Surface treatments for aluminium alloys

NASA Astrophysics Data System (ADS)

Ardelean, M.; Lascău, S.; Ardelean, E.; Josan, A.

2018-01-01

Typically, in contact with the atmosphere, the aluminium surface is covered with an aluminium oxide layer, with a thickness of less than 1-2μm. Due to its low thickness, high porosity and low mechanical strength, this layer does not protect the metal from corrosion. Anodizing for protective and decorative purposes is the most common method of superficial oxidation processes and is carried out through anodic oxidation. The oxide films, resulted from anodizing, are porous, have a thickness of 20-50μm, and are heat-resistant, stable to water vapour and other corrosion agents. Hard anodizing complies with the same obtains principles as well as decorative and protective anodization. The difference is in that hard anodizing is achieved at low temperatures and high intensity of electric current. In the paper are presented the results of decorative and hard anodization for specimens made from several aluminium alloys in terms of the appearance of the specimens and of the thickness of the anodized.

Self-Pierce Riveting of Three Aluminium Alloy and Mild Steel Sheets

DOE Office of Scientific and Technical Information (OSTI.GOV)

Mori, K.; Abe, Y.; Sakai, S.

2010-06-15

Three aluminium alloy and steel sheets were joined with a self-piercing rivet. Self-pierce riveting has the function of joining steel and aluminium alloys having very different melting points due to plastic joining. The requisites for joining the three sheets are the driving of the rivet leg through the middle sheet, the flaring of the rivet leg in the lower sheet and the prevention of the fracture of the lower sheet. The joinability for various combinations of the three sheets was determined. When the rivet leg is small, no driving through the middle sheet occurs, the lower sheet ruptures for amore » large rivet leg. In addition, 980 MPa high strength steel, mild steel and aluminium alloy sheets were joined by the self-pierce riveting.« less

Effect of rotation speed and welding speed on Friction Stir Welding of AA1100 Aluminium alloy

NASA Astrophysics Data System (ADS)

Raja, P.; Bojanampati, S.; Karthikeyan, R.; Ganithi, R.

2018-04-01

Aluminum AA1100 is the most widely used grade of Aluminium due to its excellent corrosion resistance, high ductility and reflective finish, the selected material was welded with Friction Stir Welding (FSW) process on a CNC machine, using a combination of different tool rotation speed (1500 rpm, 2500 rpm, 3500 rpm) and welding speed (10 mm/min, 30 mm/min, 50 mm/min) as welding parameters. The effect of FSW using this welding parameter was studied by measuring the ultimate tensile strength of the welded joints. A high-speed steel tool was prepared for welding the Aluminium AA1100 alloy having an 8mm shoulder diameter and pin dimension of 4mm diameter and 2.8 mm length. The welded joints were tested using the universal testing machine. It was found that Ultimate Tensile Strength of FSW specimen was highest with a value of 98.08 MPa when the weld was performed at rotation speed of 1500 RPM and welding speed of 50 mm/min.

Comparison of fatigue crack growth of riveted and bonded aircraft lap joints made of Aluminium alloy 2024-T3 substrates - A numerical study

NASA Astrophysics Data System (ADS)

Pitta, S.; Rojas, J. I.; Crespo, D.

2017-05-01

Aircraft lap joints play an important role in minimizing the operational cost of airlines. Hence, airlines pay more attention to these technologies to improve efficiency. Namely, a major time consuming and costly process is maintenance of aircraft between the flights, for instance, to detect early formation of cracks, monitoring crack growth, and fixing the corresponding parts with joints, if necessary. This work is focused on the study of repairs of cracked aluminium alloy (AA) 2024-T3 plates to regain their original strength; particularly, cracked AA 2024-T3 substrate plates repaired with doublers of AA 2024-T3 with two configurations (riveted and with adhesive bonding) are analysed. The fatigue life of the substrate plates with cracks of 1, 2, 5, 10 and 12.7mm is computed using Fracture Analysis 3D (FRANC3D) tool. The stress intensity factors for the repaired AA 2024-T3 plates are computed for different crack lengths and compared using commercial FEA tool ABAQUS. The results for the bonded repairs showed significantly lower stress intensity factors compared with the riveted repairs. This improves the overall fatigue life of the bonded joint.

On the microstructure analysis of FSW joints of aluminium components made via direct metal laser sintering

NASA Astrophysics Data System (ADS)

Scherillo, Fabio; Astarita, Antonello; di Martino, Daniela; Contaldi, Vincenzo; di Matteo, Luca; di Petta, Paolo; Casarin, Renzo; Squillace, Antonino; Langella, Antonio

2017-10-01

Additive Manufacturing (AM), applied to metal industry, is a family of processes that allow complex shape components to be realized from raw materials in the form of powders. The compaction of the powders can be achieved by local melting of the powder bed or by solid state sintering. Direct Metal Laser Sintering (DMLS) is an additive manufacturing process in which a focalized laser beam is the heat source that allows the powders to be compacted. By DMLS it is possible to realize complex shape components. One of the limits of DMLS, as for every additive layer manufacturing techniques, is the unfeasibility to realize large dimension parts. Due to this limit the study of joining process of parts made via ALM is of great interest. One of the most promising options is the Friction Stir Welding (FSW), a solid state welding technique that has been proven to be very effective in the welding of metals difficult to weld, above all aluminium alloys. Since FSW is a solid-state technique, the microstructure of the various zone of the weld bead depends not only by the process itself but also by the parent microstruct ure of the parts to be welded. Furthermore, parts made of aluminium alloy via DMLS have a particular microstructure that is the result of repeated severe thermal cycles. In the present work the authors, starting from the description of the parent microstructure of parts made of AlSi10Mg aluminium alloy, study the microstructure evolution occurred within the joint made by Friction Stir Welding, analysing in details the microstructure of the main well recognized zone of the weld bead. The structure of the parent material is characterized by the presence of melting pools with a very fine microstructure. In the joint the recrystallization, the grain refinement and, above all, the redistribution of intermetallic phases occurs, resulting in an homogenization of the microstructure and in an increase of micro hardness.

Experimental Study on Dissimilar Friction Stir welding of Aluminium Alloys (5083-H111 and 6082-T6) to investigate the mechanical properties

NASA Astrophysics Data System (ADS)

Kumar, H. M. Anil; Venkata Ramana, V.; Pawar, Mayur

2018-03-01

Friction stir welding is an innovative technology in the joining realm of metals and alloys. This technique is highly economical and suitable especially for non ferrous alloys compared to ferrous alloys. It finds many applications in various fields of aeronautics, automobile, ship building industries etc. The paper presents the comparative results of mechanical properties such as tensile strength, microstructure, macro structure and hardness on the similar and dissimilar aluminum alloys AA5083-H111 and AA6082-T6 under certain selected variables - constant tool rotational speed, its tilt angle, welding speed using friction stir welding process. It is observed from the experimental results that joint efficiency of dissimilar aluminium alloys is higher than the similar aluminum alloys.

Evaluation Of Four Welding Arc Processes Applied To 6061 Aluminium Alloy

DOE Office of Scientific and Technical Information (OSTI.GOV)

Benoit, A.; Laboratoire de Genie des Materiaux et Procedes Associes; Paillard, P.

