of deformation-mechanism research.

  4. Formability study of magnesium alloy AZ31B

    NASA Astrophysics Data System (ADS)

    Liu, Z. G.; Lasne, P.; Massoni, E.

    2011-08-01

    The main aim of this paper is to study the formability of the AZ31B magnesium alloy at various temperature and strain rates. The tensile tests are performed to describe the rheological behavior of material, and the constitutive law is identified with Voce law [1], which contains a softening item. The law is proved effectiveness by fitting the equation with the experimental data. Nakazima experiments with hemispherical punch have been performed at CEMEF on a hydraulic testing machine. Six strain paths are selected by performing various sample geometries [2]. The AramisOptical strain measurement system has been used to obtain principle forming limit strain. The Forming Limit Diagram (FLD) is obtained by the critical point on the specimen surface at various temperatures. It is shown that the forming limit curve is higher at high temperature. Based on the Voce law model, finite element simulations of deep drawing test have been done with the commercial finite element code FORGE® in order to investigate the feasibility of hot stamping process for AZ31. In the simulation, the punch load and the thickness distributions have been studied. Meanwhile, the cross-shaped cup deep drawing simulations have been conducted with the data provided in the conference Website. The similar conclusion are obtained that the formability of AZ31 improve at high temperature and the simulation is effective in hot stamping processing. The study results are helpful for the application of the stamping technology for the magnesium alloy sheet [3].

  5. Magnesium-based hydrogen storage materials modified by mechanical alloying

    SciTech Connect

    Cui, N.; He, P.; Luo, J.L.

    1999-10-26

    The effects of mechanical alloying on microstructure and electrochemical performance of a Mg-Ni-Y-Al hydrogen storage alloy in 6 M KOH solution were studied. The ball-milled powders were examined by X-ray diffraction (XRD), transmission electron microscopy (TEM), selected-area electron diffraction (SED) and energy dispersion spectrometry (EDS). TEM and EDS results clearly reveal that the smaller nickel clusters or particles were well dispersed on the surface of larger magnesium alloy particles by mechanical grinding for 72 h. With an increase in milling time to 240 h, the nickel clusters or particles disappeared and a new monophase alloy with amorphous structure was formed. The electrochemical capacity of the modified material significantly increased with increasing milling time within 72 h and then dropped to nearly nil when the milling time reached 240 h. The capacity decay, however, was always improved with increasing grinding time. Further analysis and discussion were made based on d.c. polarization and a.c. impedance spectroscopy measurement results.

  6. The microstructure, mechanical and friction properties of protective diamond like carbon films on magnesium alloy

    NASA Astrophysics Data System (ADS)

    Zou, Y. S.; Wu, Y. F.; Yang, H.; Cang, K.; Song, G. H.; Li, Z. X.; Zhou, K.

    2011-12-01

    Protective hard coatings deposited on magnesium alloys are believed to be effective for overcoming their poor wear properties. In this work, diamond-like carbon (DLC) films as hard protective films were deposited on AZ91 magnesium alloy by arc ion plating under negative pulse bias voltages ranging from 0 to -200 V. The microstructure, composition and mechanical properties of the DLC films were analyzed by scanning electron microscopy, Raman spectroscopy, X-ray photoelectron spectroscopy and nanoindentation. The tribological behavior of uncoated and coated AZ91 magnesium alloy was investigated using a ball-on-disk tribotester. The results show that the negative pulse bias voltage used for film deposition has a significant effect on the sp3 carbon content and mechanical properties of the deposited DLC films. A maximum sp3 content of 33.3% was obtained at -100 V, resulting in a high hardness of 28.6 GPa and elastic modulus of 300.0 GPa. The DLC films showed very good adhesion to the AZ91 magnesium alloy with no observable cracks and delamination even during friction testing. Compared with the uncoated AZ91 magnesium alloy, the magnesium alloy coated with DLC films exhibits a low friction coefficient and a narrow, shallow wear track. The wear resistance and surface hardness of AZ91 magnesium alloy can be significantly improved by coating a layer of DLC protective film due to its high hardness and low friction coefficient.

  7. Modeling the strength and ductility of magnesium alloys containing nanotwins

    SciTech Connect

    Gorti, Sarma B [ORNL; Radhakrishnan, Balasubramaniam [ORNL

    2013-01-01

    Magnesium alloys have been receiving much attention recently as potential lightweight alternatives to steel for automotive and other applications, but the poor formability of these alloys at low temperatures has limited their widespread adoption for automotive applications. Recent work with face centered cubic (FCC) materials has shown that introduction of twins at the nanometer scale in ultra-fine grained FCC polycrystals can provide significant increase in strength with a simultaneous improvement in ductility. This objective of this work is to explore the feasibility of extending this concept to hexagonal close packed (HCP) materials, with particular focus on using this approach to increase both strength and ductility of magnesium alloys. A crystal plasticity based finite element (CPFE) model is used to study the effect of varying the crystallographic texture and the spacing between the nanoscale twins on the strength and ductility of HCP polycrystals. Deformation of the material is assumed to occur by crystallographic slip, and in addition to the basal and prismatic slip systems, slip is also assumed to occur on the {1 0 -1 1} planes that are associated with compression twins in these materials. The slip system strength of the pyramidal systems containing the nanotwins is assumed to be much lower than the strength of the other systems, which is assumed to scale with the spacing between the nanotwins. The CPFE model is used to compute the stress-strain response for different microstrucrutral parameters, and a criterion based on a critical slip system shear strain and a critical hydrostatic stress is used to compute the limiting strength and ductility, with the ultimate goal of identifying the texture and nanotwin spacing that can lead to the optimum values for these parameters.

  8. Finite element analyses for optimization design of biodegradable magnesium alloy stent.

    PubMed

    Li, Junlei; Zheng, Feng; Qiu, Xun; Wan, Peng; Tan, Lili; Yang, Ke

    2014-09-01

    Stents made of biodegradable magnesium alloys are expected to provide a temporary opening into a narrowed arterial vessel until it remodels and will progressively disappear thereafter. Inferior mechanical properties and fast corrosion of the magnesium alloys are the two crucial factors that impede the clinical application of the magnesium alloy stents (MAS). In the present study, gradual strut width, addition of the peak-to-valley unit and introduction of the annealing technology were designed and investigated by finite element analysis in order to improve the performance of the MAS. Two experiments were carried out for a preliminary validation of the simulation. PMID:25063172

  9. Biofunctionalized anti-corrosive silane coatings for magnesium alloys.

    PubMed

    Liu, Xiao; Yue, Zhilian; Romeo, Tony; Weber, Jan; Scheuermann, Torsten; Moulton, Simon; Wallace, Gordon

    2013-11-01

    Biodegradable magnesium alloys are advantageous in various implant applications, as they reduce the risks associated with permanent metallic implants. However, a rapid corrosion rate is usually a hindrance in biomedical applications. Here we report a facile two step procedure to introduce multifunctional, anti-corrosive coatings on Mg alloys, such as AZ31. The first step involves treating the NaOH-activated Mg with bistriethoxysilylethane to immobilize a layer of densely crosslinked silane coating with good corrosion resistance; the second step is to impart amine functionality to the surface by treating the modified Mg with 3-amino-propyltrimethoxysilane. We characterized the two-layer anticorrosive coating of Mg alloy AZ31 by Fourier transform infrared spectroscopy, static contact angle measurement and optical profilometry, potentiodynamic polarization and AC impedance measurements. Furthermore, heparin was covalently conjugated onto the silane-treated AZ31 to render the coating haemocompatible, as demonstrated by reduced platelet adhesion on the heparinized surface. The method reported here is also applicable to the preparation of other types of biofunctional, anti-corrosive coatings and thus of significant interest in biodegradable implant applications. PMID:23313945

  10. Cellular response of chondrocytes to magnesium alloys for orthopedic applications

    PubMed Central

    LIAO, YI; XU, QINGLI; ZHANG, JIAN; NIU, JIALING; YUAN, GUANGYIN; JIANG, YAO; HE, YAOHUA; WANG, XINLING

    2015-01-01

    In the present study, the effects of Mg-Nd-Zn-Zr (JDBM), brushite (CaHPO4·2H2O)-coated JDBM (C-JDBM), AZ31, WE43, pure magnesium (Mg) and Ti alloy (TC4) on rabbit chondrocytes were investigated in vitro. Adhesion experiments revealed the satisfactory morphology of chondrocytes on the surface of all samples. An indirect cytotoxicity test using MTT assay revealed that C-JDBM and TC4 exhibited results similar to those of the negative control, better than those obtained with JDBM, AZ31, WE43 and pure Mg (p<0.05). There were no statistically significant differences observed between the JDBM, AZ31, WE43 and pure Mg group (p>0.05). The results of indirect cell cytotoxicity and proliferation assays, as well as those of apoptosis assay, glycosaminoglycan (GAG) quantification, assessment of collagen II (Col II) levels and RT-qPCR revealed a similar a trend as was observed with MTT assay. These findings suggested that the JDBM alloy was highly biocompatible with chondrocytes in vitro, yielding results similar to those of AZ31, WE43 and pure Mg. Furthermore, CaHPO4·2H2O coating significantly improved the biocompatibility of this alloy. PMID:25975216

  11. Cellular response of chondrocytes to magnesium alloys for orthopedic applications.

    PubMed

    Liao, Yi; Xu, Qingli; Zhang, Jian; Niu, Jialing; Yuan, Guangyin; Jiang, Yao; He, Yaohua; Wang, Xinling

    2015-07-01

    In the present study, the effects of Mg-Nd-Zn-Zr (JDBM), brushite (CaHPO4·2H2O)-coated JDBM (C-JDBM), AZ31, WE43, pure magnesium (Mg) and Ti alloy (TC4) on rabbit chondrocytes were investigated in vitro. Adhesion experiments revealed the satisfactory morphology of chondrocytes on the surface of all samples. An indirect cytotoxicity test using MTT assay revealed that C?JDBM and TC4 exhibited results similar to those of the negative control, better than those obtained with JDBM, AZ31, WE43 and pure Mg (p<0.05). There were no statistically significant differences observed between the JDBM, AZ31, WE43 and pure Mg group (p>0.05). The results of indirect cell cytotoxicity and proliferation assays, as well as those of apoptosis assay, glycosaminoglycan (GAG) quantification, assessment of collagen ? (Col ?) levels and RT-qPCR revealed a similar a trend as was observed with MTT assay. These findings suggested that the JDBM alloy was highly biocompatible with chondrocytes in vitro, yielding results similar to those of AZ31, WE43 and pure Mg. Furthermore, CaHPO4·2H2O coating significantly improved the biocompatibility of this alloy. PMID:25975216

  12. Influence of surface roughness on the corrosion behaviour of magnesium alloy

    Microsoft Academic Search

    R. Walter; M. Bobby Kannan

    2011-01-01

    In this study, the influence of surface roughness on the passivation and pitting corrosion behaviour of AZ91 magnesium alloy in chloride-containing environment was examined using electrochemical techniques. Potentiodynamic polarisation and electrochemical impedance spectroscopy tests suggested that the passivation behaviour of the alloy was affected by increasing the surface roughness. Consequently, the corrosion current and the pitting tendency of the alloy

  13. Simulation of Stresses during Casting of Binary Magnesium-Aluminum Alloys

    E-print Network

    Beckermann, Christoph

    Simulation of Stresses during Casting of Binary Magnesium-Aluminum Alloys M.G. POKORNY, C.A. MONROE forces measured during casting of two binary Mg-Al alloys. Force measurements from castings that did been developed to simulate the deformations occurring during casting of metal alloys and to ulti

  14. Finite Element Simulation Of Magnesium AZ31 Alloy Sheet In Warm Hydroforming

    Microsoft Academic Search

    Mikkel Steffensen; Joachim Danckert

    2007-01-01

    Hydroforming of magnesium (Mg) alloy sheet metal offers the possibility to form geometrically complex sheet metal parts that are applicable within automotive and electronic industry etc. However, due to the limited formability of Mg alloy at ambient temperature hydroforming of Mg alloy sheet metal has to be conducted at elevated temperature. In the present study an experimental warm hydroforming process

  15. Binary Magnesium Alloys: Searching for Novel Compounds by Computational Thermodynamics

    NASA Astrophysics Data System (ADS)

    Taylor, Richard; Curtarolo, Stefano; Hart, Gus

    2011-03-01

    Magnesium alloys are among the lightest structural materials and are of considerable technical interest. We use the high-throughput framework AFLOW to make T = 0 K ground state predictions by scanning a large set of known candidate structures for thermodynamic minima. The study presented here encompasses 34 Mg-X systems of interest (X=Al, Au, Ca, Cd, Cu, Fe, Ge, Hg, Ir, K, La, Pb, Pd, Pt, Mo, Na, Nb, Os, Rb, Re, Rh, Ru, Sc, Si, Sn, Sr, Ta, Tc, Ti, V, W, Y, Zn, Zr). Avenues for further investigation revealed by this study include stable phases found in addition to experimental phases and compound forming systems thought to be either immiscible or non-compound forming. The existence of potentially novel ordered phases presents new opportunities for materials design.

  16. Electrochemical Characteristics of AZ31 Magnesium Alloys with Microarc Oxidation Coating Alycia Berman1

    E-print Network

    Zhou, Yaoqi

    Electrochemical Characteristics of AZ31 Magnesium Alloys with Microarc Oxidation Coating Alycia of Engineering and Technology, IUPUI When considering implantable biomaterials, one possible solution that has taken to find appropriate coatings. One possibility is microarc oxidation (MAO) coating. However

  17. Microstructure and corrosion resistance of Ce-V conversion coating on AZ31 magnesium alloy

    NASA Astrophysics Data System (ADS)

    Jiang, Xiao; Guo, Ruiguang; Jiang, Shuqin

    2015-06-01

    A Ce-V conversion coating was developed to improve the corrosion resistance of AZ31 magnesium alloy. Scanning electronic microscope (SEM), energy dispersive X-ray spectroscopy (EDS), X-ray photoelectron spectrometer (XPS), grazing incidence X-ray diffraction (GIXRD) and the ball cratering test were adopted to study the morphology, chemical composition, structure and thickness of the coating. The coating has duplex structure with network and its thickness is about 2 ?m. The coating contains high contents of Ce and V, which exhibits amorphous structure. Potentiodynamic polarization shows the coating can increase the corrosion potential and reduce the corrosion current density of AZ31 magnesium alloy. Moreover, the electrochemical impedance spectra exhibit the coating significantly improves the corrosion resistance of AZ31 magnesium alloy. Results indicate that the Ce-V conversion coating can provide effective protection to AZ31 magnesium alloy.

  18. 62 FR 48607 - Pure and Alloy Magnesium From Canada; Final Results of the Second (1993) Countervailing Duty...

    Federal Register 2010, 2011, 2012, 2013, 2014

    1997-09-16

    ...NHCI's forecasted usage. The water contract and the credit are...relieved NHCI from paying its water bills, a countervailable...Duty Administrative Reviews: Pure Magnesium and Alloy Magnesium...subsidies according to their characteristics. For example, in the...

  19. A study on stress corrosion cracking and hydrogen embrittlement of AZ31 magnesium alloy

    Microsoft Academic Search

    R. G. Song; C. Blawert; W. Dietzel; A. Atrens

    2005-01-01

    The stress corrosion cracking (SCC) behavior and pre-exposure embrittlement of AZ31 magnesium alloy have been studied by slow strain rate tensile (SSRT) tests in this paper. It is showed that AZ31 sheet material is susceptible to SCC in distilled water, ASTM D1387 solution, 0.01M NaCl and 0.1M NaCl solution. The AZ31 magnesium alloy also becomes embrittled if pre-exposed to 0.01M

  20. Evaluation of sliding wear behavior of graphite particle-containing magnesium alloy composites

    Microsoft Academic Search

    Qing-ju QI

    2006-01-01

    The influence of graphite particle content on the friction and wear characteristics of AZ91 magnesium alloy matrix composite was studied. The results show that the wear resistances of graphite-containing composite are much better than those of the matrix under the test conditions. The anti-wear ability of magnesium alloy composite is improved substantially with the increase of the graphite content from

  1. Preparation and corrosion resistance studies of zirconia coating on fluorinated AZ91D magnesium alloy

    Microsoft Academic Search

    Qing Li; Xiankang Zhong; Junying Hu; Wei Kang

    2008-01-01

    Novel anti-corrosion zirconia coating was prepared via the sol–gel method for AZ91D magnesium alloy using zirconium nitrate hydrate as a precursor modified with acetylacetone (AcAc). Magnesium alloy substrates were first fluorinated in 20% HF aqueous solution at room temperature for 20h, then, the zirconia coating was deposited on the fluorinated sample by dip coating. Basing on the sol–gel process, a

  2. Novel hybrid sol–gel coatings for corrosion protection of AZ31B magnesium alloy

    Microsoft Academic Search

    S. V. Lamaka; M. F. Montemor; A. F. Galio; M. L. Zheludkevich; C. Trindade; L. F. Dick; M. G. S. Ferreira

    2008-01-01

    This work aims to develop and study new anticorrosion films for AZ31B magnesium alloy based on the sol–gel coating approach.Hybrid organic–inorganic sols were synthesized by copolymerization of epoxy-siloxane and titanium or zirconium alkoxides. Tris(trimethylsilyl) phosphate was also used as additive to confer additional corrosion protection to magnesium-based alloy. A sol–gel coating, about 5-?m thick, shows good adhesion to the metal

  3. Microstructure of a pressure die cast magnesium—4wt.% aluminium alloy modified with rare earth additions

    Microsoft Academic Search

    G. Pettersen; H. Westengen; R. Høier; O. Lohne

    1996-01-01

    Addition of cerium-rich mixtures of rare earth (RE) elements to aluminium-containing magnesium pressure die cast alloys is known to improve the creep properties at elevated temperatures. In the present investigation, a detailed description of the microstructure of a magnesium-4 wt.% aluminium alloy containing 1.4 wt.% of a cerium-rich mixture of RE elements is presented. Particle types occurring and their distribution

  4. Fatigue behaviour of friction stir processed AZ91 magnesium alloy produced by high pressure die casting

    Microsoft Academic Search

    P.. Cavaliere; P. P. De Marco

    2007-01-01

    The room temperature fatigue properties of AZ91 magnesium alloy produced by high pressure die casting (HPDC) as cast, heat treated, friction stir processed (FSP) and FSP and heat treated were studied. The fatigue properties of the material were evaluated for the HPDC magnesium alloy in the as-received state and after a solution treatment at 415 °C for 2 h and an ageing

  5. Surface nanocrystallization and its properties of a rare earth magnesium alloy induced by HVOF–SMB

    Microsoft Academic Search

    Kai-Dong Xu; Ji-Na Wang; Ai-Hua Wang; Hua Yan; Xiang-Lin Zhang; Zao-Wen Huang

    2011-01-01

    The nanocrystalline microstructure in the surface of a rare earth magnesium alloy induced by a new process named HVOF–SMB (high velocity oxygen-fuel flame supersonic microparticles bombarding) has been characterized by means of X-ray diffractometry (XRD) and high-resolution transmission electron microscopy (HRTEM). The effects of HVOF–SMB on mechanical properties and corrosion resistance of the magnesium alloy have been investigated by microhardness

  6. Low-Cycle Fatigue Deformation Behavior and Evaluation of Fatigue Life on Extruded Magnesium Alloys

    Microsoft Academic Search

    K. Shiozawa; J. Kitajima; T. Kaminashi; T. Murai; T. Takahashi

    2011-01-01

    To evaluate fatigue deformation behavior and fatigue life of extruded magnesium alloy, total strain-controlled and stress-controlled low-cycle fatigue test of three extruded magnesium alloys, AZ31, AZ61 and AZ80, were performed in ambient atmosphere at room temperature using smooth round bar specimen. Mean tensile stress during total strain-controlled fatigue process and mean compressive strain during stress-controlled fatigue process appeared due to

  7. Oxide Film and Porosity Defects in Magnesium Alloy AZ91

    SciTech Connect

    Wang, Liang [Mississippi State University (MSU); Rhee, Hongjoo [Mississippi State University (MSU); Felicelli, Sergio D. [Mississippi State University (MSU); Sabau, Adrian S [ORNL; Berry, John T. [Mississippi State University (MSU)

    2009-01-01

    Porosity is a major concern in the production of light metal parts. This work aims to identify some of the mechanisms of microporosity formation in magnesium alloy AZ91. Microstructure analysis was performed on several samples obtained from gravity-poured ingots in graphite plate molds. Temperature data during cooling was acquired with type K thermocouples at 60 Hz at three locations of each casting. The microstructure of samples extracted from the regions of measured temperature was then characterized with optical metallography. Tensile tests and conventional four point bend tests were also conducted on specimens cut from the cast plates. Scanning electron microscopy was then used to observe the microstructure on the fracture surface of the specimens. The results of this study revealed the existence of abundant oxide film defects, similar to those observed in aluminum alloys. Remnants of oxide films were detected on some pore surfaces, and folded oxides were observed in fracture surfaces indicating the presence of double oxides entrained during pouring.

  8. Ultrastrong Magnesium Alloy via Nano-Spaced Stacking Faults

    NASA Astrophysics Data System (ADS)

    Jian, Weiwei

    Magnesium and its alloys have attracted extensive attention in recent years due to their abundance, low-density, good castability and recyclability. However, the application of Mg alloys has been substantially hindered by their relatively low strengths and limited ductility at room temperature. Outside of traditional precipitation control, Mg-alloy strengthening typically relies on two general approaches: non-traditional, esoteric processing and grain refinement. Here in this research, we processed a Mg-8.5Gd-2.3Y-1.8Ag-0.4Zr (wt.%) via conventional technique (hot-rolling at 450°C) with thickness reduction up to 88%. The main contents of this research, as well as the novelties, are discussed in the following ways. Firstly, we reported a new mechanism for producing ultrahigh strengths (yield strength: ˜575 MPa, ultimate strength: ˜600 MPa) and maintaining moderate ductility (uniform elongation: ˜ 3% to 4%) in hot rolled Mg-alloy with relatively large grain sizes (13 microm). TEM studies show that a high density of nano-spaced SFs are the main defects inside of the grains and their density increased as rolling thickness reduction increased. The strength of the processed Mg alloy was found to increase as the mean spacing between adjacent SFs decreased. Nano-spaced SFs were found to be very effective in impeding the movement of dislocations and retaining strain hardening. Activation of non-basal dislocations during tensile testing accounts for the detected moderate ductility, in addition to the capability of retaining strain hardening. Secondly, we predicted and calculated contributions from different strengthening mechanisms for the unltrahigh strength of hot rolled Mg alloy including solid solution, grain refinement, precipitation and texture evolution. The results showed that grain boundary strengthening, solid solution hardening, precipitates hardening and strong texture strengthening totally contribute 249.8 MPa to 278.5 MPa for the yield strength (˜575MPa) of 88% rolled Mg alloy. In other words, the nano-spaced SFs strengthening mechanism was the main strengthening factor, which solely contributed 326.2 MPa to 296.5 MPa, around 50% of the total yield strength. Finally, the model of interactions between basal SFs and basal dislocations and non basal dislocations were established for the first time in Mg alloy. The model showed that the strengthening was proportional to the reciprocal of the SF spacing for both types of interactions between dislocations and SFs. Therefore, decreasing the SF spacing can increase interaction force which served as a barrier for a dislocation to move, and consequently improved the macroscopic strength of materials. In summary, introducing nano-spaced SFs in Mg alloy can tremendously impede the movement of dislocations and retain strain hardening. It is expected that optimization of approaches that introduce a high density of nano-spaced SFs will enable other Mg-alloys with concurrent high strength and good ductility.

  9. Cyclic Plasticity Constitutive Model for Uniaxial Ratcheting Behavior of AZ31B Magnesium Alloy

    NASA Astrophysics Data System (ADS)

    Lin, Y. C.; Liu, Zheng-Hua; Chen, Xiao-Min; Long, Zhi-Li

    2015-05-01

    Investigating the ratcheting behavior of magnesium alloys is significant for the structure's reliable design. The uniaxial ratcheting behavior of AZ31B magnesium alloy is studied by the asymmetric cyclic stress-controlled experiments at room temperature. A modified kinematic hardening model is established to describe the uniaxial ratcheting behavior of the studied alloy. In the modified model, the material parameter m i is improved as an exponential function of the maximum equivalent stress. The modified model can be used to predict the ratcheting strain evolution of the studied alloy under the single-step and multi-step asymmetric stress-controlled cyclic loadings. Additionally, due to the significant effect of twinning on the plastic deformation of magnesium alloy, the relationship between the material parameter m i and the linear density of twins is discussed. It is found that there is a linear relationship between the material parameter m i and the linear density of twins induced by the cyclic loadings.

  10. Research of {0001} crystal orientation for magnesium alloys solidified in a fashion of cellular crystals

    NASA Astrophysics Data System (ADS)

    Chang, Guo-Wei; Chen, Shu-Ying; Li, Qing-Chun; Yue, Xu-Dong; Qi, Yi-Hui

    2012-02-01

    The magnesium alloy grew in a fashion of cellular crystals during the process of unidirectional solidification, and the {0001} crystal face orientation in the cast ingot of the magnesium alloy was studied. The theoretical model and methodology were set up, and a corresponding experiment was carried out to verify the theoretical analysis results. The experimental results indicate that the {0001} crystal face of magnesium crystals parallels to the width direction for the thin-plate cast ingot when the magnesium grows in a manner of cellular crystals. The separation angle between the {0001} crystal face of magnesium crystals and the vertical axis line of the cast ingot is about 62° for the circular column cast ingot, which distributes in cone-type. The theoretical analysis results are basically in agreement with the experimental ones of previous literatures and this paper.

  11. Effects of strain rate, temperature and sheet thickness on yield locus of AZ31 magnesium alloy sheet

    Microsoft Academic Search

    Tetsuo Naka; Takeshi Uemori; Ryutaro Hino; Masahide Kohzu; Kenji Higashi; Fusahito Yoshida

    2008-01-01

    Magnesium alloys usually exhibit low ductility at the room temperature due to its hexagonal close-packed structure, but it will be improved at elevated temperature. Therefore, warm press-forming of magnesium alloy sheets is quite attractive. In order to determine the optimum condition of press-forming for magnesium alloy sheets, in the present work, the effects of strain rate, temperature and sheet thickness

  12. Effect of fetal calf serum on the corrosion behaviour of magnesium alloys

    Microsoft Academic Search

    H. Hornberger; F. Witte; N. Hort; W.-D. Mueller

    2011-01-01

    The corrosion behaviour of WE43 magnesium alloys using the mini cell system was studied. Voltammetry and impedance spectroscopy were applied to study on the one hand the effect of microstructure of the working electrode and on the other hand the effect of proteins in the electrolyte. Two types of alloy samples were produced (i) by permanent mould casting and (ii)

  13. Dry sliding wear behaviour of plasma electrolytic oxidation coated AZ91 cast magnesium alloy

    Microsoft Academic Search

    P. Bala Srinivasan; C. Blawert; W. Dietzel

    2009-01-01

    A cast AZ91 magnesium alloy was plasma electrolytic oxidation (PEO) coated using a pulsed unipolar power source in a silicate based electrolyte. Constant processing conditions for two different durations were chosen to obtain coatings of 10 and 20?m thickness. The dry sliding wear studies performed on this alloy with and without PEO coatings against an AISI 52100 steel ball counterpart

  14. Superplastic Response of Continuously Cast AZ31B Magnesium Sheet Alloys

    NASA Astrophysics Data System (ADS)

    Boileau, J. M.; Friedman, P. A.; Houston, D. Q.; Luckey, S. G.

    2010-06-01

    Magnesium sheet is typically produced for commercial applications with the traditional DC-ingot casting method. As a result of the hexagonal close-packed crystallographic structure in magnesium, multiple rolling passes and annealing steps are required to reduce the thickness of the ingots. Thus, high fabrication costs characterize the creation of magnesium sheet suitable for common forming operations. Recently, continuous casting (CC) technology, where molten metal is solidified directly into sheet form, has been applied to magnesium alloys; this method has shown the potential to significantly reduce the cost of fabricating magnesium sheet alloys. In order to understand the viability of the CC process, a study was conducted to investigate the superplastic potential of alloys produced by this method. This study focused on AZ31B Mg that was continuously-cast on twin-roll casters from three different suppliers. These three materials were compared with a production DC-cast AZ31B alloy in terms of microstructure, elevated-temperature tensile properties, and superplastic forming response. The data from this study found that microstructural features such as grain size and segregation can significantly affect the forming response. Additionally, the CC alloys can have equivalent or superior SPF response compared to DC-cast alloys, as demonstrated in both elevated temperature tensile tests and superplastic forming trials using a rectangular pan die.

  15. Investigation of the antimicrobial activity and biocompatibility of magnesium alloy coated with HA and antimicrobial peptide.

    PubMed

    Tian, Jinhuan; Shen, Si; Zhou, Changren; Dang, Xiangli; Jiao, Yanpeng; Li, Lihua; Ding, Shan; Li, Hong

    2015-02-01

    Implant-associated infection is one of the biggest problems in orthopedic surgery. Antimicrobial peptides (AMPs) are well-known components of the innate immunity and less susceptible to the development of pathogen resistance compared to conventional antibiotics. Magnesium alloys as potential biodegradable bone implants have been received much attention in biomaterials field. This study investigated the deposition of calcium phosphate (CaP) coatings and loading of AMPs on the magnesium alloy surface by a biomimetic method. Scanning electron microscope (SEM) results presented that a microporous and plate-like CaP coating was processed on the magnesium alloy surface. X-ray diffractometry (XRD) and Fourier transform infrared spectroscopy (FTIR) analysis showed the main component of coating was hydroxyapatite (HA). Degradation assay in vitro showed that the HA coating deposited onto the magnesium alloy was corroded more slowly than the bare one. The amount of AMP loaded in the HA coating was 11.16±1.99 ?g/cm2. The AMP loaded onto HA coatings had slow release for 7 days. The AMP-loaded coating showed antimicrobial activity against Staphylococcus aureus. Its bacterial inhibition rate exceeded 50% after 4 days and the antibacterial effect was sustained for 7 days. The coated magnesium alloys loaded with AMP could improve rat bone marrow mesenchymal stem cells (rBMMSCs) proliferation. Furthermore, it could also promote alkaline phosphatase (ALP) activity of rBMMSCs. Both radiographic evaluation and histopathology analysis demonstrated that implantation of the coated magnesium alloy into the rabbit femoral condyle had promoted bone repair and showed anti-inflammatory effect. The results showed that the AMP loaded onto HA coatings on the magnesium alloy surface could be considered an ideal orthopedic implant against S. aureus infection. PMID:25631264

  16. The influence of surface microchemistry in protective film formation on multi-phase magnesium alloys

    NASA Astrophysics Data System (ADS)

    Gray-Munro, J. E.; Luan, B.; Huntington, L.

    2008-02-01

    The high strength:weight ratio of magnesium alloys makes them an ideal metal for automotive and aerospace applications where weight reduction is of significant concern. Unfortunately, magnesium alloys are highly susceptible to corrosion particularly in salt-spray conditions. This has limited their use in the automotive and aerospace industries, where exposure to harsh service conditions is unavoidable. The simplest way to avoid corrosion is to coat the magnesium-based substrate by a process such as electroless plating, which is a low-cost, non line of sight process. Magnesium is classified as a difficult to plate metal due to its high reactivity. This means that in the presence of air magnesium very quickly forms a passive oxide layer that must be removed prior to plating. Furthermore, high aluminium content alloys are especially difficult to plate due to the formation of intermetallic species at the grain boundaries, resulting in a non-uniform surface potential across the substrate and thereby further complicating the plating process. The objective of this study is to understand how the magnesium alloy microstructure influences the surface chemistry of the alloy during both pretreatment and immersion copper coating of the substrate. A combination of scanning electron microscopy, energy dispersive spectroscopy and scanning Auger microscopy has been used to study the surface chemistry at the various stages of the coating process. Our results indicate that the surface chemistry of the alloy is different on the aluminum rich ? phase of the material compared to the magnesium matrix which leads to preferential deposition of the metal on the aluminum rich phase of the alloy.

  17. In vitro degradation behaviour of a friction stir processed magnesium alloy.

    PubMed

    Bobby Kannan, M; Dietzel, W; Zettler, R

    2011-11-01

    In this study, the in vitro degradation behaviour of a friction stir processed AZ31 magnesium alloy was investigated. Electrochemical experiments in simulated body fluid suggest that friction stir processing marginally enhances the degradation resistance of the alloy, which could be attributed to the dissolution of secondary phase particles. Homogenisation of the microstructure reduces galvanic corrosion. It is envisaged that the beneficial effect would be more pronounced for magnesium alloys which contain high volume fraction of galvanic corrosion inducing secondary phase particles. PMID:21894540

  18. Warm Deep Drawing Of Rectangular Cups With Magnesium Alloy AZ31 Sheets

    SciTech Connect

    Ren, L. M. [Department of Mechanical and Management Engineering (DIMeG), Polytechnic of Bari, 70126 Bari (Italy); Institute of Metal Research, Chinese Academy of Sciences, 110016 Shenyang (China); Palumbo, G.; Tricarico, L. [Department of Mechanical and Management Engineering (DIMeG), Polytechnic of Bari, 70126 Bari (Italy); Zhang, S. H. [Institute of Metal Research, Chinese Academy of Sciences, 110016 Shenyang (China)

    2007-05-17

    Recently, magnesium alloys have been widely applied in automotive and electronic industries as the lightest weight structural and functional materials. Warm forming of magnesium alloys has attracted much attention due to the very poor formability of Mg alloys at room temperature. The formability of magnesium alloy sheet at elevated temperature is significantly affected by the processing parameters. Among them the forming temperature, the punch speed, the geometrical shape of the blank, the blank holder force and the lubrication are probably the most relevant. In this research, the deep drawing of rectangular cups with AZ31 sheets was conducted at elevated temperatures with different process parameters. The finite element analyses were performed to investigate the effects of the process parameters on the formability of rectangular cup drawing and to predict the process defects during the process. The material yield condition was modeled using the isotropic Von Mises criterion. The flow stress data were obtained from tensile tests.

  19. Application of YAG Laser TIG Arc Hybrid Welding to Thin AZ31B Magnesium Alloy Sheet

    NASA Astrophysics Data System (ADS)

    Kim, Taewon; Kim, Jongcheol; Hasegawa, Yu; Suga, Yasuo

    A magnesium alloy is said to be an ecological material with high ability of recycling and lightweight property. Especially, magnesium alloys are in great demand on account of outstanding material property as a structural material. Under these circumstances, research and development of welding process to join magnesium alloy plates are of great significance for wide industrial application of magnesium. In order to use it as a structure material, the welding technology is very important. TIG arc welding process is the most ordinary process to weld magnesium alloy plates. However, since the heat source by the arc welding process affects the magnesium alloy plates, HAZ of welded joint becomes wide and large distortion often occurs. On the other hand, a laser welding process that has small diameter of heat source seems to be one of the possible means to weld magnesium alloy in view of the qualitative improvement. However, the low boiling point of magnesium generates some weld defects, including porosity and solidification cracking. Furthermore, precise edge preparation is very important in butt-welding by the laser welding process, due to the small laser beam diameter. Laser/arc hybrid welding process that combines the laser beam and the arc is an effective welding process in which these two heat sources influence and assist each other. Using the hybrid welding, a synegistic effect is achievable and the disadvantages of the respective processes can be compensated. In this study, YAG laser/TIG arc hybrid welding of thin magnesium alloy (AZ31B) sheets was investigated. First of all, the effect of the irradiation point and the focal position of laser beam on the quality of a weld were discussed in hybrid welding. Then, it was confirmed that a sound weld bead with sufficient penetration is obtained using appropriate welding conditions. Furthermore, it was made clear that the heat absorption efficiency is improved with the hybrid welding process. Finally, the tensile tests of welded joints were performed, and it was confirmed that they have sufficient mechanical properties. As a result of this study, it is confirmed that, if the appropriate welding conditions are selected, sound welded joints of AZ31B magnesium alloy are obtainable by the YAG laser/TIG arc hybrid welding process.

  20. Effect of hot working on the damping capacity and mechanical properties of AZ31 magnesium alloy

    NASA Astrophysics Data System (ADS)

    Lee, K.; Kang, C.; Kim, K.

    2015-04-01

    Magnesium alloys have received much attention for their lightweight and other excellent properties, such as low density, high specific strength, and good castability, for use in several industrial and commercial applications. However, both magnesium and its alloys show limited room-temperature formability owing to the limited number of slip systems associated with their hexagonal close-packed crystal structure. It is well known that crystallographic texture plays an important role in both plastic deformation and macroscopic anisotropy of magnesium alloys. Many authors have concentrated on improving the room- temperature formability of Mg alloys. However, despite having a lot of excellent properties in magnesium alloy, the study for various properties of magnesium alloy have not been clarified enough yet. Mg alloys are known to have a good damping capacity compared to other known metals and their alloys. Also, the damping properties of metals are generally recognized to be dependent on microstructural factors such as grain size and texture. However, there are very few studies on the relationship between the damping capacity and texture of Magnesium alloys. Therefore, in this study, specimens of the AZ31 magnesium alloy, were processed by hot working, and their texture and damping property investigated. A 60 mm × 60 mm × 40 mm rectangular plate was cut out by machining an ingot of AZ31 magnesium alloy (Mg-3Al-1Zn in mass%), and rolling was carried out at 673 K to a rolling reduction of 30%. Then, heat treatment was carried out at temperatures in the range of 573-723 K for durations in the range of 30-180 min. The samples were immediately quenched in oil after heat treatment to prevent any change in the microstructure. Texture was evaluated on the compression planes by the Schulz reflection method using nickel-filtered Cu K? radiation. Electron backscatter diffraction measurements were conducted to observe the spatial distribution of various orientations. Specimens for damping capacity measurements were machined from the rolled specimen, to have a length of 120 mm, width of 20 mm, and thickness of 1 mm. The damping capacity was measured with a flexural internal friction measurement machine at room temperature. It was found that the damping capacity increases with both increasing heat-treatment temperature and time, due to grain growth and the increased pole densities of textures.

  1. Analyses of deformation twinning in the extruded magnesium alloy AZ31 after compressive and cyclic loading

    Microsoft Academic Search

    Michael Huppmann; Martin Lentz; Sarkis Chedid; Walter Reimers

    2011-01-01

    The influence of different loading conditions on the microstructural development of extruded magnesium alloy AZ31 was investigated\\u000a by optical microscopy and electron backscattered diffraction. Extruded magnesium profiles exhibit a significant asymmetry\\u000a in the mechanical properties, due to the low activation energy of the extension twinning system $$ \\\\left\\\\{ {10\\\\overline{1} 2} \\\\right\\\\}\\\\langle {10\\\\overline{1} 1}\\\\rangle,$$ when compressing along the extrusion direction. For

  2. 62 FR 48812 - Pure and Alloy Magnesium From Canada; Final Results of the Fourth (1995) Countervailing Duty...

    Federal Register 2010, 2011, 2012, 2013, 2014

    1997-09-17

    ...Less Than Fair Value: Pure and Alloy Magnesium From...Exemption from Payment of Water Bills In the Preliminary...To the extent that the water credit relieved NHCI from paying its water bills, a countervailable...Administrative Reviews: Pure Magnesium and Alloy...

  3. Influence of shot peening on high cycle fatigue properties of the high-strength wrought magnesium alloy AZ80

    Microsoft Academic Search

    P. Zhang; J. Lindemann

    2005-01-01

    The influence of shot peening on fatigue performance of the high-strength wrought magnesium alloy AZ80 was investigated. Shot peening effectively improved the fatigue life: an improvement of 60% in the fatigue strength was obtained at the optimum condition. In addition, the magnesium alloy reacted sensitively to shot peening. This sensitivity was attributed to the limited deformability of the hexagonal crystal

  4. [Research on the mechanical properties of bone scaffold reinforced by magnesium alloy/bioceramics composite with stereolithography double channels].

    PubMed

    Li, Changhai; Lian, Qin; Zhuang, Pei; Wang, Junzhong; Li, Dichen

    2015-02-01

    Focusing on the poor mechanical strength of porous bioceramics bone scaffold, and taking into account of the good mechanical properties of biodegradable magnesium alloy, we proposed a novel method to fabricate magnesium alloy/bioceramics composite bone scaffold with stereolithography double channels. Firstly, a scaffold structure without mutually connected double channels was designed. Then, an optimized bioceramics scaffold was fabricated according to stereolithography and gel-casing. Molten AZ31 magnesium alloy was perfused into the secondary channel of scaffold by low-pressure casting, and magnesium alloy/bioceramics composite bone scaffold was obtained when magnesium alloy was solidified. The compression test showed that the strength of bioceramics scaffold with only one channel and without magnesium alloy was (9.76 ± 0.64) MPa, while the strength of magnesium alloy/bioceramics composite scaffold with double channels was (17.25 ± 0.88) MPa. It can be concluded that the magnesium alloy/bioceramics composite is obviously able to improve the scaffold strength. PMID:25997270

  5. Numerical analysis of self-pierce riveting of AZ31 magnesium alloy sheets

    NASA Astrophysics Data System (ADS)

    Han, S. L.; Wu, Y. W.; Zeng, Q. L.; Gao, Y.

    2013-05-01

    Magnesium alloy sheet has a broad development prospect for lightweight metal in automotive industry. Selfpierce Riveting (SPR) process is a suitable joining technology to fasten materials of different nature. This paper is concerned with the development of numerical models of the SPR process of AZ31 magnesium alloy sheet. Based on DEFORM-2D finite element software, a two-dimensional axisymmetric model has been built for the SPR process. Then the distribution of stress and strain, and the stroke-load curve are analyzed in the forming process of the riveting. After a 2D simulation of SPR process, the quality of riveted joint is evaluated in terms of joint cross-sectional shape. The results show a better understanding of mechanical properties of SPR joints of magnesium alloy sheets. As a sufficient interlock and bottom thickness leading to a reasonably good joint, the numerical simulation method plays a significant role to predict the final strength of the joint.

  6. Preparation and properties of super-hydrophobic coating on magnesium alloy

    NASA Astrophysics Data System (ADS)

    Yin, Bo; Fang, Liang; Hu, Jia; Tang, An-Qiong; Wei, Wen-Hou; He, Jiang

    2010-12-01

    The super-hydrophobic coating was successfully fabricated on the surface of magnesium alloy AZ31 by chemical etching and surface modification. The surface morphologies, compositions, wettability and corrosion resistance of the coating were investigated with SEM, XPS, contact angle measurement and electrochemical method, respectively. It shows that the rough and porous micro-nano-structure was presented on the surface of magnesium alloy, and the contact angle could reach up to 157.3 ± 0.5° with sliding angle smaller than 10°. The super-hydrophobic coating showed a long service life. The results of electrochemical measurements showed that anticorrosion property of magnesium alloy was improved. The super-hydrophobic phenomenon of the prepared surface was analyzed with Cassie theory, and it finds that only about 10% of the water surface is contacted with the metal substrate and the rest 90% is contacted with the air cushion.

  7. Tribological Behavior of Magnesium Alloy AZ91 Coated with TiN\\/CrN by Arc-glow Plasma Depositing

    Microsoft Academic Search

    Qiang MIAO; Cai-e CUI; Jun-de PAN; Liang-hui DUAN; Ya-ping LIU

    2006-01-01

    With advantages of high specific strength, low elastic module, good damping property et al., the magnesium alloys exhibit great potential applications in aerospace. But poor wear behavior results in limited use of magnesium alloy to static components. In this study, a 2 ?m thick coating with 12 sub-layers of CrN and TiN is deposited alternately on the surface of magnesium

  8. The aluminium-scandium-lithium-magnesium system as a potential source of superplastically formable alloys

    SciTech Connect

    Emigh, R.A.

    1990-07-01

    Alloys from the aluminum-lithium-scandium-magnesium system have been cast and rolled for study. The goal is to evaluate this system for the development of superplastically formable, high strength alloys. Aluminum-scandium-magnesium alloys have shown potential as superplastic alloys. These alloys rely on small Al{sub 3}Sc (ordered L1{sub 2}) precipitates for grain structure stabilization and strengthening. Additional precipitation strengthening is required to raise their strength to levels sufficient for aircraft applications. The addition of lithium provides this additional strengthening through the formation of Al{sub 3}Li({delta}{prime}). To produce the alloys studied in this research, a unique induction melting furnace was constructed that incorporates special features to produce aluminum-lithium alloys with low hydrogen content. The furnace also features a water cooled, copper casting mold to achieve a moderately rapid solidification rate. This is because the amount of scandium used (0.5 wt %) is in excess of the solubility limit and Al{sub 3}Sc cannot be re-solutionized to any extent. It is therefore desired to super-saturate the matrix with as much scandium as possible for later precipitation. Two high lithium alloys were produced, ALS2 (nominal composition Al-2.2Li-O.5 Sc) and AlS4 (nominal composition Al-2.0Li-2.2Mg-0.5Sc) that were strengthened with {delta}{prime} (Al{sub 3}Li). These alloys exhibited strength and ductility superior to those of aluminum-lithium-(magnesium)-zirconium alloys. This is because the scandium containing alloys have developed a finer grain structure and the Al{sub 3}Sc precipitates contribute to the alloys strength. 41 refs., 29 figs.

  9. Development of the high performance magnesium based hydrogen storage alloy

    Microsoft Academic Search

    Mustafa Anik; Fatma Karanfil; Nilüfer Küçükdeveci

    Series of MgNi type alloys with Ti, Al, Zr, Pd and Co additive elements were synthesized by mechanical alloying and their electrochemical hydrogen storage characteristics were investigated. Systematical alloy designing indicated that Mg0.80Ti0.15Al0.05Zr0.05Ni0.95 alloy has the best electrode performance. The atomic fractions in this alloy were believed to be optimum to get the reasonable amount of hydrogen storage with the

  10. Effect of laser surface melting on microstructure and corrosion characteristics of AM60B magnesium alloy

    NASA Astrophysics Data System (ADS)

    Liu, Cancan; Liang, Jun; Zhou, Jiansong; Wang, Lingqian; Li, Qingbiao

    2015-07-01

    Surface modification of laser surface melting (LSM) was applied to the AM60B magnesium alloy using a 10 kW continuous-wave CO2 laser. The microstructure, composition and corrosion resistance of AM60B magnesium alloy after LSM treatment were investigated by using scanning electron microscopy (SEM), energy-dispersive spectroscopy (EDS), X-ray diffraction (XRD) and corrosion tests, respectively. Results showed that the LSM treatment produced a continuous and homogeneous modified layer with refined grains, enriched Al element and redistributed intermetallic compounds on AM60B alloy. The corrosion resistance of the AM60B alloy was enhanced by the LSM treatment. The enhancement of the corrosion resistance was mainly attributed to the reduced corrosion susceptibility of Al enriched ?-Mg matrix and the barrier effect of uniformly distributed ?-phase of the LSM modified layer.