At a time when greenhouse gas emissions must be reduced, the use of the aluminium alloys is expanding, in particular in the transportation industry. In order to extend the possibilities of aluminium assembly design, new Metal Inert Gas (MIG) welding processes have been conceived. They work at lower temperatures than usual arc processes (classic MIG or Tungsten Inert Gas). This study compares four arc welding processes, applied to the 6061 aluminium alloy. These four weld processes have been studied through the metallurgical analysis of the weld beads. Metallography, micro-hardness testings, X Ray radiography have been carried out on the producedmore » weld beads. The processes are classified according to the quality of the beads like geometry of beads, size of the heat affected zone and presence of defects.« less

Recycling of aluminium scrap for secondary Al-Si alloys.

PubMed

Velasco, Eulogio; Nino, Jose

2011-07-01

An increasing amount of recycled aluminium is going into the production of aluminium alloy used for automotive applications. In these applications, it is necessary to control and remove alloy impurities and inclusions. Cleaning and fluxing processes are widely used during processing of the alloys for removal of inclusions, hydrogen and excess of magnesium. These processes use salt fluxes based in the system NaCl-KCl, injection of chlorine or mixture of chlorine with an inert gas. The new systems include a graphite wand and a circulation device to force convection in the melt and permit the bubbling and dispersion of reactive and cleaning agents. This paper discusses the recycling of aluminium alloys in rotary and reverberatory industrial furnaces. It focuses on the removal of magnesium during the melting process. In rotary furnaces, the magnesium lost is mainly due to the oxidation process at high temperatures. The magnesium removal is carried out by the reaction between chlorine and magnesium, with its efficiency associated to kinetic factors such as concentration of magnesium, mixing, and temperature. These factors are also related to emissions generated during the demagging process. Improvements in the metallic yield can be reached in rotary furnaces if the process starts with a proper salt, with limits of addition, and avoiding long holding times. To improve throughput in reverberatories, start the charging with high magnesium content material and inject chlorine gas if the molten metal is at the right temperature. Removal of magnesium through modern technologies can be efficiently performed to prevent environmental problems.

The effects of short pulse laser surface cleaning on porosity formation and reduction in laser welding of aluminium alloy for automotive component manufacture

NASA Astrophysics Data System (ADS)

AlShaer, A. W.; Li, L.; Mistry, A.

2014-12-01

Laser welding of aluminium alloys typically results in porosity in the fusion zones, leading to poor mechanical and corrosion performances. Mechanical and chemical cleaning of surfaces has been used previously to remove contaminants for weld joint preparations. However, these methods are slow, ineffective (e.g. due to hydrogen trapping) or lead to environmental hazards. This paper reports the effects of short pulsed laser surface cleaning on porosity formation and reduction in laser welding of AC-170PX (AA6014) aluminium sheets (coated with Ti/Zr and lubricated using a dry lubricant AlO70) with two types of joints: fillet edge and flange couch, using an AA4043 filler wire for automotive component assembly. The effect of laser cleaning on porosity reduction during laser welding using a filler wire has not been reported before. In this work, porosity and weld fusion zone geometry were examined prior to and after laser cleaning. The nanosecond pulsed Nd:YAG laser cleaning was found to reduce porosity significantly in the weld fusion zones. For the fillet edge welds, porosity was reduced to less than 0.5% compared with 10-80% without laser cleaning. For flange couch welds, porosity was reduced to 0.23-0.8% with laser cleaning from 0.7% to 4.3% without laser cleaning. This has been found to be due to the elimination of contaminations and oxide layers that contribute to the porosity formation. The laser cleaning is based on thermal ablation. This research focuses on porosity reduction in laser welding of aluminium alloy. Weld quality was investigated for two joints, fillet edge and flange couch joints. The effect of laser cleaning on porosity reduction after welding was investigated. It was found that laser cleaning reduced porosity less than 1% in both joints. Weld dimensions and strength were evaluated and discussed for both types of joints.

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

DOE Office of Scientific and Technical Information (OSTI.GOV)

Robinson, J.S., E-mail: jeremy.robinson@ul.ie; Redington, W.

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

Predicting the thermal conductivity of aluminium alloys in the cryogenic to room temperature range

NASA Astrophysics Data System (ADS)

Woodcraft, Adam L.

2005-06-01

Aluminium alloys are being used increasingly in cryogenic systems. However, cryogenic thermal conductivity measurements have been made on only a few of the many types in general use. This paper describes a method of predicting the thermal conductivity of any aluminium alloy between the superconducting transition temperature (approximately 1 K) and room temperature, based on a measurement of the thermal conductivity or electrical resistivity at a single temperature. Where predictions are based on low temperature measurements (approximately 4 K and below), the accuracy is generally better than 10%. Useful predictions can also be made from room temperature measurements for most alloys, but with reduced accuracy. This method permits aluminium alloys to be used in situations where the thermal conductivity is important without having to make (or find) direct measurements over the entire temperature range of interest. There is therefore greater scope to choose alloys based on mechanical properties and availability, rather than on whether cryogenic thermal conductivity measurements have been made. Recommended thermal conductivity values are presented for aluminium 6082 (based on a new measurement), and for 1000 series, and types 2014, 2024, 2219, 3003, 5052, 5083, 5086, 5154, 6061, 6063, 6082, 7039 and 7075 (based on low temperature measurements in the literature).

Study of Surface Roughness and Cutting force in machining for 6068 Aluminium alloy

NASA Astrophysics Data System (ADS)

Purushothaman, D.; Kaushik Yanamundra, Krishna; Krishnan, Gokul; Perisamy, C.

2018-04-01

Metal matrix composites, in particular, Aluminium Hybrid Composites are gaining increasing attention for applications in air and land because of their superior strength to weight ratio, density and high temperature resistance. Aluminium alloys are being used for a wide range of applications in Aerospace and Automobile industries, to name a few. The Aluminium Alloy 6068 has been used as the specimen. It is mainly composed of Aluminium (93.22 - 97.6 %), Magnesium (0.60 - 1.2 %), Silicon (0.60 - 1.4 %) and Bismuth (0.60 - 1.1 %). Aluminium 6068 is widely used for manufacturing aircraft structures, fuselages and wings. It is also extensively used in fabricating automobile parts such as wheel spacers. In this study, tests for the measurement of surface roughness and cutting force has been carried out on the specimen, the results evaluated and conclusions are drawn. Also the simulation of the same is carried out in a commercial FE software – ABAQUS.

Fatigue in a heat treatable high silicon containing aluminium alloy

NASA Astrophysics Data System (ADS)

González, J. A.; Talamantes-Silva, J.; Valtierra, S.; Colás, Rafael

2017-05-01

The use of cast aluminium alloys in automobiles contributes to reductions in weight and fuel consumption without impairing the safety for the occupants or the performance of the car. Most of the alloys used are heat treatable hypoeutectic Al-Si alloys, which have the drawback of exhibiting low wear resistance. So industry relies in wear resistant alloys, such as grey iron, for the liners of the combustion chambers in engine blocks, which increase the weight of the engine. Therefore, it is of interest to cast high silicon containing alloys into engine components that are able to resist wear while maintaining the mechanical properties required by the components. This work presents the result of the work carried out in a high silicon containing heat treatable aluminium alloy as it is subjected to high cycle fatigue. The alloy was prepared and cast in ingots designed to promote one dimensional solidification gradient to obtain samples to study the high cycle fatigue. The material was machined into hour-glass specimens that were tested at room temperature in a servohydraulic machine under load control following the stair case method. The results show that the resistance to fatigue depends on the microstructure of the sample, as the fatigue cracks originate in pores close to the surface of the sample and propagate through the eutectic aggregate. The results from this work are compared with those from previously obtained with hypoeutectic alloys.

Recovery of aluminium, nickel-copper alloys and salts from spent fluorescent lamps.

PubMed

Rabah, Mahmoud A

2004-01-01

This study explores a combined pyro-hydrometallurgical method to recover pure aluminium, nickel-copper alloy(s), and some valuable salts from spent fluorescent lamps (SFLs). It also examines the safe recycling of clean glass tubes for the fluorescent lamp industry. Spent lamps were decapped under water containing 35% acetone to achieve safe capture of mercury vapour. Cleaned glass tubes, if broken, were cut using a rotating diamond disc to a standard shorter length. Aluminium and copper-nickel alloys in the separated metallic parts were recovered using suitable flux to decrease metal losses going to slag. Operation variables affecting the quality of the products and the extent of recovery with the suggested method were investigated. Results revealed that total loss in the glass tube recycling operation was 2% of the SFLs. Pure aluminium meeting standard specification DIN 1712 was recovered by melting at 800 degrees C under sodium chloride/carbon flux for 20 min. Standard nickel-copper alloys with less than 0.1% tin were prepared by melting at 1250 degrees C using a sodium borate/carbon flux. De-tinning of the molten nickel-copper alloy was carried out using oxygen gas. Tin in the slag as oxide was recovered by reduction using carbon or hydrogen gas at 650-700 degrees C. Different valuable chloride salts were also obtained in good quality. Further research is recommended on the thermodynamics of nickel-copper recovery, yttrium and europium recovery, and process economics.

Results of the Experiment: Welding of Aluminium Alloy in Microgravity

NASA Astrophysics Data System (ADS)

Ferretti, S.; Amadori, K.; Boccalatte, A.; Alessandrini, M.; Freddi, A.; Persiani, F.; Poli, G.

2002-01-01

An experiment on "dendritic growth in aluminium alloy welding" was performed by the UNIBO team during the 3rd Student Parabolic Flight Campaign and the 30th Professional Parabolic Flight Campaign organised by ESA. Its purpose was to achieve a better understanding of crystal growth during tungsten inert gas (TIG) welding of an aluminium alloy to define the main parameters affecting the process under microgravity condition. The experiment had 4 phases : The paper discusses different aspects of the research, paying particularly attention not only to the influence of gravity, but also to other factors influencing welding microstructure, such as the Marangoni effect and the thermal transfer from the electrode to the material. The paper conclude the dissertation of the results offering new perspectives for welding studies and proposing a new approach to the scientific community to investigate this materials processes for manufacturing.

Hybrid FSWeld-bonded joint fatigue behaviour

NASA Astrophysics Data System (ADS)

Lertora, Enrico; Mandolfino, Chiara; Gambaro, Carla; Pizzorni, Marco

2018-05-01

Aluminium alloys, widely used in aeronautics, are increasingly involved in the automotive industry due to the good relationship between mechanical strength and specific weight. The lightening of the structures is the first objective, which allows the decreasing in the weight in motion. The use of aluminium alloys has also seen the introduction of the Friction Stir Welding (FSW) technique for the production of structural overlapping joints. FSW allows us to weld overlap joints free from defects, but with the presence of a structural notch further aggravated by the presence of a "hook" defect near the edge of the weld. Furthermore, FSW presents a weld penetration area connected to the tool geometry and penetration. The experimental activity will be focused on the combination of two different joining techniques, which can synergistically improve the final joint resistance. In particular, the welding and bonding process most commonly known as weld-bonding is defined as a hybrid process, as it combines two different junction processes. In this paper we analyse FSWelded AA6082 aluminium alloy overlapped joint with the aim of quantitatively evaluating the improvement provided by the presence of an epoxy adhesive between the plates. After optimising the weld-bonding process, the mechanical behaviour of welded joints will be analysed by static and dynamic tests. The presence of the adhesive should limit the negative effect of the structural notch inevitable in a FSW overlapped joint.

3D printing of high-strength aluminium alloys

NASA Astrophysics Data System (ADS)

Martin, John H.; Yahata, Brennan D.; Hundley, Jacob M.; Mayer, Justin A.; Schaedler, Tobias A.; Pollock, Tresa M.

2017-09-01

Metal-based additive manufacturing, or three-dimensional (3D) printing, is a potentially disruptive technology across multiple industries, including the aerospace, biomedical and automotive industries. Building up metal components layer by layer increases design freedom and manufacturing flexibility, thereby enabling complex geometries, increased product customization and shorter time to market, while eliminating traditional economy-of-scale constraints. However, currently only a few alloys, the most relevant being AlSi10Mg, TiAl6V4, CoCr and Inconel 718, can be reliably printed; the vast majority of the more than 5,500 alloys in use today cannot be additively manufactured because the melting and solidification dynamics during the printing process lead to intolerable microstructures with large columnar grains and periodic cracks. Here we demonstrate that these issues can be resolved by introducing nanoparticles of nucleants that control solidification during additive manufacturing. We selected the nucleants on the basis of crystallographic information and assembled them onto 7075 and 6061 series aluminium alloy powders. After functionalization with the nucleants, we found that these high-strength aluminium alloys, which were previously incompatible with additive manufacturing, could be processed successfully using selective laser melting. Crack-free, equiaxed (that is, with grains roughly equal in length, width and height), fine-grained microstructures were achieved, resulting in material strengths comparable to that of wrought material. Our approach to metal-based additive manufacturing is applicable to a wide range of alloys and can be implemented using a range of additive machines. It thus provides a foundation for broad industrial applicability, including where electron-beam melting or directed-energy-deposition techniques are used instead of selective laser melting, and will enable additive manufacturing of other alloy systems, such as non-weldable nickel

3D printing of high-strength aluminium alloys.