  11. Structure and properties of zirconium-bearing magnesium alloy MA14

    Microsoft Academic Search

    E. F. Volkova; G. I. Morozova

    2006-01-01

    The structure and phase composition of commercial magnesium deformable alloy MA14 are studied as a function of the process\\u000a parameters. The effect of heat treatment on the changes in the structure, phase composition, and mechanical and corrosion\\u000a properties of the alloy is considered. Conditions of formation of ZrZn2 Laves phase are analyzed. The influence of the Laves phase on the

  12. Solidification, growth mechanisms, and associated properties of aluminum-silicon and magnesium lightweight casting alloys

    Microsoft Academic Search

    Timothy Al Hosch

    2010-01-01

    Continually rising energy prices have inspired increased interest in weight reduction in the automotive and aerospace industries, opening the door for the widespread use and development of lightweight structural materials. Chief among these materials are cast Al-Si and magnesium-based alloys. Utilization of Al-Si alloys depends on obtaining a modified fibrous microstructure in lieu of the intrinsic flake structure, a process

  13. An X-ray investigation of hydrogenated Mg–30Al magnesium alloy

    Microsoft Academic Search

    Amjad Saleh El-Amoush

    2007-01-01

    The X-ray diffraction analysis of hydrogenated Mg–30Al magnesium alloy was used to determine the effect hydrogen on phase changes and lattice parameters as well as hydride formation in the investigated alloy. The results of XRD analysis showed that the ?-Mg17Al12 phase was significantly affected by hydrogenation up to 12h causing considerable lattice expansion accompanied by an increase in the interplanar

  14. Eutectic bonding of austenitic stainless steel 316L to magnesium alloy AZ31 using copper interlayer

    Microsoft Academic Search

    Waled M. Elthalabawy; Tahir I. Khan

    2011-01-01

    The eutectic bonding of magnesium alloy (AZ31) to austenitic stainless steel alloy (316L) was performed using pure Cu interlayers.\\u000a The effect of hold time on the microstructural developments across the joint region and the related effect on bond shear strength\\u000a were studied at a bonding temperature of 530°C. The bonding process took place through a sequential occurrence of solid-state\\u000a diffusion

  15. Evaluation of sliding wear behaviour of feldspar particle-reinforced magnesium alloy composites

    Microsoft Academic Search

    S. C Sharma; B Anand; M Krishna

    2000-01-01

    The unlubricated sliding wear behavior of magnesium alloy AZ91 composites reinforced with feldspar particles of size 30–50 ?m was evaluated. The content of feldspar in the alloy was varied from 1% to 5% in steps of 2-wt.%. Liquid metallurgy technique was used to fabricate the composites. A pin-on-disc wear-testing machine was used to evaluate the wear rate, in which an

  16. Electrodeposition of high corrosion resistance Cu\\/Ni–P coating on AZ91D magnesium alloy

    Microsoft Academic Search

    Shan Zhang; Fahe Cao; Linrong Chang; Junjun Zheng; Zhao Zhang; Jianqing Zhang; Chunan Cao

    2011-01-01

    High corrosion resistance Cu\\/Ni–P coatings were electrodeposited on AZ91D magnesium alloy via suitable pretreatments, such as one-step acid pickling-activation, once zinc immersion and environment-friendly electroplated copper as the protective under-layer, which made Ni–P deposit on AZ91D Mg alloy in acid plating baths successfully. The pH value and current density for Ni–P electrodeposition were optimized to obtain high corrosion resistance. With

  17. Microstructure and Microtexture Formation of AZ91D Magnesium Alloys Solidified in a Static Magnetic Field

    Microsoft Academic Search

    Mingjun Li; Takuya Tamura; Kenji Miwa

    2009-01-01

    In the present study, we solidified AZ91D magnesium alloys in a static magnetic field with a magnetic flux density up to 10 Tesla\\u000a (T). Three different regions can be identified in a solidified alloy, according to their microtexture and microstructure;\\u000a these regions are: (a) region (A), the central region with equiaxed dendrites, (b) region (B), the transitional region with\\u000a directional dendrites

  18. Rapid coating of AZ31 magnesium alloy with calcium deficient hydroxyapatite using microwave energy.

    PubMed

    Ren, Yufu; Zhou, Huan; Nabiyouni, Maryam; Bhaduri, Sarit B

    2015-04-01

    Due to their unique biodegradability, magnesium alloys have been recognized as suitable metallic implant materials for degradable bone implants and bioresorbable cardiovascular stents. However, the extremely high degradation rate of magnesium alloys in physiological environment has restricted its practical application. This paper reports the use of a novel microwave assisted coating technology to improve the in vitro corrosion resistance and biocompatibility of Mg alloy AZ31. Results indicate that a dense calcium deficient hydroxyapatite (CDHA) layer was uniformly coated on a AZ31 substrate in less than 10min. Weight loss measurement and SEM were used to evaluate corrosion behaviors in vitro of coated samples and of non-coated samples. It was seen that CDHA coatings remarkably reduced the mass loss of AZ31 alloy after 7days of immersion in SBF. In addition, the prompt precipitation of bone-like apatite layer on the sample surface during immersion demonstrated a good bioactivity of the CDHA coatings. Proliferation of osteoblast cells was promoted in 5days of incubation, which indicated that the CDHA coatings could improve the cytocompatibility of the AZ31 alloy. All the results suggest that the CDHA coatings, serving as a protective layer, can enhance the corrosion resistance and biological response of magnesium alloys. Furthermore, this microwave assisted coating technology could be a promising method for rapid surface modification of biomedical materials. PMID:25686961

  19. Phase compositions in magnesium-rare earth alloys containing yttrium, gadolinium or dysprosium

    Microsoft Academic Search

    P. J. Apps; H. Karimzadeh; J. F. King; G. W. Lorimer

    2003-01-01

    Phase compositions have been investigated, using thin foil energy dispersive X-ray spectroscopy, in three magnesium-rare earth alloys, containing yttrium, gadolinium or dysprosium. Compositions are suggested for the as-cast eutectic and ? precipitate phases and possible compositions for the ?1 precipitate phases are discussed.

  20. Ordered magnesium-lithium alloys: First-principles predictions Richard H. Taylor

    E-print Network

    Hart, Gus

    lithium at certain concentrations.11,12 Binary ordered phases have not been conclusively identified in the HT results and by phases present in experimental phase diagrams Fig. 2 . 0 20 40 60 80 100 -70 -60Ordered magnesium-lithium alloys: First-principles predictions Richard H. Taylor Department

  1. Microstructure and creep behavior of magnesium-aluminum alloys containing alkaline and rare earth additions

    Microsoft Academic Search

    Nicholas David Saddock

    2008-01-01

    In the past few decades governmental regulation and consumer demands have lead the automotive companies towards vehicle lightweighting. Powertrain components offer significant potential for vehicle weight reductions. Recently, magnesium alloys have shown promise for use in powertrain applications where creep has been a limiting factor. These systems are Mg-Al based, with alkaline earth or rare earth additions. The solidification, microstructure,

  2. Novel forging technology of a magnesium alloy impeller with twisted blades of micro-thickness

    Microsoft Academic Search

    J. H. Lee; S. H. Kang; D. Y. Yang

    2008-01-01

    In this work, a novel forging technology has been developed to produce a magnesium alloy impeller with twisted blades of micro-thickness used in a fuel cell system. Due to the very complicated blades of the impeller, a specially designed split die was adopted for successful forging of the impeller. In this split die-set, the coherence of reinforcement ring and split

  3. Effect of deep cryogenic treatment on microstructure, creep and wear behaviors of AZ91 magnesium alloy

    Microsoft Academic Search

    Kaveh Meshinchi Asl; Alireza Tari; Farzad Khomamizadeh

    2009-01-01

    This paper focuses on the effect of deep cryogenic treatment (?196°C) on microstructure and mechanical properties of AZ91 magnesium alloy. The execution of deep cryogenic treatment on samples changed the distribution of ? precipitates. The tiny laminar ? particles almost dissolved in the microstructure and the coarse divorced eutectic ? phase penetrated into the matrix. This microstructural modification resulted in

  4. Modeling of microstructure evolution of magnesium alloy during the high pressure die casting process

    NASA Astrophysics Data System (ADS)

    Wu, Mengwu; Xiong, Shoumei

    2012-07-01

    Two important microstructure characteristics of high pressure die cast magnesium alloy are the externally solidified crystals (ESCs) and the fully divorced eutectic which form at the filling stage of the shot sleeve and at the last stage of solidification in the die cavity, respectively. Both of them have a significant influence on the mechanical properties and performance of magnesium alloy die castings. In the present paper, a numerical model based on the cellular automaton (CA) method was developed to simulate the microstructure evolution of magnesium alloy during cold-chamber high pressure die casting (HPDC) process. Modeling of dendritic growth of magnesium alloy with six-fold symmetry was achieved by defining a special neighbourhood configuration and calculating of the growth kinetics from complete solution of the transport equations. Special attention was paid to establish a nucleation model considering both of the nucleation of externally solidified crystals in the shot sleeve and the massive nucleation in the die cavity. Meanwhile, simulation of the formation of fully divorced eutectic was also taken into account in the present CA model. Validation was performed and the capability of the present model was addressed by comparing the simulated results with those obtained by experiments.

  5. Low-pressure die casting of magnesium alloy AM50: Response to process parameters

    Microsoft Academic Search

    Penghuai Fu; Alan A. Luo; Haiyan Jiang; Liming Peng; Yandong Yu; Chunquan Zhai; Anil K. Sachdev

    2008-01-01

    Low-pressure die casting (LPDC) process has been successfully used to produce sound magnesium alloy AM50 castings. The influence of process parameters: filling time, pressure holding time, die temperature, holding pressure and casting temperature, on the mechanical properties, microstructure and density of LPDC castings were studied. The optimal process parameters for LPDC casting have been experimentally determined as follows: filling time

  6. Superplastic behaviour of friction stir processed AZ91 magnesium alloy produced by high pressure die cast

    Microsoft Academic Search

    P. Cavaliere; P. P. De Marco

    2007-01-01

    The room temperature and hot tensile properties of AZ91 magnesium alloy produced by high pressure die cast after friction stir processing (FSP) were studied in the present paper. Such process is a modification of classical friction stir welding one in which the sheets are not joined but the stirring action of the tool, on the bulk material, is used to

  7. Effect of surface nanocrystallization on the microstructural and corrosion characteristics of AZ91D magnesium alloy

    Microsoft Academic Search

    M. Laleh; Farzad Kargar

    2011-01-01

    Surface distinct deformed layers with thicknesses up to 150?m, with grain size in the top most surface is in the nanometer scale, were produced on AZ91D magnesium alloy using surface mechanical attrition treatment (SMAT). Effects of different ball size on the properties of the SMATed samples were investigated. The microstructural, grain size, hardness and roughness features of the treated surfaces

  8. Applications of Computer Simulation Methods in Plastic Forming Technologies for Magnesium Alloys

    SciTech Connect

    Zhang, S. H.; Zheng, W. T.; Shang, Y. L. [Institute of Metal Research, Chinese Academy of Sciences, Wenhua Road 72, Shenyang, 110016 (China); Wu, X. [Wayne State University, Detroit, MI 48202 (United States); Palumbo, G.; Tricarico, L. [Polytechnic of Bari, Bari, 70126 (Italy)

    2007-05-17

    Applications of computer simulation methods in plastic forming of magnesium alloy parts are discussed. As magnesium alloys possess very poor plastic formability at room temperature, various methods have been tried to improve the formability, for example, suitable rolling process and annealing procedures should be found to produce qualified magnesium alloy sheets, which have the reduced anisotropy and improved formability. The blank can be heated to a warm temperature or a hot temperature; a suitable temperature field is designed, tools should be heated or the punch should be cooled; suitable deformation speed should be found to ensure suitable strain rate range. Damage theory considering non-isothermal forming is established. Various modeling methods have been tried to consider above situations. The following situations for modeling the forming process of magnesium alloy sheets and tubes are dealt with: (1) modeling for predicting wrinkling and anisotropy of sheet warm forming; (2) damage theory used for predicting ruptures in sheet warm forming; (3) modeling for optimizing of blank shape and dimensions for sheet warm forming; (4) modeling in non-steady-state creep in hot metal gas forming of AZ31 tubes.

  9. Improvement on Magnesium Alloy Sheet Forming at Warm Temperatures by Computer Simulation and Experiment

    Microsoft Academic Search

    S. H. Zhang; K. Zhang; Y. C. Xu; Z. T. Wang; Z. G. Wang

    2004-01-01

    A proper forming temperature range was determined, and the effects of blank holding forces on the workpiece quality were analyzed by warm deep drawing of cups in magnesium alloy sheets. The conditions of process defects as flange wrinkling and ruptures were analyzed by computer simulation with explicit finite element method to optimize the process parameters. Therefore, appropriate process parameters were

  10. Tangential bending and stretching of thin magnesium alloy sheets in warm conditions

    Microsoft Academic Search

    G. Palumbo; D. Sorgente; L. Tricarico

    2009-01-01

    The present work aims at studying the tangential bending process (wiping) and the combined effect of a bending and stretching stress on thin (0.7mm) magnesium alloy (AZ31) sheets when working in warm conditions. The test equipment was designed in order to heat the sheet only in the bending region and to stretch the sheet after the wiping process; it was

  11. High-strength magnesium alloys for degradable implant applications

    Microsoft Academic Search

    P. Gunde; A. C. Hänzi; A. S. Sologubenko; P. J. Uggowitzer

    2011-01-01

    This article describes the design principles deployed in developing high-strength and ductile Mg–Zn–Zr–Ca–Mn(–Yb) alloys based on a concept, which aims to restrict grain growth considerably during alloy casting and forming. The efficiency of the development approach is discussed. Moreover, the microstructure and phase analysis of the alloys subjected to different thermal treatments are presented and the influence of the alloy

  12. A thousandfold creep strengthening by Ca addition in die-cast AM50 magnesium alloy

    NASA Astrophysics Data System (ADS)

    Terada, Yoshihiro; Sota, Rie; Ishimatsu, Naoya; Sato, Tatsuo; Ohori, Koichi

    2004-09-01

    The effect of calcium addition on the microstructure and creep strength of the die-cast AM50 magnesium alloy was investigated. The ?-Mg grains with the diameter of 4.9 µm are surrounded by the eutectic phases for the AM50-1.72 mass pct Ca alloy, while the ?(Mg17Al12) particles are located mainly on the grain boundaries of the ? grains for the AM50 alloy. The minimum creep rates of the AM50-1.72 mass pct Ca alloy are three orders of magnitude lower than those of the AM50 alloy at 423 K typically below 120 MPa. The thousandfold creep strengthening by the Ca addition is ascribed to the thermally stable eutectic phases appearing in the AM50-1.72 mass pct Ca alloy, which is expected to yield effective grain boundary strengthening or to resist the plastic flow of the ?-Mg grains.

  13. In vivo degradation of magnesium alloy LA63 scaffolds for temporary stabilization of biological myocardial grafts in a swine model.

    PubMed

    Schilling, Tobias; Brandes, Gudrun; Tudorache, Igor; Cebotari, Serghei; Hilfiker, Andres; Meyer, Tanja; Biskup, Christian; Bauer, Michael; Waldmann, Karl-Heinz; Bach, Friedrich-Wilhelm; Haverich, Axel; Hassel, Thomas

    2013-10-01

    Synthetic or biological patch materials used for surgical myocardial reconstruction are often fragile. Therefore, a transient support by degradable magnesium scaffolds can reduce the risk of dilation or rupture of the patch until physiological remodeling has led to a sufficient mechanical durability. However, there is evidence that magnesium implants can influence the growth and physiological behavior of the host's cells and tissue. Hence, we epicardially implanted scaffolds of the magnesium fluoride-coated magnesium alloy LA63 in a swine model to assess biocompatibility and degradation kinetics. Chemical analysis of the pigs' organs revealed no toxic accumulation of magnesium ions in the skeletal muscle, myocardium, liver, kidney, and bone of the pigs 1, 3, and 6 months postimplantation. The implants were surrounded by a fibrous granulation tissue, but no signs of necrosis were histologically evaluable. A sufficiently slow degradation rate of the magnesium alloy scaffold can be demonstrated via micro-computed tomography investigation. We conclude that stabilizing scaffolds of the magnesium fluoride-coated magnesium alloy LA63 can be used for epicardial application because no significant adverse effects to myocardial tissue were noted. Thus, degradable stabilizing scaffolds of this magnesium alloy with a slow degradation rate can extend the indication of innovative biological and synthetic patch materials. PMID:23989110

  14. Corrosion and wear resistance improvement of magnesium alloys by laser cladding with Al-Si

    NASA Astrophysics Data System (ADS)

    Carcel, Bernabe; Sampedro, Jesus; Ruescas, Ana; Toneu, Xavier

    Laser cladding with Al-Si powders have been carried out on three different magnesium alloys (AZ61, ZK30 and WE54) in order to improve their wear and corrosion properties using Nd:YAG CW laser. Optimized parameters allow obtaining crack and pore free coatings with good metallurgical bonding. Special care in shielding atmosphere is required to avoid porosity and corrosion. The hardness of the coatings is higher (130-250 HV) than that of as-received alloys. Salt spray corrosion tests and pin on disc sliding wear tests were carried out confirming that Al-Si coatings improves the wear and corrosion resistance of the alloys.

  15. Microstructural development of diffusion-brazed austenitic stainless steel to magnesium alloy using a nickel interlayer

    SciTech Connect

    Elthalabawy, Waled M., E-mail: elthalabawy@hotmail.com [Department of Mechanical and Manufacturing Engineering, University of Calgary, 2500 University Drive NW, Calgary, Alberta T2N1N4 (Canada); Khan, Tahir I. [Department of Mechanical and Manufacturing Engineering, University of Calgary, 2500 University Drive NW, Calgary, Alberta T2N1N4 (Canada)

    2010-07-15

    The differences in physical and metallurgical properties of stainless steels and magnesium alloys make them difficult to join using conventional fusion welding processes. Therefore, the diffusion brazing of 316L steel to magnesium alloy (AZ31) was performed using a double stage bonding process. To join these dissimilar alloys, the solid-state diffusion bonding of 316L steel to a Ni interlayer was carried out at 900 deg. C followed by diffusion brazing to AZ31 at 510 deg. C. Metallographic and compositional analyses show that a metallurgical bond was achieved with a shear strength of 54 MPa. However, during the diffusion brazing stage B{sub 2} intermetallic compounds form within the joint and these intermetallics are pushed ahead of the solid/liquid interface during isothermal solidification of the joint. These intermetallics had a detrimental effect on joint strengths when the joint was held at the diffusion brazing temperature for longer than 20 min.

  16. A fundamental study on the structural integrity of magnesium alloys joined by friction stir welding

    NASA Astrophysics Data System (ADS)

    Rao, Harish Mangebettu

    The goal of this research is to study the factors that influence the physical and mechanical properties of lap-shear joints produced using friction stir welding. This study focuses on understanding the effect of tool geometry and weld process parameters including the tool rotation rate, tool plunge depth and dwell time on the mechanical performance of similar magnesium alloy and dissimilar magnesium to aluminum alloy weld joints. A variety of experimental activities were conducted including tensile and fatigue testing, fracture surface and failure analysis, microstructure characterization, hardness measurements and chemical composition analysis. An investigation on the effect of weld process conditions in friction stir spot welding of magnesium to magnesium produced in a manner that had a large effective sheet thickness and smaller interfacial hook height exhibited superior weld strength. Furthermore, in fatigue testing of friction stir spot welded of magnesium to magnesium alloy, lap-shear welds produced using a triangular tool pin profile exhibited better fatigue life properties compared to lap-shear welds produced using a cylindrical tool pin profile. In friction stir spot welding of dissimilar magnesium to aluminum, formation of intermetallic compounds in the stir zone of the weld had a dominant effect on the weld strength. Lap-shear dissimilar welds with good material mixture and discontinues intermetallic compounds in the stir zone exhibited superior weld strength compared to lap-shear dissimilar welds with continuous formation of intermetallic compounds in the stir zone. The weld structural geometry like the interfacial hook, hook orientation and bond width also played a major role in influencing the weld strength of the dissimilar lap-shear friction stir spot welds. A wide scatter in fatigue test results was observed in friction stir linear welds of aluminum to magnesium alloys. Different modes of failure were observed under fatigue loading including crack propagation into the top sheet, into the bottom sheet, and interfacial separation. Investigation of the tested welds revealed that the voids in the weld nugget reduced the weld strength, resulting in lower fatigue life. A thin layer of IMCs formed along the faying surface which accelerated the fatigue failure.

  17. Thermodynamic activity of magnesium in several highly-solvating liquid alloys

    NASA Astrophysics Data System (ADS)

    Eckert, Charles A.; Irwin, Robert B.; Smith, Jeffery S.

    1983-09-01

    An emf technique is reported using porous alumina tubes to contain reference metals and alloys in a molten salt electrolyte. Data are reported for the activity of magnesium and its temperature derivative in several liquid metal solvents. These include lead (650 °C), tin (800 °C), bismuth (850 °C), antimony (850 °C), and mixtures of tin and antimony (800 °). In all cases, the solvents show strong negative deviations from ideal thermodynamic behavior, due to the effects of strong solvation caused by the formation of intermetallic compounds. The extent of this effect is Pb < Sn < Bi < Sb. The data reported are useful in evaluating solvents for the possible carbothermic reduction of magnesium oxide.

  18. Plastic Deformation Characteristics Of AZ31 Magnesium Alloy Sheets At Elevated Temperature

    SciTech Connect

    Park, Jingee; Lee, Jongshin [Graduate School, Kyungpook National University, Deagu 702-701 (Korea, Republic of); You, Bongsun [Department of Materials Technology, Korea Institute of Machinery and Materials, Changwon 641-831 (Korea, Republic of); Choi, Seogou [Digital Production Processing and Forming Team, Korea Institute of Industrial Technology, Incheon 406-800 (Korea, Republic of); Kim, Youngsuk [Department of Mechanical Engineering, Kyoungpook National University, Deagu 702-701 (Korea, Republic of)

    2007-05-17

    Using lightweight materials is the emerging need in order to reduce the vehicle's energy consumption and pollutant emissions. Being a lightweight material, magnesium alloys are increasingly employed in the fabrication of automotive and electronic parts. Presently, magnesium alloys used in automotive and electronic parts are mainly processed by die casting. The die casting technology allows the manufacturing of parts with complex geometry. However, the mechanical properties of these parts often do not meet the requirements concerning the mechanical properties (e.g. endurance strength and ductility). A promising alternative can be forming process. The parts manufactured by forming could have fine-grained structure without porosity and improved mechanical properties such as endurance strength and ductility. Because magnesium alloy has low formability resulted form its small slip system at room temperature it is usually formed at elevated temperature. Due to a rapid increase of usage of magnesium sheets in automotive and electronic industry it is necessary to assure database for sheet metal formability and plastic yielding properties in order to optimize its usage. Especially, plastic yielding criterion is a critical property to predict plastic deformation of sheet metal parts in optimizing process using CAE simulation. Von-Mises yield criterion generally well predicts plastic deformation of steel sheets and Hill'1979 yield criterion predicts plastic deformation of aluminum sheets. In this study, using biaxial tensile test machine yield loci of AZ31 magnesium alloy sheet were obtained at elevated temperature. The yield loci ensured experimentally were compared with the theoretical predictions based on the Von-Mises, Hill, Logan-Hosford, and Barlat model.

  19. Finite Element Simulation Of Magnesium AZ31 Alloy Sheet In Warm Hydroforming

    SciTech Connect

    Steffensen, Mikkel; Danckert, Joachim [Department of Production, Aalborg University, Fibigerstraede 16, 9220 Aalborg (Denmark)

    2007-05-17

    Hydroforming of magnesium (Mg) alloy sheet metal offers the possibility to form geometrically complex sheet metal parts that are applicable within automotive and electronic industry etc. However, due to the limited formability of Mg alloy at ambient temperature hydroforming of Mg alloy sheet metal has to be conducted at elevated temperature. In the present study an experimental warm hydroforming process using a low melting point alloy as forming medium is presented and on the basis of this a 2D thermo-mechanical finite element model is setup in order to analyze the temperature distribution in the Mg alloy workpiece during forming. The results show that the temperature in the workpiece is nearly uniform and nearly identical to the temperature of the forming medium.

  20. Texture Control by Selective Deformation Mechanism Activation in Magnesium Alloy

    E-print Network

    Foley, David Christopher

    2014-07-01

    strategies that increase strength in single-phase Mg alloy via grain refinement to submicron average grain size. We also established the achievable crystallographic textures in Mg alloy using 90o equal channel angular extrusion. In support of these first two...

  1. Texture Control by Selective Deformation Mechanism Activation in Magnesium Alloy 

    E-print Network

    Foley, David Christopher

    2014-07-01

    strategies that increase strength in single-phase Mg alloy via grain refinement to submicron average grain size. We also established the achievable crystallographic textures in Mg alloy using 90o equal channel angular extrusion. In support of these first two...

  2. Corrosion relationships as a function of time and surface roughness on a structural AE44 magnesium alloy

    Microsoft Academic Search

    Roxanna B. Alvarez; Holly J. Martin; M. F. Horstemeyer; Mei. Q. Chandler; Neil Williams; Paul T. Wang; Augusto Ruiz

    2010-01-01

    Pit initiation, growth, and coalescence corrosion mechanisms of an AE44 magnesium alloy subjected to a salt-water environment were quantified. Stereological quantities were evaluated using optical microscopy, scanning electron microscopy, and laser beam profilometry. Three corrosion mechanisms clearly arose: pitting, intergranular, and general. Pitting began as the result of localized galvanic dissolution between the intermetallics and magnesium matrix. Intergranular corrosion arose

  3. 62 FR 18749 - Pure and Alloy Magnesium From Canada; Final Results of the Third (1994) Countervailing Duty...

    Federal Register 2010, 2011, 2012, 2013, 2014

    1997-04-17

    ...NHCI would have paid for its water in the absence of the credit...relieved NHCI from paying its water bills, a countervailable...Duty Administrative Reviews: Pure Magnesium and Alloy Magnesium...subsidies according to their characteristics. For example, in the...

  4. Magnesium alloys as body implants: fracture mechanism under dynamic and static loadings in a physiological environment.

    PubMed

    Choudhary, Lokesh; Raman, R K Singh

    2012-02-01

    It is essential that a metallic implant material possesses adequate resistance to cracking/fracture under the synergistic action of a corrosive physiological environment and mechanical loading (i.e. stress corrosion cracking (SCC)), before the implant can be put to actual use. This paper presents a critique of the fundamental issues with an assessment of SCC of a rapidly corroding material such as magnesium alloys, and describes an investigation into the mechanism of SCC of a magnesium alloy in a physiological environment. The SCC susceptibility of the alloy in a simulated human body fluid was established by slow strain rate tensile (SSRT) testing using smooth specimens under different electrochemical conditions for understanding the mechanism of SCC. However, to assess the life of the implant devices that often possess fine micro-cracks, SCC susceptibility of notched specimens was investigated by circumferential notch tensile (CNT) testing. CNT tests also produced important design data, i.e. threshold stress intensity for SCC (KISCC) and SCC crack growth rate. Fractographic features of SCC were examined using scanning electron microscopy. The SSRT and CNT results, together with fractographic evidence, confirmed the SCC susceptibility of both smooth and notched specimens of a magnesium alloy in the physiological environment. PMID:22075121

  5. Hybrid laser–TIG welding, laser beam welding and gas tungsten arc welding of AZ31B magnesium alloy

    Microsoft Academic Search

    Liu Liming; Wang Jifeng; Song Gang

    2004-01-01

    Welding of AZ31B magnesium alloy was carried out using hybrid laser–TIG (LATIG) welding, laser beam welding (LBW) and gas tungsten arc (TIG) welding. The weldability and microstructure of magnesium AZ31B alloy welded using LATIG, LBW and TIG were investigated by OM and EMPA. The experimental results showed that the welding speed of LATIG was higher than that of TIG, which

  6. Tribological Behavior of AZ91D Magnesium Alloy against SAE52100 Steel under Ionic Liquid Lubricated Conditions

    Microsoft Academic Search

    Yanqiu Xia; Zhengfeng Jia; Junhong Jia

    \\u000a The friction and wear properties of AZ91D magnesium alloy discs sliding against SAE52100 steel balls were evaluated using\\u000a an Optimol SRV reciprocating friction and wear tester under the lubrication of several ionic liquids. The morphologies of\\u000a the worn surfaces of the AZ91D magnesium alloy discs were observed using a scanning electron microscope (SEM). In addition,\\u000a the elemental compositions and chemical

  7. PROCESS FOR THE PREPARATION OF MAGNESIUM-THORIUM ALLOY

    Microsoft Academic Search

    Reding; J. N. Jr

    1962-01-01

    A method for preparing Mg-Th alloy by reduction of ThFâ with Mg is ; outlined which gives good reduction efficiency, does not entrap the formed alloy ; in the saline phass, and prevents loss of ThFâ by conversion into oxide. ; The method comprises forming a saline mixture of ThFâ, LiF, and MgFâ ; and\\/or CaFâ and subjecting the mixture

  8. Plastic deformation and surface damage mechanisms during hot-forming of aluminum and magnesium alloy sheets

    NASA Astrophysics Data System (ADS)

    Das, Sarmistha

    Material transfer and adhesion to die surface are major tribological issues encountered during hot-forming of aluminum and magnesium alloys, reducing process efficiency. This study aimed at understanding the tribological contact interface generated between material and die surface under dynamic conditions created by simultaneous effect of temperature and strain rate. Micromechanisms of plastic deformation occurring under simulated hot-forming conditions were identified and related to the coefficient of friction (COF). Sliding contact experiments were done using specially designed tribometer (operating temperature: 25 to 545°C, strain rate: 10-3 to 10-1s-1). COF of AA5083(Al-4.5%Mg-0.7%Mn) and AZ31(Mg-3%Al-0.7%Zn) alloys were measured during their plastic deformation by the simultaneous effect of temperature and strain rate. The as received and plastically deformed surfaces were characterized using optical interferometry, SEM, FIB and TEM. Additionally, the force required to break the asperity junction formed at the first contact, or junction strength, was measured for both materials at different temperatures. Deformation mechanisms identified for AA5083 in the temperature range of 420 to 545°C and strain rate range of 5x10-3 to 4x10-2 s-1 included diffusional flow, grain boundary sliding (GBS) and solute drag (SD) creep. Friction maps outlining general relationships between tribological behaviour and micromechanisms controlling deformation under a set of temperature, strain and strain rate were developed. GBS induced high surface roughness, resulting in high COF. Low average roughness and retention of strength reduced COF in SD region. Dynamic recrystallization was an additional factor controlling material transfer in magnesium AZ31 alloy. Changes in oxide layer morphology were established based on the microstructural characterization of sample's surface and subsurface. In AA5083 alloy, crack formation at temperatures <450°C or oxide ligament formation at temperature >500°C were found in the magnesium rich surface oxide. Magnesium rich surface oxide reduced COF, and low COF was found in the material having high magnesium. AZ31 alloy always showed lower COF compared to AA5083. This was confirmed by junction strength experiment where adhesion strength was found to be low in high magnesium content material. Therefore, this investigation on the plastic deformation and surface damage mechanism, and their relation with the tribological behaviour provided better understanding of the hot-forming process.

  9. Research on super-hydrophobic surface of biodegradable magnesium alloys used for vascular stents.

    PubMed

    Wan, Peng; Wu, Jingyao; Tan, LiLi; Zhang, Bingchun; Yang, Ke

    2013-07-01

    Micro-nanometer scale structure of nubby clusters overlay was constructed on the surface of an AZ31 magnesium alloy by a wet chemical method. The super-hydrophobicity was achieved with a water contact angle of 142° and a sliding angle of about 5°. The microstructure and composition of the super-hydrophobic surface were characterized by SEM and FTIR. Potentiodynamic polarization and electrochemical impedance spectroscopy were used to evaluate the corrosion behavior, and the hemocompatibility of the super-hydrophobic surface was investigated by means of hemolytic and platelet adhesion tests. Results showed that the super-hydrophobic treatment could improve the corrosion resistance of magnesium alloys in PBS and inhibit blood platelet adhesion on the surface, which implied excellent hemocompatibility with controlled degradation. PMID:23623110

  10. Fatigue behaviour of friction stir processed AZ91 magnesium alloy produced by high pressure die casting

    SciTech Connect

    Cavaliere, P. [INFM-Dept. of 'Ingegneria dell'Innovazione', Engineering Faculty, University of Lecce, Via per Arnesano, 73100, Lecce (Italy)]. E-mail: pasquale.cavaliere@unile.it; De Marco, P.P. [INFM-Dept. of 'Ingegneria dell'Innovazione', Engineering Faculty, University of Lecce, Via per Arnesano, 73100, Lecce (Italy)

    2007-03-15

    The room temperature fatigue properties of AZ91 magnesium alloy produced by high pressure die casting (HPDC) as cast, heat treated, friction stir processed (FSP) and FSP and heat treated were studied. The fatigue properties of the material were evaluated for the HPDC magnesium alloy in the as-received state and after a solution treatment at 415 deg. C for 2 h and an ageing treatment at 220 deg. C for 4 h. The heat treatment resulted in a significant increase in the fatigue properties of the HPDC material, while no significance influence of heat treatment was recorded in the FSP condition. The morphology of fracture surfaces was examined by employing a field emission gun scanning electron microscope (FEGSEM)

  11. Cold Spray Al-5% Mg Coatings for the Corrosion Protection of Magnesium Alloys

    NASA Astrophysics Data System (ADS)

    Deforce, Brian S.; Eden, Timothy J.; Potter, John K.

    2011-12-01

    Poor corrosion resistance is a significant limitation of magnesium alloys as structural materials. To address this problem, the objective of this study was to apply to a magnesium alloy a corrosion-resistant barrier coating that has galvanic compatibility with magnesium and a hardness value no less than that of magnesium. Aluminum coatings were applied to ZE41A-T5 Mg by the cold spray process. A custom-made high-purity Al-5 wt.% Mg powder was produced by spray metal forming for the coating evaluation. In addition, coatings of commercially pure Al (99.5 wt.%), high-purity Al (99.95 wt.%), AA5356, and AA4047 were used for comparison. Coating evaluation included mechanical testing (hardness and adhesion strength) and corrosion testing (salt spray, galvanic coupling, and crevice corrosion). The Al-5% Mg powder resulted in the best overall performance, including a high hardness, 125 Hv100, and an adhesion strength, over 60 MPa, when treated for over 1000 h in a salt spray chamber and with a low galvanic current.

  12. Growth and characterization of Mg(OH) 2 film on magnesium alloy AZ31

    NASA Astrophysics Data System (ADS)

    Zhu, Yanying; Wu, Guangming; Zhang, Yun-Hong; Zhao, Qing

    2011-05-01

    Magnesium-based biomaterials have been proposed as potential candidates for biodegradable implant materials, such as bone screws, bone plates, intraluminal stents and so on. However, the poor corrosion resistance inhibits their applications in surgery. They collapse before the injured tissues are healed. In this paper, Mg(OH) 2 nonstructural film was synthesized on the substrate of AZ31 magnesium alloy by hydrothermal method with NaOH solution as mineralizer to reduce the corrosion rate of magnesium-based materials. The obtained films were characterized by XRD, SEM, and XPS. The results showed that a Mg(OH) 2 film with nanostructure surface can be synthesized by hydrothermal method. It was observed that the thickness of film increased with the holding time. Corrosion rates of the films were studied by immersing the samples in Hank's solution (37 °C). Surface deposits of samples with films soaked in Hank's solution for 31 days were investigated by XRD, SEM, EDS, XPS, and FTIR. It verified that the corrosion rate of the magnesium alloy with grown film was slowed down in the Hank's solution and the behavior of corrosion was inhibited effectively. Amorphous calcium apatite precursor was observed to deposit on the surface of the film during corrosion experiments in Hank's solution. And the tape test revealed a strong adhesion between the film and the substrate.

  13. In vitro degradation and cytocompatibility of magnesium-zinc-strontium alloys with human embryonic stem cells.

    PubMed

    Cipriano, Aaron F; Guan, Ren-Guo; Cui, Tong; Zhao, Zhan-Yong; Garcia, Salvador; Johnson, Ian; Liu, Huinan

    2012-01-01

    Magnesium-based alloys have attracted great interest for medical applications due to their unique biodegradable capability and desirable mechanical properties. When considered for medical applications, the degradation rate of these alloys must be tailored so that: (i) it does not exceed the rate at which the degradation products can be excreted from the body, and (ii) it is slow enough so that the load bearing properties of the implant are not jeopardized and do not conflict prior to and during synthesis of new tissue. Implant integration with surrounding cells and tissues and mechanical stability are critical aspects for clinical success. This study investigated Magnesium-Zinc-Strontium (ZSr41) alloy degradation rates and the interaction of the degradation products with human embryonic stem cells (hESC) over a 72 hour period. An in vitro hESC model was chosen due to the higher sensitivity of ESCs to known toxicants which allows to potentially detect toxicological effects of new biomaterials at an early stage. Four distinct ZSr41 compositions (0.15 wt.%, 0.5 wt.%, 1 wt.%, and 1.5 wt.% Sr) were designed and produced through metallurgical processing. ZSr41 alloy mechanical properties, degradation, and cytocompatibility were investigated and compared to pure polished Magnesium (Mg). Mechanical properties evaluated included hardness, ultimate tensile strength, and elongation to failure. Degradation was characterized by measuring total weight loss of samples and pH change in the cell culture media. Cytocompatibility was studied by comparing fluorescence and phase contrast images of hESCs after co-culture with Mg alloys. Results indicated that the Mg-Zn-Sr alloy with 0.15 wt.% Sr improved cytocompatibility and provided slower degradation as compared with pure Mg. PMID:23366416

  14. Process Parameters Effect on a Rectangular Tube HydroForming with Magnesium Alloy

    Microsoft Academic Search

    S. Y. Lin; C. M. Chang; S. S. Chi

    Due to the light weight and electromagnetic interference shielding capabilities in magnesium alloy material, it is widely\\u000a utilized in 3C electronic components and automobile parts. However, its formability is very poor due to the phenomenon of\\u000a negative strain hardening rate appearing in large strain deformation range, so it is usually formed as die casting or casting\\u000a styles leads to much

  15. Formability testing of AZ31B magnesium alloy tube at elevated temperature

    Microsoft Academic Search

    Zhubin He; Shijian Yuan; Gang Liu; Jia Wu; Weiwei Cha

    2010-01-01

    Magnesium alloy is a promising material for reaching the goal of weight reduction in automotive and aerospace industry. The mechanical properties of AZ31B seamless tube were tested by ring hoop tension test and compared with the results by axial tension test. Hydro-bulge test and newly proposed flatten-hydro-bulge test were also carried out to evaluate the formability of the tube. The

  16. Tribology and Tool Wear of Hot Dip Galvanized Zinc Magnesium Alloys on Cold Rolled Steel Sheets

    Microsoft Academic Search

    A. E. Raab; E. Berger; J. Freudenthaler; F. Leomann; C. Walch

    2011-01-01

    Recently zinc based coatings on cold rolled steel with improved functionality in terms of forming and\\/or corrosion behaviour have been intensively investigated in the steel industry1,2,3. One of the most promising products are zinc magnesium alloys produced in hot dip galvanizing process. These coatings were already introduced in construction industry a few years ago1. With some modifications the improved properties

  17. Low-cycle biaxial fatigue of a polycrystalline magnesium-lithium alloy

    Microsoft Academic Search

    S. Bentachfine; L. S. Toth; Z. Azari; G. Pluvinage

    1996-01-01

    We analyze the life duration of a magnesium-lithium alloy subjected to biaxial low-cycle fatigue under out-of-phase combined tension-compression and torsion. It was discovered that the life duration depends on the angle of the phase shift ? between the two perpendicular cyclic loads. The maximum life duration is attained in the case where the phase shift is absent, i.e., ?=0. It

  18. Compressive strain-rate sensitivity of magnesium–aluminum die casting alloys

    Microsoft Academic Search

    Wei Qian Song; Peter Beggs; Mark Easton

    2009-01-01

    Compressive properties of three die cast magnesium alloys (AM20, AM50, and AM60) have been investigated at a nominal strain rate range from 0.001s?1 to approximately 1700s?1. The high strain rate experiments were conducted using a Split Hopkinson Bar apparatus. The strain rate sensitivity decreased with increasing Al content at the low strain rates. At strain rates above 1500s?1 there was

  19. Effect of Equal-Channel Angular Rolling Pass on Microstructure and Properties of Magnesium Alloy Sheets

    Microsoft Academic Search

    Zhen-Hua Chen; Yong-Qi Cheng; Wei-Jun Xia

    2007-01-01

    The objective of this study was to determine the effect of rolling pass on AZ31 magnesium alloy sheets, which were produced by a new concept process, so-called equal-channel angular rolling process. Processing that causes continuous shearing deformation leads to a shifting of the crystal orientation from basal plane to non-basal plane. Compared with the as-received specimens, a lower yield strength

  20. Fatigue strength of a magnesium MA2-1 alloy after equal-channel angular pressing

    NASA Astrophysics Data System (ADS)

    Terent'ev, V. F.; Dobatkin, S. V.; Prosvirnin, D. V.; Bannykh, I. O.; Kopylov, V. I.; Serebryany, V. N.

    2010-09-01

    The fatigue strength of a magnesium MA2-1 alloy is studied after annealing and equal-channel angular pressing (ECAP). The ultrafine-grained structure formed upon ECAP is shown to increase the plasticity of the material during static tension, to decrease the cyclic life to failure, and not to decrease the fatigue limit. The mechanisms of crack nucleation and growth during cyclic deformation are investigated.

  1. Interactions between laser and arc plasma during laser–arc hybrid welding of magnesium alloy

    Microsoft Academic Search

    Liming Liu; Minghua Chen

    2011-01-01

    This paper presents the results of the investigation on the interactions between laser and arc plasma during laser–arc hybrid welding on magnesium alloy AZ31B using the spectral diagnose technique. By comparably analyzing the variation in plasma information (the shape, the electron temperature and density) of single tungsten inert gas (TIG) welding with the laser–arc hybrid welding, it is found that

  2. Effect of Welding Speed in High Speed laser-TIG Welding of Magnesium Alloy

    Microsoft Academic Search

    Chenbin Li; Minghua Chen; Shengtao Yuan; Liming Liu

    2012-01-01

    In order to investigate the effect of welding speed on microstructures and mechanical properties in high speed welding, low power laser-TIG (tungsten inert gas) hybrid welding process is proposed on AZ61 magnesium alloy. Defect-free welds are produced by employing welding speed ranging from 2000 mm\\/min to 6000 mm\\/min. It is found that welding speed has a significant influence on microstructures and mechanical

  3. Improved wear resistance of magnesium alloys AZ91 by high current pulsed electron beam treatment

    Microsoft Academic Search

    Mincai Li; Shengzhi Hao; Chuang Dong

    2009-01-01

    Surface modification of magnesium alloy AZ91 by high current pulsed electron beam (HCPEB) was investigated in the present\\u000a work. After irradiated by HCPEB, crater-like defects were found scattering on the modified surface, when increasing pulse\\u000a number, the density of craters sharply reduced. According to XRD analysis, hard intermetallic phase Mg17Al12 would sappear after several pulse of HCPEB treatment that is

  4. Testing of general and localized corrosion of magnesium alloys: A critical review

    Microsoft Academic Search

    Edward Ghali; Wolfgang Dietzel; Karl-Ulrich Kainer

    2004-01-01

    The degradation of materials generally occurs via corrosion, fatigue, and wear. Once a magnesium (Mg) alloy is chosen for\\u000a a certain application, corrosion testing is generally required as a function of the expected service environment, the type\\u000a of corrosion expected in service, and the type of surface protection, depending on the material and its use in the intended\\u000a surface. In

  5. Galvanic corrosion properties of differently PVD-treated magnesium die cast alloy AZ91

    Microsoft Academic Search

    H. Hoche; C. Blawert; E. Broszeit; C. Berger

    2005-01-01

    Different types of PVD coatings and plasma treatments were applied for the surface treatment of magnesium die cast alloy AZ91 specimens. The different types of surface treatment were all developed by the authors and the fundamental properties are described elsewhere. The coating systems were:•9 ?m CrN hard coating•3 ?m TiN coating•0.5 ?m plasma anodisation layer and 3 ?m Al2O3 coatingThe

  6. Formation process of composite plasma electrolytic oxidation coating containing zirconium oxides on AM50 magnesium alloy

    Microsoft Academic Search

    Feng LIU; Da-yong SHAN; Ying-wei SONG; En-hou HAN

    2011-01-01

    The formation processes of a composite ceramic coating on AM50 magnesium alloy prepared by plasma electrolytic oxidation (PEO) in a K2ZrF6 electrolyte solution were studied by scanning electron microscope (SEM) and energy dispersive X-ray spectroscope (EDX). Electrochemical impedance spectroscopy (EIS) tests were used to study the variation of the corrosion resistance of the coating during the PEO treatment. The results

  7. Determination of the concentrations of magnesium and aluminum in alloys by laser produced atomic emission spectroscopy 

    E-print Network

    Ashe, William Monroe

    1997-01-01

    and an aluminum sample in position . . . . . . 23 6 Sketch of the vacuum chamber, showing the chamber, the relative position of the sample inside the chamber, and the location of the micropositioners. In the side view, micropositioner lr, controls the z axis... them. Page 12 2 Trace element composition for the Al alloys. The compositions were measured by carbon arc spectroscopy [6] 12 3 Elemental compositions of the selected magnesium samples showing only the concentrations of Mg and Al...

  8. Surface nanocrystallization of magnesium alloy AZ91D by high-energy shot peening

    Microsoft Academic Search

    Jin Zhang; Xingbin Ou; Donghua Yang; Zhifu Sun

    2009-01-01

    High-energy shot peening (HESP), a method to produce severe plastic deformation by high velocity flying balls, was applied\\u000a on die cast magnesium alloy AZ91D. Effects of surface nanocrystallization by HESP and heat treatment at different temperatures\\u000a were investigated. The microstructure evolution was conducted using X-ray diffraction (XRD) and field emission scanning electronic\\u000a microscopy (FESEM). The hardness was measured by microhardness

  9. Surface nanocrystallization mechanism of a rare earth magnesium alloy induced by HVOF supersonic microparticles bombarding

    Microsoft Academic Search

    Kaidong Xu; Aihua Wang; Yang Wang; Xuanpu Dong; Xianglin Zhang; Zaowen Huang

    2009-01-01

    A nanostructured surface layer with a thickness up to 60?m was produced on a rare earth Mg–Gd–Y magnesium alloy using a new process named HVOF-SMB (high velocity oxygen-fuel flame supersonic microparticles bombarding). The microstructural features of the treated surface at various depth of the deformed layer were characterized by optical microscopy (OM), transmission electron microscopy (TEM) and high-resolution transmission electron

  10. Improvement in tribological performances of magnesium alloy using amide compounds as lubricating additives during sliding

    Microsoft Academic Search

    W. Huang; B. Hou; M. Liu; Z. Li

    2005-01-01

    The tribological characteristics of a magnesium alloy, AZ91D (die-casting), are investigated in a sliding lubricating system using various amide compounds as lubricating additives on a Timken type tester against a bearing steel (AISI52100) ring. Results indicate that a significant improvement in the tribological performance exists using the amide compounds as additives. The number of amido group (–CONH2) in additive molecules

  11. Tribological characteristics of magnesium alloy using N-containing compounds as lubricating additives during sliding

    Microsoft Academic Search

    Weijiu Huang; Changhua Du; Zhaofeng Li; Ming Liu; Weiming Liu

    2006-01-01

    The tribological characteristics of a magnesium alloy, AZ91D, were investigated in a sliding lubricating system using various N-containing compounds as lubricating additives on a Timken type tester against a bearing steel (AISI52100) ring. Results indicated that a significant improvement in the tribological performance exists using N-containing compounds as additives. The characteristics of anti-wear, anti friction and load-carrying capacity increased with

  12. Characterisation of AZ31B magnesium alloy formability in warm forming conditions

    Microsoft Academic Search

    G. Ambrogio; C. Bruni; S. Bruschi; L. Filice; A. Ghiotti; M. Simoncini

    2008-01-01

    Nowadays, magnesium alloys materials are more and more utilised in transportation industry in order to reduce the vehicles\\u000a mass, and thus to minimize air pollution and fuel consumption. Since they present a quite low formability at room temperature,\\u000a promising applications are developing in the area of sheet metal working in warm temperature conditions. The paper presents\\u000a a complete characterisation of

  13. Air bending of AZ31 magnesium alloy in warm and hot forming conditions

    Microsoft Academic Search

    C. Bruni; A. Forcellese; F. Gabrielli; M. Simoncini

    2006-01-01

    The effect of the process parameters on springback of AZ31 magnesium alloy was investigated by performing air bending tests under warm and hot forming conditions. To this purpose, air bending experiments were carried out in the temperature range varying from 100 to 400°C, with different values of the punch speed (0.45 and 4.5mm\\/s). Also the influence of the punch radius

  14. Influence of anisotropy of the magnesium alloy AZ31 sheets on warm negative incremental forming

    Microsoft Academic Search

    Qinglai Zhang; Hailing Guo; Fugui Xiao; Lin Gao; A. B. Bondarev; Weidong Han

    2009-01-01

    Single point incremental forming of the magnesium alloy AZ31 sheets, which were fabricated by hot extrusion, slab+hot\\/cold rolling, strip-casting rolling and cross-rolling, respectively, was investigated at elevated temperatures. The results show that the anisotropy of the sheets fabricated by casting slab+hot\\/cold rolling and cross-rolling is not remarkable, and the formability is improved significantly. The circular, square and rotary cone parts

  15. Warm negative incremental forming of magnesium alloy AZ31 Sheet: New lubricating method

    Microsoft Academic Search

    Qinglai Zhang; Fugui Xiao; Hailing Guo; Changsheng Li; Lin Gao; Xingwu Guo; Weidong Han; A. B. Bondarev

    2010-01-01

    The present study has been undertaken in order to investigate the suitable lubricants and lubricating methods, which can be employed to form a magnesium alloy AZ31 sheet by warm negative incremental forming (NIF). For the intended purpose, Nano-K2Ti4O9 whisker and organic binder were employed to improve the bonding strength at lubrication coating\\/sheet interface and lubricating properties at elevated temperatures. The

  16. Modelling of formula for flow stress of a magnesium alloy AZ31 sheet at elevated temperatures

    Microsoft Academic Search

    H. Takuda; T. Morishitaa; T. Kinoshita; N. Shirakawa

    2005-01-01

    For the evaluation of flow stress of a magnesium-based alloy AZ31 sheet in warm forming processes, a formula is derived by analysing the stress–strain curves measured under various temperatures and strain rates in this study. The formula is expressed in a simple form with the work-hardening exponent, n, the strain rate sensitivity exponent, m, and the stress coefficient, K. And

  17. EFFECT OF LOADING FREQUENCY ON FATIGUE BEHAVIOR OF MAGNESIUM ALLOY IN HUMID ENVIRONMENT

    Microsoft Academic Search

    Zainuddin Sajuri; Yukio Miyashita; Yoshiharu Mutoh

    Effect of loading frequency on fatigue behavior of an extruded AZ61 magnesium alloy was investigated at 50?-80%RH environment. The frequencies applied were 1 and 10 Hz. It was found that at stresses below the fatigue limit (at 20?-55%RH), the fatigue fracture was time dependent where fatigue lives for both frequencies were almost identical. In contrast, the fatigue fracture in the

  18. Modelling and Design of Magnesium and High Entropy Alloys Through Combining Statistical and Physical Models

    NASA Astrophysics Data System (ADS)

    Toda-Caraballo, Isaac; Rivera-Díaz-del-Castillo, Pedro E. J.

    2015-01-01

    Physical and statistical models are combined to describe and design magnesium and high entropy alloys. A principal component analysis is applied to merge material datasets, and it is shown that limits in properties can be envisaged. Extrapolation techniques can be employed to devise properties of non-existing alloys, such as specific heat capacity, melting point and Young's modulus. These in turn can be input to physical models to predict, for example, yield strength and modulus of toughness. The tools described herein can readily be used for materials discovery, and are being implemented in the Accelerated Metallurgy project.

  19. On the use of magnesium alloys for aerospace and defense mirrors

    NASA Astrophysics Data System (ADS)

    Woodard, Kenneth S.; Comstock, Lovell E.; Wamboldt, Leonard; Crifasi, Joseph C.

    2014-06-01

    Extreme light-weighting is important in many aerospace and defense applications but the cost associated with beryllium or other exotic materials can be prohibitive. The current standard for producing cost effective, high performance mirrors is to diamond machine mirror blanks from aluminum alloy stock. About 80% material removal is the limit for geometrical lightweighting while still retaining the structural integrity required for optical fabrication. To reduce weight further requires alternative materials. This paper summarizes the status of diamond machined finishing and coating of magnesium alloys to produce cost effective, lightweight mirrors with high, broadband reflectivity and low scatter finish.

  20. Yield Asymmetry Design of Magnesium Alloys by Integrated Computational Materials Engineering

    SciTech Connect

    Li, Dongsheng; Joshi, Vineet V.; Lavender, Curt A.; Khaleel, Mohammad A.; Ahzi, Said

    2013-11-01

    Deformation asymmetry of magnesium alloys is an important factor on machine design in automobile industry. Represented by the ratio of compressive yield stress (CYS) against tensile yield stress (TYS), deformation asymmetry is strongly related to microstructure, characterized by texture and grain size. Modified intermediate phi-model, a polycrystalline viscoplasticity model, is used to predict the deformation behavior of magnesium alloys with different grain sizes. Validated with experimental results, integrated computational materials engineering is applied to find out the route in achieving desired asymmetry by thermomechanical processing. In some texture, for example, rolled texture, CYS/TYS is smaller than 1 under different loading directions. In some texture, for example, extruded texture, asymmetry is large along normal direction. Starting from rolled texture, the asymmetry will increased to close to 1 along rolling direction after compressed to a strain of 0.2. Our model shows that grain refinement increases CYS/TYS. Besides texture control, grain refinement can also optimize the yield asymmetry. After the grain size decreased to a critical value, CYS/TYS reaches to 1 since CYS increases much faster than TYS. By tailoring the microstructure using texture control and grain refinement, it is achievable to optimize yield asymmetry in wrought magnesium alloys.

  1. IMPROVEMENTS IN OR RELATING TO THE ELECTROLYTIC COATING OF MAGNESIUM AND MAGNESIUM ALLOYS BY ANODIC TREATMENT

    Microsoft Academic Search

    M. W. Davies; W. E. Dennis

    1959-01-01

    A corrosion-protective Mg coating for Zr and Zr alloys is presented. ; After cleaning, the Zr object is placed in a molten ZnClâ flux bath at 550 ; deg C. The Zn-coated Zr is washed with water and coated with Mg by dipping in ; molten Mg at 650 to 750 deg C. (T.R.H.)

  2. Investigations on the Stress and Strain Evolution in AZ91D Magnesium Alloy Castings During Hot Tearing

    NASA Astrophysics Data System (ADS)

    Bichler, L.; Ravindran, C.

    2015-03-01

    Hot tearing in magnesium and aluminum alloys has been rigorously investigated in the past decades. To date, the interactions between the solidification parameters, microstructural development, and stress and strain at the onset of hot tearing in magnesium alloys remain unclear. In particular, the stress and strain conditions required to nucleate hot tears are unknown. In this research, ex situ neutron diffraction residual strain mapping was carried out on AZ91D magnesium alloy castings at the onset of hot tearing. The results indicate that tensile strain alone was not sufficient to nucleate a hot tear. A minimum threshold tensile stress of 12 MPa was necessary to open interdendritic shrinkage pores into hot tears and enable their propagation. Further, deformation along (10overline{1} 1) and (10overline{1} 2) crystallographic planes played a dominant role on the high-temperature deformation and hot tearing in the AZ91D alloy.

  3. Electron beam-assisted healing of nanopores in magnesium alloys

    PubMed Central

    Zheng, He; Liu, Yu; Cao, Fan; Wu, Shujing; Jia, Shuangfeng; Cao, Ajing; Zhao, Dongshan; Wang, Jianbo

    2013-01-01

    Nanopore-based sensing has emerged as a promising candidate for affordable and powerful DNA sequencing technologies. Herein, we demonstrate that nanopores can be successfully fabricated in Mg alloys via focused electron beam (e-beam) technology. Employing in situ high-resolution transmission electron microscopy techniques, we obtained unambiguous evidence that layer-by-layer growth of atomic planes at the nanopore periphery occurs when the e-beam is spread out, leading to the shrinkage and eventual disappearance of nanopores. The proposed healing process was attributed to the e-beam-induced anisotropic diffusion of Mg atoms in the vicinity of nanopore edges. A plausible diffusion mechanism that describes the observed phenomena is discussed. Our results constitute the first experimental investigation of nanopores in Mg alloys. Direct evidence of the healing process has advanced our fundamental understanding of surface science, which is of great practical importance for many technological applications, including thin film deposition and surface nanopatterning. PMID:23719630

  4. The Improvement of Tribological and Fatigue Properties of Casting Magnesium Alloy AZ91 Performed Diamond Like Carbon Coating

    NASA Astrophysics Data System (ADS)

    Akebono, Hiroyuki; Suzuki, Hideto

    In recent years, magnesium alloy has been widely used because of its low weight and ease of recycling. However, because magnesium alloys provide inferior wear resistance, it is necessary to improve this property to use magnesium alloy for more machine parts. For this study, we produced a diamond like carbon (DLC) coating that has high hardness, low friction, and excellent wear resistance. With DLC coated onto a soft material such as magnesium alloy, the adhesion strength between the substrate and the coating poses an important problem. Therefore, in this study, to acquire high adhesion strength, the DLC coating process was performed using unbalanced magnetron sputtering (UBMS). A tungsten-doped inter-layer was formed on the substrate. Onto the inter-layer, nano-order DLC coatings of two kinds were laminated. Wear tests and fatigue tests were carried out. The DLC-coated magnesium alloy exhibited excellent wear friction. Furthermore, DLC coatings raised its fatigue reliability over that of the substrate alone.

  5. Magnesium

    NASA Astrophysics Data System (ADS)

    Bechtel, H.; Bulian, W.; Bungardt, K.; Gürs, K.; Gürs, U.; Helling, W.; Kyri, H.; Laue, H. J.; Mahler, W.; Matting, A.; Meyer, F. R.; Mialki, W.; Ritter, F.; Ruge, J.; Saur, G.; Simon, W.; Strnat, K.; Weber, R.; Weigand, H. H.; Weik, H.; Ziesler, H.; Borchers, Heinz; Schmidt, Ernst

    Magnesium wird überwiegend durch Schmelzflußelektrolyse hergestellt. Das dabei anfallende Reinmagnesium hat einen Mg-Gehalt von etwa 99,9%. Hauptbeimengung ist das Eisen; Silizium und Aluminium sind nur in Spuren vorhanden. Der Anwendungsumfang des Reinmagnesiums ist gering; dagegen werden Magnesiumlegierungen zunehmend, insbesondere für den Druckguß verwendet. Neben den bis etwa zum Jahre 1950 allein gebräuchlichen Mg-Mn-, Mg-Al- und Mg-Al-Zn-Legierungen werden heute mehr und mehr die besonders warmfesten Legierungen mit Zusätzen von Zirkon, Thorium und Seltenen Erden hergestellt (siehe dazu auch Abschnitt Seltene Erden). Als Umhüllungsmaterial für Uranstäbe dient die Legierung Magnox A 12, die nach [H 3] neben 1 % Al noch geringe Mengen an Ca und Ba enthält. In den in Deutschland üblichen Kurzzeichen (DIN 1729) werden die chemischen Symbole und der ungefähre Gehalt der wichtigsten Legierungselemente angegeben. Gußlegierungen werden zusätzlich durch ein G (Sandguß oder Kokillenguß) oder ein D (Druckguß) gekennzeichnet (siehe Tab. 5).

  6. Evaluation of magnesium-yttrium alloy as an extraluminal tracheal stent.

    PubMed

    Luffy, Sarah A; Chou, Da-Tren; Waterman, Jenora; Wearden, Peter D; Kumta, Prashant N; Gilbert, Thomas W

    2014-03-01

    Tracheomalacia is a relatively rare problem, but can be challenging to treat, particularly in pediatric patients. Due to the presence of mechanically deficient cartilage, the trachea is unable to resist collapse under physiologic pressures of respiration, which can lead to acute death if left untreated. However, if treated, the outcome for patients with congenital tracheomalacia is quite good because the cartilage tends to spontaneously mature over a period of 12 to 18 months. The present study investigated the potential for the use of degradable magnesium-3% yttrium alloy (W3) to serve as an extraluminal tracheal stent in a canine model. The host response to the scaffold included the formation of a thin, vascularized capsule consisting of collagenous tissue and primarily mononuclear cells. The adjacent cartilage structure was not adversely affected as observed by bronchoscopic, gross, histologic, and mechanical analysis. The W3 stents showed reproducible spatial and temporal fracture patterns, but otherwise tended to corrode quite slowly, with a mix of Ca and P rich corrosion product formed on the surface and observed focal regions of pitting. The study showed that the approach to use degradable magnesium alloys as an extraluminal tracheal stent is promising, although further development of the alloys is required to improve the resistance to stress corrosion cracking and improve the ductility. PMID:23554285

  7. Material Behavior Based Hybrid Process for Sheet Draw-Forging Thin Walled Magnesium Alloys

    SciTech Connect

    Sheng, Z.Q.; Shivpuri, R. [Industrial, Welding and System Engineering at the Ohio State University, Columbus, Oh, 43210 (United States)

    2005-08-05

    Magnesium alloys are conventionally formed at the elevated temperatures. The thermally improved formability is sensitive to the temperature and strain rate. Due to limitations in forming speeds, tooling strength and narrow processing windows, complex thin walled parts cannot be made by traditional warm drawing or hot forging processes. A hybrid process, which is based on the deformation mechanism of magnesium alloys at the elevated temperature, is proposed that combines warm drawing and hot forging modes to produce an aggressive geometry at acceptable forming speed. The process parameters, such as temperatures, forming speeds etc. are determined by the FEM modeling and simulation. Sensitivity analysis under the constraint of forming limits of Mg alloy sheet material and strength of tooling material is carried out. The proposed approach is demonstrated on a conical geometry with thin walls and with bottom features. Results show that designed geometry can be formed in about 8 seconds, this cannot be formed by conventional forging while around 1000s is required for warm drawing. This process is being further investigated through controlled experiments.

  8. The role of diamond-like carbon coated drills on minimum quantity lubrication drilling of magnesium alloys

    Microsoft Academic Search

    S. Bhowmick; A. T. Alpas

    2011-01-01

    Minimum quantity water lubrication (H2O-MQL) and dry drilling behavior of a cast magnesium alloy (AZ91) were investigated using non-hydrogenated diamond-like carbon (NH-DLC) coated HSS drills and by measuring cutting torque as well as the temperature generated in the workpiece. Due to adhesion of magnesium to the drills that caused rapid drill failure neither uncoated HSS nor NH-DLC coated drills could

  9. Influence of texture and grain size on work hardening and ductility in magnesium-based alloys processed by ECAP and rolling

    Microsoft Academic Search

    J. A. del Valle; F. Carreño; O. A. Ruano

    2006-01-01

    Equal channel angular pressing (ECAP) and large-strain hot rolling (LSHR) are widely used methods for refining the grain size in magnesium alloys. The hardening capability of the processed materials confers the resistance to develop tensile mechanical instabilities, therefore controlling ductility. In this work various magnesium alloys were processed using ECAP, LSHR and annealing treatments in order to control the texture

  10. JOM Volume 63, Number 2 (2011): 48-52 High strain rate compressive response of magnesium-aluminum alloy/fly ash cenosphere composites

    E-print Network

    Gupta, Nikhil

    2011-01-01

    half of which is dumped in landfills. In the present work, a cast magnesium-aluminum alloy, AZ91D48 JOM Volume 63, Number 2 (2011): 48-52 High strain rate compressive response of magnesium-aluminum alloy/fly ash cenosphere composites Dung D. Luonga , Nikhil Guptaa, and Pradeep K. Rohatgib a Composite

  11. Pore formation during hybrid laser-tungsten inert gas arc welding of magnesium alloy AZ31B—mechanism and remedy

    Microsoft Academic Search

    Liming Liu; Gang Song; Guoli Liang; Jifeng Wang

    2005-01-01

    One of the major concerns during high speed welding of magnesium alloys is the presence of porosity in the weld metal that can deteriorate mechanical properties. This study seeks to analyze the presence method and quantity of pore during hybrid laser-tungsten inert gas arc (TIG) welding of magnesium alloy AZ31B by radiography, optical microscopy and electron probe microanalysis (EMPA). At

  12. Superplasticity and cavitation in an aluminum-magnesium alloy

    NASA Astrophysics Data System (ADS)

    Bae, Donghyun

    2000-10-01

    Fundamental issues related to the forming performance of superplastic metals include the mechanisms of flow and cavitation occurring during the forming process. Cavitation beyond a critical amount is damaging to the mechanical behavior of fabricated parts. Therefore, the role of process parameters which influence cavitation must be precisely documented and understood. In this study, (1) the mechanism of deformation, (2) cavity formation and growth, and (3) the effect of forming parameters on cavitation are systematically investigated in a fine grain Al-4.7%Mg-0.8%Mn-0.4%Cu alloy. The mechanical flow response of the alloy is characterized by a new type of step strain-rate test which preserves the initial microstructure of the alloy. Under isostructural condition, sigmoidal log s vs. log 3? relationship is determined and then analyzed by using a grain-mantle based quantitative model1 for superplastic flow. The activation energies in both grain-mantle creep and core creep are analyzed, and the overall controlling mechanism is found to be dislocation glide and climb. Grain-mantle creep rate in the low strain-rate region is found to be enhanced many times due to a high concentration of vacancies near grain boundaries. Cavitation caused by superplastic straining under uniaxial tension is evaluated by the SEM (for < 0.5mum size) and the number and size of cavities are monitored by image analysis through optical microscopy. Growth of pre-existing cavities and nucleation and growth of new cavities at grain boundary particles are monitored with increasing strain. Cavity nucleation and growth occur in two stages: crack-like growth along the particle-matrix interface by a constrained growth process, and beyond complete debonding growth via plastic deformation of the matrix which is modeled here. Stresses and strain-rates near the void are intensified due to the perturbed flow field near the void, and not relaxed during the time frame associated with superplastic deformation. In the model, faster cavity growth is predicted for lower m and for smaller cavity density when cavity stress fields are not overlapping. Observed cavitation quantitatively agrees with the present model, but diffusional growth is found to be too slow, which cannot explain the observed nanoscale void growth behavior. Another parameter affecting the degree of cavitation is the imposed stress-state. Cavity growth rate as well as cavity nucleation rate increase with the level of mean hydrostatic tension. For a fixed cavitation volume fraction, V, the principal surface strains, 31 and 32 , for the various stress-states can be empirically given by: 31=aVb -a32 , where a and b are constants determined from 31 values for plane-strain 32=0 . The value of b is found to be 0.2 ˜ 0.3, and alpha is 0.4 ˜ 1. 1 A. K. Ghosh, Mat. Sci. Forum, Trans. Tech. Publications, Switzerland, 170--172, 39 (1994).

  13. Microstructural Origin of Friction Stir Processed Zone in a Magnesium Alloy

    NASA Astrophysics Data System (ADS)

    Tripathi, A.; Tewari, A.; Srinivasan, N.; Reddy, G. M.; Zhu, S. M.; Nie, J. F.; Doherty, R. D.; Samajdar, I.

    2015-06-01

    This study involved edge regions of a friction stir processed (FSP) magnesium alloy (AZ31). Interleaved structures of ultra-fine, of few 100 nm, and coarser grains, several microns, were noted. Very short thermal anneals coarsened the former: generating typical micron-sized FSP grains. A model of microstructural development through grain boundary sliding of the ultra-fine grains was proposed. This model explains weaker texture in such grains and the fact that Mg-FSP shear texture did not change by successive passes.

  14. Microstructure Evolution and Deformation Feature of AZ31 Magnesium Alloy during Severe Plastic Deformation

    NASA Astrophysics Data System (ADS)

    Hou, Li-Feng; Wei, Ying-Hui; Shu, Xue-Feng

    A nanostructured surface layer was produced on commercially AZ31 magnesium alloy using surface mechanical attrition treatment (SMAT). The microstructure evolution and deformation feature along the depth of the treated surface layer were characterized by transmission electron microscope (TEM) investigations. The grain refinement process, accompanied by an increase in the surface layer, involves: the onset of twins; the formation of microbands associated with the dislocation slipping; the subdivision of microbands into low angle grains and then highly disoriented polygonal submicronic grains, and further breakdown into randomly oriented nanograins with progression of dynamic recrystallization.

  15. High Cycle Fatigue of Cast Mg-3Nd-0.2Zn Magnesium Alloys

    NASA Astrophysics Data System (ADS)

    Li, Zhenming; Wang, Qigui; Luo, Alan A.; Fu, Penghuai; Peng, Liming; Wang, Yingxin; Wu, Guohua

    2013-11-01

    This paper investigates the high cycle fatigue properties of a recently developed high-strength cast magnesium alloy [Mg-3Nd-0.2Zn (all compositions in wt pct except when otherwise stated)] with varied Zr contents for grain refinement (NZ30K) and the influence of heat treatment conditions. The NZ30K alloy containing 0.45Zr and heat treated to the peak-aged T6 condition [14 hours at 473 K (200 °C)] shows the highest fatigue strength, about 100 MPa, which is about 25 pct higher than that of commercial AZ91D-T6 alloy. In the absence of casting flaws, the high cycle fatigue properties of the NZ30K alloy strongly depend on its grain size and heat treatment conditions. The dependency of fatigue strength on grain sizes follows the Hall-Petch relationship. The NZ30K alloy also shows a significant response to heat treatments. The fatigue strength increases in a near linear fashion with increasing yield strength of the material through heat treatment.

  16. Superplastic Formability of AZ31 Magnesium Alloy Sheets Produced by Twin Roll Casting and Sequential Hot Rolling

    NASA Astrophysics Data System (ADS)

    Yu, Yandong; Lin, Kai; Jiang, Peng

    2013-07-01

    In this paper, superplastic tensile testing and gas bulging forming of AZ31 and AZ31 + Y + Sr magnesium alloys produced by twin roll casting (TRC) and sequential hot rolling were carried out. At 673 K, the superplastic formability of the TRC AZ31 magnesium alloy sheets added Y and Sr elements has improved significantly compared to the common TRC AZ31 sheets. Formations of cavities on the bulging part go through three stages of the nucleation, growth and aggregation, finally cavities merging lead to rupture at the top of the bulging part.

  17. The galvanic corrosion behavior of depleted uranium in synthetic seawater coupled to aluminum, magnesium, and mild steel

    Microsoft Academic Search

    J. F. McIntyre; E. P. LeFeave; K. A. Musselman

    1987-01-01

    The galvanic corrosion behavior of a depleted uranium-titanium alloy (Du-.75Ti) coupled to MgZk60A-T5, AA-7075-T6, bare steel-4340, and coated steel-4340 exposed to ASTM seawater was investigated by monitoring the galvanic current with time. Gravimetric measurements, polarization resistance measurements, and concepts of ''mixed-potential'' theory were used to calculate corrosion rates. It was demonstrated that galvanic currents must be monitored over extended periods

  18. Endothelialization of novel magnesium-rare earth alloys with fluoride and collagen coating.

    PubMed

    Zhao, Nan; Workman, Benjamin; Zhu, Donghui

    2014-01-01

    Magnesium (Mg) alloys are promising scaffolds for the next generation of cardiovascular stents because of their better biocompatibility and biodegradation compared to traditional metals. However, insufficient mechanical strength and high degradation rate are still the two main limitations for Mg materials. Hydrofluoric acid (HF) treatment and collagen coating were used in this research to improve the endothelialization of two rare earth-based Mg alloys. Results demonstrated that a nanoporous film structure of fluoride with thickness of ~20 µm was formed on the Mg material surface, which improved the corrosion resistance. Primary human coronary artery endothelial cells (HCAECs) had much better attachment, spreading, growth and proliferation (the process of endothelialization) on HF-treated Mg materials compared to bare- or collagen-coated ones. PMID:24670478

  19. Plastic deformation macrolocalization during serrated creep of an aluminum-magnesium Al-6 wt % Mg alloy

    NASA Astrophysics Data System (ADS)

    Shibkov, A. A.; Zolotov, A. E.; Zheltov, M. A.; Denisov, A. A.; Gasanov, M. F.

    2014-04-01

    The nonlinear dynamics of the space-time structure of macrolocalized deformation is studied by a set of high-speed in situ methods under the conditions of serrated creep in an aluminum-magnesium Al-6 wt % Mg alloy at room temperature. Macroscopic deformation jumps with an amplitude of several percent are detected in the creep curve of this alloy. It is found that a complex space-time structure of macrolocalized deformation bands moving in a correlated manner forms spontaneously in the material during the development of a deformation jump. The difference between the observed picture of deformation bands and the well-known Portevin-Le Chatelier classification of deformation bands is discussed.

  20. Endothelialization of Novel Magnesium-Rare Earth Alloys with Fluoride and Collagen Coating

    PubMed Central

    Zhao, Nan; Workman, Benjamin; Zhu, Donghui

    2014-01-01

    Magnesium (Mg) alloys are promising scaffolds for the next generation of cardiovascular stents because of their better biocompatibility and biodegradation compared to traditional metals. However, insufficient mechanical strength and high degradation rate are still the two main limitations for Mg materials. Hydrofluoric acid (HF) treatment and collagen coating were used in this research to improve the endothelialization of two rare earth-based Mg alloys. Results demonstrated that a nanoporous film structure of fluoride with thickness of ~20 ?m was formed on the Mg material surface, which improved the corrosion resistance. Primary human coronary artery endothelial cells (HCAECs) had much better attachment, spreading, growth and proliferation (the process of endothelialization) on HF-treated Mg materials compared to bare- or collagen-coated ones. PMID:24670478

  1. Identification of an advanced constitutive model of Magnesium alloy AZ31B

    NASA Astrophysics Data System (ADS)

    Liu, Z. G.; Massoni, E.

    2011-05-01

    The main aim of this paper is to study the flow behavior of the AZ31B magnesium alloy by means of tensile tests performed in extended ranges of temperature and strain rates. The flow stress-strain curves analyzed by power law type constitutive equation [1] can only fit well with experimental curves at the work-hardening stage. A new mathematical model is studied to describe the softening behavior of material based on tensile experiments. The relative parameters are obtained by fitting the equation with the experimental data. The genetic algorithm has been used to obtain the global optimal fitting parameters. The comparison between the fitted and experimental data proves the effectiveness of the model. The results indicate that this model leads to a better simulation of the flow stress during the softening stage than that of the power law equation. Based on this model, the deep drawing process has been simulated with the commercial finite element code FORGE®. The punch load and thickness distribution of AZ31 sheet have been studied. The study of the results is helpful to the application of the stamping technology for the magnesium alloy sheet.

  2. Identification of an advanced constitutive model of Magnesium alloy AZ31B

    SciTech Connect

    Liu, Z. G.; Massoni, E. [CEMEF, Centre de Mise en Forme des Materiaux, Ecole Nationale Superieure des Mines de Paris 1, rue Claude Daunesse, BP 207, 06904, Sophia-Antipolis Cedex (France)

    2011-05-04

    The main aim of this paper is to study the flow behavior of the AZ31B magnesium alloy by means of tensile tests performed in extended ranges of temperature and strain rates. The flow stress-strain curves analyzed by power law type constitutive equation can only fit well with experimental curves at the work-hardening stage. A new mathematical model is studied to describe the softening behavior of material based on tensile experiments. The relative parameters are obtained by fitting the equation with the experimental data. The genetic algorithm has been used to obtain the global optimal fitting parameters. The comparison between the fitted and experimental data proves the effectiveness of the model. The results indicate that this model leads to a better simulation of the flow stress during the softening stage than that of the power law equation. Based on this model, the deep drawing process has been simulated with the commercial finite element code FORGE registered. The punch load and thickness distribution of AZ31 sheet have been studied. The study of the results is helpful to the application of the stamping technology for the magnesium alloy sheet.

  3. Semisolid die forging process, microstructures and properties of AZ31 magnesium alloy mobile telephone shells

    NASA Astrophysics Data System (ADS)

    Guan, Ren-Guo; Chen, Li-Qing; Cao, Fu-Rong; Zhao, Zhan-Yong; Ren, Yong

    2011-12-01

    A semisolid slurry of AZ31 magnesium alloy was prepared by vibrating wavelike sloping plate process, and the semisolid die forging process, microstructures, and properties of the magnesium alloy mobile telephone shell were investigated. The semisolid forging process was performed on a YA32-315 four-column universal hydraulic press. The microstructures were observed by optical microscopy, the hardness was analyzed with a model 450SVD Vickers hardometer, the mechanical properties was measured with a CMT5105 tensile test machine, and the fractograph of elongated specimens was observed by scanning electron microscopy (SEM). The results reveal that with the increase of die forging force, the microstructures of the product become fine and dense. A lower preheating temperature and a longer dwell time are favorable to the formation of fine and dense microstructures. The optimum process conditions of preparing mobile telephone shells with excellent surface quality and microstructures are a die forging force of 2000 kN, a die preheating temperature of 250°C, and a dwell time of 240 s. After solution treatment at 430°C and aging at 220°C for 8 h, the Vickers hardness is 61.7 and the ultimate tensile strength of the product is 193 MPa. Tensile fractographs show the mixing mechanisms of quasi-cleavage fracture and ductile fracture.

  4. Stamping of Thin-Walled Structural Components with Magnesium Alloy AZ31 Sheets

    NASA Astrophysics Data System (ADS)

    Chen, Fuh-Kuo; Chang, Chih-Kun

    2005-08-01

    In the present study, the stamping process for manufacturing cell phone cases with magnesium alloy AZ31 sheets was studied using both the experimental approach and the finite element analysis. In order to determine the proper forming temperature and set up a fracture criterion, tensile tests and forming limit tests were first conducted to obtain the mechanical behaviors of AZ31 sheets at various elevated temperatures. The mechanical properties of Z31 sheets obtained from the experiments were then adopted in the finite element analysis to investigate the effects of the process parameters on the formability of the stamping process of cell phone cases. The finite element simulation results revealed that both the fracture and wrinkle defects could not be eliminated at the same time by adjusting blank-holder force or blank size. A drawbead design was then performed using the finite element simulations to determine the size and the location of drawbead required to suppress the wrinkle defect. An optimum stamping process, including die geometry, forming temperature, and blank dimension, was then determined for manufacturing the cell phone cases. The finite element analysis was validated by the good agreement between the simulation results and the experimental data. It confirms that the cell phone cases can be produced with magnesium alloy AZ31 sheet by the stamping process at elevated temperatures.

  5. Creep behavior of an AZ91 magnesium alloy reinforced with alumina fibers

    SciTech Connect

    Li, Y.; Langdon, T.G. [Univ. of Southern California, Los Angeles, CA (United States)

    1999-08-01

    Creep tests were conducted at elevated temperatures on an AZ91 alloy reinforced with 20 vol pct Al{sub 2}O{sub 3} fibers. When the creep data are interpreted by incorporating a threshold stress into the analysis, it is shown that the true stress exponent, n, is {approximately}3 at the lower stress levels and increases to >3 at the higher stresses. The true activation energy for creep is close to the value anticipated for interdiffusion of aluminum in magnesium. This behavior is interpreted in terms of a viscous glide process with n = 3 and a breakaway of the dislocations from their solute atom atmospheres at the higher stress levels. The threshold stresses in this composite appear to arise from an attractive interaction between mobile dislocations in the matrix alloy and Mg{sub 17}Al{sub 12} precipitates. The experimental results reveal several important similarities between the creep behavior of this magnesium-based composite and the well-documented creep properties of aluminum-based composites.

  6. Multipass cold drawing of magnesium alloy minitubes for biodegradable vascular stents.

    PubMed

    Fang, Gang; Ai, Wei-jiang; Leeflang, Sander; Duszczyk, Jurek; Zhou, Jie

    2013-08-01

    Magnesium alloys possess highly limited room-temperature formabilities. This presents a technological barrier to the fabrication of minitubes for biodegradable vascular stents. The research was aimed at developing precision forming technology to fabricate ZM21 magnesium alloy minitubes with a refined microstructure. A multipass cold drawing process with a moving mandrel was successfully developed to convert seamless hollow billets through five passes of cold drawing and an interpass annealing treatment into minitubes with an outside diameter of 2.9 mm and a wall thickness of 0.217 mm, ready for laser cutting into vascular stents. It was found that a cumulative reduction in cross-section area as much as 32% could be applied to the material without causing fracture. However, a further reduction in cross-section area required annealing at 300°C for 1h to change a twinned microstructure into a recrystallized grain structure and to regain formability. The interpass annealing treatment after the fourth pass led to a reduction in drawing force by 22%, in comparison with the drawing force at the fourth pass of drawing. The variations in the outside diameter and wall thickness of the minitubes could be kept within 5 and 12 ?m, respectively. Further research is directed toward improvements in dimensional precisions. PMID:23706237

  7. Study on Pressurized Solidification Behavior and Microstructure Characteristics of Squeeze Casting Magnesium Alloy AZ91D

    NASA Astrophysics Data System (ADS)

    Han, Zhiqiang; Pan, Haowei; Li, Yanda; Luo, Alan A.; Sachdev, Anil K.

    2015-02-01

    Squeeze casting technology for magnesium alloys has a great application potential in automobile manufacturing and has received increasing attention from both academic and industrial communities. In this study, the pressurized solidification behavior of magnesium alloy AZ91D in squeeze casting process was investigated using computer-aided cooling curve analysis (CA-CCA). It was found that the applied pressure increased both the start and end temperatures of primary ?-Mg formation but had little effect on the sizes of temperature ranges. Moreover, the applied pressure increased the start temperature and decreased the end temperature of eutectic reaction during the solidification, resulting in a larger temperature range of eutectic reaction compared with solidification under atmospheric pressure. The grains were remarkably refined, and the eutectic fraction increased with increasing applied pressure. The dendritic microstructure with a larger secondary dendrite arm spacing (SDAS) was observed under a higher applied pressure at the central part of the experimental casting. By correlating the CA-CCA and SDAS data, it was found that SDAS and the cooling rate at the maximum ?-Mg growth could be fit into the power law equation in classic solidification theories.

  8. Effects of the types of overlap on the mechanical properties of FSSW welded AZ series magnesium alloy joints

    NASA Astrophysics Data System (ADS)

    Wang, Dan; Shen, Jun; Wang, Lin-Zhi

    2012-03-01

    The effects of the types of overlap on the mechanical properties of the friction stir spot welding (FSSW) welded AZ series magnesium alloy joints were investigated by microstructural observations, microhardness tests, and tensile tests. The results show that the microstructure of the stir zone adjacent to the periphery of the rotating pin is mainly composed of the upper sheet. The average distance D between the longitudinal segment of the curved interface and the keyhole periphery, the tensile shear force, and the microhardness of the stir zone of the FSSW welded AZ61 alloy joint are the highest in all samples. During FSSW of AZ31 and AZ61 dissimilar magnesium alloys, the irregular deformation of the longitudinal segment of the curved interface appears, while the microhardness of the stir zone is higher when AZ61 alloy is the upper sheet. Moreover, the microhardness of the stir zone increases initially and then decreases sharply in the longitudinal test position.

  9. Solidification, growth mechanisms, and associated properties of Al-Si and magnesium lightweight casting alloys

    SciTech Connect

    Hosch, Timothy

    2010-05-16

    Continually rising energy prices have inspired increased interest in weight reduction in the automotive and aerospace industries, opening the door for the widespread use and development of lightweight structural materials. Chief among these materials are cast Al-Si and magnesium-based alloys. Utilization of Al-Si alloys depends on obtaining a modified fibrous microstructure in lieu of the intrinsic flake structure, a process which is incompletely understood. The local solidification conditions, mechanisms, and tensile properties associated with the flake to fiber growth mode transition in Al-Si eutectic alloys are investigated here using bridgman type gradient-zone directional solidification. Resulting microstructures are examined through quantitative image analysis of two-dimensional sections and observation of deep-etched sections showing three-dimensional microstructural features. The transition was found to occur in two stages: an initial stage dominated by in-plane plate breakup and rod formation within the plane of the plate, and a second stage where the onset of out-of-plane silicon rod growth leads to the formation of an irregular fibrous structure. Several microstructural parameters were investigated in an attempt to quantify this transition, and it was found that the particle aspect ratio is effective in objectively identifying the onset and completion velocity of the flake to fiber transition. The appearance of intricate out-of-plane silicon instability formations was investigated by adapting a perturbed-interface stability analysis to the Al-Si system. Measurements of silicon equilibrium shape particles provided an estimate of the anisotropy of the solid Si/liquid Al-Si system and incorporation of this silicon anisotropy into the model was found to improve prediction of the instability length scale. Magnesium alloys share many of the benefits of Al-Si alloys, with the added benefit of a 1/3 lower density and increased machinability. Magnesium castings often contain additions of heavier elements, such as zinc, zirconium, and rare earth elements, which significantly improve high temperature performance. However, additions of these elements can lead to macrosegregational effects in castings, which are detectable by radiographic scans. The effect of these flow-line indications on alloy mechanical properties is not well quantified. An examination of these flow-line indications and their effects on mechanical properties in three magnesium-based casting alloys was performed here in order to determine the best practice for dealing with affected castings. Preliminary results suggest the flow-lines do not measurably impact bulk material properties. Three additional methods of characterizing three-dimensional material structures are also presented: a minimum spanning tree analysis is utilized to quantify local structure in Cu-Zr liquid phase simulations obtained from molecular dynamics; the radial distribution function is applied to directionally solidified Al-Si structures in an attempt to extract local spacing data; and the critical diameter measurement is also defined and applied to irregular eutectic Al-Si structures.

  10. Biocorrosion behavior and cell viability of adhesive polymer coated magnesium based alloys for medical implants

    NASA Astrophysics Data System (ADS)

    Abdal-hay, Abdalla; Dewidar, Montasser; Lim, Jae Kyoo

    2012-11-01

    The present study was ultimately aimed to design novel adhesive biodegradable polymer, poly(vinyl acetate) (PVAc), coatings onto Mg based alloys by the dip-coating technique in order to control the degradation rate and enhance the biocompatibility of magnesium alloys. The influence of various solvents on PVAc surface topography and their protection of Mg alloys were dramatically studied in vitro. Electrochemical polarization, degradation, and PVAc film cytocompatibility were also tested. Our results showed that the solvent had a significant effect on coating quality. PVAc/dichloromethane solution showed a porous structure and solution concentration could control the porous size. The coatings prepared using tetrahydrofuran and dimethylformamide solvents are exceptional in their ability to generate porous morphology even at low polymer concentration. In general, the corrosion performance appears to be different on different PVAc-solvent system. Immersion tests illustrated that the porous morphology on PVAc stabilized corrosion rates. A uniform corrosion attack in artificial simulation body fluid was also exhibited. The cytocompatibility of osteoblast cells (MC3T3) revealed high adherence, proliferation, and survival on the porous structure of PVAc coated Mg alloy, which was not observed for the uncoated samples. This novel PVAc coating is a promising candidate for biodegradable implant materials, which might widen the use of Mg based implants.

  11. Microstructure and creep behavior of magnesium-aluminum alloys containing alkaline and rare earth additions

    NASA Astrophysics Data System (ADS)

    Saddock, Nicholas David

    In the past few decades governmental regulation and consumer demands have lead the automotive companies towards vehicle lightweighting. Powertrain components offer significant potential for vehicle weight reductions. Recently, magnesium alloys have shown promise for use in powertrain applications where creep has been a limiting factor. These systems are Mg-Al based, with alkaline earth or rare earth additions. The solidification, microstructure, and creep behavior of a series of Mg-4 Al- 4 X:(Ca, Ce, La, and Sr) alloys and a commercially developed AXJ530 (Mg--5 Al--3 Ca--0.15 Sr) alloy (by wt%) have been investigated. The order of decreasing freezing range of the five alloys was: AX44, AXJ530, AJ44, ALa44 and ACe44. All alloys exhibited a solid solution primary alpha-Mg phase surrounded by an interdendritic region of Mg and intermetallic(s). The primary phase was composed of grains approximately an order of magnitude larger than the cellular structure. All alloys were permanent mold cast directly to creep specimens and AXJ530 specimens were provided in die-cast form. The tensile creep behavior was investigated at 175 °C for stresses ranging from 40 to 100 MPa. The order of decreasing creep resistance was: die-cast AXJ530 and permanent mold cast AXJ530, AX44, AJ44, ALa44 and ACe44. Grain size, solute concentration, and matrix precipitates were the most significant microstructural features that influenced the creep resistance. Decreases in grain size or increases in solute concentration, both Al and the ternary addition, lowered the minimum creep rate. In the Mg-Al-Ca alloys, finely distributed Al2Ca precipitates in the matrix also improved the creep resistance by a factor of ten over the same alloy with coarse precipitates. The morphology of the eutectic region was distinct between alloys but did not contribute to difference in creep behavior. Creep strain distribution for the Mg-Al-Ca alloys developed heterogeneously on the scale of the alpha-Mg grains. As additional bulk strain accumulated, strain localized along grain boundaries between grains with significantly different Schmid factors. At these locations cavities and cracks formed that led to the eventual creep failure. Grain size influenced the plastic strain distribution during creep.

  12. High-strain-rate superplasticity at low temperature in a ZK61 magnesium alloy produced by powder metallurgy

    Microsoft Academic Search

    Hiroyuki Watanabe; Toshiji Mukai; Mamoru Mabuchi; Kenji Higashi

    1999-01-01

    In the present study, superplastic behavior of a pseudo single phase magnesium alloy, ZK61, was investigated at about half the absolute melting point. The material was produced by the P\\/M route, and had a fine grain size of [approximately]500 nm. It is demonstrated that the P\\/M ZK61 alloy can behave in a superplastic manner at a high strain rate of

  13. Transient Liquid Phase Diffusion Bonding of Magnesium Alloy (Mg-AZ31) to Titanium Alloy (Ti-6Al-4V)

    NASA Astrophysics Data System (ADS)

    Atieh, Anas Mahmoud

    The magnesium alloy Mg-AZ31 and titanium alloy Ti-6Al-4V have physical characteristics and mechanical properties that makes it attractive for a wide range of engineering applications in the aerospace and automotive industries. However, the differences in melting temperature and coefficient of thermal expansion hinder the use of traditional fusion welding techniques. Transient liquid phase (TLP) bonding of magnesium alloy Mg-AZ31 and titanium alloy Ti-6Al- 4V was performed and different interlayer types and configurations were used to facilitate joint formation. The joining of these alloys using Ni foils was successful at a bonding temperature of 515°C, bonding pressure 0.2 MPa, for bonding time of 5 minutes. At the Ni/Mg-AZ31 bond interface, the formation of a eutectic liquid between Mg and Ni was observed. The formation of Mg2Ni and Mg3AlNi2 were identified along the bond interface resulting in an isothermally solidified joint. At the Ni/Ti-6Al-4V interface, the solid-state diffusion process results in joint formation. The use of double Ni-Cu sandwich joint resulted in further enhancement in joint formation and this produced joints with greater shear strength values. The configuration of Mg-AZ31/Cu- Ni/Ti-6Al-4V or Mg-AZ31/Ni-Cu/Ti-6Al-4V influence the mechanism of bonding and the type of intermetallics formed within the joint. The application of thin Ni electrodeposited coatings resulted in further enhancements of joint quality due to better surface-to-surface contact and a reduction in the formation of intermetallics at the joint. The effect of Cu nano-particles in the coatings was found to decrease the eutectic zone width and this resulted in an increase the shear strength of the joints. The highest shear strength of 69 MPa was possible with bonds made using coatings containing Cu nano-particle dispersion.

  14. Influence of shot peening on corrosion properties of biocompatible magnesium alloy AZ31 coated by dicalcium phosphate dihydrate (DCPD).

    PubMed

    Mhaede, Mansour; Pastorek, Filip; Hadzima, Branislav

    2014-06-01

    Magnesium alloys are promising materials for biomedical applications because of many outstanding properties like biodegradation, bioactivity and their specific density and Young's modulus are closer to bone than the commonly used metallic implant materials. Unfortunately their fatigue properties and low corrosion resistance negatively influenced their application possibilities in the field of biomedicine. These problems could be diminished through appropriate surface treatments. This study evaluates the influence of a surface pre-treatment by shot peening and shot peening+coating on the corrosion properties of magnesium alloy AZ31. The dicalcium phosphate dihydrate coating (DCPD) was electrochemically deposited in a solution containing 0.1M Ca(NO3)2, 0.06M NH4H2PO4 and 10mL/L of H2O2. The effect of shot peening on the surface properties of magnesium alloy was evaluated by microhardness and surface roughness measurements. The influence of the shot peening and dicalcium phosphate dihydrate layer on the electrochemical characteristics of AZ31 magnesium alloy was evaluated by potentiodynamic measurements and electrochemical impedance spectroscopy in 0.9% NaCl solution at a temperature of 22±1°C. The obtained results were analyzed by the Tafel-extrapolation method and equivalent circuit method. The results showed that the application of shot peening process followed by DCPD coating improves the properties of the AZ31 surface from corrosion and mechanical point of view. PMID:24863232

  15. Study on Attraction of Laser to Arc Plasma in Laser-TIG Hybrid Welding on Magnesium Alloy

    Microsoft Academic Search

    Minghua Chen; Liming Liu

    2011-01-01

    This paper presents the results of investigation on the attraction of laser to the electric arc plasma in laser-tungsten inert gas (TIG) hybrid welding of magnesium alloy AZ31B plates. By comparably estimating the characteristics of arc plasma, including the shape, the electron temperature, and density of the arc plasmas in hybrid welding and single TIG welding, three interactions between laser

  16. A Crystalline Plasticity Finite Element Method for Simulation of the Plastic Deformation of AZ31 Magnesium Alloys

    Microsoft Academic Search

    Dayong Li; Shaorui Zhang; Weiqin Tang; Shiyao Huang; Yinghong Peng

    2010-01-01

    In this paper, a constitutive framework based on a crystalline plasticity model is employed to simulate the plastic deformation of AZ31 magnesium alloy, which posses the hexagonal close packed (HCP) crystal structure. Dislocation slip and mechanical twinning are taken into account in the model. The successive integration method is used to determine the active slip systems, and the contribution of

  17. Investigation of the macroscopic and microscopic electrochemical corrosion behaviour of PVD-coated magnesium die cast alloy AZ91

    Microsoft Academic Search

    H. Hoche; C. Rosenkranz; A. Delp; M. M. Lohrengel; E. Broszeit; C. Berger

    2005-01-01

    The PVD plasma anodisation method developed by the authors allows the anodisation and subsequent PVD deposition of magnesium alloys in a process step using a conventional PVD sputtering unit. In the standard salt spray test, these surfaces show corrosion behaviour superior to conventional hard coatings, and they also show good wear characteristics [H. Hoche, H. Scheerer, E. Broszeit, C. Berger,

  18. Computational microstructure analyzing technique for quantitative characterization of shrinkage and gas pores in pressure die cast AZ91 magnesium alloys

    Microsoft Academic Search

    D. G. Leo Prakash; B. Prasanna; D. Regener

    2005-01-01

    Pressure die cast AZ91 magnesium alloy contains both shrinkage and gas microporosity. Quantification and characterization of shrinkage and gas microporosity is expected to be useful to understand the processing-properties-microstructure correlations. However, conventional image analysis techniques do not permit a separate quantification and characterization of shrinkage and gas microporosity. A computational microstructural (image) analyzing technique has been developed by the use

  19. Comparative study on the biodegradation and biocompatibility of silicate bioceramic coatings on biodegradable magnesium alloy as biodegradable biomaterial

    NASA Astrophysics Data System (ADS)

    Razavi, M.; Fathi, M. H.; Savabi, O.; Razavi, S. M.; Hashemibeni, B.; Yazdimamaghani, M.; Vashaee, D.; Tayebi, L.

    2014-03-01

    Many clinical cases as well as in vivo and in vitro assessments have demonstrated that magnesium alloys possess good biocompatibility. Unfortunately, magnesium and its alloys degrade too quickly in physiological media. In order to improve the biodegradation resistance and biocompatibility of a biodegradable magnesium alloy, we have prepared three types of coating include diopside (CaMgSi2O6), akermanite (Ca2MgSi2O6) and bredigite (Ca7MgSi4O16) coating on AZ91 magnesium alloy through a micro-arc oxidation (MAO) and electrophoretic deposition (EPD) method. In this research, the biodegradation and biocompatibility behavior of samples were evaluated in vitro and in vivo. The in vitro analysis was performed by cytocompatibility and MTT-assay and the in vivo test was conducted on the implantation of samples in the greater trochanter of adult rabbits. The results showed that diopside coating has the best bone regeneration and bredigite has the best biodegradation resistance compared to others.

  20. Warm Deep Drawing of Rectangular Parts of AZ31 Magnesium Alloy Sheet Adopting Variable Blank Holder Force

    SciTech Connect

    Peng Yinghong; Chang Qunfeng; Li Dayong [School of Mechanical Engineering, Shanghai Jiaotong University, 200240 (China); Zeng Xiaoqin [School of Materials Science and Engineering, Shanghai Jiaotong University, Shanghai 200240 (China)

    2007-05-17

    AZ31 magnesium alloy sheet with good shape and formability is fabricated by warm cross rolling. Uniaxial tensile tests are conducted using a Gleeble 3500 thermal - mechanical simulator, and the mechanical properties of AZ31 magnesium alloy sheet are analyzed. A warm deep drawing process of square part is also simulated by the finite element method. The influences of blank holder force on the formability are numerically investigated. A double-action hydraulic press that can realize adjustable blank holder forces is developed and its working principle and control system are introduced. Some warm deep drawing experiments of square parts of AZ31 magnesium alloy sheet are also performed. Different variation schemes of the blank holder force with the stroke of the punch are tested, and the experiment results are compared. Results show that the suitable blank holder force variation scheme is a ladder curve with the punch stroke. Adopting the variable blank holder force technique can improve 13.2% of the drawing depth of square parts of AZ31 magnesium alloy sheet.

  1. Development and evaluation of a magnesium-zinc-strontium alloy for biomedical applications--alloy processing, microstructure, mechanical properties, and biodegradation.