PubMed

Martin, John H; Yahata, Brennan D; Hundley, Jacob M; Mayer, Justin A; Schaedler, Tobias A; Pollock, Tresa M

2017-09-20

Metal-based additive manufacturing, or three-dimensional (3D) printing, is a potentially disruptive technology across multiple industries, including the aerospace, biomedical and automotive industries. Building up metal components layer by layer increases design freedom and manufacturing flexibility, thereby enabling complex geometries, increased product customization and shorter time to market, while eliminating traditional economy-of-scale constraints. However, currently only a few alloys, the most relevant being AlSi10Mg, TiAl6V4, CoCr and Inconel 718, can be reliably printed; the vast majority of the more than 5,500 alloys in use today cannot be additively manufactured because the melting and solidification dynamics during the printing process lead to intolerable microstructures with large columnar grains and periodic cracks. Here we demonstrate that these issues can be resolved by introducing nanoparticles of nucleants that control solidification during additive manufacturing. We selected the nucleants on the basis of crystallographic information and assembled them onto 7075 and 6061 series aluminium alloy powders. After functionalization with the nucleants, we found that these high-strength aluminium alloys, which were previously incompatible with additive manufacturing, could be processed successfully using selective laser melting. Crack-free, equiaxed (that is, with grains roughly equal in length, width and height), fine-grained microstructures were achieved, resulting in material strengths comparable to that of wrought material. Our approach to metal-based additive manufacturing is applicable to a wide range of alloys and can be implemented using a range of additive machines. It thus provides a foundation for broad industrial applicability, including where electron-beam melting or directed-energy-deposition techniques are used instead of selective laser melting, and will enable additive manufacturing of other alloy systems, such as non-weldable nickel

Composite Ni-Co-fly ash coatings on 5083 aluminium alloy

NASA Astrophysics Data System (ADS)

Panagopoulos, C. N.; Georgiou, E. P.; Tsopani, A.; Piperi, L.

2011-03-01

Ni-Co-fly ash coatings were deposited on zincate treated 5083 wrought aluminium alloy substrates with the aid of the electrodeposition technique. Structural and chemical characterization of the produced composite coatings was performed with the aid of X-ray diffraction (XRD), scanning electron microscopy (SEM) and electron dispersive X-ray analysis (EDS) techniques. The Ni-Co-fly ash coatings were found to consist of a crystalline Ni-Co solid solution with dispersed fly ash particles. In addition, chemical analysis of the Ni-Co matrix showed that it consisted of 80 wt.% Ni and 20 wt.% Co. The co-deposition of fly ash particles leads to a significant increase of the microhardness of the coating. The corrosion behaviour of the Ni-Co-fly ash/zincate coated aluminium alloy, in a 0.3 M NaCl solution (pH = 3.5), was studied by means of potentiodynamic corrosion experiments.

Ballistic impact velocity response of carbon fibre reinforced aluminium alloy laminates for aero-engine

NASA Astrophysics Data System (ADS)

Mohammed, I.; Abu Talib, A. R.; Sultan, M. T. H.; Saadon, S.

2017-12-01

Aerospace and other industries use fibre metal laminate composites extensively due to their high specific strength, stiffness and fire resistance, in addition to their capability to be tailored into different forms for specific purposes. The behaviours of such composites under impact loading is another factor to be considered due to the impacts that occur in take-off, landing, during maintenance and operations. The aim of the study is to determine the specific perforation energy and impact strength of the fibre metal laminates of different layering pattern of carbon fibre reinforced aluminium alloy and hybrid laminate composites of carbon fibre and natural fibres (kenaf and flax). The composites are fabricated using the hand lay-up method in a mould with high bonding polymer matrix and compressed by a compression machine, cured at room temperature for one day and post cure in an oven for three hours. The impact tests are conducted using a gun tunnel system with a flat cylindrical bullet fired using a helium gas at a distance of 14 inches to the target. Impact and residual velocity of the projectile are recorded by high speed video camera. Specific perforation energy of carbon fibre reinforced aluminium alloy (CF+AA) for both before and after fire test are higher than the specific perforation energy of the other composites considered before and after fire test respectively. CF +AA before fire test is 55.18% greater than after. The same thing applies to impact strength of the composites where CF +AA before the fire test has the highest percentage of 11.7%, 50.0% and 32.98% as respectively compared to carbon fibre reinforced aluminium alloy (CARALL), carbon fibre reinforced flax aluminium alloy (CAFRALL) and carbon fibre reinforced kenaf aluminium alloy (CAKRALL), and likewise for the composites after fire test. The considered composites in this test can be used in the designated fire zone of an aircraft engine to protect external debris from penetrating the engine

Nanostructural hierarchy increases the strength of aluminium alloys.

PubMed

Liddicoat, Peter V; Liao, Xiao-Zhou; Zhao, Yonghao; Zhu, Yuntian; Murashkin, Maxim Y; Lavernia, Enrique J; Valiev, Ruslan Z; Ringer, Simon P

2010-09-07

Increasing the strength of metallic alloys while maintaining formability is an interesting challenge for enabling new generations of lightweight structures and technologies. In this paper, we engineer aluminium alloys to contain a hierarchy of nanostructures and possess mechanical properties that expand known performance boundaries-an aerospace-grade 7075 alloy exhibits a yield strength and uniform elongation approaching 1 GPa and 5%, respectively. The nanostructural architecture was observed using novel high-resolution microscopy techniques and comprises a solid solution, free of precipitation, featuring (i) a high density of dislocations, (ii) subnanometre intragranular solute clusters, (iii) two geometries of nanometre-scale intergranular solute structures and (iv) grain sizes tens of nanometres in diameter. Our results demonstrate that this novel architecture offers a design pathway towards a new generation of super-strong materials with new regimes of property-performance space.

A microstructure-based yield stress and work-hardening model for textured 6xxx aluminium alloys

NASA Astrophysics Data System (ADS)

Khadyko, M.; Myhr, O. R.; Dumoulin, S.; Hopperstad, O. S.

2016-04-01

The plastic properties of an aluminium alloy are defined by its microstructure. The most important factors are the presence of alloying elements in the form of solid solution and precipitates of various sizes, and the crystallographic texture. A nanoscale model that predicts the work-hardening curves of 6xxx aluminium alloys was proposed by Myhr et al. The model predicts the solid solution concentration and the particle size distributions of different types of metastable precipitates from the chemical composition and thermal history of the alloy. The yield stress and the work hardening of the alloy are then determined from dislocation mechanics. The model was largely used for non-textured materials in previous studies. In this work, a crystal plasticity-based approach is proposed for the work hardening part of the nanoscale model, which allows including the influence of the crystallographic texture. The model is evaluated by comparison with experimental data from uniaxial tensile tests on two textured 6xxx alloys in five temper conditions.

A hybrid aluminium alloy and its zoo of interacting nano-precipitates

DOE Office of Scientific and Technical Information (OSTI.GOV)

Wenner, Sigurd, E-mail: sigurd.wenner@ntnu.no; Marioara, Calin Daniel; Andersen, Sigmund Jarle

An alloy with aluminium as its base element is heat treated to form a multitude of precipitate phases known from different classes of industrial alloys: Al–Cu(–Mg), Al–Mg–Si–Cu, and Al–Zn–Mg. Nanometer-sized needle-shaped particles define the starting point of the phase nucleation, after which there is a split in the precipitation sequence into six phases of highly diverse compositions and morphologies. There are several unique effects of phases from different alloy systems being present in the same host lattice, of which we concentrate on two: the replacement of Ag by Zn on the Ω interface and the formation of combined plates ofmore » the θ′ and C phases. Using atomically resolved scanning transmission electron microscopy and energy-dispersive X-ray spectroscopy, we investigate the formation mechanisms, crystal structures and compositions of the precipitates. - Graphical abstract: Display Omitted - Highlights: • An aluminium alloy composition in-between the 2/6/7xxx systems was investigated. • Six different phases from the three systems coexist in an over-aged state. • All phases with 〈001〉{sub Al} coherencies can nucleate on 6xxx needle precipitates. • Modified theta′ and omega interfaces are observed.« less

Further studies of the anodic dissolution in sodium chloride electrolyte of aluminium alloys containing tin and gallium

NASA Astrophysics Data System (ADS)

Nestoridi, Maria; Pletcher, Derek; Wharton, Julian A.; Wood, Robert J. K.