    PubMed

    Guan, Ren-guo; Cipriano, Aaron F; Zhao, Zhan-yong; Lock, Jaclyn; Tie, Di; Zhao, Tong; Cui, Tong; Liu, Huinan

    2013-10-01

    A new biodegradable magnesium-zinc-strontium (Mg-Zn-Sr) alloy was developed and studied for medical implant applications. This first study investigated the alloy processing (casting, rolling, and heat treatment), microstructures, mechanical properties, and degradation properties in simulated body fluid (SBF). Aging treatment of the ZSr41 alloy at 175 °C for 8h improved the mechanical properties when compared to those of the as-cast alloy. Specifically, the aged ZSr41 alloy had an ultimate tensile strength of 270 MPa, Vickers hardness of 71.5 HV, and elongation at failure of 12.8%. The mechanical properties of the ZSr41 alloy were superior as compared with those of pure magnesium and met the requirements for load-bearing medical implants. Furthermore, the immersion of the ZSr41 alloy in SBF showed a degradation mode that progressed cyclically, alternating between pitting and localized corrosion. The steady-state average degradation rate of the aged ZSr41 alloy in SBF was 0.96 g/(m(2)·hr), while the pH of SBF immersion solution increased. The corrosion current density of the ZSr41 alloy in SBF solution was 0.41 mA/mm(2), which was much lower than 1.67 mA/mm(2) for pure Mg under the same conditions. In summary, compared to pure Mg, the mechanical properties of the new ZSr41 alloy improved while the degradation rate decreased due to the addition of Zn and Sr alloying elements and specific processing conditions. The superior mechanical properties and corrosion resistance of the new ZSr41 alloy make it a promising alloy for next-generation implant applications. PMID:23910262

  2. Biocorrosion resistance of coated magnesium alloy by microarc oxidation in electrolyte containing zirconium and calcium salts

    NASA Astrophysics Data System (ADS)

    Wang, Ya-Ming; Guo, Jun-Wei; Wu, Yun-Feng; Liu, Yan; Cao, Jian-Yun; Zhou, Yu; Jia, De-Chang

    2014-09-01

    The key to use magnesium alloys as suitable biodegradable implants is how to adjust their degradation rates. We report a strategy to prepare biocompatible ceramic coating with improved biocorrosion resistance property on AZ91D alloy by microarc oxidation (MAO) in a silicate-K2ZrF6 solution with and without Ca(H2PO4)2 additives. The microstructure and biocorrosion of coatings were characterized by XRD and SEM, as well as electrochemical and immersion tests in simulated body fluid (SBF). The results show that the coatings are mainly composed of MgO, Mg2SiO4, m-ZrO2 phases, further Ca containing compounds involve the coating by Ca(H2PO4)2 addition in the silicate-K2ZrF6 solution. The corrosion resistance of coated AZ91D alloy is significantly improved compared with the bare one. After immersing in SBF for 28 d, the Si-Zr5-Ca0 coating indicates a best corrosion resistance performance.

  3. Parametric Study of Friction Stir Processing of Magnesium-Based AE42 Alloy

    NASA Astrophysics Data System (ADS)

    Arora, H. S.; Singh, H.; Dhindaw, B. K.

    2012-11-01

    Friction stir processing (FSP) is one of the severe plastic deformation processes which can significantly affect the material properties. The friction stir processed (FSPed) zone is extremely sensitive to the FSP parameters. The main aim of the current investigation is to analyze the simultaneous influence of the major FSP parameters on the mechanical behavior of a magnesium-based AE42 alloy. In this investigation, Taguchi's experimental design approach was utilized to determine the optimized set of investigated FSP parameters for processing the AE42 alloy. Hardness of the FSPed specimens was considered as the output response of the experimental design. Cooling temperature during FSP, FSP tool rotational speed, and number of FSP passes were found to be the most influential FSP parameters in the current investigation. A nonlinear regression equation for the output response and the FSP process parameters was also developed using MINITAB 16 software. The developed equation was found to accurately predict the output response of the FSPed AE42 alloy

  4. Failure Analysis of Warm Stamping of Magnesium Alloy Sheet Based on an Anisotropic Damage Model

    NASA Astrophysics Data System (ADS)

    Zhao, P. J.; Chen, Z. H.; Dong, C. F.

    2014-08-01

    Based on the frame work of continuum damage mechanics, a research work of anisotropic damage evolution in warm stamping process of magnesium alloy sheets has been carried out by means of a combined experimental-numerical method. The aim was to predict formability of warm stamping of AZ31 Mg alloy sheets by taking the thermal and damage effects into account. In the presented work, a temperature-dependent anisotropic yield function suitable for cold rolling sheet metals together with an anisotropic damage model was implemented into the a VUMAT subroutine for ABAQUS/EXPLICIT. The evolution of internal damage in the form of void growth and coalescence in AZ31 Mg alloy sheet was observed by means of scanning electron microscopy (SEM). Moreover, a coupled thermo-mechanical simulation of the stamping process was performed using the implemented code at different temperatures. The parameters employed in the simulation were determined by the standard tensile tests and algebraic manipulation. The overall anisotropic damage process from crack initiation to final propagation in local area of blank was simulated. Numerical results show that the prediction of the site of crack initiation and the orientation of crack propagation are consistent with the data observed in warm stamping experiments.

  5. Failure Analysis of Warm Stamping of Magnesium Alloy Sheet Based on an Anisotropic Damage Model

    NASA Astrophysics Data System (ADS)

    Zhao, P. J.; Chen, Z. H.; Dong, C. F.

    2014-11-01

    Based on the frame work of continuum damage mechanics, a research work of anisotropic damage evolution in warm stamping process of magnesium alloy sheets has been carried out by means of a combined experimental-numerical method. The aim was to predict formability of warm stamping of AZ31 Mg alloy sheets by taking the thermal and damage effects into account. In the presented work, a temperature-dependent anisotropic yield function suitable for cold rolling sheet metals together with an anisotropic damage model was implemented into the a VUMAT subroutine for ABAQUS/EXPLICIT. The evolution of internal damage in the form of void growth and coalescence in AZ31 Mg alloy sheet was observed by means of scanning electron microscopy (SEM). Moreover, a coupled thermo-mechanical simulation of the stamping process was performed using the implemented code at different temperatures. The parameters employed in the simulation were determined by the standard tensile tests and algebraic manipulation. The overall anisotropic damage process from crack initiation to final propagation in local area of blank was simulated. Numerical results show that the prediction of the site of crack initiation and the orientation of crack propagation are consistent with the data observed in warm stamping experiments.

  6. Design factors influencing weldability of the Mg-4Y-3RE cast magnesium alloy

    NASA Astrophysics Data System (ADS)

    Kierzek, A.; Adamiec, J.

    2011-05-01

    Due to low density and good strength properties, magnesium alloys are increasingly used as a structural material They are used, amongst others, for large-size castings in sand moulds, pressure and precision castings. Welding and pad welding is used to repair casting defects, such as misruns, micro-shrinkage, cracks, etc. The most frequent reason for disqualifying of welded joints made to repair the castings is hot cracking which occurs as a result of tensile stresses formed in the material during welding. The Mg-4Y-3RE (WE43) alloy with addition of yttrium and rare earth and zirconium elements used for testing is creep resistant to 300°C. The alloy is used in the automotive industry, for example for engine blocks and in aerospace industry for gearbox housings. This paper describes the welding and remelting tests of the Mg-4Y-3RE (WE43) castings in conditions of constant and variable stiffness. It has been concluded that hot cracks are formed as a result of eutectic melting in the areas of contact of ? - Mg solid solution crystals.

  7. Mathematical modeling and experimental study of squeeze casting of magnesium alloy AM50A and aluminum alloy A356

    NASA Astrophysics Data System (ADS)

    Yu, Fang

    In recent years, the squeeze casting process has been widely used with various aluminum alloys to manufacture near-net shape automotive components. Preliminary research has also demonstrated technical feasibility potential of squeeze casting for magnesium. A better understanding of squeeze casting process is essential for applying the process for the production of large automotive components, such as engine block, using aluminum and magnesium. Meanwhile, simulation can help to achieve the analysis and optimization of the casting process. Unfortunately, for squeeze casting, no appropriate model is presently available. In this study, a mathematical model has been developed to simulate the transport phenomena and solidification occurring in squeeze casting process. The model was based on the control-volume finite difference approach and on an enthalpy method. An experimental system was developed capable of characterizing local in-cavity pressures, determining casting/die interfacial heat transfer, and observing pressurized solidification phenomena taking place in squeeze casting of aluminum and magnesium alloys. It was found that, during squeeze casting process, the local cavity pressure distribution was inhomogeneous. Experimental correlations of heat transfer coefficient were integrated into the model with local cavity pressures estimated by a force balance approach. Hence, instead of using static boundary condition, a dynamic boundary condition was established in the model. In order to minimize the deviation of calculation, experimental correlations between solidification temperatures and applied pressures were also integrated into the model. The predicted results, including cooling curves, solidification times, and local pressure cavity pressures, were compared with the experimental measurements and they were found to be in good agreement. The model was further advanced to predict shrinkage porosity during squeeze casting by a newly proposed criterion based on "burst-feeding" theory. The proposed model is able to predict the occurrence and location of porosity formation under a specified applied pressure and holding time. Comparison of the experimental results with the result of computations, the model not only successfully predicted the occurrence of porosity under certain circumstances, but also indicated the correct locations where porosity formed. Hence, it can be used for the optimization of the squeeze casting process.

  8. Zirconium, calcium, and strontium contents in magnesium based biodegradable alloys modulate the efficiency of implant-induced osseointegration

    PubMed Central

    Mushahary, Dolly; Sravanthi, Ragamouni; Li, Yuncang; Kumar, Mahesh J; Harishankar, Nemani; Hodgson, Peter D; Wen, Cuie; Pande, Gopal

    2013-01-01

    Development of new biodegradable implants and devices is necessary to meet the increasing needs of regenerative orthopedic procedures. An important consideration while formulating new implant materials is that they should physicochemically and biologically mimic bone-like properties. In earlier studies, we have developed and characterized magnesium based biodegradable alloys, in particular magnesium-zirconium (Mg-Zr) alloys. Here we have reported the biological properties of four Mg-Zr alloys containing different quantities of strontium or calcium. The alloys were implanted in small cavities made in femur bones of New Zealand White rabbits, and the quantitative and qualitative assessments of newly induced bone tissue were carried out. A total of 30 experimental animals, three for each implant type, were studied, and bone induction was assessed by histological, immunohistochemical and radiological methods; cavities in the femurs with no implants and observed for the same period of time were kept as controls. Our results showed that Mg-Zr alloys containing appropriate quantities of strontium were more efficient in inducing good quality mineralized bone than other alloys. Our results have been discussed in the context of physicochemical and biological properties of the alloys, and they could be very useful in determining the nature of future generations of biodegradable orthopedic implants. PMID:23976848

  9. Effect of preheat on TIG welding of AZ61 magnesium alloy

    NASA Astrophysics Data System (ADS)

    Shen, Jun; Xu, Nan

    2012-04-01

    The effects of preheat treatments on the microstructures and mechanical properties of tungsten inert gas (TIG)-welded AZ61 magnesium alloy joints were studied by microstructural observations, microhardness tests and tensile tests. The results showed that the volume fraction of the lamellar ?-Mg17(Al,Zn)12 intermetallic compound of in fusion zone (FZ) increased from 15% to 66% with an increase in preheat temperature. Moreover, the microhardness of the FZ and the ultimate tensile strength of the welded joints reached their maximum values when the preheat temperature was 300°C because more lamellar ?-Mg17(Al,Zn)12 intermetallic compounds were distributed at the ?-Mg grain boundaries and no cracks and pores formed in the FZ of the welded joint.

  10. Fatigue and material characteristics of a hot-formed AZ31 magnesium alloy

    NASA Astrophysics Data System (ADS)

    Suh, Chang-Min; Hor, Kwang-Ho; Nahm, Seung-Hoon; Suh, Min-Soo

    2015-03-01

    Magnesium alloys are known to be hard-forming materials at room temperature owing to their material structure. This study analyzes the optimal temperature conditions of warm-forming and the forming process by using a high-pressure laminating test and FM analysis, respectively. The effect of temperatures on the fatigue limit was examined from the collected specimens by analyzing the material properties after the fatigue test. The material formed at a temperature of 230°C shows occasional defects, but the best forming quality was obtained at 270°C. The optimal temperature for the forming process was found to be 250°C considering the material quality and thermal efficiency. The overall fatigue life of specimens decreases with an increase in the processing temperature. The fatigue limit of AZ31 formed at 250°C was approximately 100 MPa after 106 cycles.

  11. Achieving High Strength and High Ductility in Friction Stir-Processed Cast Magnesium Alloy

    NASA Astrophysics Data System (ADS)

    Yuan, Wei; Panigrahi, Sushanta K.; Mishra, Rajiv S.

    2013-08-01

    Friction stir processing (FSP) is emerging as an effective tool for microstructural modification and property enhancement. As-cast AZ91 magnesium alloy was friction stir processed with one-pass and two-pass to examine the influence of processing conditions on microstructural evolution and corresponding mechanical properties. Grain refinement accompanied with development of strong basal texture was observed for both processing conditions. Ultrafine-grained (UFG) AZ91 was achieved under two-pass FSP with fine precipitates distributed on the grain boundary. The processed UFG AZ91 exhibited a high tensile strength of ~435 MPa (117 pct improvement) and tensile fracture elongation of ~23 pct. The promising combination of strength and ductility is attributed to the elimination of casting porosity, and high density of fine precipitates in an UFG structure with quite low dislocation density. The effects of grain size, precipitate, and texture on deformation behavior have been discussed.

  12. Validation of Predicted Residual Stresses within Direct Chill Cast Magnesium Alloy Slab

    NASA Astrophysics Data System (ADS)

    Turski, Mark; Paradowska, Anna; Zhang, Shu-Yan; Mortensen, Dag; Fjaer, Hallvard; Grandfield, John; Davis, Bruce; DeLorme, Rick

    2012-05-01

    A significant level of cold cracking has been observed within direct chill (DC) cast, high-strength magnesium alloy Elektron WE43. These cracks have been attributed to the formation of significant residual stresses during casting. A finite-element modeling (FEM) code, which is called ALSIM, has been used to predict the residual stress within the DC-cast slab. Verification of the predicted residual stress field within an 870 × 315-mm sized slab has been carried out using neutron diffraction measurements. Given that measurements in such large-scale components using diffraction measurements are particularly challenging and expensive, the efficient use of neutron diffraction measurements is emphasized. This has included the use of sectioning, allowing the residual stress within the slab to be mapped in detail.

  13. Crystal plasticity finite element modelling of the extrusion texture of a magnesium alloy

    NASA Astrophysics Data System (ADS)

    Shao, Yichuan; Tang, Tao; Li, Dayong; Tang, Weiqin; Peng, Yinghong

    2015-07-01

    In this paper, a crystal plasticity finite-element model (CPFEM) is developed to simulate the hot extrusion texture of the magnesium alloy AZ31. The crystal plasticity model is implemented in ABAQUS™ via user interface VUMAT subroutine. The elasto-plastic self-consistent (EPSC) model is used as the basic polycrystal framework to simulate the slip and twinning during the extrusion. Furthermore, this framework is extended to account for the effects of the dynamically recrystallized (DRX) grains on the extrusion textures. Good agreement is found between the experimentally measured and simulated textures. The simulation results show that the presence of a secondary texture component around < 11.0> || extrusion direction (ED) can be attributed to the lattice rotation around the c-axis during the formation of the DRX grains. In addition, the shear strain imposed on the extruded material affects the resulting texture by enhancing the basal < a> slip mode as the material passes through the extrusion opening.

  14. Microstructure, texture, and residual stress in a friction stir processed AZ31B magnesium alloy

    SciTech Connect

    Woo, Wan Chuck [ORNL; Choo, Hahn [ORNL; Feng, Zhili [ORNL; Clausen, B [Los Alamos National Laboratory (LANL); Prime, Michael B [ORNL

    2008-01-01

    Spatial variations of microstructure, hardness, chemical composition, tensile behavior, texture and residual stresses were investigated in a friction-stir-processed (FSP) AZ31B magnesium alloy. The residual stresses were measured using two different methods: neutron diffraction and the contour method. No significant variations in the hardness and chemical compositions were found in the FSP zones, including the severely deformed stir zone (SZ), which showed a finer grain size compared to the heat-affected zone and base material. On the other hand, significant changes in the tensile yield strength, texture, and residual stresses were observed in the FSP zones. The relationship between the texture variations and yield strength reduction; and its influence on the decrease in the residual stress near the SZ is discussed. Finally, the residual stresses measured by neutron diffraction and the contour method are compared and the effect of the texture on neutron diffraction residual stress measurements is discussed.

  15. Multi-Objective Optimization of a Wrought Magnesium Alloy for High Strength and Ductility

    SciTech Connect

    Radhakrishnan, Balasubramaniam [ORNL; Gorti, Sarma B [ORNL; Patton, Robert M [ORNL; Simunovic, Srdjan [ORNL

    2013-01-01

    An optimization technique is coupled with crystal plasticity based finite element (CPFE) computations to aid the microstructural design of a wrought magnesium alloy for improved strength and ductility. The initial microstructure consists of a collection of sub-micron sized grains containing deformation twins. The variables used in the simulations are crystallographic texture, and twin spacing within the grains. It is assumed that plastic deformation occurs mainly by dislocation slip on two sets of slip systems classified as hard and soft modes. The hard modes are those slip systems that are inclined to the twin planes and the soft mode consists of dislocation glide along the twin plane. The CPFE code calculates the stress-strain response of the microstructure as a function of the microstructural parameters and the length-scale of the features. A failure criterion based on a critical shear strain and a critical hydrostatic stress is used to define ductility. The optimization is based on the sequential generation of an initial population defined by the texture and twin spacing variables. The CPFE code and the optimizer are coupled in parallel so that new generations are created and analyzed dynamically. In each successive generation, microstructures that satisfy at least 90% of the mean strength and mean ductility in the current generation are retained. Multiple generation runs based on the above procedure are carried out in order to obtain maximum strength-ductility combinations. The implications of the computations for the design of a wrought magnesium alloy are discussed. Research sponsored by the Laboratory Directed Research and Development Program of Oak Ridge National Laboratory, managed by UT-Battelle, LLC, for the U. S. Department of Energy.

  16. Mechanism and Microstructure of Oxide Fluxes for Gas Tungsten Arc Welding of Magnesium Alloy

    NASA Astrophysics Data System (ADS)

    Liu, L. M.; Zhang, Z. D.; Song, G.; Wang, L.

    2007-03-01

    Five single oxide fluxes—MgO, CaO, TiO2, MnO2, and Cr2O3—were used to investigate the effect of active flux on the depth/width ratio in AZ31B magnesium alloy. The microstructure and mechanical property of the tungsten inert gas (TIG) welding seam were studied. The oxygen content in the weld seam and the arc images during the TIG welding process were analyzed. A series of emission spectroscopy of weld arc for TIG welding for magnesium with and without flux were developed. The results showed that for the five single oxide fluxes, all can increase the weld penetration effectively and grain size in the weld seam of alternating current tungsten inert gas (ACTIG) welding of the Mg alloy. The oxygen content of the welds made without flux is not very different from those produced with oxide fluxes not considering trapped oxide. However, welds that have the best penetration have a relatively higher oxygen content among those produced with flux. It was found that the arc images with the oxide fluxes were only the enlarged form of the arc images without flux; the arc constriction was not observed. The detection of arc spectroscopy showed that the metal elements in the oxides exist as the neutral atom or the first cation in the weld arc. This finding would influence the arc properties. When TIG simulation was carried out on a plate with flux applied only on one side, the arc image video showed an asymmetric arc, which deviated toward the flux free side. The thermal stability, the dissociation energy, and the electrical conductivity of oxide should be considered when studying the mechanism for increased TIG flux weld penetration.

  17. Electrochemical behaviors of the magnesium alloy substrates in various pretreatment solutions

    NASA Astrophysics Data System (ADS)

    Zhu, Yanping; Yu, Gang; Hu, Bonian; Lei, Xiping; Yi, Haibo; Zhang, Jun

    2010-02-01

    Interface reactions and film features of AZ91D magnesium alloy in pickling, activation and zinc immersion solutions have been investigated. The surface morphologies of the specimens were observed with scanning electron microscope (SEM). Electrochemical behaviors of AZ91D magnesium alloy in the baths of pickling, activation and zinc immersion were analyzed based on the open circuit potential (OCP) - time curves in various solutions. The results show that the corrosive rate in HNO 3 + CrO 3 or HNO 3 + H 3PO 4 pickling solution was more rapid than in KMnO 4 pickling-activation solution. Both ? phase and ? phase of the substrates were uniformly corroded in HNO 3 + CrO 3 or HNO 3 + H 3PO 4 pickling solution, the coarse surface can augment the mechanical occlusive force between the subsequent coatings and the substrates, so coatings with good adhesion can be obtained. In HF activation solution, the chromic compound formed via HNO 3 + CrO 3 pickling was removed and a compact MgF 2 film was formed on the substrate surface. In K 4P 2O 7 activation solution, the corrosion products formed via HNO 3 + H 3PO 4 pickling were removed, a new thin film of oxides and hydroxides was formed on the substrate surface. In KMnO 4 pickling-activation solution, a film of manganic oxides and phosphates was adhered on the substrate surface. Zinc film was symmetrically produced via K 4P 2O 7 activation or KMnO 4 pickling-activation, so it was good interlayer for Ni or Cu electroplating. Asymmetrical zinc film was produced because the MgF 2 film obtained in the HF activation solution had strong adhesive attraction and it was not suitable for interlayer for electroplating. However, the substrate containing compact MgF 2 film without zinc immersion was fit for direct electroless Ni-P plating.

  18. Analysis of Solid State Bonding in the Extrusion Process of Magnesium Alloys --Numerical Prediction and Experimental Verification

    NASA Astrophysics Data System (ADS)

    Alharthi, Nabeel H.

    The automotive industry developments focused on increasing fuel efficiency are accomplished by weight reduction of vehicles, which consequently results in less negative environmental impact. Usage of low density materials such as Magnesium alloys is an approach to replace heavier structural components. One of the challenges in deformation processing of Magnesium is its low formability attributed to the hexagonal close packed (hcp) crystal structure. The extrusion process is one of the most promising forming processes for Magnesium because it applies a hydrostatic compression state of stress during deformation resulting in improved workability. Many researchers have attempted to fully understand solid state bonding during deformation in different structural materials such as Aluminum, Copper and other metals and alloys. There is a lack of sufficient understanding of the extrusion welding in these materials as well as very limited knowledge on this subject for hollow profiles made from Magnesium alloys. The weld integrity and the characteristic of the welding microstructure are generally unknown. In this dissertation three related research projects are investigated by using different tools such as microstructure characterization, mechanical testing, thermo-mechanical physical simulation and finite element numerical modeling. Project 1: Microstructure characterization supported by mechanical testing of the extrusion welding regions in Magnesium alloy AM30 extrudate. The microstructure characterization was conducted using Light Optical Microscopy (LOM), in addition to LOM the electron backscattered diffraction (EBSD) technique was implemented to characterize in depth the deformed and welded microstructure. Project 2: Finite element numerical simulation of AM30 extrudate to model different process parameters and their influence on localized state variables such as strain, strain rate, temperature and normal pressure within the weld zone. Project 3: Physical simulation of the extrusion welding by using Gleeble 3500 thermo-mechanical simulator to create deformation welds in Magnesium alloy AM30 samples in compression test under various temperatures and strain rates conditions. Based on the obtained results from the performed research projects and literature review, a new qualitative criterion of extrusion welding has been introduced as contribution to the field. The criterion and its analysis have provided better understanding of material response to processing parameters and assisted in selecting the processing windows for good practices in the extrusion process. In addition, the new approach contributed to better understanding and evaluating the quality of the solid state bonding of Mg alloy. Accordingly, the criteria help to avoiding formation of potential mechanical and metallurgical imperfections.

  19. Alloy development for the enhanced stability of Omega precipitates in aluminum-copper-magnesium-(silver) alloys

    Microsoft Academic Search

    Brian M. Gable

    2004-01-01

    This research involved a combined analytical and experimental approach to the design of an age-hardenable Al-Cu-Mg-Ag alloy for moderate temperature application. The applied methodology involved the complimentary techniques of thermal analysis, calculated phase diagrams, analytical microscopy and quantitative microstructural characterization. The objective of this research was to exploit several avenues for enhancing the coarsening resistance and thermal stability of the

  20. Transient Heat and Material Flow Modeling of Friction Stir Processing of Magnesium Alloy using Threaded Tool

    SciTech Connect

    Yu, Zhenzhen [ORNL; Zhang, Wei [ORNL; Choo, Hahn [ORNL; Feng, Zhili [ORNL

    2012-01-01

    A three-dimensional transient computational fluid dynamics (CFD) model was developed to investigate the material flow and heat transfer during friction stir processing (FSP) in an AZ31B magnesium alloy. The material was assumed to be a non-Newtonian viscoplastic fluid, and the Zener-Hollomon parameter was used to describe the dependence of material viscosity on temperature and strain rate. The material constants used in the constitutive equation were determined experimentally from compression tests of the AZ31B Mg alloy under a wide range of strain rates and temperatures. A dynamic mesh method, combining both Lagrangian and Eulerian formulations, was used to capture the material flow induced by the movement of the threaded tool pin. Massless inert particles were embedded in the simulation domain to track the detailed history of material flow. The actual FSP was also carried out on a wrought Mg plate where temperature profiles were recorded by embedding thermocouples. The predicted transient temperature history was found to be consistent with that measured during FSP. Finally, the influence of the thread on the simulated results of thermal history and material flow was studied by comparing two models: one with threaded pin and the other with smooth pin surface.

  1. Surface nanocrystallization mechanism of a rare earth magnesium alloy induced by HVOF supersonic microparticles bombarding

    NASA Astrophysics Data System (ADS)

    Xu, Kaidong; Wang, Aihua; Wang, Yang; Dong, Xuanpu; Zhang, Xianglin; Huang, Zaowen

    2009-11-01

    A nanostructured surface layer with a thickness up to 60 ?m was produced on a rare earth Mg-Gd-Y magnesium alloy using a new process named HVOF-SMB (high velocity oxygen-fuel flame supersonic microparticles bombarding). The microstructural features of the treated surface at various depth of the deformed layer were characterized by optical microscopy (OM), transmission electron microscopy (TEM) and high-resolution transmission electron microscopy (HRTEM) with an aim to reveal the formation mechanism. Results showed that three steps during grain refinement process were found, i.e., twinning dominates the plastic deformation and divides the coarse grains into finer twin platelets at the initial stage, stacking faults are generated and a number of dislocation slip systems are activated leading to the cross slips with increasing strain and strain rate, eventually high-density dislocation networks, dislocation cells and dislocation arrays are formed, which further subdivides the twin platelets and residual microbands into sub-microstructures. As a result, homogeneous nanostructure with a grain size of about 10-20 nm is formed through dynamic recrystallization in the topmost surface layer. Based on the experimental observations, a grain refinement mechanism induced by plastic deformation with higher strain rate during the HVOF-SMB treatment in the rare earth Mg-Gd-Y alloy was proposed.

  2. Effect of magnesium on the lead induced corrosion and SCC of alloy 800 in neutral crevice solution at high temperature

    NASA Astrophysics Data System (ADS)

    Palani, A.; Lu, B. T.; Tian, L. P.; Luo, J. L.; Lu, Y. C.

    2010-01-01

    Dissolved magnesium species in the feed water reduce the incidence of lead-induced stress corrosion cracking (PbSCC) of Alloy 800. The passivity of material was improved by replacing a part of chlorides in the lead-contaminated chemistry with magnesium chloride, as indicated by: (1) a higher pitting potential; (2) lower passive current densities; (3) a film structure with less defects and more spinel oxides. According to the constant extension rate tensile (CERT) tests conducted in the neutral crevice solutions at 300 °C, lead contamination would reduce the ultimate tensile strength (UTS) and elongation of material. The CERT test results were in agreement with the fracture morphology observations. Magnesium addition significantly reduced the detrimental effect of lead contamination.

  3. Effects of heat input on the low power Nd:YAG pulse laser conduction weldability of magnesium alloy AZ61

    NASA Astrophysics Data System (ADS)

    Min, Dong; Shen, Jun; Lai, Shiqiang; Chen, Jie; Xu, Nan; Liu, Hui

    2011-01-01

    The effects of heat input on the low power Nd:YAG pulse laser conduction weldability of magnesium alloy AZ61 plates were investigated. The results show that for a hot-extruded AZ61 magnesium alloy plate laser conduction welding, the penetration depth and area of welds cross-section increased with an increase of the heat input. The microstructure of a band zone, which is located in the fusion zone (FZ) and close to the fusion boundary, evolved with an increase of the heat input. Moreover, an increase of the heat input increased the tendency of the formation of solidification cracking and liquation cracking. The porosities and average diameters of pores increased with an increase of the heat input but reduced sharply when a relatively large heat input was achieved. In addition, the degree of formation of craters increased linearly with an increase of the heat input.

  4. Insitu grown superhydrophobic Zn-Al layered double hydroxides films on magnesium alloy to improve corrosion properties

    NASA Astrophysics Data System (ADS)

    Zhou, Meng; Pang, Xiaolu; Wei, Liang; Gao, Kewei

    2015-05-01

    A hierarchical superhydrophobic zinc-aluminum layered double hydroxides (Zn-Al LDHs) film has been fabricated on a magnesium alloy substrate via a facile hydrothermal crystallization method following chemical modification. The characteristics of the films were investigated by X-ray diffraction (XRD), scanning electronic microscope (SEM), and energy dispersive spectroscopy (EDS). XRD patterns and SEM images showed that the micro/nanoscale hierarchical LDHs film surfaces composed of ZnO nanorods and Zn-Al LDHs nanowalls structures. The static contact angle (CA) for the prepared surfaces was observed at around 165.6°. The corrosion resistance of the superhydrophobic films was estimated by electrochemical impedance spectroscopy (EIS) and potentiondynamic polarization measurement. EIS and polarization measurements revealed that the superhydrophobic Zn-Al LDHs coated magnesium alloy had better corrosion resistance in neutral 3.5 wt.% NaCl solution.

  5. A Crystalline Plasticity Finite Element Method for Simulation of the Plastic Deformation of AZ31 Magnesium Alloys

    SciTech Connect

    Li Dayong; Peng Yinghong [School of Mechanical and Power Engineering, Shanghai Jiaotong University, 800 Dongchuan Road, Shanghai (China); State Key Laboratory of Mechanical System and Vibration, Shanghai Jiaotong University, 800 Dongchuan Road, Shanghai (China); Zhang Shaorui; Tang Weiqin; Huang Shiyao [School of Mechanical and Power Engineering, Shanghai Jiaotong University, 800 Dongchuan Road, Shanghai (China)

    2010-06-15

    In this paper, a constitutive framework based on a crystalline plasticity model is employed to simulate the plastic deformation of AZ31 magnesium alloy, which posses the hexagonal close packed (HCP) crystal structure. Dislocation slip and mechanical twinning are taken into account in the model. The successive integration method is used to determine the active slip systems, and the contribution of twinning to the grain reorientation is treated by the PTR method. The FE model is introduced into ABAQUS/Explicit through a user material subroutine (VUMAT). Three deformation processes of AZ31 magnesium alloy, including tension, compression and a stamping process, are simulated with the present method. The simulation results are compared with experiment and those presented in the literature.

  6. A Crystalline Plasticity Finite Element Method for Simulation of the Plastic Deformation of AZ31 Magnesium Alloys

    NASA Astrophysics Data System (ADS)

    Li, Dayong; Zhang, Shaorui; Tang, Weiqin; Huang, Shiyao; Peng, Yinghong

    2010-06-01

    In this paper, a constitutive framework based on a crystalline plasticity model is employed to simulate the plastic deformation of AZ31 magnesium alloy, which posses the hexagonal close packed (HCP) crystal structure. Dislocation slip and mechanical twinning are taken into account in the model. The successive integration method is used to determine the active slip systems, and the contribution of twinning to the grain reorientation is treated by the PTR method. The FE model is introduced into ABAQUS/Explicit through a user material subroutine (VUMAT). Three deformation processes of AZ31 magnesium alloy, including tension, compression and a stamping process, are simulated with the present method. The simulation results are compared with experiment and those presented in the literature.

  7. Influence of Microstructure of Friction Stir Welded Joints on Growth and Properties of Microarc Oxidation Coatings on AZ31B Magnesium Alloy

    NASA Astrophysics Data System (ADS)

    Chen, Tingfang; Li, Yongliang; Xue, Wenbin; Yang, Chaolin; Qu, Yao; Hua, Ming

    2015-03-01

    Ceramic coatings on friction stir welded (FSW) joints of AZ31B magnesium alloy were fabricated by microarc oxidation (MAO) method in silicate electrolyte. Microstructure, phase constituents, microhardness and electrochemical corrosion behaviors of bare and coated magnesium alloys at different zones of FSW joints for different oxidation time were investigated. The influence of microstructure at different zones on the growth of MAO coatings was analyzed. The results show that the MAO coatings on FSW joints are uniform, and they have almost the same morphology, phase constituents, hardness and corrosion resistance at base metal, stir zone and heat-affected zone. The properties of MAO coatings are independent on the microstructures of AZ31B alloy. In addition, the microstructures of magnesium alloy near the coating/alloy interface at different zones of FSW joint was not changed by microarc discharge process.

  8. Characterization of High Strain Rate Mechanical behavior of AZ31 magnesium alloy using 3D Digital Image Correlation

    Microsoft Academic Search

    Yanli Wang; Hanbing Xu; DONALD L ERDMAN; J Michael Starbuck; Srdjan Simunovic

    2011-01-01

    Characterization of the material mechanical behavior at sub-Hopkinson regime (0.1 to 1000 s¹) is very challenging due to instrumentation limitations and the complexity of data analysis involved in dynamic loading. In this study, AZ31 magnesium alloy sheet specimens are tested using a custom designed servo-hydraulic machine in tension at nominal strain rates up to 1000 s¹. In order to resolve

  9. Improvement of laser keyhole formation with the assistance of arc plasma in the hybrid welding process of magnesium alloy

    Microsoft Academic Search

    Liming Liu; Xinfeng Hao

    2009-01-01

    In the previous work, low-power laser\\/arc hybrid welding technique is used to weld magnesium alloy and high-quality weld joints are obtained. In order to make clear the interactions between low-power laser pulse and arc plasma, the effect of arc plasma on laser pulse is studied in this article. The result shows that the penetration of low-power laser welding with the

  10. Strengthening effect of nickel and copper interlayers on hybrid laser-TIG welded joints between magnesium alloy and mild steel

    Microsoft Academic Search

    Liming Liu; Xiaodong Qi

    2010-01-01

    AZ31B magnesium alloy and Q235 mild steel were lap joined with Ni and Cu interlayers using hybrid laser-TIG welding technique. Microstructure and mechanical properties of joints were examined. The results showed that the shear strength of Cu-added joint was a little higher than that of Ni-added joint, and the strength of both joints exceeded that of base material AZ31B Mg

  11. Spectral Analysis of the Plasma in Low-Power Laser\\/Arc Hybrid Welding of Magnesium Alloy

    Microsoft Academic Search

    Xinfeng Hao; Gang Song

    2009-01-01

    The previous work indicated that there were interactions between laser beam and arc plasma in low-power laser\\/arc hybrid welding. In order to study the interactions, the spectra of plasmas in tungsten inert gas (TIG) welding and hybrid laser\\/TIG welding of magnesium alloy are acquired, and the differences between them are analyzed. In hybrid welding, the intensities of emission spectra of

  12. Experimental and numerical study of the effects of porosity on fatigue crack initiation of HPDC magnesium AM60B alloy

    Microsoft Academic Search

    Y. Lu; F. Taheri; M. A. Gharghouri; H. P. Han

    2009-01-01

    In this study, high-cycle fatigue tests were conducted on specimens machined from 50 sequentially cast instrument panels made from high-pressure die-cast (HPDC) AM60B magnesium alloy. The fatigue life data were described by a two-parameter Weibull model. SEM analyses on the fracture surfaces showed the initiation of the fatigue cracks occurred exclusively at casting pores close to the machined surfaces. The

  13. Combined kinematic\\/isotropic hardening behavior study for magnesium alloy sheets to predict ductile fracture of rotational incremental forming

    Microsoft Academic Search

    Nguyen Duc-Toan; Park Jin-Gee; Kim Young-Suk

    2010-01-01

    In order to predict the ductile fracture of rotational incremental forming for magnesium alloy sheet , a combination of kinematic\\u000a and isotropic hardening law is implemented and ev aluated from the histories of ductile fracture value (I) by means of finite\\u000a element analysis. Here, the criterion for a ductile fracture, as developed by OYANE, [J. Mech. Work. Tech. 4 (1980),

  14. CrN–TiN multilayer coating on magnesium alloy AZ91 by arc-glow plasma depositing process

    Microsoft Academic Search

    Q. Miao; C. E. Cui; J. D. Pan

    2007-01-01

    CrN–TiN multilayer films were deposited on magnesium alloy AZ91 by a novel method of arc-glow plasma depositing to improve its wear resistance. The total thickness of the coating was about 2 ?m with 12 sub-layers of CrN and TiN deposited alternately.The composition and microstructure of the coating layer were analyzed by means of X-ray diffraction (XRD) and glow discharge spectrum (GDS).

  15. Wear and corrosion resistance of AZ31 magnesium alloy irradiated by high-intensity pulsed ion beam

    NASA Astrophysics Data System (ADS)

    Li, P.; Han, X. G.; Xin, J. P.; Zhu, X. P.; Lei, M. K.

    2008-09-01

    The wear and corrosion resistance of AZ31 magnesium alloy irradiated by high-intensity pulsed ion beam (HIPIB) at an ion current density of 100-300 A/cm 2 with shot number of 1-10 are investigated by sliding wear test and potentiodynamic polarization measurement. The surface and cross-sectional morphologies, phase structure and surface microhardness of the irradiated AZ31 magnesium alloy samples are characterized by scanning electron microscopy (SEM), optical microscopy, X-ray diffraction (XRD) and Vickers tester, respectively. The HIPIB irradiation produces the hardened surface layers and improves abrasive wear resistance of all the samples. The wear volume of the irradiated samples at 200 A/cm 2 and 300 A/cm 2 with 10 shots as well as 100 A/cm 2 with 5 shots is about four times less than that of the original sample. The apparent increase in corrosion resistance is achieved for all the irradiated samples in 0.01 mol/l NaCl solution with a pH value of 12. The corrosion potential and pitting breakdown potential for the samples irradiated at 100 A/cm 2 with 5 shots are 560 and 630 mV higher than those of the original sample, -1560 mV and -1300 mV (SCE), respectively. It is found that the combined improvement in wear and corrosion resistance of AZ31 magnesium alloy is achieved by HIPIB irradiation, which is ascribed to the microstructural refinement and the chemical homogeneity of the irradiated magnesium alloy.

  16. On the influence of process variables on the thermal conditions and properties of high pressure die-cast magnesium alloys

    Microsoft Academic Search

    Nahed A. El-Mahallawy; Mohamed A Taha; Engenius Pokora; Friedrich Klein

    1998-01-01

    The influence of pressure and velocity in high-pressure magnesium die casting on the thermal conditions and on the casting properties is studied. Specimens with the shape of a tensile test plate with a thickness of 12 mm and a length of 295 mm were cast using the alloys AM20HP, AM50HP, AS41, AE42, AZ91HP. Two gate velocities of the liquid metal

  17. The Effect of Thermomechanical Processing on the Tensile, Fatigue, and Creep Behavior of Magnesium Alloy AM60

    Microsoft Academic Search

    Zhe Chen; J. Huang; R. F. Decker; S. E. Lebeau; Larry R Walker; Odis Burl Cavin; Thomas R Watkins; C. J. Boehlert

    2011-01-01

    Tensile, fatigue, fracture toughness, and creep experiments were performed on a commercially available magnesium-aluminum\\u000a alloy (AM60) after three processing treatments: (1) as-THIXOMOLDED (as-molded), (2) THIXOMOLDED then thermomechanically processed\\u000a (TTMP), and (3) THIXOMOLDED then TTMP then annealed (annealed). The TTMP procedure resulted in a significantly reduced grain\\u000a size and a tensile yield strength greater than twice that of the as-molded material

  18. Application of neutron diffraction in characterization of texture evolution during high-temperature creep in magnesium alloys

    SciTech Connect

    Vogel, Sven C [Los Alamos National Laboratory; Sediako, Dimitry [CANADIAN NEUTRON BEAM; Shook, S [APPLIED MAGNESIUM INTERNATIONAL; Sediako, A [MCGILL UNIV

    2010-01-01

    A good combination of room-temperature and elevated temperature strength and ductility, good salt-spray corrosion resistance and exceUent diecastability are frequently among the main considerations in development of a new alloy. Unfortunately, there has been much lesser effort in development of wrought-stock alloys for high temperature applications. Extrudability and high temperature performance of wrought material becomes an important factor in an effort to develop new wrought alloys and processing technologies. This paper shows some results received in creep testing and studies of in-creep texture evolution for several wrought magnesium alloys developed for use in elevated-temperature applications. These studies were performed using E3 neutron spectrometer of the Canadian Neutron Beam Centre in Chalk River, ON, and HIPPO time-of-flight (TOF) spectrometer at Los Alamos Neutron Science Center, NM.

  19. Microstructure characterization and micro- and nanoscale mechanical behaviour of magnesium-aluminum and magnesium-aluminum-calcium alloys

    NASA Astrophysics Data System (ADS)

    Han, Lihong

    The application in the automotive industry of the as-cast AM50 alloy (Mg-5.0 wt.%%Al-0.3 wt.%Mn) has been limited by its low creep resistance at elevated temperatures. Permanent mold cast (PM) Mg-Al-Ca alloys with calcium additions (0 ˜ 2.0 wt.%) were investigated in this study due to their potential for improving the high temperature creep strength. The microstructures of the die cast (DC) or PM AM50 alloys consisted of an intergranular beta-Mg17Al12 phase surrounded by a region of Al-rich eutectic alpha-Mg phase, sometimes with attached Al8Mn5 particles. In this study, significant grain refinement was observed in the PM Mg-Al-Ca alloys with Ca addition to the AM50 alloy. The grain refining effect was confirmed by quantitative image analysis through measurement of the secondary dendrite arm spacing (SDAS). The intergranular phases in Mg-Al-Ca alloys with 0.5 or 1.0 wt.% Ca were beta-Mg17Al 12 and (Al, Mg)2Ca phases. As the Ca addition was increased to 1.5 wt.% Ca, the (beta-Mg17Al12 phase was completely replaced by a (Al, Mg)2Ca phase. Differential scanning calorimetry (DSC) results showed that the (Al, Mg)2Ca phase was thermally more stable than the beta-Mg 17Al12 phase, which contributed to the better creep strength of the Mg-Al-Ca alloys. The change in heating/cooling rates played an important role in the redistribution of alloying elements and the dissolution or precipitation of the eutectic phases in the as-cast Mg alloys during DSC runs. The micro- and nano-scale hardness and composite modulus of the PM Mg-Al-Ca alloys increased with increasing Ca content, and the indentation size effect (ISE) was also observed in the as-cast Mg-Al and Mg-Al-Ca alloys. PM AC52 alloy (Mg-5.0wt.%Al-2.0wt.%Ca) was a much more creep resistant alloy than other Mg-Al-Ca alloys with lower Ca contents because of the higher solute content in the primary alpha-Mg in the as-cast state and also because of the presence of nano precipitates within the primary alpha-Mg. The size and volume fraction of the precipitates and the solute content within the primary alpha-Mg of the AC52 alloys were related to the different solidification rates, which directly influence the nano indentation creep strength of the alloys.

  20. A layer-by-layer approach to natural polymer-derived bioactive coatings on magnesium alloys.

    PubMed

    Kunjukunju, Sangeetha; Roy, Abhijit; Ramanathan, Madhumati; Lee, Boeun; Candiello, Joe E; Kumta, Prashant N

    2013-11-01

    The development of polyelectrolyte multilayered coatings on magnesium alloy substrates that can be used for controlled delivery of growth factors and required biomolecules from the surface of these degradable implants could have a significant impact in the field of bone tissue regeneration. The current work reports on the fabrication of multilayered coatings of alginate and poly-L-lysine on alkaline- and fluoride-pretreated AZ31 substrates using a layer-by-layer (LbL) technique under physiological conditions. Furthermore, these coatings were surface functionalized by chemical cross-linking and fibronectin immobilization, and the resultant changes in surface properties have been shown to influence the cellular activity of these multilayered films. The physicochemical characteristics of these coated substrates have been investigated using attenuated total reflectance Fourier transform infrared spectroscopy, atomic force microscopy, scanning electron microscopy and energy-dispersive X-ray spectroscopy. Cytocompatibility studies using MC3T3-E1 osteoblasts show that the fluoride-pretreated, cross-linked and fibronectin-immobilized LbL-coated substrates are more bioactive and less cytotoxic than the hydroxide-pretreated, cross-linked and fibronectin-immobilized LbL-coated samples. The in vitro degradation results show that the multilayered coatings of these natural polysaccharide- and synthetic polyamino acid-based polyelectrolytes do not alter the degradation kinetics of the substrates; however, the pretreatment conditions have a significant impact on the overall coating degradation behavior. These preliminary results collectively show the potential use of LbL coatings on magnesium-based degradable scaffolds to improve their surface bioactivity. PMID:23707500

  1. Effect of cerium additive on aluminum-based chemical conversion coating on AZ91D magnesium alloy

    NASA Astrophysics Data System (ADS)

    Wang, Ximei; Zhu, Liqun; He, Xiang; Sun, Fenglou

    2013-09-01

    Based on environmentally friendly and recycling of magnesium alloys, chemical conversion coatings were prepared in aluminum nitrate solutions with cerium nitrate additive on AZ91D magnesium alloys surfaces. Effect of additive's concentration on the surface morphology, composition and corrosion resistance of aluminum-based conversion coating on magnesium alloys was studied. The surface morphology, composition, microstructure and corrosion resistance of conversion coatings were investigated using scanning electron microscopy (SEM), X-ray energy dispersion spectrometry (EDS), X-ray diffraction (XRD), X-ray photoelectron spectroscopy (XPS) and electrochemical tests respectively. The results show that the cerium content of the conversion coatings surface increased with increasing additive concentration. The conversion coatings’ morphologies first gradually became dense and the micro-cracks on the coating surface became narrow with the increase of the additive concentration. Then the coatings’ morphologies became bad and the micro-cracks widened after the additive concentration reached 0.005 mol/L. When the additive concentration was 0.005 mol/L, the conversion coating consists of Al(OH)3, Al2O3, Mg(OH)2, MgO, CeO2 and Ce2O3; the conversion coating surface morphology was the densest and the micro-cracks were the narrowest, and the corrosion resistance was also the best.

  2. Preparation and corrosion resistance of electroless Ni-P/SiC functionally gradient coatings on AZ91D magnesium alloy

    NASA Astrophysics Data System (ADS)

    Wang, Hui-Long; Liu, Ling-Yun; Dou, Yong; Zhang, Wen-Zhu; Jiang, Wen-Feng

    2013-12-01

    In this paper, the protective electroless Ni-P/SiC gradient coatings on AZ91D magnesium alloy substrate were successfully prepared. The prepared Ni-P/SiC gradient coatings were characterized for its microstructure, morphology, microhardness and adhesion to the substrate. The deposition reaction kinetics was investigated and an empirical rate equation for electroless Ni-P/SiC plating on AZ91D magnesium alloy was developed. The anticorrosion properties of the Ni-P/SiC gradient coatings in 3.5 wt.% NaCl solution were evaluated by potentiodynamic polarization and electrochemical impedance spectroscopy (EIS) studies. The potentiodynamic polarization measurements revealed that the SiC concentration in the bath and heat treatment can influence the corrosion protection performance of electroless deposited Ni-P/SiC gradient coatings. EIS studies indicated that higher charge transfer resistance and slightly lower capacitance values were obtained for Ni-P/SiC gradient coatings compared to Ni-P coatings. The corrosion resistance of the Ni-P/SiC gradient coatings increases initially and decreases afterwards with the sustained increasing of immersion time in the aggressive medium. The electroless Ni-P/SiC gradient coatings can afford better corrosion protection for magnesium alloy substrate compared with Ni-P coatings.

  3. Microstructure and corrosion behavior of die-cast AM60B magnesium alloys in a complex salt solution: A slow positron beam study

    SciTech Connect

    Liu, Y.F. [Wuhan University] [Wuhan University; Qin, Q.L. [Wuhan University] [Wuhan University; Yang, W. [Wuhan University] [Wuhan University; Wen, W. [University of Kentucky] [University of Kentucky; Zhai, T. [University of Kentucky] [University of Kentucky; Yu, B. [University of Alberta] [University of Alberta; Liu, D.Y. [University of Alberta] [University of Alberta; Luo, A. [GM Research and Development Center] [GM Research and Development Center; Song, GuangLing [ORNL] [ORNL

    2014-01-01

    The microstructure and corrosion behavior of high pressure die-cast (HPDC) and super vacuum die-cast (SVDC) AM60B magnesium alloys were investigated in a complex salt solution using slow positron beam technique and potentiodynamic polarization tests. The experiments revealed that a CaCO3 film was formed on the surface of the alloys and that the rate of CaCO3 formation for the SVDC alloy with immersion time was slower than that of the HPDC alloy. The larger volume fraction of b-phase in the skin layer of the SVDC alloy than that of the HPDC alloy was responsible for the better corrosion resistance.

  4. Effect of alloying elements on the texture and the anisotropy of the mechanical properties of magnesium alloys with REM, lithium, and aluminum

    NASA Astrophysics Data System (ADS)

    Betsofen, S. Ya.; Rokhlin, L. L.; Wu, R.; Lozovan, A. A.; Voskresenskaya, I. I.

    2014-11-01

    The formation of the texture and the anisotropy of the mechanical properties in extruded rods of commercial alloys MA5, MA18, MA21 and also experimental Mg-Y-based and Mg-Y-Ce-based alloys are studied by X-ray diffraction and the measurement of the hardness and the tensile and compressive properties. It is shown that the magnesium alloys can be separated into three groups according to the anisotropy of the mechanical properties. The first group consists of the alloys not containing rare-earth metals and lithium, and the second group is the alloys with yttrium for which the yield strength in the axial direction of the rods are significantly higher than those in the transverse direction. The alloys of the first group demonstrate a substantial excess of the yield strength in the axial direction in the tension tests as compared to those in compression tests, and the second group alloys do not demonstrate such a difference. The ceriumand lithium-containing alloys (the third group) exhibit a weak anisotropy of the strength properties. A method for estimating the anisotropy of the strength properties is developed on the basis of calculation of the Taylor factors for basal slip averaged over all orientations of crystallites, and a quantitative method is developed for determining the phase composition by measuring the solid solution lattice parameter.

  5. Influence of circumferential notch and fatigue crack on the mechanical integrity of biodegradable magnesium-based alloy in simulated body fluid.

    PubMed

    Bobby Kannan, M; Singh Raman, R K; Witte, F; Blawert, C; Dietzel, W

    2011-02-01

    Applications of magnesium alloys as biodegradable orthopaedic implants are critically dependent on the mechanical integrity of the implant during service. In this study, the mechanical integrity of an AZ91 magnesium alloy was studied using a constant extension rate tensile (CERT) method. The samples in two different geometries that is, circumferentially notched (CN), and circumferentially notched and fatigue cracked (CNFC), were tested in air and in simulated body fluid (SBF). The test results show that the mechanical integrity of the AZ91 magnesium alloy decreased substantially (?50%) in both the CN and CNFC samples exposed to SBF. Fracture surface analysis revealed secondary cracks suggesting stress corrosion cracking susceptibility of the alloy in SBF. PMID:21210510

  6. Effect of gd on the Microstructures and Corrosion Behaviors of Magnesium Alloy Mg-8.0Al-1.0Zn

    NASA Astrophysics Data System (ADS)

    Li, Lei; Xie, Shuisheng; Huang, Guojie

    2011-06-01

    Magnesium alloy is a promising candidate for use as biodegradable implant material. However, its corrosion rate is too fast in human body fluid. Thereby, improving corrosion resistance is an urgent problem for application of the magnesium alloy in the medical field. Presently, Mg-8.0Al-1.0Zn-xGd alloys were prepared. Effect of rare earth Gd on the microstructures and corrosion resistance of magnesium alloy were investigated. Results showed that the most of Al3Gd particles, a high melting point rare earth compound, are distributed in ? phases (Mg17Al12). With the increase of the content of Gd, the amount of precipitation of ? phases increased and interconnected each other. Fine network-like ? phases acted as corrosion barrier and effectively impeded the corrosion extending. The corrosion resistance improved with the increase of rare earth Gd.

  7. Microstructure and mechanical properties of AZ91 magnesium alloy subject to deep cryogenic treatments

    NASA Astrophysics Data System (ADS)

    Li, Gui-rong; Wang, Hong-ming; Cai, Yun; Zhao, Yu-tao; Wang, Jun-jie; Gill, Simon P. A.

    2013-09-01

    AZ91 magnesium alloy was subjected to a deep cryogenic treatment. X-ray diffraction (XRD), scanning electronic microscopy (SEM), and transmission electronic microscopy (TEM) methods were utilized to characterize the composition and microstructure of the treated samples. The results show that after two cryogenic treatments, the quantity of the precipitate hardening ? phase increases, and the sizes of the precipitates are refined from 8-10 ?m to 2-4 ?m. This is expected to be due to the decreased solubility of aluminum in the matrix at low temperature and the significant plastic deformation owing to internal differences in thermal contraction between phases and grains. The polycrystalline matrix is also noticeably refined, with the sizes of the subsequent nanocrystalline grains in the range of 50-100 nm. High density dislocations are observed to pile up at the grain boundaries, inducing the dynamic recrystallization of the microstructure, leading to the generation of a nanocrystalline grain structure. After two deep cryogenic treatments, the tensile strength and elongation are found to be substantially increased, rising from 243 MPa and 4.4% of as-cast state to 299 MPa and 5.1%.

  8. Effects of heat input on microstructure and tensile properties of laser welded magnesium alloy AZ31

    SciTech Connect

    Quan, Y.J. [School of Materials Science and Engineering, Hunan University, Changsha 410082 (China)], E-mail: quanyj_2006@yahoo.com.cn; Chen, Z.H.; Gong, X.S.; Yu, Z.H. [School of Materials Science and Engineering, Hunan University, Changsha 410082 (China)

    2008-10-15

    A 3 kW CO{sub 2} laser beam was used to join wrought magnesium alloy AZ31 sheets, and the effects of heat input on the quality of butt welding joints were studied. By macro and microanalysis, it is found that the welding heat input plays an important role in laser welding process for AZ31 wrought sheets. After welding, the grains far from the weld centre present the typical rolled structure. But the microstructure out of the fusion zone gradually changes to complete equiaxed crystals as the distance from the weld centre decreases. Adjacent to the fusion boundary, there is a band region with columnar grains, and its growth direction is obviously perpendicular to the solid/liquid line. The microstructure in fusion centre consists of fine equiaxed grains and the many precipitated particles are brittle phase Mg{sub 17}Al{sub 12} or Mg{sub 17}(Al,Zn){sub 12}. With increasing the heat input, the band width of columnar grains varies, the grains in fusion zone get coarser, and the distribution of precipitates changes from intragranularly scattered particles to intergranularly packed ones. The results of tensile test show that the change trend of ultimate tensile strength (UTS) and elongation of the welded joints is to increase at first and then decrease with the heat input increasing. When the heat input reaches 24 J mm{sup -1}, the maximum value of the UTS is up to 96.8% of the base metal.

  9. A Microstructure Study on an AZ31 Magnesium Alloy Tube after Hot Metal Gas Forming Process

    NASA Astrophysics Data System (ADS)

    Liu, Yi; Wu, Xin

    2007-06-01

    An AZ31 magnesium alloy tube has been deformed by the hot metal gas forming (HMGF) technique. Microstructures before and after deformation have been investigated by using Electron Backscattered Diffraction (EBSD) and Electron Microscopy. Due to the inhomogeneous distribution by induction heating, there is a temperature gradient distribution along the tube axis. Accordingly, the deformation mechanism is also different. In the middle area of deformation zone where the temperature is ˜410 °C, almost no twinning has been found, whereas at the edge areas of deformation zone where the temperature is ˜200 °C, a high density of twins has been found. EBSD experiments show a weak (0001) fiber texture along the radial direction of the tube before and after deformation in the high-temperature zone. EBSD experiments on the low temperature deformation region were not successful due to the high stored energy. Schmid factor analysis on the EBSD data shows that, despite the (0001) fiber texture, there are still many grains favoring basal slip along both the axis direction and hoop direction.

  10. Microstructure and properties of duplex (Ti:N)-DLC/MAO coating on magnesium alloy

    NASA Astrophysics Data System (ADS)

    Yang, Wei; Ke, Peiling; Fang, Yong; Zheng, He; Wang, Aiying

    2013-04-01

    Ti and N co-doped diamond-like carbon ((Ti:N)-DLC) film was deposited on the MAO coated substrate using a hybrid beam deposition system, which consists of a DC magnetron sputtering of Ti target and a linear ion source (LIS) with C2H2 and N2 precursor gas. The microstructure and properties of the duplex (Ti:N)-DLC/MAO coating were investigated. Results indicate that the (Ti:N)-DLC top film with TiN crystalline phase was formed. Ti and N co-doping resulted in the increasing ID/IG ratio. The significant improvement in the wear and corrosion resistance of duplex (Ti:N)-DLC/MAO coating was mainly attributed to the increased binding strength, lubrication characteristics and chemical inertness of (Ti:N)-DLC top film. The superior low-friction and anti-corrosion properties of duplex (Ti:N)-DLC/MAO coating make it a good candidate as protective coating on magnesium alloy.

  11. Influence of chemical liquids on the fatigue crack growth of the AZ31 magnesium alloy

    NASA Astrophysics Data System (ADS)

    Wang, Zhang-Zhong; He, Xian-Cong; Bai, Yun-Qiang; Ba, Zhi-Xin; Dai, Yu-Ming; Zhou, Heng-Zhi

    2012-03-01

    The fatigue crack growth behavior of an AZ31 magnesium alloy was investigated by comparing the effect of zirconate and phosphate chemical liquids. The morphology, components, and phase compositions of the chemical depositions at the fatigue crack tip were analyzed by employing scanning electron microscopy (SEM), energy dispersive spectroscopy (EDS), and X-ray diffraction (XRD), respectively. For samples with and without the chemical liquids, their stress-intensity factor values at the fatigue crack tip were compared by using a stress-strain gauge. The results demonstrated that a zirconate film (Zr x O y ·Zn x O y ) and a phosphate film (Zn3(PO4)2·4H2O and MgZnP2O7) could be formed on the fatigue crack-surface at the fatigue crack tip. The stress distribution was changed because of the chemical depositions and the causticity of the chemical liquids. This could decrease the stress-intensity factor value and thus effectively cause fatigue crack closure, which reduces the fatigue crack growth rate. Moreover, it was found that the fatigue crack closure effect of zirconates was more positive than that of phosphates.

  12. Friction properties of protective DLC films on magnesium alloy in aqueous NaCl solution

    NASA Astrophysics Data System (ADS)

    Choi, Junho; Kim, Jongduk; Nakao, Setsuo; Ikeyama, Masami; Kato, Takahisa

    2007-04-01

    Friction properties of DLC films deposited on magnesium alloy, AZ31 (Mg-3%Al-1%Zn) were investigated using a ball-on-flat type reciprocal friction tester in aqueous 0.05 M NaCl solution. The DLC, DLC/interlayer and Si-DLC films were prepared on the sputter-deposited AZ31 films on glass substrates using a bi-polar type plasma based ion implantation and deposition (PBII&D). The DLC/interlayer/AZ31 sample shows good friction and wear properties in NaCl solution, but the large corrosion pits were developed on the surface during the friction test in NaCl solution. The low adhesion strength and high internal stress of the DLC coatings on the AZ31 are the reason for the poor corrosion properties in corrosive NaCl solution. The Si-DLC coating on the AZ31 has high adhesion strength and a low internal stress, and no large corrosion pits are observed on the surface after the friction test in NaCl solution. The Si-DLC coating also shows stable friction properties.

  13. In-vitro characterization of stress corrosion cracking of aluminium-free magnesium alloys for temporary bio-implant applications.

    PubMed

    Choudhary, Lokesh; Singh Raman, R K; Hofstetter, Joelle; Uggowitzer, Peter J

    2014-09-01

    The complex interaction between physiological stresses and corrosive human body fluid may cause premature failure of metallic biomaterials due to the phenomenon of stress corrosion cracking. In this study, the susceptibility to stress corrosion cracking of biodegradable and aluminium-free magnesium alloys ZX50, WZ21 and WE43 was investigated by slow strain rate tensile testing in a simulated human body fluid. Slow strain rate tensile testing results indicated that each alloy was susceptible to stress corrosion cracking, and this was confirmed by fractographic features of transgranular and/or intergranular cracking. However, the variation in alloy susceptibility to stress corrosion cracking is explained on the basis of their electrochemical and microstructural characteristics. PMID:25063163

  14. Simulation on welding thermal effect of AZ61 magnesium alloy based on three-dimensional modeling of vacuum electron beam welding heat source

    Microsoft Academic Search

    Yi Luo; Guoqiang You; Hong Ye; Jinhe Liu

    2010-01-01

    The deep-penetration thermal effect of keyhole and surface thermal effect of high-temperature metal vapor by the direct-acting mechanism during vacuum electron beam welding were analyzed. According to the thermal effect, a composite source model working for magnesium alloy welding was developed. This model was composed of Gaussian surface source and conical heat source. By the welding experiments on AZ61 magnesium

  15. Effects of Sn Addition on the Microstructures and Mechanical Properties of Mg-6Zn-3Cu-xSn Magnesium Alloys

    NASA Astrophysics Data System (ADS)

    Zhang, Tao; Shen, Jun; Sang, Jia-Xin; Li, Yang; He, Pei-Pei

    2015-05-01

    In this paper, Mg-6Zn-3Cu-xSn (ZC63-xSn) magnesium alloys with different Sn contents (0, 1, 2, 4 wt pct) were fabricated and subjected to different heat treatments. The microstructures and mechanical properties of the obtained ZC63-xSn samples were investigated by optical microscopy, X-ray diffraction, scanning electron microscopy, Vickers hardness testing, and tensile testing. It was found that the As-cast Mg-6Zn-3Cu (ZC63) magnesium alloy mainly contained ?-Mg grains and Mg(Zn,Cu) particles. Sn dissolved in ?-Mg grains when Sn content was below 2 wt pct while Mg2Sn phase forms in the case of Sn content was above 4 wt pct. Addition of Sn refined both ?-Mg grains and Mg(Zn,Cu) particles, and increased the volume fraction of Mg(Zn,Cu) particles. Compared with the Sn-free alloy, the microhardness of Sn-containing alloys increased greatly and that of As-extrude ZC63-4Sn sample achieved the highest value. The strength of ZC63 magnesium alloy was significantly enhanced because of Sn addition, which was attributed to grain refinement strengthening, solid solution strengthening, and precipitation strengthening. Furthermore, the ultimate yield stress, yield strength, and elongation of ZC63-xSn magnesium alloys were increased owing to the deceasing grain size induced by extrusion process.

  16. Investigation of the effect of electric current on serrated deformation and acoustic emission in the aluminum-magnesium alloy 5056

    NASA Astrophysics Data System (ADS)

    Shibkov, A. A.; Denisov, A. A.; Zheltov, M. A.; Zolotov, A. E.; Gasanov, M. F.; Ivolgin, V. I.

    2015-06-01

    The effect of direct electric current on the serrated deformation of the aluminum-magnesium alloy 5056 has been studied using the acoustic emission method and high-speed video filming of propagating deformation bands. The phenomenon of the electric current-induced suppression of low-frequency acoustic emission signals has been revealed in the range of 1 Hz-2 kHz, which is connected with the development of Portevin-Le Chatelier deformation bands. The characteristic times of damping and growth of plastic instabilities and acoustic signals caused by them after current turn-on and turn-off, respectively, have been estimated.

  17. Microstructure and second-phase particles in low- and high-pressure die-cast magnesium alloy AM50

    Microsoft Academic Search

    Val Y. Gertsman; Jian Li; Su Xu; James P. Thomson; Mahi Sahoo

    2005-01-01

    The microstructure and phase composition of low-pressure die-cast (LPDC) and high-pressure diecast (HPDC) magnesium alloy\\u000a AM50 were examined by transmission electron microscopy (TEM) techniques in combination with optical microscopy, scanning electron\\u000a microscopy (SEM), and electron-probe microanalysis (EPMA). It has been established that the dimensions and morphology of the\\u000a constituent phases (?-Mg solid solution, Mg17Al12, and Al8Mn5) depend on the processing

  18. Mechanical Properties, Microstructure and Crystallographic Texture of Magnesium AZ91-D Alloy Welded by Friction Stir Welding (FSW)

    NASA Astrophysics Data System (ADS)

    Kouadri-Henni, A.; Barrallier, L.

    2014-10-01

    The objective of the study was to characterize the properties of a magnesium alloy welded by friction stir welding. The results led to a better understanding of the relationship between this process and the microstructure and anisotropic properties of alloy materials. Welding principally leads to a large reduction in grain size in welded zones due to the phenomenon of dynamic recrystallization. The most remarkable observation was that crystallographic textures appeared from a base metal without texture in two zones: the thermo-mechanically affected and stir-welded zones. The latter zone has the peculiarity of possessing a marked texture with two components on the basal plane and the pyramidal plane. These characteristics disappeared in the thermo-mechanically affected zone (TMAZ), which had only one component following the basal plane. These modifications have been explained by the nature of the plastic deformation in these zones, which occurs at a moderate temperature in the TMAZ and high temperature in the SWZ.

  19. Characterization of High-Frequency Induction Brazed Magnesium Alloy Joint with an Al-Mg-Zn Filler Metal

    NASA Astrophysics Data System (ADS)

    Ma, Li; He, Dingyong; Li, Xiaoyan; Jiang, Jianmin

    2011-03-01

    In this paper, a novel Al-Mg-Zn filler metal was designed to join magnesium alloy AZ31B plates by means of high-frequency induction brazing in argon gas shield condition. The microstructure and the mechanical properties of the brazed joint were investigated. The experimental results showed that the brazed joint contained large amount of ?-Mg and ?-Mg17(Al, Zn)12 phases. The homogeneous Mg32(Al, Zn)49 phase in the original filler metal was consumed due to the intensive alloying during the brazing process. The results indicate that the shear strength of the brazed joint is 35 MPa. The fracture morphology of the brazed joint exhibits intergranular fracture mode, and the fracture originates from the hard ?-Mg17(Al, Zn)12 phase.

  20. Dynamic behavior and constitutive modeling of magnesium alloys AZ91D and AZ31B under high strain rate compressive loading

    NASA Astrophysics Data System (ADS)

    Xiao, Jing; Ahmad, Iram Raza; Shu, D. W.

    2014-03-01

    The dynamic stress-strain characteristics of magnesium alloys have not been sufficiently studied experimentally. Thus, the present work investigated compressive dynamic stress-strain characteristics of two representative magnesium alloys: AZ91D and AZ31B at high strain rates and elevated temperatures. In order to use the stress-strain characteristics in numerical simulations to predict the impact response of components, the stress-strain characteristics must be modeled. The most common approach is to use accepted constitutive laws. The results from the experimental study of the response of magnesium alloys AZ91D and AZ31B under dynamic compressive loading, at different strain rates and elevated temperatures are presented here. Johnson-Cook model was used to best fit the experimental data. The material parameters required by the model were obtained and the resultant stress-strain curves of the two alloys for each testing condition were plotted. It is found that the dynamic stress-strain relationship of both magnesium alloys are strain rate and temperature dependent and can be described reasonably well at high strain rates and room temperature by Johnson-Cook model except at very low strains. This might be due to the fact that the strain rate is not strictly constant in the early stage of deformation.

  1. A New Constitutive Model for AZ31B Magnesium Alloy Sheet Deformed at Elevated Temperatures and Various Strain Rates

    NASA Astrophysics Data System (ADS)

    Nguyen, Duc-Toan

    2014-12-01

    In this study, a new constitutive model is established for AZ31B magnesium alloy sheet at elevated temperatures and strain rates in order to describe two competing mechanisms for deformation, i.e. both work-hardening and softening stage of AZ31B magnesium alloy sheet. Stress-strain curves obtained by conducting uni-axial tensile tests at elevated and strain rates were first separated at the maximum stress and corresponding strain values. Voce's law [25] was then employed to fit separated hardening and softening stage. A MATLAB tool is used to determine material parameters by using least square fitting method at various temperatures and strain rate. The mergence of separated work-hardening and softening equations is in good agreement with experimental data. The parameters of fitting curves are utilized to determine them as a function of temperature and strain rate using a surface fitting method. The final equation is then implemented to predict stress-strain curves at various temperatures and strain rates. The proposed equation showed the good comparability between the simulation results and the corresponding experiments.

  2. The galvanic corrosion behavior of depleted uranium in synthetic seawater coupled to aluminum, magnesium, and mild steel

    SciTech Connect

    McIntyre, J.F.; LeFeave, E.P.; Musselman, K.A.

    1987-01-01

    The galvanic corrosion behavior of a depleted uranium-titanium alloy (Du-.75Ti) coupled to MgZk60A-T5, AA-7075-T6, bare steel-4340, and coated steel-4340 exposed to ASTM seawater was investigated by monitoring the galvanic current with time. Gravimetric measurements, polarization resistance measurements, and concepts of ''mixed-potential'' theory were used to calculate corrosion rates. It was demonstrated that galvanic currents must be monitored over extended periods of time to detect changes in the galvanic corrosion behavior. Good agreement was obtained for corrosion rates calculated using the concepts of ''mixed-potential'' theory and those obtained from gravimetric measurements.

  3. Study of the effect of low-power pulse laser on arc plasma and magnesium alloy target in hybrid welding by spectral diagnosis technique

    Microsoft Academic Search

    Liming Liu; Xinfeng Hao

    2008-01-01

    In order to study the effect of laser pulses on arc plasma and target metal in the hybrid welding process, the spectra of the plasmas in the welding process of magnesium alloys are analysed in this paper. The acquisition system of plasma spectra is set up and the spectral lines of welding plasma are acquired. Compared with tungsten-inert gas (TIG)

  4. In vivo assessment of the host reactions to the biodegradation of the two novel magnesium alloys ZEK100 and AX30 in an animal model

    PubMed Central

    2012-01-01

    Background Most studies on biodegradable magnesium implants published recently use magnesium-calcium-alloys or magnesium-aluminum-rare earth-alloys. However, since rare earths are a mixture of elements and their toxicity is unclear, a reduced content of rare earths is favorable. The present study assesses the in vivo biocompatibility of two new magnesium alloys which have a reduced content (ZEK100) or contain no rare earths at all (AX30). Methods 24 rabbits were randomized into 4 groups (AX30 or ZEK100, 3 or 6 months, respectively) and cylindrical pins were inserted in their tibiae. To assess the biodegradation ?CT scans and histological examinations were performed. Results The ?CT scans showed that until month three ZEK100 degrades faster than AX30, but this difference is leveled out after 6 months. Histology revealed that both materials induce adverse host reactions and high numbers of osteoclasts in the recipient bone. The mineral apposition rates of both materials groups were high. Conclusions Both alloys display favorable degradation characteristics, but they induce adverse host reactions, namely an osteoclast-driven resorption of bone and a subsequent periosteal formation of new bone. Therefore, the biocompatibility of ZEK100 and AX30 is questionable and further studies, which should focus on the interactions on cellular level, are needed. PMID:22429539

  5. Interfacial reaction in squeeze cast SiCw/AZ91 magnesium alloy composite

    SciTech Connect

    Wu, K.; Zheng, M.; Zhao, M.; Yao, C. [Harbin Inst. of Tech. (China). School of Materials Science and Engineering] [Harbin Inst. of Tech. (China). School of Materials Science and Engineering; Li, J. [Academic Sinica, Shengyang (China). Lab. of Atomic Imaging of Solids] [Academic Sinica, Shengyang (China). Lab. of Atomic Imaging of Solids

    1996-08-15

    It is well known that the interface between the matrix and the reinforcement plays an important role in the properties of metal matrix composites (MMCs). Interfacial structure and its effect on the properties of aluminum matrix composites have been extensively studied. The interface of Mg-MMCs is very different from that of Al-MMCs, due to high reactivity of magnesium. As magnesium have natural affinity for wetting or bonding to ceramic reinforcement, and furthermore, magnesium does not form any carbides, SiC is one of the most suitable reinforcement for magnesium matrix composite, SiCw/AZ91 magnesium matrix composites have excellent properties compared with other discontinuously reinforced Mg-MMCs. The aim of the present study is to investigate the interfacial reactions in SiCw/AZ91 composites prepared by squeeze casting method, with particular emphasis on the morphology, structure and the formation mechanisms of the reaction products using electron microscopy, in order to provide a better understanding of the relationship between the interfacial structure and the properties of the composites.

  6. Film Breakdown and Nano-Porous Mg(OH)2 Formation from Corrosion of Magnesium Alloys in Salt Solutions

    SciTech Connect

    Brady, Michael P [ORNL; Rother, Gernot [ORNL; Anovitz, Lawrence {Larry} M [ORNL; Littrell, Ken [ORNL; Unocic, Kinga A [ORNL; Elsentriecy, Hassan H [ORNL; Song, GuangLing [ORNL; Thomson, Jeffery K [ORNL; Gallego, Nidia C [ORNL; Davis, Dr. Bruce [Magnesium Elektron North America

    2015-01-01

    Small angle neutron scattering (SANS) and cross-section scanning transmission electron microscopy (STEM) were used to study film formation by magnesium alloys AZ31B (Mg-3Al-1Zn base) and ZE10A (Elektron 717, E717: Mg-1Zn + Nd, Zr) in H2O and D2O with and without 1 or 5 wt.% NaCl. No SANS scattering changes were observed after 24 h D2O or H2O exposures compared with unreacted alloy, consistent with relatively dense MgO-base film formation. However, exposure to 5 wt.% NaCl resulted in accelerated corrosion, with resultant SANS scattering changes detected. The SANS data indicated both particle and rough surface scattering, but with no preferential size features. The films formed in 5 wt.% NaCl consisted of a thin, inner MgO-base layer, and a nano-porous and filamentous Mg(OH)2 outer region tens of microns thick. Chlorine was detected extending to the inner MgO-base film region, with segregation of select alloying elements also observed in the inner MgO, but not the outer Mg(OH)2. Modeling of the SANS data suggested that the outer Mg(OH)2 films had very high surface areas, consistent with loss of film protectiveness. Implications for the NaCl corrosion mechanism, and the potential utility of SANS for Mg corrosion, are discussed.

  7. A study of aluminum-lithium alloys: Strength profile in 2090 aluminum-lithium-copper-magnesium-zirconium alloy

    SciTech Connect

    Soepriyanto, S.

    1991-01-01

    Aluminum-containing lithium alloys are undergoing intensive development as replacements for conventional aluminum alloys 2024 and 7075 in aircraft structural applications. Lithium is a very reactive metal so that an elevated temperature heat treatments can cause lithium diffusion to the surface and reaction with the atmosphere. Solid state diffusion of lithium within the 2090 alloy and subsequent surface oxidation during solution heat treatment were investigated. Thermodynamic and kinetic analyses were used to evaluate the alloy's thermal oxidation behavior. A mathematical model based on simultaneous diffusion and surface oxidation of lithium was developed to predict lithium concentration profiles across the specimen. Agreement was obtained between the predicted lithium concentration profiles and their corresponding experimental results. Microhardness and yield strength profiles were found also to follow the corresponding lithium concentration profiles. Various heat treatment procedures were studied on this 2090 alloy to give a greater understanding of precipitate strengthening.

  8. Influence of sodium borate concentration on properties of anodic coatings obtained by micro arc oxidation on magnesium alloys

    NASA Astrophysics Data System (ADS)

    Zhang, R. F.; Zhang, S. F.; Shen, Y. L.; Zhang, L. H.; Liu, T. Z.; Zhang, Y. Q.; Guo, S. B.

    2012-06-01

    The influence of sodium borate concentration on the formation and properties of anodic coatings obtained by micro arc oxidation (MAO) on magnesium alloys was systematically studied in an alkaline solution with addition of 0-40 g/L sodium borate. It is shown that sodium borate can decrease the solution conductivity, take part in the coating formation and increase the coating thickness. With the increase of sodium borate concentration, the boron content in the coatings increases in the range of 10-20 g/L but decreases within the range of 20-40 g/L. Sodium borate cannot further improve the corrosion resistance attributed to the development of porous or rough anodic coatings.

  9. Variant selection of twins with low Schmid factors in cross grain boundary twin pairs in a magnesium alloy

    NASA Astrophysics Data System (ADS)

    Shi, Z.-Z.; Zhang, Y. D.; Wagner, F.; Juan, P.-A.; Berbenni, S.; Capolungo, L.; Lecomte, J.-S.; Richeton, T.

    2015-04-01

    Samples of magnesium AZ31 alloys are deformed in compression at room temperature under a strain rate of 1×10?3 s?1. The initial texture with respect to the loading direction is favorable for {10-12}<-1011> extension twinning during the deformation. At an engineering strain of 2.75%, many extension twins are found to be connected with each other at grain boundaries, forming cross grain boundary twin pairs. Some have low positive or even negative Schmid factors (SFs). The variant selection of them are interpreted in terms of shear accommodations. The observed twin variants require the least or no accommodation through deformation modes with high CRSSs, but the most or more accommodation through those with low CRSSs.

  10. Preparation and characterization of HA microflowers coating on AZ31 magnesium alloy by micro-arc oxidation and a solution treatment

    NASA Astrophysics Data System (ADS)

    Tang, Hui; Yu, Dezhen; Luo, Yan; Wang, Fuping

    2013-01-01

    Magnesium and its alloys are potential biodegradable implant materials due to their attractive biological properties. But the use of magnesium is still hampered by its poor corrosion resistance in physiological fluids. In this work, hydroxyapatite microflowers coating is fabricated by micro-arc oxidation and a solution treatment on AZ31 magnesium alloy. The microstructure and composition are analyzed by scanning electron microscopy (SEM), X-ray diffraction (XRD) and Fourier transform infrared spectroscopy (FT-IR). The potentiodynamic polarization and electrochemical impedance spectroscopy are studied in simulated body fluid (SBF) solution, and the apatite-forming ability is studied also. The results show that the corrosion resistance of the magnesium alloy has been enhanced by MAO coating. And the solution treatment can improve the corrosion resistance of the MAO sample, by forming a barrier layer on the surface of the MAO coating, and by penetrating into the outer layer of the MAO film, sealing the micropores and micro-cracks existed in the MAO coating. In addition, the MAO-ST coating also exhibits a high ability to form apatite.

  11. Investigation of corrosion behavior of biodegradable magnesium alloys using an online-micro-flow capillary flow injection inductively coupled plasma mass spectrometry setup with electrochemical control

    NASA Astrophysics Data System (ADS)

    Ulrich, A.; Ott, N.; Tournier-Fillon, A.; Homazava, N.; Schmutz, P.

    2011-07-01

    The development of biodegradable metallic materials designed for implants or medical stents is new and is one of the most interesting new fields in material science. Besides biocompatibility, a detailed understanding of corrosion mechanisms and dissolution processes is required to develop materials with tailored degradation behavior. The materials need to be sufficiently stable as long as they have to fulfill their medical task. However, subsequently they should dissolve completely in a controlled manner in terms of maximum body burden. This study focuses on the elemental and time resolved dissolution processes of a magnesium rare earth elements alloy which has been compared to pure magnesium with different impurity level. The here described investigations were performed using a novel analytical setup based on a micro-flow capillary online-coupled via a flow injection system to a plasma mass spectrometer. Differences in element-specific and time-dependent dissolution were monitored for various magnesium alloys in contact with sodium chloride or mixtures of sodium and calcium chloride as corrosive media. The dissolution behavior strongly depends on bulk matrix elements, secondary alloying elements and impurities, which are usually present even in pure magnesium.

  12. Polishing-assisted galvanic corrosion in the dissimilar friction stir welded joint of AZ31 magnesium alloy to 2024 aluminum alloy

    SciTech Connect

    Liu, C. [Department of Mechanical and Industrial Engineering, Ryerson University, 350 Victoria Street, Toronto, Ontario M5B 2K3 (Canada); Chen, D.L. [Department of Mechanical and Industrial Engineering, Ryerson University, 350 Victoria Street, Toronto, Ontario M5B 2K3 (Canada)], E-mail: dchen@ryerson.ca; Bhole, S. [Department of Mechanical and Industrial Engineering, Ryerson University, 350 Victoria Street, Toronto, Ontario M5B 2K3 (Canada); Cao, X.; Jahazi, M. [Aerospace Manufacturing Technology Centre, Institute For Aerospace Research, National Research Council Canada, 5145 Decelles Avenue, Montreal, Quebec H3T 2B2 (Canada)

    2009-05-15

    Galvanic corrosion of a dissimilar friction stir welded 2024-T3 Al/AZ31B-H24 Mg joint prepared using a water-based and a non-water-based polishing solution was characterized. Microstructure and the distribution of chemical elements were analyzed using optical microscopy, scanning electron microscopy and energy dispersive X-ray spectroscopy. The stir zone polished using water-based solution was observed to be much more susceptible to galvanic corrosion attack than that obtained using non-water-based polishing solution. The location of corrosion attack was observed in the narrow regions of AZ31 Mg alloy adjacent to Al2024 regions in the stir zone. The occurrence of galvanic corrosion was due to the formation of Mg/Al galvanic couples with a small ratio of anode-to-cathode surface area. The corrosion product was primarily the porous magnesium hydroxide with characteristic microcracks and exhibited a low microhardness value.

  13. The Role of Microstructure on Ductility of Die-Cast AM50 and AM60 Magnesium Alloys

    NASA Astrophysics Data System (ADS)

    Chadha, Gurjeev; Allison, John E.; Jones, J. Wayne

    2007-02-01

    Die-cast AM50 and AM60 magnesium alloys have been examined to determine the fracture processes in bending and tension and to elucidate the influences of microstructure and porosity distribution on mechanical properties. The effect of section thickness has been explored using 2-, 6-, and 10-mm-thick die-cast plates. The processes of damage accumulation in terms of crack initiation, growth, and linkage leading to eventual failure have been studied qualitatively using progressive tensile straining experiments and three-point bend studies. The presence of a heterogeneous distribution of porosity played a critical role in the observed differences between strains to fracture in tension and in bending. More rapid damage accumulation at lower strains was observed in the high porosity regions with the rate of damage accumulation strongly dependent on the loading mode. Fracture processes at the microstructural level were characterized by scanning electron microscopy using an in-situ bending fixture. Crack initiation and growth occurred predominantly in the interdendritic eutectic regions, both in the presence of porosity and, to a lesser extent, in pore-free regions. The role of porosity volume fraction and distribution on ductility in these alloys has been examined using a modified Brown-Embury model. This model allows the prediction of fracture location in either loading mode by predicting the critical strains for the onset of cracking in differently strained regions of the test samples.

  14. Fatigue characterization of high pressure die-cast magnesium AM60B alloy using experimental and computational investigations

    NASA Astrophysics Data System (ADS)

    Lu, You

    The object of the current dissertation is to foster fundamental advances in microstructure-fatigue characteristics of a high pressure die cast magnesium AM60B alloy. First, high cycle fatigue staircase experiments were conducted on specimens extracted from automobile instrument panels. The resulting fracture surfaces were then examined with scanning electron microscopic imaging to elucidate the fatigue crack initiation sites and propagation paths at different stages of the fatigue life. Due to the fact that the qualification of the crack initiation and propagation mechanisms through experiment alone is difficult, complementary micromechanical finite element simulations were conducted. Particularly, the effects of different applied loading conditions and the porosity morphology (e.g. pore shape, pore size, pore spacing, proximity to the free surface) on the maximum plastic shear strain range, as a driving force for crack initiation, were analyzed. Moreover, at the microstructually small crack (MSC) propagation stage, the shielding effects of beta-phase Mg17Al12 particles were systematically studied. Based on the distribution of the maximum principal stress within the particles and the maximum hydrostatic stress along the particle/matrix interfaces, the relative influence of the pre-damaged (fractured or debonded) particles and various particle cluster morphologies were carefully investigated. In the finite element simulations, the constitutive behaviours of AM60B alloy and the alpha-matrix were simulated by the advanced kinematic hardening law tuned with experimentally determined material parameters under cyclic loading.

  15. Study of deformation texture in an AZ31 magnesium alloy rolled at wide range of rolling speed and reductions

    NASA Astrophysics Data System (ADS)

    Sanjari, M.; Tamimi, S.; Su, J.; Kabir, A. S.; Hara, K.; Utsunomiya, H.; Petrov, R.; Yue, S.; Kestens, L.

    2015-04-01

    The plasticity of Mg is restricted at low temperatures because: (a) only a small number of deformation mechanisms can be activated, and (b) a preferred crystallographic orientation (texture) develops in wrought alloys, especially in flat-rolled sheets. This causes problems in thin sheet processing as well as component manufacturing from the sheet. In this study, different rolling speeds from 15 to 1000 m/min were employed to warm-roll AZ31B magnesium alloy to different reductions. The results show that AZ31B sheets rolled at 15 m/min and 100 °C has fractured for reductions of more than 30% per pass. However, by increasing the rolling speed to 1000 m/min the rollability was improved significantly and the material can be rolled to reductions of more than 70% per pass. The results show that with increasing strain rate at 100°C, the splitting of basal poles was observed, indicating the activation of more contraction twins and secondary twins.

  16. Reduction mechanism of surface oxide in aluminum alloy powders containing magnesium studied by x-ray photoelectron spectroscopy using synchrotron radiation

    NASA Astrophysics Data System (ADS)

    Kimura, Atsushi; Shibata, Masahiro; Kondoh, Katsuyoshi; Takeda, Yoshinobu; Katayama, Makoto; Kanie, Tomohiko; Takada, Hiroshi

    1997-06-01

    We investigated the reduction mechanism of surface oxide on aluminum alloy powders containing magnesium, by x-ray photoelectron spectroscopy using synchrotron radiation (SR-XPS). The reduction is the initial reaction in a new aluminum nitridation method developed by one of the authors. In heating the powders to 823 K, magnesium soluted in the powders moves from the inner region to the surface at temperatures below 573 K, and finally, above 773 K, the magnesium reduces the aluminum oxide of powder surfaces by chemical reaction, which breaks the surface oxide films, and metallic aluminum appears on the topmost surface of the powders. These results suggest that the SR-XPS system is very useful for dynamic chemical reaction analysis of the surface via in situ measurement.

  17. Effect of Carbon Nanotube on High-Temperature Formability of AZ31 Magnesium Alloy

    NASA Astrophysics Data System (ADS)

    Hassan, S. Fida; Paramsothy, M.; Gasem, Z. M.; Patel, F.; Gupta, M.

    2014-08-01

    Room-temperature tensile properties of AZ31 alloy have significantly been improved when reinforced with carbon nanotube via ingot metallurgy process. However, high-temperature (up to 250 °C) elongation-to-failure tensile test of the developed nanocomposite revealed a considerable softening in the AZ31 alloy matrix accompanied by an incredible ductility increment (up to 132%). Microstructural characterization of the fractured samples revealed that the dynamic recrystallization process has induced a complete recrystallization in the AZ31 alloy at a lower temperature (150 °C) followed by substantial grain growth at a higher temperature used in this study. Fractography on the fractured surfaces revealed that the room-temperature mixed brittle-ductile modes of fracture behavior of AZ31 alloy have transformed into a complete ductile mode of fracture at high temperature.

  18. Dry Sliding Wear Characteristics of Gravity Die-Cast Magnesium Alloys

    NASA Astrophysics Data System (ADS)

    Poddar, Palash; Das, Arpan; Sahoo, K. L.

    2014-04-01

    The paper deals with the wear behavior of conventional cast Mg-Sn-based alloys. The alloys were studied through pin- on- disk wear test under four different loading conditions; namely, 9.8, 19.6, 29.4, and 39.2 N. The study highlights the cumulative wear loss, volumetric wear loss, dry sliding wear rate, and coefficient of friction of the alloys. The volumetric wear increased with increasing applied load. The wear mechanism was studied with scanning electron microscope. The wear occurs mainly by plowing mechanism and also by delamination. During wear, extensive plastic deformation and work hardening occurred. Microstructural analysis has been carried out for all the alloys at different loading conditions.

  19. Mechanical Flow Response and Anisotropy of Ultra-Fine Grained Magnesium and Zinc Alloys

    E-print Network

    Al Maharbi, Majid H.

    2011-02-22

    textures for revealing the relationship between microstructural parameters, crystallographic texture and resulting flow stress anisotropy at room temperature. For AZ31B Mg alloy, the texture evolution during ECAE following conventional and hybrid ECAE...

  20. Effect of Texture on Formability and Mechanical Anisotropy of a Severe Plastically Deformed Magnesium Alloy

    E-print Network

    Modarres Razavi, Sonia

    2012-02-14

    experimentally the effect of crystallographic texture generated during severe plastic deformation (SPD), on the subsequent formability and mechanical flow anisotropy in AZ31B Mg alloy. The proper control of grain size and texture through SPD is expected to result...

  1. Titanium and Magnesium Co-Alloyed Hematite Thin Films for Photoelectrochemical Water Splitting

    SciTech Connect

    Tang, H.; Yin, W. J.; Matin, M. A.; Wang, H.; Deutsch, T.; Al-Jassim, M. M.; Turner, J. A.; Yan, Y.

    2012-04-01

    Using a combination of density functional theory calculation and materials synthesis and characterization we examine the properties of charge-compensated Ti and Mg co-alloyed hematite thin films for the application of photoelectrochemical (PEC) water splitting. We find that the charge-compensated co-alloying results in the following effects: (1) It enhances the solubility of Mg and Ti, which leads to reduced electron effective mass and therefore increased electron mobility; (2) It tunes the carrier density and therefore allows the optimization of electrical conductivity; and (3) It reduces the density of charged defects and therefore reduces carrier recombination. As a result, the Ti and Mg co-alloyed hematite thin films exhibit improved water oxidation photocurrent magnitudes as compared to pure hematite thin films. Our results suggest that charge-compensated co-alloying is a plausible approach for engineering hematite for the application of PEC water splitting.

  2. Hydrogen-environment-assisted cracking of an aluminum-zinc-magnesium(copper) alloy

    Microsoft Academic Search

    George Aloysius Young Jr.

    1999-01-01

    There is strong evidence to indicate that hydrogen embrittlement plays a significant, if not controlling, role in the environmentally assisted cracking of 7XXX series aluminum alloys. In order to better understand hydrogen environment assisted cracking (HEAC), crack growth rate tests in the K-independent stage II crack growth regime were conducted on fracture mechanics specimens of an Al-6.09Zn-2.14Mg-2.19Cu alloy (AA 7050)

  3. Creep deformation mechanisms in high-pressure die-cast magnesium-aluminum-base alloys

    Microsoft Academic Search

    W. Blum; Y. J. Li; X. H. Zeng; P. Zhang; B. von Großmann; C. Haberling

    2005-01-01

    Creep of die-cast Mg alloys is described as an integral part of their plastic deformation behavior in terms of stress-strain-rate-strain\\u000a relations. Creep tests yield information on yield stress, work hardening, maximum deformation resistance (minimum creep rate),\\u000a and work softening. Testing in compression avoids influences by fracture. Data on the alloy AJ52 (5Al, 2Sr) in the temperature\\u000a range between 135 °C

  4. Fabrication and characterization of AZ91\\/CNT magnesium matrix composites

    Microsoft Academic Search

    Yong-Ha Park; Yong-Ho Park; Ik-Min Park; Jeong-Jung Oak; Hisamichi Kimura; Kyung-Mox Cho

    2008-01-01

    Carbon Nano Tube (CNT) reinforced AZ91 metal matrix composites (MMC) were fabricated by the squeeze infiltrated method. Properties of magnesium alloys have been improved by impurity reduction, surface treatment and alloy design, and thus the usage for the magnesium alloys has been extended recently. However there still remain barriers for the adaption of magnesium alloys for engineering materials. In this

  5. Two- and three- dimensional studies of dendritic morphology in magnesium alloy by means of synchrotron X-ray microtomography and cellular automaton modelling

    NASA Astrophysics Data System (ADS)

    Yang, M.; Guo, Z.; Xiong, S.

    2015-06-01

    Magnesium is the lightest structural material. As one of the dominant microstructure features, dendritic pattern determines the mechanical behaviour and performance of magnesium alloys. Dendritic topological observation was carried out on Mg-based alloy using synchrotron X-ray micro-tomography and the microstructure pattern of ?-Mg dendrite was obtained. It was found that the ?-Mg dendrite grew with eighteen primary stems, of which six lay in the (0001) basal plane, and the other twelve in the (1010) plane. An according numerical model based on the cellular automata method was developed. By defining a specific capturing functional mechanism, simulation of ?-Mg dendrite in 3-D with eighteen branches was successfully achieved. The simulation results show that the model could reasonably describe the evolution of the dendritic microstructure and the subsequent dendrite morphology agrees well with that observed in the synchrotron X-ray tomography experiment.

  6. Effect of pH of working media on long-time strength of a magnesium alloy MA2-1

    Microsoft Academic Search

    S. V. Pushkina; V. V. Romanov

    1973-01-01

    The reduction in the long-time strength of magnesium alloys in electrolyte solutions is in most cases associated with two phenomena [1]: stress-corrosion cracking [2] and corrosion damage. The loss of strength due to corrosion is associated either with a reduction in the specimen cross-section area due to uniform dissolution of the material or with the appearance of effective stress raisers

  7. Codeposition of Al–Zn on AZ91D magnesium alloy in AlCl 3–1-ethyl-3-methylimidazolium chloride ionic liquid

    Microsoft Academic Search

    Szu-Jung Pan; Wen-Ta Tsai; Jeng-Kuei Chang; I-Wen Sun

    2010-01-01

    The co-deposition of Al and Zn on AZ91D magnesium alloy from a Lewis acidic aluminum chloride–1-ethyl-3-methylimidazolium chloride (AlCl3–EMIC, with a molar ratio of 60:40) ionic liquid containing 1wt% ZnCl2 at room temperature was studied. The effect of potential on the deposition rate, the microstructure and the chemical composition of the deposit was explored. The experimental results show that the simultaneous

  8. Electroless NiP\\/NiB duplex coatings for improving the hardness and the corrosion resistance of AZ91D magnesium alloy

    Microsoft Academic Search

    W. X. Zhang; Z. H. Jiang; G. Y. Li; Q. Jiang; J. S. Lian

    2008-01-01

    The Ni-P\\/Ni-B duplex coatings were deposited on AZ91D magnesium alloy by electroless plating process and their structure, morphology, microhardness and corrosion resistance were evaluated. The duplex coatings were prepared using dual baths (acidic hypophosphite- and alkaline borohydride-reduced electroless nickel baths) with Ni-P as the inner layer. The coatings were amorphous in as-plated condition and crystallized and produced nickel borides upon

  9. Structural and electrochemical behavior of sol–gel ZrO 2 ceramic film on chemically pre-treated AZ91D magnesium alloy

    Microsoft Academic Search

    Qing Li; Bo Chen; Shuqiang Xu; Hui Gao; Liang Zhang; Chao Liu

    2009-01-01

    In the present investigation sol–gel-based ZrO2 ceramic film was obtained using zirconium acetate as the precursor material. The film was deposited on AZ91D magnesium alloy by a dip-coating technique. An uniform stannate conversion coating as chemical pretreatment was employed as an intermediate layer prior to deposition of the ZrO2 film in order to provide advantage for the formation of sol–gel-based

  10. Electrochemical study of tailored sol–gel thin films as pre-treatment prior to organic coating for AZ91 magnesium alloy

    Microsoft Academic Search

    V. Barranco; N. Carmona; J. C. Galván; M. Grobelny; L. Kwiatkowski; M. A. Villegas

    2010-01-01

    The behaviour\\/resistance of four optimised sol–gel coating systems (inorganic, hybrid organic–inorganic, containing zirconium ions and containing cerium ions) against corrosion of AZ91 magnesium alloy were studied. The coatings obtained by the sol–gel process were evaluated as autonomous protective coatings as well as a pre-treatment prior to acrylic top coat. The coating obtained from tetramethoxysilane (TMOS) and diethoxydimethylsilane (DEDMS) as precursors

  11. Constitutive prediction and dependence of tensile properties of high-pressure die-cast AM60B and AZ91D magnesium alloy on microporosity

    Microsoft Academic Search

    Choong Do Lee

    2006-01-01

    The effect of micro-voids on the tensile property of high-pressure die-cast AM60B and AZ91D magnesium alloy was investigated\\u000a through systematic experimental approaches, with a constitutive prediction on the load carrying capacity and strain-related\\u000a factors. The strain rate sensitivity was measured through the incremental strain rate change test, and the microporosity was\\u000a measured from a comparison between the area of the

  12. Heat-Transfer Coefficient and In-Cavity Pressure at the Casting-Die Interface during High-Pressure Die Casting of the Magnesium Alloy AZ91D

    Microsoft Academic Search

    A. Hamasaiid; G. Dour; M. S. Dargusch; T. Loulou; C. Davidson; G. Savage

    2008-01-01

    The present article deals with the application of a new measurement method to determine the heat-transfer coefficient (HTC)\\u000a and the heat flux density at the casting-die interface during high-pressure die casting (HPDC) and solidification of the magnesium\\u000a AZ91D alloy. The main measurements during the trial included velocity and the position of the piston that delivers the metal\\u000a into the die,

  13. Mechanical properties and structural evolution during deformation of fine grain magnesium and aluminum alloys

    NASA Astrophysics Data System (ADS)

    Yang, Qi

    Grain refinement improves the formability and the strength of wrought Mg and Al alloys. Ultrafine grain Mg is produced by a new process for severe plastic deformation, called Alternate Biaxial Reverse Corrugation (ABRC). Fine grain structure in Al is produced by creating a new composition capable of precipitating dispersed intermetallics in the alloy. Slip and twinning subdivide an initial bimodal grain structure of Mg alloy during processing. Dynamic recovery and recrystallization lead to the formation of nearly uniform ultrafine microstructure of average grain size 1.4mum, containing many submicron grains. In Mg, twinning causes grain refinement in the early stages, but it is inhibited when grain size becomes finer. A strong basal texture is created after several corrugation and flattening steps, but eventually weakened as grain size becomes finer. Grain rotation and possible dynamic recrystallization are believed to cause a drop in the intensity of basal texture. At room temperature, grain refinement causes a considerable increase in strain rate sensitivity of flow stress (m) leading to the enhancement of post-uniform elongation. Yield strength increases, and becomes more isotropic due to the inhibition of twinning in fine grain Mg alloy, compared to coarse grain alloy. Normal anisotropy ratio (R value) for fine grain Mg at room temperature is higher than that for coarse grain alloy. At warm temperatures, formability is significantly increased due to an increase in strain rate sensitivity of flow stress and diffuse quasistable flow in fine grain Mg, as compared with coarse grain alloy. At 200°C and strain rates below 2x10-4s-1, the fine grain alloy demonstrates a high rate of strain hardening up to a true strain of 0.6 in addition to its high strain rate sensitivity (m ˜ 0.4-0.5), leading to a high elongation of 300-400%. There is competition between dynamic grain growth and grain refinement during straining at warm temperature. Mg exhibits isotropic deformation behavior (R ˜ 1.0) at elevated temperatures in sharp contrast with its room temperature behavior, i.e. textural effects are minimized. For Al-based alloy containing low Mg (Al-3wt% Mg-1.3wt% Zn-1wt% Cu-0.5wt% Sc-0.2wt% Zr), the effects of different thermomechanical treatments on recrystallization, superplastic response, and age-hardening response are investigated. This alloy produces tensile elongations over 400% at a strain rate of 10-3 s-1 and 500--525°C. During superplastic deformation, dynamic recrystallization and strain-induced grain growth occur to cause a bimodal microstructure to transform into a uniform structure with a stable grain size. Room temperature yield strength of this new alloy is 235MPa, considerably higher than conventional Al-Mg alloys containing higher levels of Mg.