As part of a programme to develop a high power density, Al/air battery with a NaCl brine electrolyte, the high rate dissolution of an aluminium alloy containing tin and gallium was investigated in a small volume cell. The objective was to define the factors that limit aluminium dissolution in condition that mimic a high power density battery. In a cell with a large ratio of aluminium alloy to electrolyte, over a range of current densities the extent of dissolution was limited to ∼1000 C cm -2 of anode surface by a thick layer of loosely bound, crystalline deposit on the Al alloy anode formed by precipitation from solution. This leads to a large increase in impedance and acts as a barrier to transport of ions.

A Fundamental Approach to Developing Aluminium based Bulk Amorphous Alloys based on Stable Liquid Metal Structures and Electronic Equilibrium - 154041

DTIC Science & Technology

2017-03-28

AFRL-AFOSR-JP-TR-2017-0027 A Fundamental Approach to Developing Aluminium-based Bulk Amorphous Alloys based on Stable Liquid -Metal Structures and...to 16 Dec 2016 4.  TITLE AND SUBTITLE A Fundamental Approach to Developing Aluminium-based Bulk Amorphous Alloys based on Stable Liquid -Metal...including Al, Cu, Ni, Zr, Mg, Pd, Ga , Ca. Many new Al-based amorphous alloys were found within the numerous alloy systems studied in this project, and

Evaluation of AA5052 alloy anode in alkaline electrolyte with organic rare-earth complex additives for aluminium-air batteries

NASA Astrophysics Data System (ADS)

Wang, Dapeng; Li, Heshun; Liu, Jie; Zhang, Daquan; Gao, Lixin; Tong, Lin

2015-10-01

Behaviours of the AA5052 aluminium alloy anode of the alkaline aluminium-air battery are studied by the hydrogen evolution test, the electrochemical measurements and the surface analysis method. The combination of amino-acid and rare earth as electrolyte additives effectively retards the self-corrosion of AA5052 aluminium alloy in 4 M NaOH solution. It shows that the combination of L-cysteine and cerium nitrate has a synergistic effect owing to the formation of a complex film on AA5052 alloy surface. The organic rare-earth complex can decrease the anodic polarisation, suppress the hydrogen evolution and increase the anodic utilization rate.

High rate constitutive modeling of aluminium alloy tube

NASA Astrophysics Data System (ADS)

Salisbury, C. P.; Worswick, M. J.; Mayer, R.

2006-08-01

As the need for fuel efficient automobiles increases, car designers are investigating light-weight materials for automotive bodies that will reduce the overall automobile weight. Aluminium alloy tube is a desirable material to use in automotive bodies due to its light weight. However, aluminium suffers from lower formability than steel and its energy absorption ability in a crash event after a forming operation is largely unknown. As part of a larger study on the relationship between crashworthiness and forming processes, constitutive models for 3mm AA5754 aluminium tube were developed. A nominal strain rate of 100/s is often used to characterize overall automobile crash events, whereas strain rates on the order of 1000/s can occur locally. Therefore, tests were performed at quasi-static rates using an Instron test fixture and at strain rates of 500/s to 1500/s using a tensile split Hopkinson bar. High rate testing was then conducted at rates of 500/s, 1000/s and 1500/s at 21circC, 150circC and 300circC. The generated data was then used to determine the constitutive parameters for the Johnson-Cook and Zerilli-Armstrong material models.

Effect of pulsed current GTA welding parameters on the fusion zone microstructure of AA 6061 aluminium alloy

NASA Astrophysics Data System (ADS)

Kumar, T. Senthil; Balasubramanian, V.; Babu, S.; Sanavullah, M. Y.

2007-08-01

AA6061 aluminium alloy (Al-Mg-Si alloy) has gathered wide acceptance in the fabrication of food processing equipment, chemical containers, passenger cars, road tankers, and railway transport systems. The preferred process for welding these aluminium alloys is frequently Gas Tungsten Arc (GTA) welding due to its comparatively easy applicability and lower cost. In the case of single pass GTA welding of thinner sections of this alloy, the pulsed current has been found beneficial due to its advantages over the conventional continuous current processes. The use of pulsed current parameters has been found to improve the mechanical properties of the welds compared to those of continuous current welds of this alloy due to grain refinement occurring in the fusion zone. In this investigation, an attempt has been made to develop a mathematical model to predict the fusion zone grain diameter incorporating pulsed current welding parameters. Statistical tools such as design of experiments, analysis of variance, and regression analysis are used to develop the mathematical model. The developed model can be effectively used to predict the fusion grain diameter at a 95% confidence level for the given pulsed current parameters. The effect of pulsed current GTA welding parameters on the fusion zone grain diameter of AA 6061 aluminium alloy welds is reported in this paper.

Quantitative prediction of solute strengthening in aluminium alloys.

PubMed

Leyson, Gerard Paul M; Curtin, William A; Hector, Louis G; Woodward, Christopher F

2010-09-01

Despite significant advances in computational materials science, a quantitative, parameter-free prediction of the mechanical properties of alloys has been difficult to achieve from first principles. Here, we present a new analytic theory that, with input from first-principles calculations, is able to predict the strengthening of aluminium by substitutional solute atoms. Solute-dislocation interaction energies in and around the dislocation core are first calculated using density functional theory and a flexible-boundary-condition method. An analytic model for the strength, or stress to move a dislocation, owing to the random field of solutes, is then presented. The theory, which has no adjustable parameters and is extendable to other metallic alloys, predicts both the energy barriers to dislocation motion and the zero-temperature flow stress, allowing for predictions of finite-temperature flow stresses. Quantitative comparisons with experimental flow stresses at temperature T=78 K are made for Al-X alloys (X=Mg, Si, Cu, Cr) and good agreement is obtained.

Analysis of wear properties of aluminium based journal bearing alloys with and without lubrication.

NASA Astrophysics Data System (ADS)

Mathavan, J. Joy; Patnaik, Amar

2016-09-01

Apart from classical bearing materials, Aluminium alloys are used as bearing materials these days because of their superior quality. In this analysis, new Aluminium based bearing materials, with filler metals Si, Ni, and Cr are prepared by metal mould casting in burnout furnace machine, and tribological properties of these alloys with and without lubrication were tested. The experiments for wear with lubrication are conducted on multiple specimen tester and experiments without lubrication is conducted on Pin on disk tribometer. The disc material used was SAE 1050 steel. Wear tests were conducted at a sliding speed of 0.785 m/s and at a normal load of 20 N. Coefficient of friction values, temperature changes and wear of the specimens were plotted on graph according to the above mentioned working conditions. Hardness and weight losses of the specimens were calculated. The obtained results demonstrate how the friction and wear properties of these samples have changed with the % addition of Silicon, Chromium and Nickel to the base metal aluminium.

Carbon treated commercial aluminium alloys as anodes for aluminium-air batteries in sodium chloride electrolyte

NASA Astrophysics Data System (ADS)

Pino, M.; Herranz, D.; Chacón, J.; Fatás, E.; Ocón, P.

2016-09-01

An easy treatment based in carbon layer deposition into aluminium alloys is presented to enhance the performance of Al-air primary batteries with neutral pH electrolyte. The jellification of aluminate in the anode surface is described and avoided by the carbon covering. Treated commercial Al alloys namely Al1085 and Al7475 are tested as anodes achieving specific capacities above 1.2 Ah g-1vs 0.5 Ah g-1 without carbon covering. The influence of the binder proportion in the treatment as well as different carbonaceous materials, Carbon Black, Graphene and Pyrolytic Graphite are evaluated as candidates for the covering. Current densities of 1-10 mA cm-2 are measured and the influence of the alloy explored. A final battery design of 4 cells in series is presented for discharges with a voltage plateau of 2 V and 1 Wh g-1 energy density.

Deviatoric response of the aluminium alloy, 5083

NASA Astrophysics Data System (ADS)

Appleby-Thomas, Gareth; Hazell, Paul; Millett, Jeremy; Bourne, Neil

2009-06-01

Aluminium alloys such as 5083 are established light weight armour materials. As such, the shock response of these materials is of great importance. The shear strength of a material under shock loading provides an insight into its ballistic performance. In this investigation embedded manganin stress gauges have been employed to measure both the longitudinal and lateral components of stress during plate impact experiments over a range of impact stresses. In turn, these results were used to determine the shear strength and to investigate the time dependence of lateral stress behind the shock front to give an indication of material response.

Industrial based volume manufacturing of lightweight aluminium alloy panel components with high-strength and complex-shape for car body and chassis structures

NASA Astrophysics Data System (ADS)

Anyasodor, Gerald; Koroschetz, Christian

2017-09-01

To achieve the high volume manufacture of lightweight passenger cars at economic cost as required in the automotive industry, low density materials and new process route will be needed. While high strength aluminium alloy grades: AA7075 and AA6082 may provide the alternative material solution, hot stamping process used for high-strength and ultrahigh strength steels such as boron steel 22mnb5 can enable the volume manufacture of panel components with high-strength and complex-shape for car body and chassis structures. These aluminium alloy grades can be used to manufacture panel components with possible yield strengths ≥ 500 MPa. Due to the differences in material behaviors, hot stamping process of 22mnb5 cannot be directly applied to high strength aluminium alloy grades. Despite recorded successes in laboratories, researches and niche hot forming processes of high strength aluminium alloy grades, not much have been achieved for adequate and efficient volume manufacturing system applicable in the automotive industry. Due to lack of such system and based on expert knowledge in hot stamping production-line, AP&T presents in this paper a hot stamping processing route for high strength aluminium alloys been suitable for production-line development and volume manufacturing.

Performance of AA5052 alloy anode in alkaline ethylene glycol electrolyte with dicarboxylic acids additives for aluminium-air batteries

NASA Astrophysics Data System (ADS)

Wang, DaPeng; Zhang, DaQuan; Lee, KangYong; Gao, LiXin

2015-11-01

Dicarboxylic acid compounds, i.e. succinic acid (SUA), adipic acid (ADA) and sebacic acid (SEA), are used as electrolyte additives in the alkaline ethylene glycol solution for AA5052 aluminium-air batteries. It shows that the addition of dicarboxylic acids lowers the hydrogen gas evolution rate of commercial AA5052 aluminium alloy anode. AA5052 aluminium alloy has wide potential window for electrochemical activity and better discharge performance in alkaline ethylene glycol solution containing dicarboxylic acid additives. ADA has the best inhibition effect for the self-corrosion of AA5052 anode among the three dicarboxylic acid additives. Fourier transform infrared spectroscopy (FT-IR) reveals that dicarboxylic acids and aluminium ions can form coordination complexes. Quantum chemical calculations shows that ADA has a smaller energy gap (ΔE, the energy difference between the lowest unoccupied orbital and the highest occupied orbital), indicating that ADA has the strongest interaction with aluminium ions.

Hot Tearing in Aluminium — Copper Alloys

NASA Astrophysics Data System (ADS)

Viano, David; StJohn, David; Grandfield, John; Cáceres, Carlos

For many aluminium alloys, hot tearing susceptibility follows a lambda curve relationship when hot tearing severity is plotted as a function of solute content. In the past, there has been some difficulty quantifying hot tearing. Traditional methods rely upon measuring electrical resistivity or the number and/or length of cracks in tests such as the ring test. In this experimental program, a hot tear test rig was used to investigate a series of binary Al-Cu alloys. This device measures the load imposed on the mushy zone during solidification. Hot tearing susceptibility was quantified in two ways. The first method involved measuring the load at the solidus temperature (548°C). The second method was to radiograph the hot spot and measure the image density of the cracks. Both methods had advantages and disadvantages. It was found that the results from the hot tear rig correlates with other published data using different experimental methods.

Performance of commercial aluminium alloys as anodes in gelled electrolyte aluminium-air batteries

NASA Astrophysics Data System (ADS)

Pino, M.; Chacón, J.; Fatás, E.; Ocón, P.

2015-12-01

The evaluation of commercial aluminium alloys, namely, Al2024, Al7475 and Al1085, for Al-air batteries is performed. Pure Al cladded Al2024 and Al7475 are also evaluated. Current rates from 0.8 mA cm-2 to 8.6 mA cm-2 are measured in a gel Al-air cell composed of the commercial alloy sample, a commercial air-cathode and an easily synthesizable gelled alkaline electrolyte. The influence of the alloying elements and the addition to the electrolyte of ZnO and ZnCl2, as corrosion inhibitors is studied and analysed via EDX/SEM. Specific capacities of up to 426 mAh/g are obtained with notably flat potential discharges of 1.3-1.4 V. The competition between self-corrosion and oxidation reactions is also discussed, as well as the influence of the current applied on that process. Al7475 is determined to have the best behaviour as anode in Al-air primary batteries, and cladding process is found to be an extra protection against corrosion at low current discharges. Conversely, Al1085 provided worse results because of an unfavourable metallic composition.

IEC 61267: Feasibility of type 1100 aluminium and a copper/aluminium combination for RQA beam qualities.