  14. Formability of Wrought Magnesium Alloys by Hot Compression Testing and Laboratory-Scale Extrusion

    NASA Astrophysics Data System (ADS)

    Ge, Q.; Vedani, M.

    2011-05-01

    The present study is aimed at investigating the high-temperature behaviour of commercially available alloys under conditions of interest for their extrusion. The AZ31B and ZM21 alloys were studied by hot compression testing in the temperature range 320-450° C (selecting four different levels for each alloy, depending on its composition) and at four values of initial strain rates, lying in the range 5.56?10-4 s-1 -2.78?10-2 s-1. A laboratory-scale extrusion rig was also adopted to produce extrudates in the form of bars and hollow tubes (external diameters from 8 down to 4 mm) according to the optimized parameters defined by the hot compression tests. Microstructural analyses were carried out to deeply investigate the evolution of microstructure during extrusion and to draw comparisons among hot compressed and extruded samples.

  15. MAGNESIUM ALLOYS IN US MILITARY APPLICATIONS: PAST, CURRENT AND FUTURE SOLUTIONS

    SciTech Connect

    Mathaudhu, Suveen N.; Nyberg, Eric A.

    2010-02-26

    Since the 1940’s Mg-alloys have been used for military applications, from aircraft components to ground vehicles. The drive for usage was primarily availability and lightweighting of military systems. But the promise of widespread military usage was not met largely based on corrosion and flammability concerns, poor mechanical behavior and inferior ballistic response. This review paper will cover historical, current and potential future applications with a focus on scientific, engineering and social barriers relevant to integration of Mg-alloy. It will also present mechanical and physical property improvements solutions which are currently being developed to address these issues.

  16. Evaluation of the delayed hydride cracking mechanism for transgranular stress corrosion cracking of magnesium alloys

    Microsoft Academic Search

    N. Winzer; A. Atrens; W. Dietzel; G. Song; K. U. Kainer

    2007-01-01

    This paper evaluates the important elements of delayed hydride cracking (DHC) for transgranular stress corrosion cracking (TGSCC) of Mg alloys. A DHC model was formulated with the following components: (i) transient H diffusion towards the crack tip driven by stress and H concentration gradients; (ii) hydride precipitation when the H solvus is exceeded; and (iii) crack propagation through the extent

  17. Creep Characterization of Aluminum-Magnesium Solid-Solution Alloy through Self-Similar Microindentation*1

    E-print Network

    Dao, Ming

    as a rice grain. A conical diamond indenter was pressed into a test surface with a constant load F (n ¼$ 5, ''m > ''c or _""in > _""c) is approximately equivalent to that for the lattice diffusion to that for the mutual diffusion of this alloy. With load-jump tests, F was abruptly increased in the indentation creep

  18. Assessment of Biodegradable Magnesium Alloys for Enhanced Mechanical and Biocompatible Properties

    Microsoft Academic Search

    Puneet Kamal S Gill

    2012-01-01

    Biomaterials have been used for more than a century in the human body to improve body functions and replace damaged tissues. Currently approved and commonly used metallic biomaterials such as, stainless steel, titanium, cobalt chromium and other alloys have been found to have adverse effects leading in some cases, to mechanical failure and rejection of the implant. The physical or

  19. Failure analysis of AZ31 magnesium alloy sheets based on the extended GTN damage model

    NASA Astrophysics Data System (ADS)

    Wang, Rui-ze; Chen, Zhang-hua; Li, Yu-jie; Dong, Chao-fang

    2013-12-01

    Based on the Gurson-Tvergaard-Needleman (GTN) model and Hill's quadratic anisotropic yield criterion, a combined experimental-numerical study on fracture initiation in the process of thermal stamping of Mg alloy AZ31 sheets was carried out. The aim is to predict the formability of thermal stamping of the Mg alloy sheets at different temperatures. The presented theoretical framework was implemented into a VUMAT subroutine for ABAQUS/EXPLICIT. Internal damage evolution due to void growth and coalescence developed at different temperatures in the Mg alloy sheets was observed by scanning electron microscopy (SEM). Moreover, the thermal effects on the void growth, coalescence, and fracture behavior of the Mg alloy sheets were analyzed by the extended GTN model and forming limit diagrams (FLD). Parameters employed in the GTN model were determined from tensile tests and numerical iterative computation. The distribution of major and minor principal strains in the specimens was determined from the numerical results. Therefore, the corresponding forming limit diagrams at different stress levels and temperatures were drawn. The comparison between the predicted forming limits and the experimental data shows a good agreement.

  20. Experimental investigation on fiber and CO2 inert gas fusion cutting of AZ31 magnesium alloy sheets

    NASA Astrophysics Data System (ADS)

    Scintilla, L. D.; Tricarico, L.

    2013-03-01

    The influence of processing parameters and laser source type on cutting edge quality of AZ31 magnesium alloy sheets and differences in cutting efficiency between fiber and CO2 lasers were studied. A first part of the cutting experiments compared a fiber and CO2 laser source when cutting 1 mm thick sheets in continuous wave mode and using Argon as an assist gas. The effects of cutting speed and assist gas pressure were investigated and optimal conditions were identified. In the second part of the experimental investigation, 3.3 mm thick sheets were cut using fiber laser. Focal position and cutting speed were varied in order to detect the optimal combination of processing parameters to obtain the best edge quality. For both sheet thicknesses investigated, surface roughness, dross height, and striation pattern inclination were measured. Cutting quality assessment and classification was carried out according to UNI EN ISO 9013 standard. Results showed that productivity, process efficiency and cutting edges quality obtained using fiber lasers outperform CO2 laser performances and therefore are considered suitable for application like sheet metal trimming.

  1. Improvement of laser keyhole formation with the assistance of arc plasma in the hybrid welding process of magnesium alloy

    NASA Astrophysics Data System (ADS)

    Liu, Liming; Hao, Xinfeng

    2009-11-01

    In the previous work, low-power laser/arc hybrid welding technique is used to weld magnesium alloy and high-quality weld joints are obtained. In order to make clear the interactions between low-power laser pulse and arc plasma, the effect of arc plasma on laser pulse is studied in this article. The result shows that the penetration of low-power laser welding with the assistance of TIG arc is more than two times deeper than that of laser welding alone and laser welding transforms from thermal-conduction mode to keyhole mode. The plasma behaviors and spectra during the welding process are studied, and the transition mechanism of laser-welding mode is analyzed in detail. It is also found that with the assistance of arc plasma, the threshold value of average power density to form keyhole welding for YAG laser is only 3.3×10 4 W/cm 2, and the average peak power density is 2.6×10 5 W/cm 2 in the present experiment. Moreover, the distribution of energy density during laser pulse is modulated to improve the formation and stability of laser keyholes.

  2. Ductile Fracture Prediction in Rotational Incremental Forming for Magnesium Alloy Sheets Using Combined Kinematic/Isotropic Hardening Model

    NASA Astrophysics Data System (ADS)

    Nguyen, Duc-Toan; Park, Jin-Gee; Kim, Young-Suk

    2010-08-01

    To predict the ductile fracture of a magnesium alloy sheet when using rotational incremental forming, a combined kinematic and isotropic hardening law is implemented and evaluated from the histories of the ductile fracture value ( I) using a finite element analysis. Here, the criterion for a ductile fracture, as developed by Oyane ( J. Mech. Work. Technol., 1980, vol. 4, pp. 65-81), is applied via a user material based on a finite element analysis. To simulate the effect of the large amount of heat generation at elements in the contact area due to the friction energy of the rotational tool-specimen interface on the equivalent stress-strain evolution in incremental forming, the Johnson-Cook (JC) model was applied and the results compared with equivalent stress-strain curves obtained from tensile tests at elevated temperatures. The finite element (FE) simulation results for a ductile fracture were compared with the experimental results for a (80 mm × 80 mm × 25 mm) square shape with a 45 and 60 deg wall angle, respectively, and a (80 mm × 80 mm × 20 mm) square shape with a 70 deg wall angle. The trends of the FE simulation results agreed quite well with the experimental results. Finally, the effects of the process parameters, i.e., the tool down-step and tool radius, on the ductile fracture value and FLC at fracture (FLCF) were also investigated using the FE simulation results.

  3. Numerical Assessment of the Role of Slip and Twinning in Magnesium Alloy AZ31B During Loading Path Reversal

    NASA Astrophysics Data System (ADS)

    Wang, Huamiao; Wu, Peidong; Wang, Jian

    2015-07-01

    Magnesium alloy AZ31B plastically deforms via twinning and slip. Corresponding to the unidirectional nature of twinning, the activity of twinning/detwinning is directly related to loading history and materials texture. Using the elastic viscoplastic self-consistent model implementing with the twinning and detwinning model (EVPSC-TDT), we revisited experimental data of AZ31B sheets under four different strain paths: (1) tension-compression-tension along rolling direction, (2) tension-compression-tension along transverse direction, (3) compression-tension-compression along rolling direction, and (4) compression-tension-compression along transverse direction, and identified the dominant deformation mechanisms with respect to the strain path. We captured plastic deformation behaviors observed in experiments and quantitatively interpreted experimental observations in terms of the activities of different deformation mechanisms and the evolution of texture. It is found that the in-plane pre-tension has slight effect on the subsequent deformation, and the pre-compression and the reverse tension after compression have significant effect on the subsequent deformation. The inelastic behavior under compressive unloading is found to be insignificant at a small strain level but pronounced at a large strain level. Such significant effect is mainly ascribed to the activity of twinning and detwinning.

  4. Fusion cutting of aluminum, magnesium, and titanium alloys using high-power fiber laser

    NASA Astrophysics Data System (ADS)

    Scintilla, Leonardo Daniele; Tricarico, Luigi

    2013-07-01

    The effects of cutting speed and assist gas pressure on laser cutting of 1-mm thick Al 1050, AZ31, and Ti6Al4V lightweight alloys are experimentally investigated. Fiber laser cutting of these materials is not broadly investigated and the acquisition of a new level of knowledge is of fundamental importance for applications like sheet metal trimming in automotive industry. The main process outputs are in depth compared with results reported in literature and obtained by cutting with CO2 and Nd?YAG lasers. The good cut quality, the high productivity, and the easy delivery of the beam obtained at the same time, corroborate the advantage of using fiber lasers for thin sheets lightweight alloys cutting.

  5. Ignition and combustion of aluminum/magnesium alloy particles in O2 at high pressures

    NASA Technical Reports Server (NTRS)

    Roberts, Ted A.; Burton, Rodney L.; Krier, Herman

    1993-01-01

    The ignition and combustion of Al, Mg, and Al/Mg alloy particles in 99 percent O2/1 percent N2 mixtures is investigated at high temperatures and pressures for rocket engine applications. The 20-micron particles contain 0, 5, 10, 20, 40, 60, 80, and 100 wt pct Mg alloyed with Al, and are ignited in oxygen using the reflected shock in a single-pulse shock tube near the endwall. Using this technique, the ignition delay and combustion times of the particles are measured at temperatures up to 3250 K as a function of Mg content for oxygen pressures of 8.5, 17, and 34 atm. An ignition model is developed that employs a simple lumped capacitance energy equation and temperature and pressure dependent particle and gas properties. Good agreement is achieved between the measured and predicted trends in the ignition delay times.

  6. Surface characterization and cytocompatibility evaluation of silanized magnesium alloy AZ91 for biomedical applications

    NASA Astrophysics Data System (ADS)

    Witecka, Agnieszka; Yamamoto, Akiko; Dybiec, Henryk; Swieszkowski, Wojciech

    2012-12-01

    Mg alloys with high Al contents have superior corrosion resistance in aqueous environments, but poor cytocompatibility compared to that of pure Mg. We have silanized the cast AZ91 alloy to improve its cytocompatibility using five different silanes: ethyltriethoxysilane (S1), 3-aminopropyltriethoxysilane (S2), 3-isocyanatopyltriethoxysilane (S3), phenyltriethoxysilane (S4) and octadecyltriethoxysilane (S5). The surface hydrophilicity/hydrophobicity was evaluated by water contact angle measurements. X-ray photoelectron analysis was performed to investigate the changes in surface states and chemical composition. All silane reagents increased adsorption of the albumin to the modified surface. In vitro cytocompatibility evaluation revealed that silanization improved cell growth on AZ91 modified by silane S1. Measurement of the concentration of Mg2+ ions released during the cell culture indicated that silanization does not affect substrate degradation.

  7. Spectral and dynamic analysis of plastic instabilities during serrated creep of the aluminum-magnesium alloy

    NASA Astrophysics Data System (ADS)

    Shibkov, A. A.; Zolotov, A. E.; Zheltov, M. A.; Denisov, A. A.; Gasanov, M. F.

    2014-05-01

    The force response to the development of a macroscopic plastic deformation jump under the conditions of serrated creep of the aluminummagnesium alloy 5456 has been studied using spectral and dynamic analysis methods. The flicker-noise structure of the force response indicating the self-organized criticality state has been revealed. It has been found that a short-term state of plastic instability flatter spontaneously appears during the development of the macroscopic deformation step.

  8. Wear performance of TiC as reinforcement of a magnesium alloy matrix composite

    Microsoft Academic Search

    L. Falcon-Franco; E. Bedolla-Becerril; J. Lemus-Ruiz; J. G. Gonzalez-Rodríguez; R. Guardian; I. Rosales

    2011-01-01

    Metallic matrix composites (MMC) have been fabricated using Mg-AZ91 alloy and TiC as reinforcement by pressureless infiltration technique. The composites were worn against different AISI 4140, AISI 1045 and H13 steels. Wear resistance was evaluated under dry sliding condition at different loads. Chemical analyses have shown the creation during the test of different oxides corresponding to the elements present in

  9. Sliding wear map for the magnesium alloy Mg9Al0.9 Zn (AZ91)

    Microsoft Academic Search

    H Chen; A. T Alpas

    2000-01-01

    Dry sliding wear tests were performed on a Mg-9.0%, Al-0.9%, Zn (AZ91) alloy using a block on-ring (AISI 52100 steel) configuration. Wear rates were measured within a load range of 1–350N and a sliding velocity range of 0.1–2.0m\\/s Compositions, morphologies and microstructures of worn surfaces and wear debris were characterised by scanning electron microscope (SEM), energy dispersive X-ray spectrometer (EDS)

  10. Influence of silane on corrosion resistance of magnesium alloy AZ31 with thermally sprayed aluminum coatings

    Microsoft Academic Search

    Rongchang Zeng; Jun Chen; Jun Kuang; Jin Zhang; Ying Wang

    2010-01-01

    Aluminum coatings on Mg alloy AZ31 were fabricated using the thermal spraying technique, and then sealed with silane. The\\u000a surface morphology and chemical groups were discerned using scanning electron microscopy and examined using Fourier transformation\\u000a infrared spectroscopy, respectively. The salt fog tests and the potentiodynamic electrochemical technique were applied to\\u000a evaluate the influence of silane on corrosion of the AZ31

  11. Hot compression behavior of the AZ91 magnesium alloy produced by high pressure die casting

    Microsoft Academic Search

    E. Cerri; P. Leo; P. P. De Marco

    2007-01-01

    The hot deformation behavior of a Mg–9Al–1Zn alloy produced by high pressure die casting has been investigated by means of compression tests in the temperature and strain rate ranges of 125–300°C and 1.6×10?5 to 10?1s?1, respectively. The samples were deformed in the high pressure die casting state or after an exposure at 415°C for 2h to evaluate any different response

  12. Study of the effect of low-power pulse laser on arc plasma and magnesium alloy target in hybrid welding by spectral diagnosis technique

    NASA Astrophysics Data System (ADS)

    Liu, Liming; Hao, Xinfeng

    2008-10-01

    In order to study the effect of laser pulses on arc plasma and target metal in the hybrid welding process, the spectra of the plasmas in the welding process of magnesium alloys are analysed in this paper. The acquisition system of plasma spectra is set up and the spectral lines of welding plasma are acquired. Compared with tungsten-inert gas (TIG) welding, the intensities of the spectral lines of magnesium increase sharply while those of Ar decrease for strong evaporation and ionization of magnesium alloys in low-power laser/arc hybrid welding. The electron temperature and density are estimated by the Boltzmann plot method and the Stark broadening effect. The result shows that the electron temperature of arc plasma in the hybrid welding process is much lower than that in TIG welding, especially in the laser beam-affected zone. In contrast, the electron density of the plasma is enhanced. The influences of laser parameters on electron temperature are also studied. The changes in electron temperature and density indicate that the effect of laser pulse on the target metal is the dominant factor influencing the electron temperature and density in low-power laser/arc hybrid welding.

  13. Friction Stir Welded AZ31 Magnesium Alloy: Microstructure, Texture, and Tensile Properties

    NASA Astrophysics Data System (ADS)

    Chowdhury, S. H.; Chen, D. L.; Bhole, S. D.; Cao, X.; Wanjara, P.

    2013-01-01

    This study was aimed at characterizing the microstructure, texture and tensile properties of a friction stir welded AZ31B-H24 Mg alloy with varying tool rotational rates and welding speeds. Friction stir welding (FSW) resulted in the presence of recrystallized grains and the relevant drop in hardness in the stir zone (SZ). The base alloy contained a strong crystallographic texture with basal planes (0002) largely parallel to the rolling sheet surface and < {11bar{2}0} rangle directions aligned in the rolling direction (RD). After FSW the basal planes in the SZ were slightly tilted toward the TD determined from the sheet normal direction (or top surface) and also slightly inclined toward the RD determined from the transverse direction (or cross section) due to the intense shear plastic flow near the pin surface. The prismatic planes (10bar{1}0) and pyramidal planes (10bar{1}1) formed fiber textures. After FSW both the strength and ductility of the AZ31B-H24 Mg alloy decreased with a joint efficiency in-between about 75 and 82 pct due to the changes in both grain structure and texture, which also weakened the strain rate dependence of tensile properties. The welding speed and rotational rate exhibited a stronger effect on the YS than the UTS. Despite the lower ductility, strain-hardening exponent and hardening capacity, a higher YS was obtained at a higher welding speed and lower rotational rate mainly due to the smaller recrystallized grains in the SZ arising from the lower heat input.

  14. Effect of Texture on Formability and Mechanical Anisotropy of a Severe Plastically Deformed Magnesium Alloy 

    E-print Network

    Modarres Razavi, Sonia

    2012-02-14

    . As explained in section 2.1, ECAE has been a good solution to enhance both strength and ductility in different materials, including Mg alloys, by reducing the grain size [17, 34, 35, 54-58]. However, in some cases (e.g. [59]) lower yield stresses were... and pyramidal planes is ~36 mJ/m2 , ~265 mJ/m2 and ~344 mJ/m2 , respectively [68]. Jiang et al. [60] carried out six-pass ECAE at route BC on Mg-9Al-1Zn and found out that optimum room temperature mechanical properties exist with elevated processing...

  15. Magnesium Gluconate

    MedlinePLUS

    Magnesium gluconate is used to treat low blood magnesium. Low blood magnesium is caused by gastrointestinal disorders, prolonged vomiting or ... disease, or certain other conditions. Certain drugs lower magnesium levels as well.This medication is sometimes prescribed ...

  16. Phase field simulation on microstructure evolution in solidification and aging process of squeeze cast magnesium alloy

    NASA Astrophysics Data System (ADS)

    Pan, H. W.; Han, G. M.; Han, Z. Q.; Liu, B. C.

    2015-06-01

    Phase-field models have been developed to simulate the dendritic growth in pressurized solidification of Mg-Al alloy during squeeze casting and the precipitation of multivariant ?-Mg17Al12 phases during the subsequent aging process. For the pressurized solidification, the effects of pressure on the Gibbs free energy and chemical potential of solid and liquid phases, and the solute diffusion coefficient were considered. For the precipitation during aging process, the effects of elastic strain energy, anisotropy of interfacial energy, and anisotropy of interface mobility coefficient were considered. The results showed that the dendritic growth rate tends to increase and the secondary dendrite arms are more developed as the pressure is increased from 0.1 to 100MPa, which showed a good agreement with the experimental results of direct squeeze casting of Mg-Al alloy. The 2D and 3D simulated precipitates had lath shapes with lozenge ends, and the precipitate variants were parallel to the basal plane and oriented in directions with an angular interval of 60 degrees, which is in good agreement with experimental observations.

  17. The corrosion performance of die-cast magnesium alloy MRI230D in 3.5% NaCl solution saturated with Mg(OH){sub 2}

    SciTech Connect

    Aghion, E., E-mail: egyon@bgu.ac.il; Lulu, N.

    2010-11-15

    The environmental behavior of die-cast magnesium alloy MRI230D designated for high-temperature applications was evaluated in comparison with regular AZ91D alloy. The microstructure examination was carried out using SEM, TEM, and X-ray diffraction analysis; the corrosion performance in 3.5% NaCl solution was evaluated by immersion test, salt spray testing, potentiodynamic polarization analysis, and stress corrosion behavior by Slow Strain Rate Testing (SSRT). Although the general corrosion resistance of MRI230D was slightly improved compared to that of AZ91D alloy its stress corrosion resistance was relatively reduced. The variations in the environmental behavior of the two alloys were mainly due to the differences in their chemical composition and microstructure after die casting. In particular, the differences were related to the reduced Al content in MRI230D and the addition of Ca to this alloy, which consequently affected its relative microstructure and electrochemical characteristics. - Research Highlights: {yields}Corrosion and SCC resistance of a new Mg alloy MRI230D was evaluated vs. regular AZ91D. {yields}MRI230D has a minor advantage in corrosion performance compared with AZ91D. {yields}The SCC resistance of MRI230D by SSRT analysis was relatively reduced. {yields}The reduced SCC resistance of MRI230D was due to the detrimental effect of Ca on ductility.

  18. Recrystallization and superplasticity at 300 C in an aluminum-magnesium alloy

    NASA Technical Reports Server (NTRS)

    Hales, S. J.; Mcnelley, T. R.; Mcqueen, H. J.

    1991-01-01

    Variations in thermomechanical processing (TMP) which regulate the microstructural characteristics and superplastic response of an Al-10Mg-0.1Zr alloy at 300 C were evaluated. Mechanical property data revealed that the superplastic ductility can be enhanced by simultaneously increasing the total rolling strain, the reduction per pass, and the duration of reheating intervals between passes during isothermal rolling. Texture and microscopy data were consistent with the development of a refined microstructure by recovery-dominated processes, i.e., continuous recrystallization, during the processing. The mechanisms by which a refined substructure can be progressively converted into a fine-grained structure during repeated cycles of deformation and annealing are addressed. A qualitative description of the complex sequence of developments leading to a microstructure better suited to support superplastic response is presented.

  19. Magnesium Research and Technology Development

    SciTech Connect

    Nyberg, Eric A.; Joost, William; Smith, Mark T.

    2009-12-30

    The Magnesium Research and Technical Development (MR&TD) project supports efforts to increase using magnesium in automotive applications, including improving technology, lowering costs and increasing the knowledge needed to enable alloy and manufacturing process optimization. MR&TD supports the U.S. Department of Energy (DOE)/United States Automotive Materials Partnership (USAMP) Magnesium Front End Research and Development (MFERD) project in collaboration with China and Canada. The MR&TD projects also maintains the magnesium bibliographic database at magnesium.pnl.gov.

  20. Effects of copper addition on microstructure and strength of the hybrid laser-TIG welded joints between magnesium alloy and mild steel

    Microsoft Academic Search

    Liming Liu; Xiaodong Qi

    2009-01-01

    Lap joint of magnesium alloy AZ31B to mild steel Q235 with the addition of copper interlayer by hybrid laser-TIG welding technique\\u000a was investigated. The microstructure, element distribution at interfaces, and intermediate phases of joints were examined\\u000a by scanning electron microscopy (SEM), electron probe micro-analyzer (EPMA), and X-ray diffraction (XRD), respectively. The\\u000a results showed that intermetallic compounds Mg2Cu with rod-like structure

  1. Superplastic Forming of Multipass Friction Stir Processed Aluminum-Magnesium Alloy

    NASA Astrophysics Data System (ADS)

    Pradeep, S.; Pancholi, Vivek

    2014-12-01

    Multipass friction stir processing (FSP) of AA5086 Al-Mg alloy was carried out to obtain bulk fine grain material for superplastic forming. FSP produced inhomogeneous microstructure in the thickness direction. The aim of the present work was to understand superplastic forming behavior of distinct microstructural layers, i.e., nugget layer (NL) containing microstructure from nugget zone, thermo-mechanically affected/heat-affected layer (TL) containing microstructure from thermo-mechanically affected/heat-affected (TMAZ/HAZ) zone, and composite layer (CL) containing microstructure from both the above zones (nugget and TMAZ/HAZ). Superplastic forming of NL, TL, and CL blanks was carried out at constant gas pressure. Three different forming gas pressures of 0.75, 1.15, and 1.5 MPa corresponding to strain rates of 5 × 10-4 s-1, 1 × 10-3 s-1 , and 5 × 10-3 s-1, respectively, were used. Forming characteristics of CL were found to be comparable to that of NL and even better at higher forming pressures. Concomitant microstructural evolution during bulging of CL and NL plays an important role here.

  2. Superplastic Forming of Multipass Friction Stir Processed Aluminum-Magnesium Alloy

    NASA Astrophysics Data System (ADS)

    Pradeep, S.; Pancholi, Vivek

    2014-09-01

    Multipass friction stir processing (FSP) of AA5086 Al-Mg alloy was carried out to obtain bulk fine grain material for superplastic forming. FSP produced inhomogeneous microstructure in the thickness direction. The aim of the present work was to understand superplastic forming behavior of distinct microstructural layers, i.e., nugget layer (NL) containing microstructure from nugget zone, thermo-mechanically affected/heat-affected layer (TL) containing microstructure from thermo-mechanically affected/heat-affected (TMAZ/HAZ) zone, and composite layer (CL) containing microstructure from both the above zones (nugget and TMAZ/HAZ). Superplastic forming of NL, TL, and CL blanks was carried out at constant gas pressure. Three different forming gas pressures of 0.75, 1.15, and 1.5 MPa corresponding to strain rates of 5 × 10-4 s-1, 1 × 10-3 s-1 , and 5 × 10-3 s-1, respectively, were used. Forming characteristics of CL were found to be comparable to that of NL and even better at higher forming pressures. Concomitant microstructural evolution during bulging of CL and NL plays an important role here.

  3. Texture Development in a Friction Stir Lap-Welded AZ31B Magnesium Alloy

    NASA Astrophysics Data System (ADS)

    Naik, B. S.; Chen, D. L.; Cao, X.; Wanjara, P.

    2014-09-01

    The present study was aimed at characterizing the microstructure, texture, hardness, and tensile properties of an AZ31B-H24 Mg alloy that was friction stir lap welded (FSLWed) at varying tool rotational rates and welding speeds. Friction stir lap welding (FSLW) resulted in the presence of recrystallized grains and an associated hardness drop in the stir zone (SZ). Microstructural investigation showed that both the AZ31B-H24 Mg base metal (BM) and SZ contained ?-Mg17Al12 and Al8Mn5 second phase particles. The AZ31B-H24 BM contained a type of basal texture (0001)<110> with the (0001) plane nearly parallel to the rolled sheet surface and <110> directions aligned in the rolling direction. FSLW resulted in the formation of another type of basal texture (0001)<100> in the SZ, where the basal planes (0001) became slightly tilted toward the transverse direction, and the prismatic planes (100) and pyramidal planes (101) exhibited a 30 deg + ( n - 1) × 60 deg rotation ( n = 1, 2, 3, …) with respect to the rolled sheet normal direction, due to the shear plastic flow near the pin surface that occurred from the intense local stirring. With increasing tool rotational rate and decreasing welding speed, the maximum intensity of the basal poles (0001) in the SZ decreased due to a higher degree of dynamic recrystallization that led to a weaker or more random texture. The tool rotational rate and welding speed had a strong effect on the failure load of FSLWed joints. A combination of relatively high welding speed (20 mm/s) and low tool rotational rate (1000 rpm) was observed to be capable of achieving a high failure load. This was attributed to the relatively small recrystallized grains and high intensity of the basal poles in the SZ arising from the low heat input as well as the presence of a small hooking defect.

  4. Mechanisms operating during continuous dynamic recrystallization in an aluminum-4magnesium-0.3scandium alloy

    NASA Astrophysics Data System (ADS)

    Dougherty, Lisa Marie

    The mechanisms operating during continuous static and continuous dynamic recrystallization in the heat-treatable aluminum alloy Al-4Mg-0.3Sc have been determined. Bulk tensile specimens were fabricated from cold-worked material in the peak-aged and over-aged conditions. These specimens were superplastically tested at 733 K and a strain rate of 10-3 sec -1 to final elongations exceeding 300%. During the early stages of superplastic testing, every specimen dynamically recrystallized to a fine grain structure A series of specimens from both the peak-aged and over-aged conditions were deformed to intermediate true strains of 0.1, 0.2, 0.4 and 0.8, and quenched under load with a liquid nitrogen spray. Post-mortem TEM examinations revealed microstructural changes with increasing strain in the specimen gauge sections such as subgrain growth, inhomogeneous dislocation distribution, and increasing complexity of dislocation interactions with particles, boundaries and other dislocations. These observations indicate the importance of dislocation dynamics during continuous dynamic recrystallization. Orientation imaging microscopy (OIM) revealed a variation in texture with distance from the surface of the specimen. A rolling texture dominated near the center of the specimen and randomized with increasing strain. A rotated cube texture dominated near the surface and sharpened with increasing strain. In-situ TEM experiments were used to directly observe the mechanisms operating during continuous static and continuous dynamic recrystallization. The static process was observed to occur much more rapidly than the dynamic process. The dominant mechanism of continuous static recrystallization appears to be the rapid generation of dislocations at sources in grain boundaries and at grain boundary triple points. These dislocations slip across the subgrains and either interact with other dislocations or enter nearby grain boundaries. Low-angle grain boundaries were observed to disintegrate, but the mechanism by which this occurred was unclear. The primary mechanism of continuous dynamic recrystallization appears to be the process of subgrain rotation, manifested as the migration and disintegration of dislocation structures and the disintegration of subgrain boundary triple points. Subgrain rotation resulting in increased boundary misorientation was not observed; however, the restraints imposed by the thin foil geometry of the tensile TEM samples may be the reason for this.

  5. Optimizing critical current density through composition and microstructure in mechanically alloyed magnesium diboride

    NASA Astrophysics Data System (ADS)

    Senkowicz, Ben James

    Carbon doped MgB2 is an emerging superconductor with potential for operation in the 0-10 Tesla range at 4.2 K or 3-4 T up to ˜25 K. In order to be a viable conductor option, mid to high-field Jc(H) must be improved from Jc(8T,4.2K) ˜ 3x10 4 A/cm2 typical of conductors made by in-situ powder in tube reaction. Jc(H) is controlled by H* (a function of Hc2 and flux pinning), flux pinning itself (largely a function of grain size), and connectivity. Current in-situ wires are limited by a trade-off between connectivity and grain size because aggressive sintering heat treatments grow grains. In order to escape this dilemma, this work examines bulk C-doped MgB2 made by sintering pre-reacted powder. An engineering approach was adopted, studying the effect of processing parameters on our primary metric, Jc(H). In this work we used high energy ball milling to simultaneously do the following: (1) Alloy MgB2 with C, (2) refine grains, (3) break up oxide sintering barriers on particle surfaces, and (4) disperse second phases on a fine scale. By this method we obtained extremely fine 20-30 nm grains even after heat treatment at 1000°C---probably due to dispersed second phases retarding grain growth. Heat treatment optimization revealed a temperature window between 900°C and 1000°C (depending on composition and milling time) which was sufficiently hot for sintering, but did not result in excessive grain growth. In this way (combined with hot isostatic pressing) we were able to repeatedly obtain Jc(8T,4.2K) = 7x10 4 A/cm2 or higher---within a factor of 2 of optimized NbTi. An additional benefit of this work is the discovery that C-solubility in MgB2 is a strong function of T for T < 1150°C, which could open the door for further processing strategies.

  6. The Formation and Structure of Aluminum-Copper - (lithium, Magnesium) Icosahedral Alloys.

    NASA Astrophysics Data System (ADS)

    Shen, Yong

    Quasicrystals have orientational order but lack periodic translational order. Sharp electron diffraction spots imply that they differ from amorphous materials. On the other hand, the aperiodic array of diffraction spots is inconsistent with conventional crystallography, which allows only two-, three-, four-, or sixfold symmetry axes. The discovery of the first icosahedral quasicrystal in a rapidly solidified Al-Mn alloy has created a flurry of activities in studying their structure and thermodynamics. AlCuLi icosahedral phase (i-phase) is the first stable quasicrystalline phase; and centimeter size quasicrystals can be obtained. Thus, AlCuLi i-phase is a model system for understanding the structure and thermodynamics of quasicrystalline materials. The research I have done consists of three parts: (1) Structural studies using high resolution x-ray diffraction. We found that Al(Cu) were decorated at the edge centers and vertices of two types of Penrose tiles, which are the basic units of Penrose tiling. Our results are the first successful determination of the atomic position in quasicrystalline materials, and prove that the Penrose tiling is a better description of quasicrystalline materials than other structural models. (2) Structural studies using pulsed neutron scattering. The dominant contribution to the AlCuLi x-ray spectrum comes from Al and Cu atoms since Li is a weak scatterer. However, the scattering length of the Li atom in neutron diffraction is comparable to that of Al(Cu). Furthermore, Li and Mg have opposite signs in scattering length. Thus, isomorphic substitution of Li by Mg results in contrast variation in neutron diffraction spectra, which demonstrates how Li atoms affect the diffraction. Using the pair distribution function analysis, we convincingly reveal the role of Li atoms in the structure. (3) Stability and formation. We investigate the formation of i-phase by varying preparation condition and stoichiometry. By using differential scanning calorimetry and x-ray diffraction, we established the thermodynamic relationship between the i-phase and the related crystalline phase.

  7. Controlling microstructure and texture in magnesium alloy sheet by shear-based deformation processing

    NASA Astrophysics Data System (ADS)

    Sagapuram, Dinakar

    Application of lightweight Mg sheet is limited by its low workability, both in production of sheet (typically by multistep hot and cold-rolling) and forming of sheet into components. Large strain extrusion machining (LSEM), a constrained chip formation process, is used to create Mg alloy AZ31B sheet in a single deformation step. The deformation in LSEM is shown to be intense simple shear that is confined to a narrow zone, which results in significant deformation-induced heating up to ~ 200°C and reduces the need for pre-heating to realize continuous sheet forms. This study focuses on the texture and microstructure development in the sheet processed by LSEM. Interestingly, deep, highly twinned steady-state layer develops in the workpiece subsurface due to the compressive field ahead of the shear zone. The shear deformation, in conjunction with this pre-deformed twinned layer, results in tilted-basal textures in the sheet with basal planes tilted well away from the surface. These textures are significantly different from those in rolled sheet, where basal planes are nearly parallel to the surface. By controlling the strain path, the basal plane inclination from the surface could be varied in the range of 32-53°. B-fiber (basal plane parallel to LSEM shear plane), associated with basal slip, is the major texture component in the sheet. An additional minor C2-fiber component appears above 250°C due to the thermal activation of pyramidal slip. Together with these textures, microstructure ranges from severely cold-worked to (dynamically) recrystallized type, with the corresponding grain sizes varying from ultrafine- (~ 200 nm) to fine- (2 mum) grained. Small-scale limiting dome height (LDH) confirmed enhanced formability (~ 50% increase in LDH) of LSEM sheet over the conventional rolled sheet. Premature, twinning-driven shear fractures are observed in the rolled sheet with the basal texture. In contrast, LSEM sheet with a tilted-basal texture favorably oriented for basal slip exhibits ductile tensile-type fracture. A two-fold increase in ductility is also observed for the LSEM sheet under uniaxial tensile testing without significant changes in the strength. Among texture and microstructure (grain size), texture is shown to be more critical for Mg sheet formability. However, in conjunction with a favorable texture, fine recrystallized microstructure provides for additional enhancement of strain-hardening capacity and formability. In-situ imaging of material flow during uniaxial tensile testing revealed new, interesting flow localization phenomena and fracture behavior. It is shown that the deformation behavior of Mg sheet is highly texture dependent, and also radically different from that of conventional ductile metals both in terms of necking and fracture. The implications of these observations for the LDH test results and formability of Mg sheet, in general, are briefly discussed.

  8. Magnesium Oxide

    MedlinePLUS

    Magnesium is an element your body needs to function normally. Magnesium oxide may be used for different reasons. Some ... to relieve heartburn, sour stomach, or acid indigestion. Magnesium oxide also may be used as a laxative ...

  9. Microstructural evolution and mechanical properties of high strength magneisum alloys fabricated by deformation processing

    NASA Astrophysics Data System (ADS)

    Mansoor, Bilal

    The goal of this research was to develop high strength Mg by thermo-mechanical processing. Several novel techniques were developed to impart large plastic strains on Mg alloys and Mg based composites. The main emphasis of this work was on investigating the effect of different processing schemes on grain-refinement and texture modification of processed material. The room-temperature and elevated-temperature mechanical behavior of processed-Mg was studied in detail. Biaxial corrugated pressing, also known as alternate biaxial reverse corrugation processing was applied to twin-roll cast AZ31 Mg and warm-extruded ZK60 Mg. Friction stir processing to partial depths was applied to thixomolded AM60 Mg and warm-extruded ZK60 Mg. A new process called "bending reverse-bending", was developed and applied to hot rolled AZ31-H24 Mg. A Mg/Al laminated composite was developed by hot pressing and rolling. In processed condition, Mg alloys exhibit enhancement in room-temperature strength and ductility, as well as elevated temperature formability. It was concluded that improvement in mechanical properties of processed-Mg is strongly influenced by grain size and precipitates; while ductility largely depends on resulting deformation textures.

  10. Characterization of the effects of process parameters on macrosegregation in a high-pressure die-cast Magnesium alloy

    Microsoft Academic Search

    Soon Gi Lee; G. R. Patel; A. M. Gokhale

    2005-01-01

    Normal and inverse solute segregations have been reported to occur in several Al-alloys as well as in some other nonferrous alloys. Nonetheless, these phenomena have not been studied in high-pressure die-cast (HPDC) Mg-alloys. This contribution reports an experimental metallographic evidence of inverse surface macrosegregation in a HPDC AM60 Mg-alloy and the effects of process parameters on the extent of inverse

  11. Effect of alloying elements on interface microstructure of Mg–Al–Zn magnesium alloys and titanium joint by friction stir welding

    Microsoft Academic Search

    Masayuki Aonuma; Kazuhiro Nakata

    2009-01-01

    An effect of alloying element on interfacial microstructure of Mg–Al–Zn alloys and Ti dissimilar butt joints by friction stir welding (FSW) was studied. Mg–Al–Zn alloy and Ti plates of 2mm in thickness were successfully butt joined by inserting a probe into the Mg alloy plate and slightly offsetting it by 0.5mm into the Ti plate side. Al-rich thin layers and

  12. The influence of tool coatings in machining of magnesium

    Microsoft Academic Search

    H. K. Tönshoff; J. Winkler

    1997-01-01

    Magnesium is the lightest metal used in construction and therefore offers the greatest potential for weight reduction. The automotive industry in particular has an upcoming interest in the use of magnesium alloys. To observe the interactions between workpiece material and tool material and coating, respectively, turning experiments were carried out machining the alloy AZ91 HP. When machining magnesium dry, flank

  13. Surface modification of a biodegradable magnesium alloy with phosphorylcholine (PC) and sulfobetaine (SB) functional macromolecules for reduced thrombogenicity and acute corrosion resistance.

    PubMed

    Ye, Sang-Ho; Jang, Yong-Seok; Yun, Yeo-Heung; Shankarraman, Venkat; Woolley, Joshua R; Hong, Yi; Gamble, Lara J; Ishihara, Kazuhiko; Wagner, William R

    2013-07-01

    Siloxane functionalized phosphorylcholine (PC) or sulfobetaine (SB) macromolecules (PCSSi or SBSSi) were synthesized to act as surface modifying agents for degradable metallic surfaces to improve acute blood compatibility and slow initial corrosion rates. The macromolecules were synthesized using a thiol-ene radical photopolymerization technique and then utilized to modify magnesium (Mg) alloy (AZ31) surfaces via an anhydrous phase deposition of the silane functional groups. X-ray photoelectron spectroscopy surface analysis results indicated successful surface modification based on increased nitrogen and phosphorus or sulfur composition on the modified surfaces relative to unmodified AZ31. In vitro acute thrombogenicity assessment after ovine blood contact with the PCSSi and SBSSi modified surfaces showed a significant decrease in platelet deposition and bulk phase platelet activation compared with the control alloy surfaces. Potentiodynamic polarization and electrochemical impedance spectroscopy data obtained from electrochemical corrosion testing demonstrated increased corrosion resistance for PCSSi- and SBSSi-modified AZ31 versus unmodified surfaces. The developed coating technique using PCSSi or SBSSi showed promise in acutely reducing both the corrosion and thrombotic processes, which would be attractive for application to blood contacting devices, such as vascular stents, made from degradable Mg alloys. PMID:23705967

  14. Effects of Mechanical Vibration and Wall Thickness on Microstructure and Mechanical Properties of AZ91D Magnesium Alloy Processed by Expendable Pattern Shell Casting

    NASA Astrophysics Data System (ADS)

    Jiang, Wenming; Fan, Zitian; Chen, Xu; Wang, Benjing; Wu, Hebao

    2015-04-01

    Mechanical vibration was introduced into the solidification process of AZ91D magnesium alloy during the expendable pattern shell casting process, and the combined effects of mechanical vibration and wall thickness on the microstructure and mechanical properties were investigated. The results indicate that with the increase of wall thickness, the morphologies in ?-Mg phase and ?-Mg17Al12 phase of the samples obtained without vibration evolved from a fine dendrite to a coarse dendrite and from a fine continuous network structure to a coarse continuous network structure, respectively, and the mechanical properties and density of AZ91D alloy continuously decreased. With the application of mechanical vibration, the coarser dendrites transformed into fine equiaxed grains, and the previous coarse continuous network structure of the ?-Mg17Al12 phase was changed to a discontinuous granular morphology. Meanwhile, the mechanical properties and density of AZ91D alloy greatly increased. The effect of mechanical vibration on the microstructure and mechanical properties increased with increasing vibration frequency and wall thickness. The fractographs of the tensile samples show a change in fracture surface from brittle to that of a tough fracture with the addition of vibration.

  15. Magnesium basics

    PubMed Central

    Ketteler, Markus

    2012-01-01

    As a cofactor in numerous enzymatic reactions, magnesium fulfils various intracellular physiological functions. Thus, imbalance in magnesium status—primarily hypomagnesaemia as it is seen more often than hypermagnesaemia—might result in unwanted neuromuscular, cardiac or nervous disorders. Measuring total serum magnesium is a feasible and affordable way to monitor changes in magnesium status, although it does not necessarily reflect total body magnesium content. The following review focuses on the natural occurrence of magnesium and its physiological function. The absorption and excretion of magnesium as well as hypo- and hypermagnesaemia will be addressed.

  16. The influence of laser pulse waveform on laser–TIG hybrid welding of AZ31B magnesium alloy

    Microsoft Academic Search

    Gang Song; Zhimin Luo

    2011-01-01

    By dividing laser pulse duration into two parts, three kinds of laser waveforms are designed, including a high power density pulse (HPDP) laser in a short duration set at the beginning of the laser waveform. This paper aims to find out the laser pulse waveform and idiographic critical values of HPDP, which can affect the magnesium penetration in laser–tungsten inert

  17. Numerical and experiment analysis of residual stress on magnesium alloy and steel butt joint by hybrid laser-TIG welding

    Microsoft Academic Search

    Zhi Zeng; Xunbo Li; Yugang Miao; Gang Wu; Zijun Zhao

    2011-01-01

    Hybrid welding technology has received significant attention in the welding of dissimilar materials recently. While, great welding residual stress and deformation often result by the difference of coefficient of thermal expansion This study describes the thermal elastic–plastic analysis using finite element techniques to analyze the thermo mechanical behavior and evaluate the residual stresses and welding distortion on the AZ31B magnesium

  18. Comparison of the microstructure and the mechanical properties of AX41 magnesium alloy processed by EX-ECAP via three different routes A, Bc and C

    NASA Astrophysics Data System (ADS)

    Kraj?ák, T.; Máthis, K.; Jane?ek, M.; Gubicza, J.

    2014-08-01

    This work is devoted to the creep-resistant AX41 magnesium alloy (Mg-4 wt.% Al-1 wt.% Ca), processed by extrusion and consecutive Equal Channel Angular Pressing (EX- ECAP) up to total of eight passes, via route A, Bc and C at 220 °C. Beyond the deformation behavior the change of the microstructures was studied by electron back-scattering and X-ray diffraction methods. Significant grain refinement was found for all processing routes (grain sizes decreased below 1 pm after 8 passes). The X-ray line profile analysis performed by Convolutional Multiple Whole Profile (CMWP) fitting method has not revealed differences between the particular dislocation structures. Route A was found to be the most effective processing route from the point of view of grain size refinement and the room temperature strength. The influence of the texture and the dislocation structure on the plastic deformation processes is discussed in detail.

  19. High-compactness coating grown by plasma electrolytic oxidation on AZ31 magnesium alloy in the solution of silicate-borax

    NASA Astrophysics Data System (ADS)

    Shen, M. J.; Wang, X. J.; Zhang, M. F.

    2012-10-01

    A ceramic coating was formed on the surface of AZ31 magnesium alloy by plasma electrolytic oxidation (PEO) in the silicate solution with and without borax doped. The composition, morphology, elements and roughness as well as mechanical property of the coating were investigated by X-ray diffraction (XRD), scanning electron microscope (SEM), energy dispersive X-ray spectrometry (EDS), X-ray photoelectron spectroscopy (XPS), atomic force microscopy (AFM) and reciprocal-sliding tribometer. The results show that the PEO coating is mainly composed of magnesia. When using borax dope, boron element is permeating into the coating and the boron containing phase exist in the form of amorphous. In addition, the microhardness and compactness of the PEO coating are improved significantly due to doped borax.

  20. Nano-hydroxyapatite reinforced AZ31 magnesium alloy by friction stir processing: a solid state processing for biodegradable metal matrix composites.

    PubMed

    Ratna Sunil, B; Sampath Kumar, T S; Chakkingal, Uday; Nandakumar, V; Doble, Mukesh

    2014-04-01

    Friction stir processing (FSP) was successfully adopted to fabricate nano-hydroxyapatite (nHA) reinforced AZ31 magnesium alloy composite as well as to achieve fine grain structure. The combined effect of grain refinement and the presence of embedded nHA particles on enhancing the biomineralization and controlling the degradation of magnesium were studied. Grain refinement from 56 to ~4 and 2 ?m was observed at the stir zones of FSP AZ31 and AZ31-nHA composite respectively. The immersion studies in super saturated simulated body fluid (SBF 5×) for 24 h suggest that the increased wettability due to fine grain structure and nHA particles present in the AZ31-nHA composite initiated heterogeneous nucleation which favored the early nucleation and growth of calcium-phosphate mineral phase. The nHA particles as nucleation sites initiated rapid biomineralization in the composite. After 72 h of immersion the degradation due to localized pitting was observed to be reduced by enhanced biomineralization in both the FSPed AZ31 and the composite. Also, best corrosion behavior was observed for the composite before and after immersion test. MTT assay using rat skeletal muscle (L6) cells showed negligible toxicity for all the processed and unprocessed samples. However, cell adhesion was observed to be more on the composite due to the small grain size and incorporated nHA. PMID:24375146

  1. Influence of Elevated Temperature and Stress Ratio on the Fatigue Response of AM60B Magnesium Alloy

    NASA Astrophysics Data System (ADS)

    Nur-Hossain, Md.; Taheri, Farid

    2012-07-01

    The fatigue response of a high pressure die-cast AM60B Mg alloy is studied at room and elevated temperatures. The fatigue tests are conducted with stress ratio of R = 0.1 and frequency of 30 Hz. The main objective is to determine whether elevated temperature would affect the fatigue response of the alloy. In addition, fatigue crack growth characteristics of the alloy is investigated at room temperature. The purpose of this test is to ascertain the capability and accuracy of a finite element approach coupled with the Walker model in assessing the life cycle of the alloy, in consideration of the influence of stress ratio.

  2. Fabrication and characterization of AZ91/CNT magnesium matrix composites

    NASA Astrophysics Data System (ADS)

    Park, Yong-Ha; Park, Yong-Ho; Park, Ik-Min; Oak, Jeong-jung; Kimura, Hisamichi; Cho, Kyung-Mox

    2008-12-01

    Carbon Nano Tube (CNT) reinforced AZ91 metal matrix composites (MMC) were fabricated by the squeeze infiltrated method. Properties of magnesium alloys have been improved by impurity reduction, surface treatment and alloy design, and thus the usage for the magnesium alloys has been extended recently. However there still remain barriers for the adaption of magnesium alloys for engineering materials. In this study, we report light-weight, high strength heat resistant magnesium matrix composites. Microstructural study and tensile test were performed for the squeeze infiltrated magnesium matrix composites. The wear properties were characterized and the possibility for the application to automotive power train and engine parts was investigated. It was found that the squeeze infiltration technique is a proper method to fabricate magnesium matrix composites reducing casting defects such as pores and matrix/reinforcement interface separation etc. Improved tensile and mechanical properties were obtained with CNT reinforcing magnesium alloys

  3. Corrosion Resistance Enhancement of AZ91D Magnesium Alloy by Electroless Ni-Co-P Coating and Ni-Co-P-SiO2 Nanocomposite

    NASA Astrophysics Data System (ADS)

    Seifzadeh, Davod; Rahimzadeh Hollagh, Amin

    2014-08-01

    Electroless Ni-Co-P coating and Ni-Co-P-SiO2 nanocomposites were successfully applied on AZ91D magnesium alloy via environmentally friendly cerium-lanthanum-permanganate treatment and their properties were compared with traditionally binary Ni-P coating. The prepared coatings were analyzed using scanning electron microscopy, x-ray diffraction, and energy dispersive x-ray spectroscopy. Moreover, the corrosion behavior of the coatings in 3.5 wt.% NaCl was evaluated by two electrochemical methods. It is found that the Ni-Co-P coating possesses more uniform and compact structure and better corrosion protection characteristics in comparison with the Ni-P coating. The plating rate of Ni-Co-P bath is relatively lower than the Ni-P bath, but it significantly increases after addition of SiO2 nanoparticles more probably due to adsorption of silica nanoparticles on alloy surface. The corrosion resistance of Ni-Co-P-SiO2 composite coatings was superior with respect to Ni-P and Ni-Co-P coatings due to formation of thick and compact coating with tortuous grain boundaries.

  4. Magnesium Hydroxide

    MedlinePLUS

    Magnesium hydroxide is used on a short-term basis to treat constipation.This medication is sometimes prescribed ... Magnesium hydroxide come as a tablet and liquid to take by mouth. It usually is taken as ...

  5. Growth process and corrosion resistance of micro-arc oxidation coating on Mg-Zn-Gd magnesium alloys

    Microsoft Academic Search

    Ping WANG; Dao-xin LIU; Jian-ping LI; Yong-chun GUO; Zhong YANG

    2010-01-01

    A Mg-6Zn-3Gd (mass fraction, %) alloy, noted as ZG63, was coated by different micro-arc oxidation (MAO) processes, and the coating structure and corrosion resistance of the alloy were studied using scanning electron microscopy (SEM), glancing angle X-ray diffractometry (GAXRD) and various electrochemical methods. The micro-arc oxidation process consists of three stages and corresponds with different coating structures. In the initial

  6. Evaluation of the corrosion behavior of nickel- and copper-base alloys in high-magnesium brine

    Microsoft Academic Search

    Westerman

    1988-01-01

    The reference design of a package for containing high-level nuclear waste in a salt repository utilizes a mile steel container. An alternate material, selected from a group of six Ni- and Cu-base alloys, is being considered for this waste package application in the event that the mild steel proves inadequate as a corrosion barrier. The corrosion behavior of Ni-base alloys

  7. The Effects of Adding Elements of Zinc and Magnesium on Ag-Cu Eutectic Alloy for Warming Acupuncture

    PubMed Central

    Park, Il Song; Kim, Keun Sik; Lee, Min Ho

    2013-01-01

    The warming acupuncture for hyperthermia therapy is made of STS304. However, its needle point cannot be reached to a desirable temperature due to heat loss caused by low thermal conductivity, and the quantification of stimulation condition and the effective standard establishment of warming acupuncture are required as a heat source. Accordingly, in this study, after Ag-Cu alloys with different composition ratios were casted and then mixed with additives to improve their physical and mechanical properties, the thermal conductivity and biocompatibility of the alloy specimens were evaluated for selecting suitable material. Ag-Cu binary alloys and ternary alloys added 5?wt% Zn or 2?wt% Mg were casted and then cold drawn to manufacture needles for acupuncture, and their physical properties, thermal conductivity, and biocompatibility were evaluated for their potential use in warming acupuncture. The results of this study showed that the physical and mechanical properties of the Ag-Cu alloys were improved by additives and that the thermal conductivity, machinability, and biocompatibility of the Ag-Cu alloys were improved by Mg addition. PMID:24078827

  8. Nanophasic biodegradation enhances the durability and biocompatibility of magnesium alloys for the next-generation vascular stents

    NASA Astrophysics Data System (ADS)

    Mao, Lin; Shen, Li; Niu, Jialin; Zhang, Jian; Ding, Wenjiang; Wu, Yu; Fan, Rong; Yuan, Guangyin

    2013-09-01

    Biodegradable metal alloys emerge as a new class of biomaterials for tissue engineering and medical devices such as cardiovascular stents. Deploying biodegradable materials to fabricate stents not only obviates a second surgical intervention for implant removal but also circumvents the long-term foreign body effect of permanent implants. However, these materials for stents suffer from an un-controlled degradation rate, acute toxic responses, and rapid structural failure presumably due to a non-uniform, fast corrosion process. Here we report that highly uniform, nanophasic degradation is achieved in a new Mg alloy with unique interstitial alloying composition as the nominal formula Mg-2.5Nd-0.2Zn-0.4Zr (wt%, hereafter, denoted as JDBM). This material exhibits highly homogeneous nanophasic biodegradation patterns as compared to other biodegradable metal alloy materials. Consequently it has significantly reduced degradation rate determined by electrochemical characterization. The in vitro cytotoxicity test using human vascular endothelial cells indicates excellent biocompatibility and potentially minimal toxic effect on arterial vessel walls. Finally, we fabricated a cardiovascular stent using JDBM and performed in vivo long-term assessment via implantation of this stent in an animal model. The results confirmed the reduced degradation rate in vivo, excellent tissue compatibility and long-term structural and mechanical durability. Thus, this new Mg-alloy with highly uniform nanophasic biodegradation represents a major breakthrough in the field and a promising material for manufacturing the next generation biodegradable vascular stents.

  9. Magnesium Metabolism

    PubMed Central

    Park, Tae Jin

    2008-01-01

    Magnesium is the second most common intracellular divalent cation. Magnesium balance in the body is controlled by a dynamic interplay among intestinal absorption, exchange with bone, and renal excretion. Intestinal magnesium absorption proceeds in both a passive paracellular and an active transcellular manner. Regulation of serum magnesium concentrations is achieved mainly by control of renal magnesium reabsorption. Only 20% of filtered magnesium is reabsorbed in the proximal tubule, whereas 60% is reclaimed in the cortical thick ascending limb (TAL) and another 5-10% in the distal convoluted tubule (DCT). The passive paracellular transport of magnesium in the TAL is closely related with the mutations in claudin-16/paracellin-1 and is responsible for familial hypomagnesemia with hypercalciuria and nephrocalcinosis. The active transcellular transport of magnesium in the DCT was similarly enhanced by the realization that defects in transient receptor potential melastatin 6 (TRPM6) cause hypomagnesemia with secondary hypocalcemia. This channel regulates the apical entry of magnesium into epithelia and alters whole-body magnesium homeostasis by controlling urinary excretion. TRPM6 is regulated at the transcriptional level by acid-base status, 17?-estradiol, and both FK506 and cyclosporine. The molecular identity of the protein responsible for the basolateral exit of magnesium from the epithelial cell remains unidentified. PMID:24459527

  10. Reconstruction and visualization of complex 3D pore morphologies in a high-pressure die-cast magnesium alloy

    Microsoft Academic Search

    S. G. Lee; A. M. Gokhale; A. Sreeranganathan

    2006-01-01

    Visualization and representation of three-dimensional (3D) pore morphologies in the high-pressure die-cast Mg alloys are of significant interest for understanding and modeling processing–microstructure–properties relationships. In this contribution, an efficient and unbiased montage serial sectioning technique is applied for reconstruction of large volume (?1.24×109?m3) high-resolution (?1?m) 3D microstructure of a high-pressure die-cast AM50 Mg alloy containing gas (air) and shrinkage pores.

  11. The effect of silicon content on the microstructure and creep behavior in die-cast magnesium AS alloys

    NASA Astrophysics Data System (ADS)

    Dargusch, M. S.; Dunlop, G. L.; Bowles, A. L.; Pettersen, K.; Bakke, P.

    2004-06-01

    The effect of increasing levels of silicon on the microstructure and creep properties of high-pressure die-cast Mg-Al-Si (AS) alloys has been investigated. The morphology of the Mg2Si phase in die-cast AS alloys was found to be a function of the silicon content. The Mg2Si particles in castings with up to 1.14 wt pct Si have a Chinese script morphology. For AS21 alloys with silicon contents greater than 1.4 wt pct Si (greater than the ?-Mg2Si binary eutectic point), some Mg2Si particles have a coarse “blocky” shape. Increasing the silicon content above the eutectic level results in an increase in the number of coarse faceted Mg2Si particles in the microstructure. Creep rates at 100 hours were found to decrease with increasing silicon content in AS-type alloys. The decrease in creep rate was most dramatic for silicon contents up to 1.1 wt pct. Further additions of silicon of up to 2.64 wt pct also resulted in significant decreases in creep rate.

  12. Modeling texture evolution during rolling process of AZ31 magnesium alloy with elasto-plastic self consistent model

    Microsoft Academic Search

    Shi-yao HUANG; Shao-rui ZHANG; Da-yong LI; Ying-hong PENG

    2011-01-01

    To gain a better understanding about texture evolution during rolling process of AZ31 alloy, polycrystalline plasticity model was implemented into the explicit FE package, ABAQUS\\/Explicit by writing a user subroutine VUMAT. For each individual grain in the polycrystalline aggregate, the rate dependent model was adopted to calculate the plastic shear strain increment in combination with the Voce hardening law to

  13. A Model to Predict the Resulting Grain Size of Friction-Stir-Processed AZ31 Magnesium Alloy

    NASA Astrophysics Data System (ADS)

    Darras, Basil M.

    2012-07-01

    One of the most important issues that hinder the widespread use of friction stir (FS) processing, an effective microstructural modification technique, is the lack of accurate predictive tools that enable the selection of suitable processing parameters to obtain the desired grain structure. In this study, a model that is capable of predicting the resulting average grain size of a FS-processed material from process parameters is presented. The proposed model accounts for both dynamic recrystallization and grain growth. Several AZ31 magnesium samples were FS processed in different combinations of rotational and translational speeds. The thermal fields and resulting average grain size were measured, and the effective strain rates were approximated analytically. The results show that the proposed model is capable of predicting the resulting grain size of FS-processed materials.

  14. Formation and breakdown of chromate conversion coatings on aluminum-zinc-magnesium-copper 7X75 alloys

    NASA Astrophysics Data System (ADS)

    Yoon, Yuhchae

    The objective of this study was to characterize the formation and breakdown of chromate conversion coatings (CCCs) on aluminum alloys Al-Zn-Mg-Cu 7075 and 7475 with a focus on the effect of alloy temper, alloy purity and selected coating processing variables. Overall, results consistently pointed to a slight temper effect. Conversion coated AA7475-T7 was significantly more corrosion resistant than conversion coated AA7475-T6. In AA7075, there was only a slight difference in corrosion resistance between the two tempers. This was attributed to the effect of constituent particles on coating formation and breakdown, which are present to a much greater extent in AA7075 than in AA7475. The difference in the corrosion resistance between the T6 and T7 tempers in the coated and uncoated conditions is about the same suggesting that the origin of any "temper effect" in conversion coated materials is ultimately due to the intrinsic change in corrosion susceptibility of the alloy itself. Thicker coating formed on AA7475-T7 has the effect of increasing corrosion resistance, which could be associated with the 860 cm-1 Raman intensity band. Studies were also conducted with alloys in retrogression and reaged tempers and the W temper. Results with these tempers were mixed and no general conclusions could be drawn. In terms of electrochemically derived measures of corrosion resistance (electrochemical impedance, and pitting potential measurements), the magnitude of the temper effect was about the same as the effect due to the purity difference between AA7075 and AA7475. The temper effect was less significant than effects due to increasing coating time from 1 to 3 minutes, withholding certain substrate precleaning steps, or withholding key ingredients from the coating bath. Scanning probe microscopy, scanning Kelvin probe force microscopy (SKPFM) and scanning electron microscopy were used to characterize coating formation in the vicinity of constituent intermetallic particles (IMPs) present in the alloys. Coatings formed on IMPS exhibited different morphologies and were much thinner that coatings formed on the matrix. Coatings were thinnest on S phase particles, and in post-coating exposure to aggressive chloride environments coating breakdown was almost always associated with these particles. The difference in coating thickness between particles and the surrounding matrix was established within the first tens of seconds of coating. The thickness differential was then observed to remain constant for the remainder of the coating immersion time. (Abstract shortened by UMI.)

  15. The effect of manganese on the precipitation of Mg 17 Al 12 phase in magnesium alloy AZ 91

    Microsoft Academic Search

    Y. Tamura; Y. Kida; H. Tamehiro; N. Kono; H. Soda; A. McLean

    2008-01-01

    Non-uniform continuous precipitation of the ?-phase is known to occur within the solution-treated grains of AZ91 alloys during\\u000a aging. In the present study, the segregation profiles of solute elements in the as-cast, solution heat-treated, and aged specimens\\u000a of AZ91E were examined by electron probe micro analysis. The results were correlated with optical and SEM observations of\\u000a the microstructures. It was

  16. Characterization and wear resistance of macro-arc oxidation coating on magnesium alloy AZ91 in simulated body fluids

    Microsoft Academic Search

    Jun CHEN; Rong-chang ZENG; Wei-jiu HUANG; Zi-qing ZHENG; Zhen-lin WANG; Jun WANG

    2008-01-01

    The mechanical characteristics of the macro-arc oxidation (MAO) coating on Mg alloy AZ91 were examined by means of nano scratch tester. The corrosion and erosion corrosion behavior of AZ91 with and without MAO coating were investigated by using potentiodynamic electrochemical technique and micro-abrasion tribometer in simulated body fluids, respectively. The influence of HCO3? ions on the erosion corrosion was discussed.

  17. The use of Al–Al 2O 3 cold spray coatings to improve the surface properties of magnesium alloys

    Microsoft Academic Search

    K. Spencer; D. M. Fabijanic; M.-X. Zhang

    2009-01-01

    Pure Al and 6061 aluminium alloy based Al2O3 particle-reinforced composite coatings were produced on AZ91E substrates using cold spray. The strength of the coating\\/substrate interface in tension was found to be stronger than the coating itself. The coatings have corrosion resistance similar to that of bulk pure aluminium in both salt spray and electrochemical tests. The wear resistance of the

  18. In Vitro Corrosion and Cytocompatibility Properties of Nano-Whisker Hydroxyapatite Coating on Magnesium Alloy for Bone Tissue Engineering Applications

    PubMed Central

    Yang, Huawei; Yan, Xueyu; Ling, Min; Xiong, Zuquan; Ou, Caiwen; Lu, Wei

    2015-01-01

    We report here the successful fabrication of nano-whisker hydroxyapatite (nHA) coatings on Mg alloy by using a simple one-step hydrothermal process in aqueous solution. The nHA coating shows uniform structure and high crystallinity. Results indicate that nHA coating is promising for improving the in vitro corrosion and cytocompatibility properties of Mg-based implants and devices for bone tissue engineering. In addition, the simple hydrothermal deposition method used in the current study is also applicable to substrates with complex shapes or surface geometries. PMID:25789500

  19. The mechanical properties and microstructures of AZ91D magnesium alloy processed by selective laser cladding with Al powder

    NASA Astrophysics Data System (ADS)

    Lin, Pengyu; Zhang, Zhihui; Ren, Luquan

    2014-08-01

    This work focuses on the effects of selective laser cladding using Al powder on the properties and microstructure of Mg alloy AZ91D, with different experimental parameters. The scanning strategy was inspired by the alternately hard-soft shell surface structures. The microstructure was greatly refined. Furthermore, the growth of the ?-Mg17Al12 dendrite was curbed. The treatment depth is ~900 ?m. The UTS, YS and microhardness were notably increased. However, the ductility was decreased by a part. The output power of 2200 W and the scanning speed of 180 mm/min are the optimum combination. The resulting wear resistance was thus the highest of all.

  20. APPLICATION OF ALUMINUM COATINGS FOR THE CORROSION PROTECTION OF MAGNESIUM BY COLD SPRAY

    Microsoft Academic Search

    Brian DeForce; Tim Eden; John Potter; Victor Champagne; Phil Leyman; Dennis Helfritch

    Magnesium alloys are frequently used in the fabrication of aircraft components due to their good mechanical properties and low density. Due to poor corrosion resistance, magnesium alloys require multi-layer hazardous coating systems and frequent repair or replacement. A low-cost environmentally friendly solution is the application of an aluminum barrier coating to the magnesium by the Cold Spray (CS) process. CS

  1. In-Situ White Beam Microdiffraction Study of the Deformation Behavior in Polycrystalline Magnesium Alloy During Uniaxial Loading

    SciTech Connect

    Lynch, P. A. [Commonwealth Scientific and Industrial Research Organisation (CSIRO), Minerals, Private Bag 33, Clayton South MDC, 3169 (Australia); CSIRO, Manufacturing and Infrastructure Technology (Australia); Stevenson, A. W.; Liang, D.; Parry, D.; Wilkins, S. [CSIRO, Manufacturing and Infrastructure Technology (Australia); Madsen, I. C. [Commonwealth Scientific and Industrial Research Organisation (CSIRO), Minerals, Private Bag 33, Clayton South MDC, 3169 (Australia); Bettles, C. [ARC Centre of Excellence for Design in Light Metals, Department of Materials Engineering, Monash University, Clayton, 3800, Victoria (Australia); Tamura, N.; Geandier, G. [Lawrence Berkeley National Laboratory, 1 Cyclotron Road, Berkeley, CA 94720 (United States)

    2007-01-19

    Scanning white beam X-ray microdiffraction has been used to study the heterogeneous grain deformation in a polycrystalline Mg alloy (MgAZ31). The high spatial resolution achieved on beamline 7.3.3 at the Advanced Light Source provides a unique method to measure the elastic strain and orientation of single grains as a function of applied load. To carry out in-situ measurements a light weight ({approx}0.5kg) tensile stage, capable of providing uniaxial loads of up to 600kg, was designed to collect diffraction data on the loading and unloading cycle. In-situ observation of the deformation process provides insight about the crystallographic deformation mode via twinning and dislocation slip.

  2. NUCLEATION PHENOMENON IN SiC PARTICULATE REINFORCED MAGNESIUM COMPOSITE

    E-print Network

    Zhou, Wei

    performance of matrix metals and alloys. Most magnesium alloy based MMCs are produced via a casting process in hypereutectic Al-Si alloy. However, it is also reported [5] that in hypoeutectic Al-Si alloy, primary -aluminum Avenue, Singapore 639798 (Received May 5, 1999) (Accepted June 24, 1999) Keywords: Casting; Nucleation

  3. Magnesium compounds

    USGS Publications Warehouse

    Kramer, D.A.

    2011-01-01

    Seawater and natural brines accounted for about 54 percent of U.S. magnesium compounds production in 2010. Dead-burned magnesia was produced by Martin Marietta Magnesia Specialties from well brines in Michigan. Caustic-calcined magnesia was recovered from seawater by Premier Magnesia in Florida, from well brines in Michigan by Martin Marietta and from magnesite in Nevada by Premier Magnesia. Intrepid Potash-Wendover and Great Salt Lake Minerals Corp. recovered magnesium chloride brines from the Great Salt Lake in Utah. Magnesium hydroxide was produced from seawater by SPI Pharma in Delaware and Premier Magnesia in Florida, and by Martin Marietta from its operation mentioned above.

  4. Magnesium compounds

    USGS Publications Warehouse

    Kramer, D.A.

    2010-01-01

    Seawater and natural brines accounted for about 40 percent of U.S. magnesium compounds production in 2009. Dead-burned magnesia was produced by Martin Marietta Magnesia Specialties from well brines in Michigan. Caustic-calcined magnesia was recovered from seawater by Premier Chemicals in Florida, from well brines in Michigan by Martin Marietta and from magnesite in Nevada by Premier Chemicals. Intrepid Potash-Wendover, and Great Salt Lake Minerals Corp. recovered magnesium chloride brines from the Great Salt Lake in Utah. Magnesium hydroxide was produced from seawater by SPI Pharma in Delaware and Premier Chemicals in Florida, and by Martin Marietta from its operation mentioned above.

  5. Surface alloying of Mg alloys after surface nanocrystallization.

    PubMed

    Zhang, Ming-Xing; Shi, Yi-Nong; Sun, Haiqing; Kelly, Patrick M

    2008-05-01

    Surface nanocrystallization using a surface mechanical attrition treatment effectively activates the surface of magnesium alloys due to the increase in grain boundary diffusion channels. As a result, the temperature of subsequent surface alloying treatment of pure Mg and AZ91 alloy can be reduced from 430 degrees C to 380 degrees C. Thus, it is possible to combine the surface alloying process with the solution treatment for this type of alloy. After surface alloying, the hardness of the alloyed layer is 3 to 4 times higher than that of the substrate and this may significantly improve the wear resistance of magnesium alloys. PMID:18572716

  6. Growth behavior of intermetallic compounds during reactive diffusion between aluminum alloy 1060 and magnesium at 573-673 K

    NASA Astrophysics Data System (ADS)

    Xiao, Lin; Wang, Ning

    2015-01-01

    A potential new research reactor fuel design proposes to use U-Mo fuel in a Mg matrix clad with Al. Interdiffusion between the Mg containing fuel core and Al cladding can result in the formation of intermetallic compounds that can be detrimental to fuel element performance. The kinetics of the reactive diffusion in the binary Al-Mg system was experimentally studied. Layers of the intermetallic compounds, ? (Al3Mg2) and ? (Al12Mg17) phases, were formed between the Al alloy 1060 and Mg during annealing. The ? layer was observed to grow faster than the ? phase. The thickness of each layer can be expressed by a power function of the annealing time with the exponent n close to 0.5 for the ? phase and less than 0.5 for the ? phase. The results suggest that the growth of ? phase is controlled by lattice diffusion and that of the ? phase by grain boundary and lattice diffusion. Metallographic examination showed the grain boundary diffusion in the form of columnar growth of ? phase during annealing. Based on the reactive diffusion equation developed in this work, in the absence of irradiation effects, it will take more than 110 h to consume a half thickness of 400 ?m of the cladding.

  7. Fiber Laser Welded AZ31 Magnesium Alloy: The Effect of Welding Speed on Microstructure and Mechanical Properties

    NASA Astrophysics Data System (ADS)

    Chowdhury, S. H.; Chen, D. L.; Bhole, S. D.; Powidajko, E.; Weckman, D. C.; Zhou, Y.

    2012-06-01

    This study was aimed at characterizing microstructural change and evaluating tensile and fatigue properties of fiber laser welded AZ31B-H24 Mg alloy with special attention to the effect of welding speed. Laser welding led to the formation of equiaxed dendrites in the fusion zone and columnar dendrites near the fusion zone boundary along with divorced eutectic Mg17Al12 particles and recrystallized grains in the heat-affected zone. The lowest hardness across the weld appeared in the fusion zone. Although the yield strength, ductility, and fatigue life decreased, the hardening capacity increased after laser welding, with a joint efficiency reaching about 90 pct. A higher welding speed resulted in a narrower fusion zone, smaller grain size, higher yield strength, and longer fatigue life, as well as a slightly lower strain-hardening capacity mainly because of the smaller grain sizes. Tensile fracture occurred in the fusion zone, whereas fatigue failure appeared essentially in between the heat-affected zone and the fusion zone. Fatigue cracks initiated from the near-surface welding defects and propagated by the formation of fatigue striations together with secondary cracks.

  8. Production of magnesium metal

    DOEpatents

    Blencoe, James G. (Harriman, TN) [Harriman, TN; Anovitz, Lawrence M. (Knoxville, TN) [Knoxville, TN; Palmer, Donald A. (Oliver Springs, TN) [Oliver Springs, TN; Beard, James S. (Martinsville, VA) [Martinsville, VA

    2010-02-23

    A process of producing magnesium metal includes providing magnesium carbonate, and reacting the magnesium carbonate to produce a magnesium-containing compound and carbon dioxide. The magnesium-containing compound is reacted to produce magnesium metal. The carbon dioxide is used as a reactant in a second process. In another embodiment of the process, a magnesium silicate is reacted with a caustic material to produce magnesium hydroxide. The magnesium hydroxide is reacted with a source of carbon dioxide to produce magnesium carbonate. The magnesium carbonate is reacted to produce a magnesium-containing compound and carbon dioxide. The magnesium-containing compound is reacted to produce magnesium metal. The invention further relates to a process for production of magnesium metal or a magnesium compound where an external source of carbon dioxide is not used in any of the reactions of the process. The invention also relates to the magnesium metal produced by the processes described herein.

  9. Magnesium bioavailability from magnesium citrate and magnesium oxide.

    PubMed

    Lindberg, J S; Zobitz, M M; Poindexter, J R; Pak, C Y

    1990-02-01

    This study compared magnesium oxide and magnesium citrate with respect to in vitro solubility and in vivo gastrointestinal absorbability. The solubility of 25 mmol magnesium citrate and magnesium oxide was examined in vitro in solutions containing varying amounts of hydrochloric acid (0-24.2 mEq) in 300 ml distilled water intended to mimic achlorhydric to peak acid secretory states. Magnesium oxide was virtually insoluble in water and only 43% soluble in simulated peak acid secretion (24.2 mEq hydrochloric acid/300 ml). Magnesium citrate had high solubility even in water (55%) and was substantially more soluble than magnesium oxide in all states of acid secretion. Reprecipitation of magnesium citrate and magnesium oxide did not occur when the filtrates from the solubility studies were titrated to pH 6 and 7 to stimulate pancreatic bicarbonate secretion. Approximately 65% of magnesium citrate was complexed as soluble magnesium citrate, whereas magnesium complexation was not present in the magnesium oxide system. Magnesium absorption from the two magnesium salts was measured in vivo in normal volunteers by assessing the rise in urinary magnesium following oral magnesium load. The increment in urinary magnesium following magnesium citrate load (25 mmol) was significantly higher than that obtained from magnesium oxide load (during 4 hours post-load, 0.22 vs 0.006 mg/mg creatinine, p less than 0.05; during second 2 hours post-load, 0.035 vs 0.008 mg/mg creatinine, p less than 0.05). Thus, magnesium citrate was more soluble and bioavailable than magnesium oxide. PMID:2407766

  10. Effect of iron-intermetallics and porosity on tensile and impact properties of aluminum-silicon-copper and aluminum-silicon-magnesium cast alloys

    Microsoft Academic Search

    Zheyuan Ma

    2002-01-01

    Aluminum-silicon (Al-Si) alloys are an important class of materials that constitute the majority of aluminum cast parts produced, due to their superior properties and excellent casting characteristics. Within this family of alloys, Al-Si-Cu and Al-Si-Mg cast alloys are frequently employed in automotive applications. The commercially popular 319 and 356 alloys, representing these two alloy systems, were selected for study in

  11. Production of magnesium metal

    DOEpatents

    Blencoe, James G. (Harriman, TN); Anovitz, Lawrence M. (Knoxville, TN); Palmer, Donald A. (Oliver Springs, TN); Beard, James S. (Martinsville, VA)

    2012-04-10

    A process of producing magnesium metal includes providing magnesium carbonate, and reacting the magnesium carbonate to produce a magnesium-containing compound and carbon dioxide. The magnesium-containing compound is reacted to produce magnesium metal. The carbon dioxide is used as a reactant in a second process. In another embodiment of the process, a magnesium silicate is reacted with a caustic material to produce magnesium hydroxide. The magnesium hydroxide is reacted with a source of carbon dioxide to produce magnesium carbonate. The magnesium carbonate is reacted to produce a magnesium-containing compound and carbon dioxide. The magnesium-containing compound is reacted to produce magnesium metal. The invention also relates to the magnesium metal produced by the processes described herein.

  12. Magnesium compounds

    USGS Publications Warehouse

    Kramer, D.A.

    2012-01-01

    Seawater and natural brines accounted for about 57 percent of magnesium compounds produced in the United States in 2011. Dead-burned magnesia was produced by Martin Marietta Magnesia Specialties LLC from well brines in Michigan. Caustic-calcined magnesia was recovered from seawater by Premier Magnesia LLC in Florida, from well brines in Michigan by Martin Marietta and from magnesite in Nevada by Premier Magnesia. Intrepid Potash Wendover LLC and Great Salt Lake Minerals Corp. recovered magnesium chloride brines from the Great Salt Lake in Utah. Magnesium hydroxide was produced from seawater by SPI Pharma Inc. in Delaware and Premier Magnesia in Florida, and by Martin Marietta from its brine operation in Michigan.

  13. Magnesium compounds

    USGS Publications Warehouse

    Kramer, D.A.

    2002-01-01

    Seawater and natural brines accounted for about 60% of US magnesium compounds production in 2001. Dead-burned and caustic-calcined magnesias were recovered from seawater in Florida by Premier Chemicals. They were also recovered from Michigan well brines by Dow Chemical, Martin Marietta Magnesia Specialties and Rohm & Haas. And Premier Chemicals recovered dead-burned and caustic-calcined magnesias from magnesite in Nevada. Reilly Industries and Great Salt Lake Minerals recovered magnesium chloride brines from the Great Salt Lake in Utah.

  14. Magnesium compounds

    USGS Publications Warehouse

    Kramer, D.A.

    2001-01-01

    Seawater and natural brines accounted for about 63% of US magnesium compounds production during 2000. Premier Services in Florida, Dow Chemical in Michigan, Martin Marietta Magnesia Specialties, and Rohm & Haas recovered dead-burned and caustic-calcined magnesias from seawater. And Premier Services' recoveries, in Nevada, were from magnasite.

  15. Magnesium compounds

    USGS Publications Warehouse

    Kramer, D.A.

    2007-01-01

    Seawater and natural brines accounted for about 52 percent of U.S. magnesium compounds production in 2006. Dead-burned magnesia was produced by Martin Marietta Magnesia Specialties from well brines in Michigan. Caustic-calcined magnesia was recovered from sea-water by Premier Chemicals in Florida; from well brines in Michigan by Martin Marietta and Rohm and Haas; and from magnesite in Nevada by Premier Chemicals. Intrepid Potash-Wendover and Great Salt Lake Minerals recovered magnesium chloride brines from the Great Salt Lake in Utah. Magnesium hydroxide was produced from brucite by Applied Chemical Magnesias in Texas, from seawater by SPI Pharma in Delaware and Premier Chemicals in Florida, and by Martin Marietta and Rohm and Haas from their operations mentioned above. About 59 percent of the magnesium compounds consumed in the United States was used for refractories that are used mainly to line steelmaking furnaces. The remaining 41 percent was consumed in agricultural, chemical, construction, environmental and industrial applications.

  16. Magnesium compounds

    USGS Publications Warehouse

    Kramer, D.A.

    2004-01-01

    Dead-burned and caustic-calcined magnesias were recovered from seawater by Premier Chemicals in Florida; from well brines in Michigan by Dow Chemical, Martin Marietta Magnesia Specialties, and Rohm & Haas; and from magnesite in Nevada by Premier Chemicals. Reilly Industries and Great Salt Lake Minerals recovered magnesium chloride brines from the Great Salt Lake in Utah.

  17. Immunological Response to Biodegradable Magnesium Implants

    NASA Astrophysics Data System (ADS)

    Pichler, Karin; Fischerauer, Stefan; Ferlic, Peter; Martinelli, Elisabeth; Brezinsek, Hans-Peter; Uggowitzer, Peter J.; Löffler, Jörg F.; Weinberg, Annelie-Martina

    2014-04-01

    The use of biodegradable magnesium implants in pediatric trauma surgery would render surgical interventions for implant removal after tissue healing unnecessary, thereby preventing stress to the children and reducing therapy costs. In this study, we report on the immunological response to biodegradable magnesium implants—as an important aspect in evaluating biocompatibility—tested in a growing rat model. The focus of this study was to investigate the response of the innate immune system to either fast or slow degrading magnesium pins, which were implanted into the femoral bones of 5-week-old rats. The main alloying element of the fast-degrading alloy (ZX50) was Zn, while it was Y in the slow-degrading implant (WZ21). Our results demonstrate that degrading magnesium implants beneficially influence the immune system, especially in the first postoperative weeks but also during tissue healing and early bone remodeling. However, rodents with WZ21 pins showed a slightly decreased phagocytic ability during bone remodeling when the degradation rate reached its maximum. This may be due to the high release rate of the rare earth-element yttrium, which is potentially toxic. From our results we conclude that magnesium implants have a beneficial effect on the innate immune system but that there are some concerns regarding the use of yttrium-alloyed magnesium implants, especially in pediatric patients.

  18. Modeling Asymmetric Rolling Process of Mg alloys

    SciTech Connect

    Cho, Jaehyung; Kim, Hyung-Wuk; Kang, Suk-Bong [Korea Institute of Materials Science, 66 Sangnam-dong, Changwon-city, Kyungnam, 641-010 (Korea, Republic of)

    2010-06-15

    Asymmetric deformation during rolling can arise in various ways: difference in the radii, speeds, frictions of the top and bottom rolls. Asymmetric warm rolling processes of magnesium alloys were modeled using a lagrangian incremental approach. A constitutive equation representing flow behaviors of AZ31 magnesium alloys during warm deformation was implemented to the modeling. Various roll speed ratios were introduced to investigate deformation behaviors of the magnesium alloys. Bending and texturing of the strips were examined.

  19. Magnesium compounds

    USGS Publications Warehouse

    Kramer, D.A.

    2003-01-01

    Seawater and natural brines accounted for about 60 percent of U.S. magnesium compounds production during 2002. Dead-burned and caustic-calcined magnesias were recovered from seawater by Premier Chemicals in Florida. They were also recovered from well brines in Michigan by Dow Chemical, Martin Marietta Magnesia Specialties and Rohm & Haas. And they were recovered from magnesite in Nevada by Premier Chemicals.

  20. Magnesium compounds

    USGS Publications Warehouse

    Kramer, D.A.

    2006-01-01

    In 2005, seawater and natural brines accounted for 51% of US magnesium compounds production. World magnesia production was estimated to be 14.5 Mt. Most of the production came from China, North Korea, Russia and Turkey. Although no specific production figures are available, Japan and the United States are estimated to account for almost one-half of the world's capacity from seawater and brines.

  1. Post-treatment of thermal spray coatings on magnesium

    Microsoft Academic Search

    Hanna Pokhmurska; Bernhard Wielage; Thomas Lampke; Thomas Grund; Mykhajlo Student; Natalia Chervinska

    2008-01-01

    Magnesium alloys have a beneficial combination of high strength to weight ratio, good machinability and high recycling potential. Despite this, the application of magnesium still is behind that of other constructive materials mainly due to low wear and corrosion resistance. For more demanding applications, a large amount of surface treatment methods are developed to overcome this problem. Thermal spraying is

  2. Magnesium in diet

    MedlinePLUS

    Diet - magnesium ... Magnesium is needed for more than 300 biochemical reactions in the body. It helps to maintain normal ... There is ongoing research into the role of magnesium in preventing and managing disorders such as high ...

  3. Comparison of Lost Foam Casting of AM60B Alloy and A356 Alloy

    SciTech Connect

    Han, Qingyou [ORNL; Dinwiddie, Ralph Barton [ORNL; Sklad, Philip S [ORNL; Currie, Kenneth [Tennessee Technological University; Vondra, Fred [Tennessee Technological University; Abdelrahman, Mohamed [Tennessee Technological University; Walford, Graham [Walford Technologies; Nolan, Dennis J [Foseco-Morval; Nedkova, Teodora [Kaiser Aluminum

    2007-01-01

    The article describes the research activities at Oak Ridge National Laboratory and Tennessee Technological University on lost foam casting of magnesium alloys. The work was focused on castings of simple geometries such as plate castings and window castings in order to compare the difference in castability between magnesium alloys and aluminum alloy using the lost foam casting process. Significant differences between lost foam aluminum casting and lost foam magnesium casting have been observed.

  4. Inverse surface macro-segregation in high-pressure die-cast AM60 magnesium alloy and its effects on fatigue behavior

    Microsoft Academic Search

    S. G. Lee; G. R. Patel; A. M. Gokhale

    2005-01-01

    Metallographic evidence is presented for existence of inverse surface macro-segregation in a HPDC AM60 Mg-alloy. The process conditions that facilitate the inverse surface macro-segregation are identified, and the effects of macro-segregation on the low and high cycle fatigue behavior of the HPDC alloy are studied.

  5. Manufacturing of SiCp Reinforced Magnesium Composite Tubes by Hot Extrusion Processes

    Microsoft Academic Search

    Yeong-Maw Hwang; Song-Jeng Huang; Yu-San Huang

    2011-01-01

    Magnesium alloys have higher specific strength compared with other metals, such as aluminum, copper and steel. Nevertheless, their ductility is still not good for further metal forming and their strength is not large enough for real structure applications. The aim of this paper is to develop magnesium alloy composite tubes reinforced with SiC particulates by the stir-casting method and hot

  6. Prediction of the electronic structures, thermodynamic and mechanical properties in manganese doped magnesium-based alloys and their saturated hydrides based on density functional theory

    NASA Astrophysics Data System (ADS)

    Zhang, Ziying; Zhang, Huizhen; Zhao, Hui; Yu, Zhishui; He, Liang; Li, Jin

    2015-04-01

    The crystal structures, electronic structures, thermodynamic and mechanical properties of Mg2Ni alloy and its saturated hydride with different Mn-doping contents are investigated using first-principles density functional theory. The lattice parameters for the Mn-doped Mg2Ni alloys and their saturated hydrides decreased with an increasing Mn-doping content because of the smaller atomic size of Mn compared with that of Mg. Analysis of the formation enthalpies and electronic structures reveal that the partial substitution of Mg with Mn reduces the stability of Mg2Ni alloy and its saturated hydride. The calculated elastic constants indicate that, although the partial substitution of Mg with Mn lowers the toughness of the hexagonal Mg2Ni alloy, the charge/discharge cycles are elevated when the Mn-doping content is high enough to form the predicted intermetallic compound Mg3MnNi2.

  7. Effect of calcium on intermetallic compound layer at interface of calcium added magnesium–aluminum alloy and titanium joint by friction stir welding

    Microsoft Academic Search

    Masayuki Aonuma; Kazuhiro Nakata

    2010-01-01

    Commercial AMCa602 alloy (Mg–6% Al–2% Ca) and AM60 alloy (Mg–6% Al) were joined to titanium plates by friction stir welding to evaluate the effect of a calcium on the reaction layer at the dissimilar joint interface and the joint tensile strength. At the titanium and AM60 joint interface, a TiAl3 intermetallic compound layer was formed. The thickness of this layer

  8. Electrodeposition of aluminum on magnesium alloy in aluminum chloride (AlCl 3)–1-ethyl-3-methylimidazolium chloride (EMIC) ionic liquid and its corrosion behavior

    Microsoft Academic Search

    Jeng-Kuei Chang; Su-Yau Chen; Wen-Ta Tsai; Ming-Jay Deng; I-Wen Sun

    2007-01-01

    A dense and adhesive Al layer was successfully electrodeposited on a Mg alloy in aluminum chloride–1-ethyl-3-methylimidazolium chloride ionic liquid. The corrosion resistance of the uncoated and Al-coated samples was evaluated by electrochemical impedance spectroscopy and potentiodynamic polarization measurements in 3.5wt% NaCl solution. It was confirmed that the protective Al layer significantly reduces the corrosion rate of the Mg alloy. However,

  9. Magnesium Powder Metallurgy: Process and Materials Opportunities

    NASA Astrophysics Data System (ADS)

    Bettles, Colleen J.

    2008-06-01

    The major efforts in magnesium alloy development for automotive applications have concentrated on creep resistant alloys produced by permanent mould and high-pressure die casting routes. While large components, such as crankcases, will never be produced by powder metallurgy, there are smaller components in and around the powertrain which could be fabricated from powder precursors. This article will explore the potential of some of the more recent powder compaction developments, and discuss the alloy development strategies that emerge for magnesium-based components as a consequence of these process developments. In particular, the viability of direct powder extrusion of semi-finished product, using conventional extrusion or equal channel angular processing, combined with T6 heat treatments, will be considered.

  10. Magnesium degradation products: effects on tissue and human metabolism.

    PubMed

    Seitz, J-M; Eifler, R; Bach, Fr-W; Maier, H J

    2014-10-01

    Owing to their mechanical properties, metallic materials present a promising solution in the field of resorbable implants. The magnesium metabolism in humans differs depending on its introduction. The natural, oral administration of magnesium via, for example, food, essentially leads to an intracellular enrichment of Mg(2+) . In contrast, introducing magnesium-rich substances or implants into the tissue results in a different decomposition behavior. Here, exposing magnesium to artificial body electrolytes resulted in the formation of the following products: magnesium hydroxide, magnesium oxide, and magnesium chloride, as well as calcium and magnesium apatites. Moreover, it can be assumed that Mg(2+) , OH(-) ions, and gaseous hydrogen are also present and result from the reaction for magnesium in an aqueous environment. With the aid of physiological metabolic processes, the organism succeeds in either excreting the above mentioned products or integrating them into the natural metabolic process. Only a burst release of these products is to be considered a problem. A multitude of general tissue effects and responses from the Mg's degradation products is considered within this review, which is not targeting specific implant classes. Furthermore, common alloying elements of magnesium and their hazardous potential in vivo are taken into account. PMID:24222399

  11. Interfacial structure of the joints between magnesium alloy and mild steel with nickel as interlayer by hybrid laser-TIG welding

    Microsoft Academic Search

    Xiaodong Qi; Gang Song

    2010-01-01

    The joint interface of Mg alloy to steel with Ni interlayer was investigated. Comparing with that without any interlayer, the joint shear strength was improved significantly. The characterization of interfaces in the joint with Ni interlayer was analyzed and discussed. The results show that the formation of intermetallic compound Mg2Ni and solid solution of Ni in Fe at the interface

  12. The history of biodegradable magnesium implants: a review.

    PubMed

    Witte, Frank

    2010-05-01

    Today, more than 200years after the first production of metallic magnesium by Sir Humphry Davy in 1808, biodegradable magnesium-based metal implants are currently breaking the paradigm in biomaterial science to develop only highly corrosion resistant metals. This groundbreaking approach to temporary metallic implants is one of the latest developments in biomaterials science that is being rediscovered. It is a challenging topic, and several secrets still remain that might revolutionize various biomedical implants currently in clinical use. Magnesium alloys were investigated as implant materials long ago. A very early clinical report was given in 1878 by the physician Edward C. Huse. He used magnesium wires as ligature for bleeding vessels. Magnesium alloys for clinical use were explored during the last two centuries mainly by surgeons with various clinical backgrounds, such as cardiovascular, musculoskeletal and general surgery. Nearly all patients benefited from the treatment with magnesium implants. Although most patients experienced subcutaneous gas cavities caused by rapid implant corrosion, most patients had no pain and almost no infections were observed during the postoperative follow-up. This review critically summarizes the in vitro and in vivo knowledge and experience that has been reported on the use of magnesium and its alloys to advance the field of biodegradable metals. PMID:20172057

  13. Serum magnesium - test

    MedlinePLUS

    A high magnesium level may indicate: Addison disease Chronic renal failure Dehydration Diabetic acidosis Oliguria A low magnesium level may indicate: Alcoholism Chronic diarrhea Delirium tremens Hemodialysis Hepatic (liver) ...

  14. Enhancements in Magnesium Die Casting Impact Properties

    SciTech Connect

    David Schwam; John F. Wallace; Yulong Zhu; Srinath Viswanathan; Shafik Iskander

    2000-06-30

    The need to produce lighter components in transportation equipment is the main driver in the increasing demand for magnesium castings. In many automotive applications, components can be made of magnesium or aluminum. While being lighter, often times the magnesium parts have lower impact and fatigue properties than the aluminum. The main objective of this study was to identify potential improvements in the impact resistance of magnesium alloys. The most common magnesium alloys in automotive applications are AZ91D, AM50 and AM60. Accordingly, these alloys were selected as the main candidates for the study. Experimental quantities of these alloys were melted in an electrical furnace under a protective atmosphere comprising sulfur hexafluoride, carbon dioxide and dry air. The alloys were cast both in a permanent mold and in a UBE 315 Ton squeeze caster. Extensive evaluation of tensile, impact and fatigue properties was conducted at CWRU on permanent mold and squeeze cast test bars of AZ91, AM60 and AM50. Ultimate tensile strength values between 20ksi and 30ksi were obtained. The respective elongations varied between 25 and 115. the Charpy V-notch impact strength varied between 1.6 ft-lb and 5 ft-lb depending on the alloy and processing conditions. Preliminary bending fatigue evaluation indicates a fatigue limit of 11-12 ksi for AM50 and AM60. This is about 0.4 of the UTS, typical for these alloys. The microstructures of the cast specimens were investigated with optical and scanning electron microscopy. Concomitantly, a study of the fracture toughness in AM60 was conducted at ORNL as part of the study. The results are in line with values published in the literature and are representative of current state of the art in casting magnesium alloys. The experimental results confirm the strong relationship between aluminum content of the alloys and the mechanical properties, in particular the impact strength and the elongation. As the aluminum content increases from about 5% in AM50 to over 9% in AZ91, more of the intermetallic Mg17Al12 is formed in the microstructure. For instance, for 15 increase in the aluminum content from AM50 to AM60, the volume fraction of eutectic present in the microstructure increases by 35%! Eventually, the brittle Mg17Al12 compound forms an interconnected network that reduces ductility and impact resistance. The lower aluminum in AM50 and AM60 are therefore a desirable feature in applications that call for higher impact resistance. Further improvement in impact resistance depends on the processing condition of the casting. Sound castings without porosity and impurities will have better mechanical properties. Since magnesium oxidizes readily, good melting and metal transfer practices are essential. The liquid metal has to be protected from oxidation at all times and entrainment of oxide films in the casting needs to be prevented. In this regard, there is evidence that us of vacuum to evacuate air from the die casting cavity can improve the quality of the castings. Fast cooling rates, leading to smaller grain size are beneficial and promote superior mechanical properties. Micro-segregation and banding are two additional defect types often encountered in magnesium alloys, in particular in AZ91D. While difficult to eliminate, segregation can be minimized by careful thermal management of the dies and the shot sleeve. A major source of segregation is the premature solidification in the shot sleeve. The primary solid dendrites are carried into the casting and form a heterogeneous structure. Furthermore, during the shot, segregation banding can occur. The remedies for this kind of defects include a hotter shot sleeve, use of insulating coatings on the shot sleeve and a short lag time between pouring into the shot sleeve and the shot.