PubMed

Leong, David L; Rainford, Louise; Zhao, Wei; Brennan, Patrick C

2016-01-01

In the course of performance acceptance testing, benchmarking or quality control of X-ray imaging systems, it is sometimes necessary to harden the X-ray beam spectrum. IEC 61267 specifies materials and methods to accomplish beam hardening and, unfortunately, requires the use of 99.9% pure aluminium (Alloy 1190) for the RQA beam quality, which is expensive and difficult to obtain. Less expensive and more readily available filters, such as Alloy 1100 (99.0% pure) aluminium and copper/aluminium combinations, have been used clinically to produce RQA series without rigorous scientific investigation to support their use. In this paper, simulation and experimental methods are developed to determine the differences in beam quality using Alloy 1190 and Alloy 1100. Additional simulation investigated copper/aluminium combinations to produce RQA5 and outputs from this simulation are verified with laboratory tests using different filter samples. The results of the study demonstrate that although Alloy 1100 produces a harder beam spectrum compared to Alloy 1190, it is a reasonable substitute. A combination filter of 0.5 mm copper and 2 mm aluminium produced a spectrum closer to that of Alloy 1190 than Alloy 1100 with the added benefits of lower exposures and lower batch variability. Copyright © 2015 Associazione Italiana di Fisica Medica. Published by Elsevier Ltd. All rights reserved.

Survey of Nickel-Aluminium-Bronze Casting Alloys on Marine Applications,

DTIC Science & Technology

1981-04-01

and corrosion performance of nickel-aluminium bronze (NAB)/covered by naval specification DGS-8520 and DGS-348 have been investigated. No evidence was...found to suggest that there would be any significant difference in corrosion performance between alloys meeting the two specifications. Early... corrosion problems associated with the weld repair areas of castings have been overcome largely by using improved foundry and welding techniques followed by a

Experimental investigations on thermo mechanical behaviour of aluminium alloys subjected to tensile loading and laser irradiation

NASA Astrophysics Data System (ADS)

Jelani, Mohsan; Li, Zewen; Shen, Zhonghua; Sardar, Maryam; Tabassum, Aasma

2017-05-01

The present work reports the investigation of the thermal and mechanical behaviour of aluminium alloys under the combined action of tensile loading and laser irradiations. The two types of aluminium alloys (Al-1060 and Al-6061) are used for the experiments. The continuous wave Ytterbium fibre laser (wavelength 1080 nm) was employed as irradiation source, while tensile loading was provided by tensile testing machine. The effects of various pre-loading and laser power densities on the failure time, temperature distribution and on deformation behaviour of aluminium alloys are analysed. The experimental results represents the significant reduction in failure time and temperature for higher laser powers and for high load values, which implies that preloading may contribute a significant role in the failure of the material at elevated temperature. The reason and characterization of material failure by tensile and laser loading are explored in detail. A comparative behaviour of under tested materials is also investigated. This work suggests that, studies considering only combined loading are not enough to fully understand the mechanical behaviour of under tested materials. For complete characterization, one must consider the effect of heating as well as loading rate.

Fabrication of self-healing super-hydrophobic surfaces on aluminium alloy substrates

DOE Office of Scientific and Technical Information (OSTI.GOV)

Wang, Yang; Wei Liu, Xiao; Zhang, Hai Feng, E-mail: wy3121685@163.com

We present a method to fabricate a super-hydrophobic surface with a self-healing ability on an aluminium alloy substrate. The coatings are obtained by combining a two-step process (first, the substrate is immersed in a solution of HCl, HF and H{sub 2}O, and then in boiling water) and succeeding surface fluorination with a solution of poly(vinylidene-fluoride-co-hexafluoropropylene) and a fluoroalkyl silane. The morphological features and chemical composition were studied by scanning electron micrometry and energy-dispersive X-ray spectroscopy. The prepared super-hydrophobic aluminium surfaces showed hierarchical structures forming pores, petals and particles with a contact angle of 161° and a sliding angle of 3°.

Deviatoric Response of AN Armour-Grade Aluminium Alloy

NASA Astrophysics Data System (ADS)

Appleby-Thomas, G. J.; Hazell, P. J.; Millett, J.; Bourne, N. K.

2009-12-01

Aluminium alloys such as 5083 H32 are established light-weight armour materials. As such, the shock response of these materials is of great importance. The shear strength of a material under shock loading provides an insight into its ballistic performance. In this investigation embedded manganin stress gauges have been employed to measure both the longitudinal and lateral components of stress during plate-impact experiments over a range of impact stresses. In turn, these results were used to determine the shear strength and to investigate the time dependence of lateral stress behind the shock front to give an indication of material response.

Modelling the strength of an aluminium-steel nailed joint

NASA Astrophysics Data System (ADS)

Goldspiegel, Fabien; Mocellin, Katia; Michel, Philippe

2018-05-01

For multi-material applications in automotive industry, a cast aluminium (upper layer) and dual-phase steel (lower layer) superposition joined with High-Speed Nailing process is investigated through an experimental vs numerical framework. Using FORGE® finite-element software, results from joining simulations have been inserted into models in charge of nailed-joint mechanical testings. Numerical Shear and Cross-tensile tests are compared to experimental ones to discuss discrepancy and possible improvements.

Characteristic evaluation of process parameters of friction stir welding of aluminium 2024 hybrid composites

NASA Astrophysics Data System (ADS)

Sadashiva, M.; Shivanand, H. K.; Vidyasagar, H. N.

2018-04-01

The Current work is aimed to investigate the effect of process parameters in friction stir welding of Aluminium 2024 base alloy and Aluminium 2024 matrix alloy reinforced with E Glass and Silicon Carbide reinforcements. The process involved a set of synthesis techniques incorporating stir casting methodology resulting in fabrication of the composite material. This composite material that is synthesized is then machined to obtain a plate of dimensions 100 mm * 50 mm * 6 mm. The plate is then friction stir welded at different set of parameters viz. the spindle speed of 600 rpm, 900 rpm and 1200 rpm and feed rate of 40 mm/min, 80 mm/min and 120 mm/min for analyzing the process capability. The study of the given set of parameters is predominantly important to understand the physics of the process that may lead to better properties of the joint, which is very much important in perspective to its use in advanced engineering applications, especially in aerospace domain that uses Aluminium 2024 alloy for wing and fuselage structures under tension.

Numerical analysis of heat treatment of TiCN coated AA7075 aluminium alloy

NASA Astrophysics Data System (ADS)

Srinath, M. K.; Prasad, M. S. Ganesha

2018-04-01

The Numerical analysis of heat treatments of TiCN coated AA7075 aluminium alloys is presented in this paper. The Convection-Diffusion-Reaction (CDR) equation with solutions in the Streamlined-Upward Petrov-Galerkin (SUPG) method for different parameters is provided for the understanding of the process. An experimental process to improve the surface properties of AA-7075 aluminium alloy was attempted through the coatings of TiCN and subsequent heat treatments. From the experimental process, optimized temperature and time was obtained which gave the maximum surface hardness and corrosion resistance. The paper gives an understanding and use of the CDR equation for application of the process. Expression to determine convection, diffusion and reaction parameters are provided which is used to obtain the overall expression of the heat treatment process. With the substitution of the optimized temperature and time, the governing equation may be obtained. Additionally, the total energy consumed during the heat treatment process is also developed to give a mathematical formulation of the energy consumed.

Experimental investigations of visco-plastic properties of the aluminium and tungsten alloys used in KE projectiles

NASA Astrophysics Data System (ADS)

Kruszka, L.; Magier, M.