  15. Improved biological performance of magnesium by micro-arc oxidation

    PubMed Central

    Ma, W.H.; Liu, Y.J.; Wang, W.; Zhang, Y.Z.

    2014-01-01

    Magnesium and its alloys have recently been used in the development of lightweight, biodegradable implant materials. However, the corrosion properties of magnesium limit its clinical application. The purpose of this study was to comprehensively evaluate the degradation behavior and biomechanical properties of magnesium materials treated with micro-arc oxidation (MAO), which is a new promising surface treatment for developing corrosion resistance in magnesium, and to provide a theoretical basis for its further optimization and clinical application. The degradation behavior of MAO-treated magnesium was studied systematically by immersion and electrochemical tests, and its biomechanical performance when exposed to simulated body fluids was evaluated by tensile tests. In addition, the cell toxicity of MAO-treated magnesium samples during the corrosion process was evaluated, and its biocompatibility was investigated under in vivo conditions. The results of this study showed that the oxide coating layers could elevate the corrosion potential of magnesium and reduce its degradation rate. In addition, the MAO-coated sample showed no cytotoxicity and more new bone was formed around it during in vivo degradation. MAO treatment could effectively enhance the corrosion resistance of the magnesium specimen and help to keep its original mechanical properties. The MAO-coated magnesium material had good cytocompatibility and biocompatibility. This technique has an advantage for developing novel implant materials and may potentially be used for future clinical applications. PMID:25517917

  16. Improved biological performance of magnesium by micro-arc oxidation.

    PubMed

    Ma, W H; Liu, Y J; Wang, W; Zhang, Y Z

    2015-03-01

    Magnesium and its alloys have recently been used in the development of lightweight, biodegradable implant materials. However, the corrosion properties of magnesium limit its clinical application. The purpose of this study was to comprehensively evaluate the degradation behavior and biomechanical properties of magnesium materials treated with micro-arc oxidation (MAO), which is a new promising surface treatment for developing corrosion resistance in magnesium, and to provide a theoretical basis for its further optimization and clinical application. The degradation behavior of MAO-treated magnesium was studied systematically by immersion and electrochemical tests, and its biomechanical performance when exposed to simulated body fluids was evaluated by tensile tests. In addition, the cell toxicity of MAO-treated magnesium samples during the corrosion process was evaluated, and its biocompatibility was investigated under in vivo conditions. The results of this study showed that the oxide coating layers could elevate the corrosion potential of magnesium and reduce its degradation rate. In addition, the MAO-coated sample showed no cytotoxicity and more new bone was formed around it during in vivo degradation. MAO treatment could effectively enhance the corrosion resistance of the magnesium specimen and help to keep its original mechanical properties. The MAO-coated magnesium material had good cytocompatibility and biocompatibility. This technique has an advantage for developing novel implant materials and may potentially be used for future clinical applications. PMID:25517917

  17. Life-Cycle Assessment of the Recycling of Magnesium Vehicle Components

    NASA Astrophysics Data System (ADS)

    Ehrenberger, Simone; Friedrich, Horst E.

    2013-10-01

    Life-cycle assessment is basically the assessment of a product from the cradle to the grave. Ideally, a product is recycled after its useful life is complete and the end-of-life of the first life cycle leads to the beginning of a new product system. For the end-of-life of magnesium vehicle parts, there are various possible paths to a second life cycle. When magnesium parts are dismantled or magnesium is separated after shredding, the resulting magnesium alloys can be used for secondary, noncritical applications. However, the typical case for magnesium components is that the magnesium postconsumer scrap ends up in the nonferrous metals fraction that consists primarily of aluminum, magnesium, and heavy metals. Today, aluminum is typically fed into a second life cycle as a secondary alloy, and magnesium becomes part of the aluminum cycle as an alloy addition. In this article, we evaluate the environmental effects of using magnesium in the aluminum cycle. We also assess the influence of end-of-life scenarios on the overall environmental impact of a component's life cycle. The primary focus of our analysis is the evaluation of the effects of magnesium vehicle components on greenhouse gas emissions.

  18. In vivo implantation of porous titanium alloy implants coated with magnesium-doped octacalcium phosphate and hydroxyapatite thin films using pulsed laser depostion.

    PubMed

    Mróz, Waldemar; Budner, Bogus?aw; Syroka, Renata; Niedzielski, Kryspin; Gola?ski, Grzegorz; Slósarczyk, Anna; Schwarze, Dieter; Douglas, Timothy E L

    2015-01-01

    The use of porous titanium-based implant materials for bone contact has been gaining ground in recent years. Selective laser melting (SLM) is a rapid prototyping method by which porous implants with highly defined external dimensions and internal architecture can be produced. The coating of porous implants produced by SLM with ceramic layers based on calcium phosphate (CaP) remains relatively unexplored, as does the doping of such coatings with magnesium (Mg) to promote bone formation. In this study, Mg-doped coatings of the CaP types octacalcium phosphate and hydroxyapatite (HA) were deposited on such porous implants using the pulsed laser deposition method. The coated implants were subsequently implanted in a rabbit femoral defect model for 6 months. Uncoated implants served as a reference material. Bone-implant contact and bone volume in the region of interest were evaluated by histopathological techniques using a tri-chromatographic Masson-Goldner staining method and by microcomputed tomography (µCT) analysis of the volume of interest in the vicinity of implants. Histopathological analysis revealed that all implant types integrated directly with surrounding bone with ingrowth of newly formed bone into the pores of the implants. Biocompatibility of all implant types was demonstrated by the absence of inflammatory infiltration by mononuclear cells (lymphocytes), neutrophils, and eosinophils. No osteoclastic or foreign body reaction was observed in the vicinity of the implants. µCT analysis revealed a significant increase in bone volume for implants coated with Mg-doped HA compared to uncoated implants. PMID:24801401

  19. Rapidly solidified alloys and their mechanical and magnetic properties

    Microsoft Academic Search

    B. C. Giessen; D. E. Polk; A. I. Taub

    1986-01-01

    This book is organized under the following headings: Processing; Amorphous Alloys Formation; Amorphous Alloys-Relaxation and Phase Transformation; Amorphous Alloys-Consolidation, Mechanical, and Chemical Properties; Amorphous Alloys-Magnetic Properties; Crystalline Magnetic Materials; Quasicrystals; Microstructure and Properties of Crystalline RSP Alloys-Light Metals: Aluminum, Magnesium, Titanium; Microstructure and Properties of Crystalline RSP Alloys-Nickel, Iron and Cobalt Alloysl; Microstructure and Properties of Crystallilne RSP Alloys-Other Systems.

  20. Magnesium in disease

    PubMed Central

    Wanner, Christoph

    2012-01-01

    Although the following text will focus on magnesium in disease, its role in healthy subjects during physical exercise when used as a supplement to enhance performance is also noteworthy. Low serum magnesium levels are associated with metabolic syndrome, Type 2 diabetes mellitus (T2DM) and hypertension; consequently, some individuals benefit from magnesium supplementation: increasing magnesium consumption appears to prevent high blood pressure, and higher serum magnesium levels are associated with a lower risk of developing a metabolic syndrome. There are, however, conflicting study results regarding magnesium administration with myocardial infarction with and without reperfusion therapy. There was a long controversy as to whether or not magnesium should be given as a first-line medication. As the most recent trials have not shown any difference in outcome, intravenous magnesium cannot be recommended in patients with myocardial infarction today. However, magnesium has its indication in patients with torsade de pointes and has been given successfully to patients with digoxin-induced arrhythmia or life-threatening ventricular arrhythmias. Magnesium sulphate as an intravenous infusion also has an important established therapeutic role in pregnant women with pre-eclampsia as it decreases the risk of eclamptic seizures by half compared with placebo.

  1. Sea water magnesium fuel cell power supply

    NASA Astrophysics Data System (ADS)

    Hahn, Robert; Mainert, Jan; Glaw, Fabian; Lang, K.-D.

    2015-08-01

    An environmentally friendly magnesium fuel cell system using seawater electrolyte and atmospheric oxygen was tested under practical considerations for use as maritime power supply. The hydrogen rate and therefore the power density of the system were increased by a factor of two by using hydrogen evolution cathodes with a gas separation membrane instead of submerged cathodes without gas separation. Commercial magnesium AZ31 rolled sheet anodes can be dissolved in seawater for hydrogen production, down to a thickness below 100 ?m thickness, resulting in hydrogen generation efficiency of the anode of over 80%. A practical specific energy/energy density of the alloy of more than 1200 Wh/kg/3000 Wh/l was achieved when coupled to a fuel cell with atmospheric air breathing cathode. The performance of several AZ31 alloy anodes was tested as well as the influence of temperature, electrolyte concentration and anode - cathode separation. The excess hydrogen produced by the magnesium hydrogen evolving cell, due to the negative difference effect, is proportional to the cell current in case of the AZ31 alloys, which simplifies system control considerably. Stable long-term operation of the system was demonstrated at low pressures which can be maintained in an open-seawater-submerged hydrogen generator.

  2. AZ31 magnesium deep drawing experiments and finite element simulation

    Microsoft Academic Search

    D. Ghaffari Tari; M. J. Worswick; J. Mckinley; R. Bagheriasl

    2010-01-01

    In recent years magnesium alloy sheet products have been attracting more attention because of their potential applications\\u000a as coverings of portable electrical devices and automotive panels e.g. rocker and quarter panels. However, magnesium alloy\\u000a sheets are usually formed at high temperatures because of their poor formability at room temperature, which requires a more\\u000a complex tooling system.\\u000a \\u000a \\u000a In this paper, a

  3. Development of zirconium alloys. Part II

    Microsoft Academic Search

    A. D. Schwope; W. Chubb

    1952-01-01

    A number of alloys of zirconium have been investigated as part of a program aimed at improving the high-temperature tensile and creep strength of zirconium. These alloys include aluminum, beryllium, lead, magnesium, molybdenum, niobium, tantalum, tin, titanium, tungsten, vanadium, and zinc, binary and ternary alloys. The data indicate that aluminum, lead, molybdenum niobium, tin, titanium, tungsten, and vanadium can be

  4. Corrosion protection of different environmentally friendly coatings on powder metallurgy magnesium

    Microsoft Academic Search

    M. Carboneras; L. S. Hernández; J. A. del Valle; M. C. García-Alonso; M. L. Escudero

    2010-01-01

    Pure magnesium was processed by a powder metallurgy (PM) route to generate microstructural features that provide higher mechanical properties than those of cast pure magnesium and commercial AZ31 alloy. Nevertheless, corrosion resistance of PM Mg needs to be improved if this material is to be used for structural applications in a corrosive medium. In the present work, the corrosion protection

  5. SIMULATION OF POROSITY AND HOT TEARS IN A SQUEEZE CAST MAGNESIUM CONTROL ARM

    E-print Network

    Beckermann, Christoph

    formation and growth during casting solidification. This model solves a pressure equation that is derivedSIMULATION OF POROSITY AND HOT TEARS IN A SQUEEZE CAST MAGNESIUM CONTROL ARM K.D. Carlson1 , C: Magnesium Alloys, Casting, Shrinkage Porosity, Hot Tears, Modeling Abstract Simulations are performed

  6. Tribological evaluation of aluminum and magnesium sheet forming at high temperatures

    Microsoft Academic Search

    M. David Hanna

    2009-01-01

    The tribological mechanisms during interaction of aluminum and magnesium sheets with ferrous metal tools at high temperature are very complex and involve friction, wear, transfer of material, and deformation simultaneously. The tribological behaviour of both AA5083 aluminum and AZ31B magnesium alloy sheets sliding against tool steel were found to impact the quality of components manufactured with elevated temperature metal forming

  7. Al and Zn Impurity Diffusion in Binary and Ternary Magnesium Solid-Solutions

    SciTech Connect

    Kammerer, Catherine [University of Central Florida, Orlando; Kulkarni, Nagraj S [ORNL; Warmack, Robert J Bruce [ORNL; Sohn, Yong Ho [University of Central Florida

    2014-01-01

    Magnesium alloys are considered for implementation into structural components where energy-efficiency and light-weighting are important. Two of the most common alloying elements in magnesium alloys are Aluminum and Zinc. The present work examines impurity diffusion coefficients of Al and Zn in Mg(Zn) and Mg(Al) binary solid solutions, respectively. Experimental investigation is carried out with ternary diffusion couples with polycrystalline alloys. Concentration profiles were measured by electron microprobe micro-analysis and the impurity diffusion coefficients were determined by the Hall Method. Results of Al and Zn impurity diffusion in Mg solid solutions are reported, and examined as a function of composition of Mg solid solution.

  8. INTRAVENOUS MAGNESIUM SULPHATE WITH AND WITHOUT EDTA AS A MAGNESIUM LOAD TEST - IS MAGNESIUM DEFICIENCY WIDESPREAD?

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Magnesium deficiency has been linked to a number of clinical conditions including hypertension, myocardial infarction, cardiac dysrhythmias, coronary spasm, premature artherosclerosis and diabetes. Serum/plasma measurements do not reflect magnesium deficits in clinical situations and magnesium load...

  9. Mechanochemical processing for metals and metal alloys

    DOEpatents

    Froes, Francis H. (Moscow, ID); Eranezhuth, Baburaj G. (Moscow, ID); Prisbrey, Keith (Moscow, ID)

    2001-01-01

    A set of processes for preparing metal powders, including metal alloy powders, by ambient temperature reduction of a reducible metal compound by a reactive metal or metal hydride through mechanochemical processing. The reduction process includes milling reactants to induce and complete the reduction reaction. The preferred reducing agents include magnesium and calcium hydride powders. A process of pre-milling magnesium as a reducing agent to increase the activity of the magnesium has been established as one part of the invention.

  10. Experimental study of the ternary magnesium–aluminium–strontium system

    Microsoft Academic Search

    M. A. Parvez; M. Medraj; E. Essadiqi; A. Muntasar; G. Dénès

    2005-01-01

    The phase diagram of the ternary magnesium–aluminium–strontium (Mg–Al–Sr) system has been investigated with 22 different alloys by DSC, XRD and metallography. Liquidus temperature and enthalpy were determined. Al4Sr and (Mg) were found to be the dominating phases in the investigated alloys. Four new phase fields have been identified; the new phases were tentatively designated as ?1, ?2, ?3 and ?4

  11. Rare earth transition metal magnesium compounds—An overview

    NASA Astrophysics Data System (ADS)

    Rodewald, Ute Ch.; Chevalier, Bernard; Pöttgen, Rainer

    2007-05-01

    Intermetallic rare earth-transition metal-magnesium compounds play an important role as precipitations in modern light weight alloys and as host materials for hydrogen storage applications. Recent results on the crystal chemistry, the chemical bonding peculiarities, physical properties, and hydrogenation behavior of these materials are reviewed.

  12. Method for production of magnesium

    DOEpatents

    Diaz, Alexander F. (Cambridge, MA); Howard, Jack B. (Winchester, MA); Modestino, Anthony J. (Hanson, MA); Peters, William A. (Lexington, MA)

    1998-01-01

    A continuous process for the production of elemental magnesium is described. Magnesium is made from magnesium oxide and a light hydrocarbon gas. In the process, a feed stream of the magnesium oxide and gas is continuously fed into a reaction zone. There the magnesium oxide and gas are reacted at a temperature of about 1400.degree. C. or greater in the reaction zone to provide a continuous product stream of reaction products, which include elemental magnesium. The product stream is continuously quenched after leaving the reaction zone, and the elemental magnesium is separated from other reaction products.

  13. The effect of different rare earth elements content on microstructure, mechanical and wear behavior of Mg–Al–Zn alloy

    Microsoft Academic Search

    Kaveh Meshinchi Asl; Afshin Masoudi; Farzad Khomamizadeh

    2010-01-01

    The effect of Rare earths addition to AZ91 magnesium alloy and its influence on the microstructure and mechanical properties was investigated in this study. Addition of cerium rich misch metal to AZ91 alloy resulted in formation of needle shape particles, which had a very high thermal stability, providing superior mechanical properties compared to AZ91 magnesium alloy. As a result, the

  14. Magnesium battery disposal characteristics

    NASA Astrophysics Data System (ADS)

    Soffer, Louis; Atwater, Terrill

    1994-12-01

    This study assesses the disposal characteristics of U.S. Army procured military magnesium batteries under current Resource Conservation and Recovery Act (RCRA) hazardous waste identification regulations administered by the U.S. Environmental Protection Agency. Magnesium batteries were tested at 100, 50, 10 and 0 percent remaining state of charge. Present findings indicate that magnesium batteries with less than 50 percent remaining charge do not exceed the federal regulatory limit of 5.0 mg/L for chromium. All other RCRA contaminates were below regulatory limits at all levels of remaining charge. Assay methods, findings, disposal requirements and design implications are discussed.

  15. Burning Magnesium (GCMP)

    NSDL National Science Digital Library

    Burning Magnesium: this is a resource in the collection "General Chemistry Multimedia Problems". In this problem we will look at the reactions of two elements with oxygen in air. We will begin by observing the reaction of magnesium metal with oxygen when the metal is heated in air. General Chemistry Multimedia Problems ask students questions about experiments they see presented using videos and images. The questions asked apply concepts from different parts of an introductory course, encouraging students to decompartmentalize the material.

  16. Interstellar magnesium abundances

    NASA Technical Reports Server (NTRS)

    Murray, M. J.; Dufton, P. L.; Hibbert, A.; York, D. G.

    1984-01-01

    An improved evaluation of the Mg II 1240 A doublet oscillator strength is used in conjunction with recently published Copernicus observations to derive accurate Mg II column densities toward 74 stars. These imply an average of 40 percent of interstellar magnesium is in the gaseous phase. Magnesium depletion is examined as a function of various interstellar extinction and density parameters, and the results are briefly discussed in terms of current depletion theories.

  17. Rechargeable Magnesium Power Cells

    NASA Technical Reports Server (NTRS)

    Koch, Victor R.; Nanjundiah, Chenniah; Orsini, Michael

    1995-01-01

    Rechargeable power cells based on magnesium anodes developed as safer alternatives to high-energy-density cells like those based on lithium and sodium anodes. At cost of some reduction in energy density, magnesium-based cells safer because less susceptible to catastrophic meltdown followed by flames and venting of toxic fumes. Other advantages include ease of handling, machining, and disposal, and relatively low cost.

  18. Magnesium batteries. January 1970-April 1989 (Citations from the COMPENDEX data base). Report for January 1970-April 1989

    SciTech Connect

    Not Available

    1989-04-01

    This bibliography contains citations concerning magnesium battery development, performance, and electrochemistry. Magnesium alloy electrolytes are discussed in depth. Seawater, solar, and thermal batteries are discussed. (This updated bibliography contains 107 citations, 29 of which are new entries to the previous edition.)

  19. Analysis of the potential for new automotive uses of magnesium

    SciTech Connect

    Stodolsky, F.; Gaines, L.; Cuenca, R.; Wu, S.

    1994-12-31

    This paper describes the scope of a new project, just initiated, for the Lightweight Materials Program within the Office of Transportation Materials. The Center for Transportation Research and the Energy Technology Division at Argonne National Laboratory will assess the feasibility and technical potential of using magnesium and its alloys in place of steel or aluminum for automotive structural and sheet applications in order to enable more energy-efficient, lightweight passenger vehicles. The analysis will provide an information base to help guide magnesium research and development in the most promising directions.

  20. Comparison of Selective Laser Melted Titanium and Magnesium Implants Coated with PCL.

    PubMed

    Matena, Julia; Petersen, Svea; Gieseke, Matthias; Teske, Michael; Beyerbach, Martin; Kampmann, Andreas; Murua Escobar, Hugo; Gellrich, Nils-Claudius; Haferkamp, Heinz; Nolte, Ingo

    2015-01-01

    Degradable implant material for bone remodeling that corresponds to the physiological stability of bone has still not been developed. Promising degradable materials with good mechanical properties are magnesium and magnesium alloys. However, excessive gas production due to corrosion can lower the biocompatibility. In the present study we used the polymer coating polycaprolactone (PCL), intended to lower the corrosion rate of magnesium. Additionally, improvement of implant geometry can increase bone remodeling. Porous structures are known to support vessel ingrowth and thus increase osseointegration. With the selective laser melting (SLM) process, defined open porous structures can be created. Recently, highly reactive magnesium has also been processed by SLM. We performed studies with a flat magnesium layer and with porous magnesium implants coated with polymers. The SLM produced magnesium was compared with the titanium alloy TiAl6V4, as titanium is already established for the SLM-process. For testing the biocompatibility, we used primary murine osteoblasts. Results showed a reduced corrosion rate and good biocompatibility of the SLM produced magnesium with PCL coating. PMID:26068455

  1. Comparison of Selective Laser Melted Titanium and Magnesium Implants Coated with PCL

    PubMed Central

    Matena, Julia; Petersen, Svea; Gieseke, Matthias; Teske, Michael; Beyerbach, Martin; Kampmann, Andreas; Escobar, Hugo Murua; Gellrich, Nils-Claudius; Haferkamp, Heinz; Nolte, Ingo

    2015-01-01

    Degradable implant material for bone remodeling that corresponds to the physiological stability of bone has still not been developed. Promising degradable materials with good mechanical properties are magnesium and magnesium alloys. However, excessive gas production due to corrosion can lower the biocompatibility. In the present study we used the polymer coating polycaprolactone (PCL), intended to lower the corrosion rate of magnesium. Additionally, improvement of implant geometry can increase bone remodeling. Porous structures are known to support vessel ingrowth and thus increase osseointegration. With the selective laser melting (SLM) process, defined open porous structures can be created. Recently, highly reactive magnesium has also been processed by SLM. We performed studies with a flat magnesium layer and with porous magnesium implants coated with polymers. The SLM produced magnesium was compared with the titanium alloy TiAl6V4, as titanium is already established for the SLM-process. For testing the biocompatibility, we used primary murine osteoblasts. Results showed a reduced corrosion rate and good biocompatibility of the SLM produced magnesium with PCL coating. PMID:26068455

  2. Calcium carbonate with magnesium overdose

    MedlinePLUS

    The combination of calcium carbonate and magnesium is commonly found in antacids, which are medicines that provide heartburn relief. Calcium carbonate with magnesium overdose occurs when someone accidentally or ...

  3. Theoretical Studies of Hydrogen Storage Alloys

    Microsoft Academic Search

    Hannes

    2012-01-01

    Theoretical calculations were carried out to search for lightweight alloys that can be used to reversibly store hydrogen in mobile applications, such as automobiles. Our primary focus was on magnesium based alloys. While MgHâ is in many respects a promising hydrogen storage material, there are two serious problems which need to be solved in order to make it useful: (i)

  4. Quenching defects in binary aluminium alloys

    Microsoft Academic Search

    G. Thomas

    1959-01-01

    Thin foils of binary aluminium alloys containing various amounts of copper, silver, zinc and magnesium in solid solution have been prepared from quenched specimens and examined by transmission electron microscopy. In all the alloys closed loops of dislocation line and complex dislocation networks were observed. The dislocation loops did not show any stacking fault contrast so they are glissile dislocations

  5. Role of magnesium in hypertension

    Microsoft Academic Search

    Bruno Sontia; Rhian M. Touyz

    2007-01-01

    Magnesium affects blood pressure by modulating vascular tone and reactivity. It acts as a calcium channel antagonist, it stimulates production of vasodilator prostacyclins and nitric oxide and it alters vascular responses to vasoactive agonists. Magnesium deficiency has been implicated in the pathogenesis of hypertension with epidemiological and experimental studies demonstrating an inverse correlation between blood pressure and serum magnesium levels.

  6. Lead alloys for electric storage battery

    SciTech Connect

    Dawson, J.L.; Mcwhinnie, J.

    1980-11-11

    A lead alkaline earth metal alloy comprising lead, calcium, barium or strontium or mixtures thereof in an amount of 075a/40% to 0.13a/40% by weight where a is the atomic weight of alkaline earth metal; 0.005% to 0.05% magnesium and preferably 005% to 0.01% aluminium is disclosed and has improved corrosion resistance combined with tensile strength as compared to alloys with magnesium and aluminium contents outside these defined ranges. The alloy is useful for grids in lead acid electric storage batteries.

  7. WARM WATER SCALE MODEL EXPERIMENTS FOR MAGNESIUM DIE CASTING

    SciTech Connect

    Sabau, Adrian S [ORNL

    2006-01-01

    High-pressure die casting (HPDC) involves the filling of a cavity with the molten metal through a thin gate. High gate velocities yield jet break-up and atomization phenomena. In order to improve the quality of magnesium parts, the mold filling pattern, including atomization phenomena, needs to be understood. The goal of this study was to obtain experimental data on jet break-up characteristics for conditions similar to that of magnesium HPDC, and measure the droplet velocity and size distribution. A scale analysis is first presented in order to identify appropriate analogue for liquid magnesium alloys. Based on the scale analysis warm water was chosen as a suitable analogue and different nozzles were manufactured. A 2-D component phase Doppler particle analyzer (PDPA) and 2-D component particle image velocimetry (PIV) were then used to obtain fine particle diameter and velocity distributions in 2-D plane.

  8. DLC coating on Mg–Li alloy

    Microsoft Academic Search

    N. Yamauchi; N. Ueda; A. Okamoto; T. Sone; M. Tsujikawa; S. Oki

    2007-01-01

    The Mg–14mass%Li alloy is an ultra-light metallic material that is lighter than pure magnesium. However, this alloy has some disadvantages, in particular its poor wear and corrosion resistance. In this study a diamond-like carbon (DLC) coating was applied to the surface of the Mg–14mass%Li alloy and the extent to which it improved the wear and corrosion resistance was evaluated. As

  9. Retardation of surface corrosion of biodegradable magnesium-based materials by aluminum ion implantation

    NASA Astrophysics Data System (ADS)

    Wu, Guosong; Xu, Ruizhen; Feng, Kai; Wu, Shuilin; Wu, Zhengwei; Sun, Guangyong; Zheng, Gang; Li, Guangyao; Chu, Paul K.

    2012-07-01

    Aluminum ion implantation is employed to modify pure Mg as well as AZ31 and AZ91 magnesium alloys and their surface degradation behavior in simulated body fluids is studied. Polarization tests performed in conjunction with scanning electron microscopy (SEM) reveal that the surface corrosion resistance after Al ion implantation is improved appreciably. This enhancement can be attributed to the formation of a gradient surface structure with a gradual transition from an Al-rich oxide layer to Al-rich metal layer. Compared to the high Al-content magnesium alloy (AZ91), a larger reduction in the degradation rate is achieved from pure magnesium and AZ31. Our results reveal that the surface corrosion resistance of Mg alloys with no or low Al content can be improved by Al ion implantation.

  10. Improved corrosion resistance on biodegradable magnesium by zinc and aluminum ion implantation

    NASA Astrophysics Data System (ADS)

    Xu, Ruizhen; Yang, Xiongbo; Suen, Kai Wong; Wu, Guosong; Li, Penghui; Chu, Paul K.

    2012-12-01

    Magnesium and its alloys have promising applications as biodegradable materials, and plasma ion implantation can enhance the corrosion resistance by modifying the surface composition. In this study, suitable amounts of zinc and aluminum are plasma-implanted into pure magnesium. The surface composition, phases, and chemical states are determined, and electrochemical tests and electrochemical impedance spectroscopy (EIS) are conducted to investigate the surface corrosion behavior and elucidate the mechanism. The corrosion resistance enhancement after ion implantation is believed to stem from the more compact oxide film composed of magnesium oxide and aluminum oxide as well as the appearance of the ?-Mg17Al12 phase.

  11. Highly Soluble Alkoxide Magnesium Salts for Rechargeable Magnesium Batteries

    SciTech Connect

    Liao, Chen [ORNL] [ORNL; Guo, Bingkun [ORNL] [ORNL; Jiang, Deen [ORNL] [ORNL; Custelcean, Radu [ORNL] [ORNL; Mahurin, Shannon Mark [ORNL] [ORNL; Sun, Xiao-Guang [ORNL] [ORNL; Dai, Sheng [ORNL] [ORNL

    2014-01-01

    A unique class of air-stable and non-pyrophoric magnesium electrolytes has been developed based on alkoxide magnesium compounds. The crystals obtained from this class of electrolytes exhibit a unique structure of tri-magnesium cluster, [Mg3Cl3(OR)2(THF)6]+ [(THF)MgCl3] . High reversible capacities and good rate capabilities were obtained in Mg-Mo6S8 batteries using these new electrolytes at both 20 and 50 oC.

  12. Hyperfine Magnetic Field Measurements in the Heusler Alloys COBALT(2)-TITANIUM-Z, COBALT(2)-MAGNESIUM-Z (z = Silicon, Germanium, and Tin) and COBALT(2)-MAGNESIUM- Gallium Using the Moessbauer Effect (me) and the Time Differential Perturbed Angular Correlation (tdpac) Techniques

    NASA Astrophysics Data System (ADS)

    Lahamer, Amer Said

    1990-01-01

    Measurements of the hyperfine magnetic field in a series of Heusler alloys were performed. The probes were in (^{119}Sn) and cadmium (^{111}Cd). These measurements were performed at the University of Cincinnati in Cincinnati, Ohio. Two techniques were used. The first technique was the Mossbauer effect, which was used to measure the hyperfine magnetic field on ^{119 }Sn in Co_2TiZ (Z = Si, Ge, and Sn), and the second technique was the Time Differential Perturbed Angular Correlation which was used to measure the hyperfine magnetic field on ^ {111}Cd in the Co_2MnZ (Z = Si, Ge, Sn, and Ga). The probes are expected to go to the Z sites of the alloys. The hyperfine magnetic field measurements on ^{119}Sn in Co _2TiZ (Z = Si, Ge, and Sn) alloys were done at room, dry ice and liquid nitrogen temperatures by using the Mossbauer effect technique. The data were fitted by using a least squares fit from which three parameters were extracted. These parameters are the isomer shift, the quadrupole splitting and the hyperfine magnetic field. Temperature variation measurements of the hyperfine magnetic field were performed on ^{111 }Cd in Co_2MnZ (Z = Si, Ge, Sn, and Ga) alloys. The data were fitted again by using a least squares fit from which the Larmor frequency which is related to the hyperfine magnetic field was extracted. Also the Fourier Transforms were taken of the data, on the one hand to confirm the results of the least squares fit and on the other hand to look for more frequencies. Results of the Fourier Transforms show that some of the probe, ^{111}In, did go to the Co site in the Co_2MnZ (Z = Ga, Si, and Ge) alloys. The hmf on ^{111 }Cd in the Co site of these alloys is found to be 68 kOe which is consistent with the value found in the literature. Two theoretical models were examined for the trends of hyperfine magnetic field on ^{119 }Sn and ^{111}Cd in Co_2MnZ (Z = Si, Ge, Sn, and Ga) alloys. These are the Campbell and Blandin model and the Stearns' overlap model. Results show that the Campbell and Blandin model does predict the trends of the hyperfine magnetic field on ^{111}Cd but it fails in predicting any trends on ^ {119}Sn in Co_2MnZ (Z = Si, Ge, Sn, and Ga) alloys. The overlap model did not predict any trends of hmf on either probe in these alloys. A new relationship was found between the hyperfine magnetic field and the lattice constants of these alloys.

  13. Constraining magnesium cycling in marine sediments using magnesium isotopes

    NASA Astrophysics Data System (ADS)

    Higgins, J. A.; Schrag, D. P.

    2010-09-01

    Magnesium concentrations in deep-sea sediment pore-fluids typically decrease down core due to net precipitation of dolomite or clay minerals in the sediments or underlying crust. To better characterize and differentiate these processes, we have measured magnesium isotopes in pore-fluids and sediment samples from Ocean Drilling Program sites (1082, 1086, 1012, 984, 1219, and 925) that span a range of oceanographic settings. At all sites, magnesium concentrations decrease with depth. At sites where diagenetic reactions are dominated by the respiration of organic carbon, pore-fluid ? 26Mg values increase with depth by as much as 2‰. Because carbonates preferentially incorporate 24Mg (low ? 26Mg), the increase in pore-fluid ? 26Mg values at these sites is consistent with the removal of magnesium in Mg-carbonate (dolomite). In contrast, at sites where the respiration of organic carbon is not important and/or weatherable minerals are abundant, pore-fluid ? 26Mg values decrease with depth by up to 2‰. The decline in pore-fluid ? 26Mg at these sites is consistent with a magnesium sink that is isotopically enriched relative to the pore-fluid. The identity of this enriched magnesium sink is likely clay minerals. Using a simple 1D diffusion-advection-reaction model of pore-fluid magnesium, we estimate rates of net magnesium uptake/removal and associated net magnesium isotope fractionation factors for sources and sinks at all sites. Independent estimates of magnesium isotope fractionation during dolomite precipitation from measured ? 26Mg values of dolomite samples from sites 1082 and 1012 are very similar to modeled net fractionation factors at these sites, suggesting that local exchange of magnesium between sediment and pore-fluid at these sites can be neglected. Our results indicate that the magnesium incorporated in dolomite is 2.0-2.7‰ depleted in ? 26Mg relative to the precipitating fluid. Assuming local exchange of magnesium is minor at the rest of the studied sites, our results suggest that magnesium incorporated into clay minerals is enriched in ? 26Mg by 0‰ to +1.25‰ relative to the precipitating fluid. This work demonstrates the utility of magnesium isotopes as a tracer for magnesium sources/sinks in low-temperature aqueous systems.

  14. Low brain magnesium in migraine

    Microsoft Academic Search

    N. M. Ramadan; H. Halvorson; A. Vande-Linde; Steven R. Levine; J. A. Helpern; K. M. A. Welch

    1989-01-01

    Brain magnesium was measured in migraine patients and control subjects using in vivo 31-Phosphorus Nuclear Magnetic Resonance Spectroscopy. pMg and pH were calculated from the chemical shifts between Pi, PCr and ATP signals. Magnesium levels were low during a migraine attack without changes in pH. We hypothesize that low brain magnesium is an important factor in the mechanism of the

  15. Low brain magnesium in migraine

    SciTech Connect

    Ramadan, N.M.; Halvorson, H.; Vande-Linde, A.; Levine, S.R.; Helpern, J.A.; Welch, K.M.

    1989-10-01

    Brain magnesium was measured in migraine patients and control subjects using in vivo 31-Phosphorus Nuclear Magnetic Resonance Spectroscopy. pMg and pH were calculated from the chemical shifts between Pi, PCr and ATP signals. Magnesium levels were low during a migraine attack without changes in pH. We hypothesize that low brain magnesium is an important factor in the mechanism of the migraine attack.

  16. Biodegradation of metallic magnesium elicits an inflammatory response in primary nasal epithelial cells.

    PubMed

    Schumacher, S; Roth, I; Stahl, J; Bäumer, W; Kietzmann, M

    2014-02-01

    Resorbable magnesium-based implants hold great promise for various biomedical applications, such as osteosynthesis and coronary stenting. They also offer a new therapeutic option for the treatment of chronic rhinosinusitis, but little data is yet available regarding the use of magnesium in the nasal cavity. To model this field of application, primary porcine nasal epithelial cells were used to test the biocompatibility of degrading pure magnesium and investigate whether the degradation products may also affect cellular metabolism. Magnesium specimens did not induce apoptosis and we found no major influence on enzyme activities or protein synthesis, but cell viability was reduced and elevated interleukin 8 secretion indicated proinflammatory reactions. Necrotic damage was most likely due to osmotic stress, and our results suggest that magnesium ion build-up is also involved in the interleukin 8 release. Furthermore, the latter seems to be mediated, at least in part, by the p38 signaling pathway. These effects probably depended on the accumulation of very high concentrations of magnesium ions in the in vitro set-up, which might not be achieved in vivo, although we cannot exclude that further, as yet unknown, factors played a role in the inflammatory response during the degradation process. In conclusion, the biocompatibility of pure magnesium with cells in the immediate vicinity appears less ideal than is often supposed, and this needs to be considered in the evaluation of magnesium materials containing additional alloying elements. PMID:24211732

  17. 21 CFR 582.1425 - Magnesium carbonate.

    Code of Federal Regulations, 2010 CFR

    2010-04-01

    ... 2010-04-01 2010-04-01 false Magnesium carbonate. 582.1425 Section 582.1425...General Purpose Food Additives § 582.1425 Magnesium carbonate. (a) Product. Magnesium carbonate. (b) Conditions of use....

  18. 76 FR 69284 - Pure Magnesium From China

    Federal Register 2010, 2011, 2012, 2013, 2014

    2011-11-08

    ...731-TA-696 (Third Review)] Pure Magnesium From China Determination On the basis...of the antidumping duty order on pure magnesium from China would be likely to lead to...4274 (October 2011), entitled Pure Magnesium from China: Investigation No....

  19. 21 CFR 582.1428 - Magnesium hydroxide.

    Code of Federal Regulations, 2010 CFR

    2010-04-01

    ... 2010-04-01 2010-04-01 false Magnesium hydroxide. 582.1428 Section 582.1428...General Purpose Food Additives § 582.1428 Magnesium hydroxide. (a) Product. Magnesium hydroxide. (b) Conditions of use....

  20. 21 CFR 582.1425 - Magnesium carbonate.

    Code of Federal Regulations, 2011 CFR

    2011-04-01

    ... 2011-04-01 2011-04-01 false Magnesium carbonate. 582.1425 Section 582.1425...General Purpose Food Additives § 582.1425 Magnesium carbonate. (a) Product. Magnesium carbonate. (b) Conditions of use....

  1. 21 CFR 582.1428 - Magnesium hydroxide.

    Code of Federal Regulations, 2011 CFR

    2011-04-01

    ... 2011-04-01 2011-04-01 false Magnesium hydroxide. 582.1428 Section 582.1428...General Purpose Food Additives § 582.1428 Magnesium hydroxide. (a) Product. Magnesium hydroxide. (b) Conditions of use....

  2. 21 CFR 582.1425 - Magnesium carbonate.

    Code of Federal Regulations, 2012 CFR

    2012-04-01

    ... 2012-04-01 2012-04-01 false Magnesium carbonate. 582.1425 Section 582.1425...General Purpose Food Additives § 582.1425 Magnesium carbonate. (a) Product. Magnesium carbonate. (b) Conditions of use....

  3. 21 CFR 582.1425 - Magnesium carbonate.

    Code of Federal Regulations, 2014 CFR

    2014-04-01

    ... 2014-04-01 2014-04-01 false Magnesium carbonate. 582.1425 Section 582.1425...General Purpose Food Additives § 582.1425 Magnesium carbonate. (a) Product. Magnesium carbonate. (b) Conditions of use....

  4. 21 CFR 582.1428 - Magnesium hydroxide.

    Code of Federal Regulations, 2013 CFR

    2013-04-01

    ... 2013-04-01 2013-04-01 false Magnesium hydroxide. 582.1428 Section 582.1428...General Purpose Food Additives § 582.1428 Magnesium hydroxide. (a) Product. Magnesium hydroxide. (b) Conditions of use....

  5. 21 CFR 582.1428 - Magnesium hydroxide.

    Code of Federal Regulations, 2012 CFR

    2012-04-01

    ... 2012-04-01 2012-04-01 false Magnesium hydroxide. 582.1428 Section 582.1428...General Purpose Food Additives § 582.1428 Magnesium hydroxide. (a) Product. Magnesium hydroxide. (b) Conditions of use....

  6. 21 CFR 582.1425 - Magnesium carbonate.

    Code of Federal Regulations, 2013 CFR

    2013-04-01

    ... 2013-04-01 2013-04-01 false Magnesium carbonate. 582.1425 Section 582.1425...General Purpose Food Additives § 582.1425 Magnesium carbonate. (a) Product. Magnesium carbonate. (b) Conditions of use....

  7. 21 CFR 582.1428 - Magnesium hydroxide.

    Code of Federal Regulations, 2014 CFR

    2014-04-01

    ... 2014-04-01 2014-04-01 false Magnesium hydroxide. 582.1428 Section 582.1428...General Purpose Food Additives § 582.1428 Magnesium hydroxide. (a) Product. Magnesium hydroxide. (b) Conditions of use....

  8. Magnesium ions facilitate integrin alpha 2- and alpha 3-mediated proliferation and enhance alkaline phosphatase expression and activity in hBMSCs.

    PubMed

    Leem, Yea-Hyun; Lee, Kang-Sik; Kim, Jung-Hwa; Seok, Hyun-Kwang; Chang, Jae-Suk; Lee, Dong-Ho

    2014-02-25

    Magnesium metal and its alloys have been proposed as a novel class of bone implant biomaterials because of their biodegradability and mechanical properties. The purpose of this study was to determine whether magnesium ions, which are released abundantly from alloys, affect proliferation and differentiation of human bone marrow-derived stromal cells (hBMSCs). High levels of magnesium ions did not induce cytotoxicity in hBMSCs, but treatment with 2.5-10?mm magnesium ions for 48-72?h significantly increased hBMSC proliferation. The expression of integrins ?2 and ?3, but not ?1, was upregulated compared with the control and shifted from ?3 to ?2 in hBMSCs treated with magnesium ions. Knockdown of integrins ?2 and/or ?3 significantly reduced magnesium-induced proliferation of hBMSCs. Magnesium exposure profoundly enhanced alkaline phosphatase (ALP) gene expression and activity even at a relatively low magnesium concentration (2.5?mm). Exposure to magnesium ions facilitated hBMSC proliferation via integrin ?2 and ?3 expression and partly promoted differentiation into osteoblasts via the alteration of ALP expression and activity. Accordingly, magnesium could be a useful biomaterial for orthopaedic applications such as bone implant biomaterials for repair and regeneration of bone defects in orthopaedic and dental fields. Copyright © 2014 John Wiley & Sons, Ltd. PMID:24616281

  9. DESIGN NOTE: Ultrasonic imaging in molten magnesium

    NASA Astrophysics Data System (ADS)

    Ono, Yuu; Moisan, Jean-François; Jen, Cheng-Kuei

    2004-02-01

    Processing magnesium (Mg) and its alloys in the molten state is often necessary for the refining and recycling, and for the casting to achieve the net shape forming. The containers to hold the molten Mg are commonly made of steel. There is a concern that the steel wall of the container will corrode from the inside, which might induce cracks resulting in dangerous and expensive spillage. In this note, development of ultrasonic techniques for imaging in molten Mg using clad steel buffer rods operated at 10 MHz is presented. The probing end of the buffer rod, having an ultrasonic lens, was immersed into molten Mg, while the other end, with an ultrasonic transducer, was air cooled to room temperature. An ultrasonic image of a character 'N', engraved on a stainless steel plate, which simulates a surface defect on a plate, immersed in molten Mg has been successfully observed at 690 °C using the focused probe.

  10. Wear Mechanism for In Situ TiC Particle Reinforced AZ91 Magnesium Matrix Composites

    Microsoft Academic Search

    Junping YaoWen; Wen Li; Lei Zhang; Fajun Wang; Mingshan Xue; Hongliu Jiang; Jinshan Lu

    2010-01-01

    TiC reinforced AZ91 magnesium matrix composites have been fabricated by a melt in situ reaction spray deposition. The microstructures\\u000a of spray-deposited alloys were studied by using scanning electron microscopy (SEM) and X-ray diffraction (XRD). The dry sliding\\u000a wear behavior of the alloys was investigated by using a pin-on-disc machine under five loads, namely 10, 20, 30, 40, and 50 N.\\u000a The

  11. Synthesis of magnesium diboride by magnesium vapor infiltration process (MVIP)

    DOEpatents

    Serquis, Adriana C. (Los Alamos, NM); Zhu, Yuntian T. (Los Alamos, NM); Mueller, Frederick M. (Los Alamos, NM); Peterson, Dean E. (Los Alamos, NM); Liao, Xiao Zhou (Los Alamos, NM)

    2003-01-01

    A process of preparing superconducting magnesium diboride powder by heating an admixture of solid magnesium and amorphous boron powder or pellet under an inert atmosphere in a Mg:B ratio of greater than about 0.6:1 at temperatures and for time sufficient to form said superconducting magnesium diboride. The process can further include exposure to residual oxygen at high synthesis temperatures followed by slow cooling. In the cooling process oxygen atoms dissolved into MgB.sub.2 segregated to form nanometer-sized coherent Mg(B,O) precipitates in the MgB.sub.2 matrix, which can act as flux pinning centers.

  12. Minerals yearbook, 1993: Magnesium and magnesium compounds. Annual report

    SciTech Connect

    Kramer, D.A.

    1994-09-01

    U.S. primary magnesium metal production declined slightly in 1993 and imports, primarily from Russia and Ukraine, provided an increased percentage of domestic demand. In addition, inventories of magnesium increased significantly from the low level at the end of 1992. These increases in inventories and imports prompted two of the three U.S. producers to announce cutbacks in production rates near the end of 1993. This oversupply situation was reflected in free market prices for primary magnesium during the year. Prices dropped steadily through the first three quarters of 1993 before rebounding slightly during the last 3 months.

  13. Rare earth–transition metal–magnesium compounds—An overview

    Microsoft Academic Search

    Ute Ch. Rodewald; Bernard Chevalier; Rainer Poettgen

    2007-01-01

    Intermetallic rare earth–transition metal–magnesium compounds play an important role as precipitations in modern light weight alloys and as host materials for hydrogen storage applications. Recent results on the crystal chemistry, the chemical bonding peculiarities, physical properties, and hydrogenation behavior of these materials are reviewed.

  14. Development of structural test articles from magnesium-lithium and beryllium

    NASA Technical Reports Server (NTRS)

    Alario, R.

    1969-01-01

    Study on the fabrication and testing of a magnesium-lithium box beam shows the formability and machinability characteristics of that alloy to be excellent. Results of forming tests for shrink and stretch flanges show values for both flange heights that may be used in future beryllium design.

  15. Mineral resource of the month: magnesium

    USGS Publications Warehouse

    Kramer, Deborah A.

    2012-01-01

    Magnesium is the eighthmost abundant element in Earth’s crust, and the second-most abundant metal ion in seawater. Although magnesium is found in more than 60 minerals, only brucite, dolomite, magnesite and carnallite are commercially important for their magnesium content. Magnesium and its compounds also are recovered from seawater, brines found in lakes and wells, and bitterns (salts).

  16. Magnesium therapy for acute myocardial infarction

    Microsoft Academic Search

    LeRoy E. Rabbani

    1995-01-01

    The use of magnesium therapy for acute myocardial infarction remains controversial despite recent clinical trials such as ISIS-4. Magnesium has numerous beneficial effects in the setting of myocardial infarction, including inhibitory effects on platelet aggregation. Clinical trials of magnesium therapy for myocardial infarction have yielded conflicting results that may be related to the difference in the timing of magnesium administration.

  17. Delamination of a sensitized commercial AlMg alloy during fatigue crack growth

    E-print Network

    Rollins, Andrew M.

    on the thermal exposure and level of DK (and Kmax) employed. Reduced S­T fracture properties were directly­Mg alloy machined from the L­T orientation. Thermal exposures for times of up to 10,000 h at 80, 100. Keywords: Aluminum alloys; Fatigue; Toughness; Delamination Aluminum­magnesium (5xxx series) alloys

  18. Corrosion behaviour of high pressure die-cast and semi-solid cast AZ91D alloys

    Microsoft Academic Search

    S Mathieu; C Rapin; J Hazan; P Steinmetz

    2002-01-01

    The microstructure and the corrosion behaviour of high pressure die-cast and semi-solid cast AZ91D magnesium alloys have been investigated. Semi-solid processing leads to a structure with large rounded grains of a solid solution of magnesium (? phase) whereas die-cast alloys are more homogeneous. Electrochemical measurements, particularly with impedance spectroscopy, have shown that the semi-solid cast alloy possesses a corrosion rate

  19. Switchable mirrors based on nickel-magnesium films

    SciTech Connect

    Richardson,Thomas J.; Slack, Jonathan L.; Armitage, Robert D.; Kostecki, Robert; Farangis, Baker; Rubin, Michael D.

    2001-01-16

    A new type of electrochromic mirror electrode based on reversible uptake of hydrogen in nickel magnesium alloy films is reported. Thin,magnesium-rich Ni-Mg films prepared on glass substrates by cosputtering from Ni and Mg targets are mirror-like in appearance and have low visible transmittance. Upon exposure to hydrogen gas or on reduction in alkaline electrolyte, the films take up hydrogen and become transparent. When hydrogen is removed, the mirror properties are recovered. The transition is believed to result from reversible formation of Mg2NiH4 and MgH2. A thin overlayer of palladium was found to enhance the kinetics of hydrogen insertion and extraction,and to protect the metal surface against oxidation.

  20. Hypereutectic aluminum-silicon casting alloy

    Microsoft Academic Search

    W. G. Hesterberg; R. J. Donahue; B. L. Sheaffer

    1986-01-01

    An engine block is described for an internal combustion engine, comprising a cast block composed of a hypereutectic aluminium silicon alloy and having at least one cylinder bore therein. The alloys consists essentially of 16% to 19% by weight of silicon, 0.4% to 0.7% by weight of magnesium, up to 1.4% by weight of iron, up to 0.3% by weight