2012-08-01

The main aim of studies on dynamic behaviour of construction materials at high strain rates is to determine the variation of mechanical properties (strength, plasticity) in function of the strain rate and temperature. On the basis of results of dynamic tests on the properties of constructional materials the constitutive models are formulated to create numerical codes applied to solve constructional problems with computer simulation methods. In the case of military applications connected with the phenomena of gunshot and terminal ballistics it's particularly important to develop a model of strength and armour penetration with KE projectile founded on reliable results of dynamic experiments and constituting the base for further analyses and optimization of projectile designs in order to achieve required penetration depth. Static and dynamic results of strength investigations of the EN AW-7012 aluminium alloy (sabot) and tungsten alloy (penetrator) are discussed in this paper. Static testing was carried out with the INSTRON testing machine. Dynamic tests have been conducted using the split Hopkinson pressure bars technique at strain rates up to 1,2 ṡ 104s-1 (for aluminium alloy) and 6 ṡ 103s-1 (for tungsten alloy).

Vibrational response and mechanical properties characterization of aluminium alloy 6061/Sic composite

NASA Astrophysics Data System (ADS)

Kumbhar, A. P.; Vyavahare, R. T.; Kulkarni, S. G.

2018-05-01

Aluminium alloy based metal matrix composites (AAMMC) are mainly used in sliding wear application, automobile, Aircraft and aerospace components, Marine fittings, Transport and other industry are becoming highly advantageous due to their excellent wear resistance, lighter weight, higher strength and durability. In this paper the effect of reinforcement percentage on vibration response and mechanical properties of metal matrix composite has been investigated. Composite material was prepared by varying Sic (0, 3, 6, and 9 wt. %) by stir casting method. Natural frequency, tensile strength, rockwell hardness and compressive strength were analyzed. The result shows that, addition of sic in aluminium matrix increases natural frequency, hardness, tensile strength, compressive strength and 9 wt. % showed maximum natural frequency, hardness, tensile strength, compressive strength.

Modeling Dynamic Anisotropic Behaviour and Spall Failure in Commercial Aluminium Alloys AA7010

NASA Astrophysics Data System (ADS)

Mohd Nor, M. K.; Ma'at, N.; Ho, C. S.

2018-04-01

This paper presents a finite strain constitutive model to predict a complex elastoplastic deformation behaviour involves very high pressures and shockwaves in orthotropic materials of aluminium alloys. The previous published constitutive model is used as a reference to start the development in this work. The proposed formulation that used a new definition of Mandel stress tensor to define Hill's yield criterion and a new shock equation of state (EOS) of the generalised orthotropic pressure is further enhanced with Grady spall failure model to closely predict shockwave propagation and spall failure in the chosen commercial aluminium alloy. This hyperelastic-plastic constitutive model is implemented as a new material model in the Lawrence Livermore National Laboratory (LLNL)-DYNA3D code of UTHM's version, named Material Type 92 (Mat92). The implementations of a new EOS of the generalised orthotropic pressure including the spall failure are also discussed in this paper. The capability of the proposed constitutive model to capture the complex behaviour of the selected material is validated against range of Plate Impact Test data at 234, 450 and 895 ms-1 impact velocities.

The fracture of boron fibre-reinforced 6061 aluminium alloy

NASA Technical Reports Server (NTRS)

Wright, M. A.; Welch, D.; Jollay, J.

1979-01-01

The fracture of 6061 aluminium alloy reinforced with unidirectional and cross-plied 0/90 deg, 0/90/+ or - 45 deg boron fibres has been investigated. The results have been described in terms of a critical stress intensity, K(Q). Critical stress intensity factors were obtained by substituting the failure stress and the initial crack length into the appropriate expression for K(Q). Values were obtained that depended on the dimensions of the specimens. It was therefore concluded that, for the size of specimen tested, the values of K(Q) did not reflect any basic materials property.

A survey of some metallographic etching reagents for restoration of obliterated engraved marks on aluminium-silicon alloy surfaces.

PubMed

Uli, Norjaidi; Kuppuswamy, R; Amran, Mohd Firdaus Che

2011-05-20

A brief survey to assess the sensitivity and efficacy of some common etching reagents for revealing obliterated engraved marks on Al-Si alloy surfaces is presented. Experimental observations have recommended use of alternate swabbing of 10% NaOH and 10% HNO(3) on the obliterated surfaces for obtaining the desired results. The NaOH etchant responsible for bringing back the original marks resulted in the deposition of some dark coating that has masked the recovered marks. The coating had been well removed by dissolving it in HNO(3) containing 10-20% acid. However, the above etching procedure was not effective on aluminium (99% purity) and Al-Zn-Mg-Cu alloy surfaces. Also the two reagents (i) immersion in 10% aq. phosphoric acid and (ii) alternate swabbing of 60% HCl and 40% NaOH suggested earlier for high strength Al-Zn-Mg-Cu alloys [23] were quite ineffective on Al-Si alloys. Thus different aluminium alloys needed different etching treatments for successfully restoring the obliterated marks. Al-Si alloys used in casting find wide applications especially in the manufacture of engine blocks of motor vehicles. Hence, the results presented in this paper are of much relevance in serial number restoration problems involving this alloy. Copyright © 2010 Elsevier Ireland Ltd. All rights reserved.

Effect of the nature of grain boundary regions on cavitation of a superplastically deformed aluminium alloy

DOE Office of Scientific and Technical Information (OSTI.GOV)

Blandin, J.J.; Varloteaux, A.; Suery, M.

Superplastic deformation of aluminium alloys induces cavity formation throughout the material, so that superplastic forming usually requires to be carried out under superimposed gas pressure to minimize strain-induced damage. This paper deals with the beneficial effects of heat treatment at high temperature for several hours before deformation on cavitation behavior of a superplastically deformed 7475 alloy. Transmission electron microscopy observations show that several microstructural transformations are induced by superplastic deformation and affected by the heat treatment. At first, the generation of dispersoid free zones at the periphery of the grains is observed, the composition of which depends on the priormore » history of the specimen. Secondly, the formation of long thin fibers extending in the cavities in the as received specimens, these fibers being no longer present in the heat-treated conditions. A TEM characterization of the fibers is presented and a mechanism of their formation is discussed. Such a reduction of the cavitation level for a given strain is interesting in view of superplastic forming of aluminium alloys under atmospheric pressure.« less

Recoil-free Fraction in Amorphous and Nanocrystalline Aluminium Based Alloys

NASA Astrophysics Data System (ADS)

Sitek, Jozef

2008-10-01

Aluminium based rapidly quenched alloys of nominal composition Al90Fe7Nb3 and Al94Fe2V4 were studied by Mössbauer spectroscopy. We have measured the recoil-free fraction and thermal shift at room and liquid nitrogen temperature. The frequency modes of atomic vibrations were determined and consequently the characteristic Debye temperature was derived. Characteristic temperature calculated from f-factor was lower than those fitted from second order Doppler shift. This indicates the presence of different frequency modes for amorphous and nanocrystalline states.

Investigation on local ductility of 6xxx-aluminium sheet alloys

NASA Astrophysics Data System (ADS)

Henn, P.; Liewald, M.; Sindel, M.

2017-09-01

Within the scope of this paper influence of localization of loading conditions on the ductility of two different 6xxx-aluminium sheet alloys is investigated. In order to improve the prediction of sheet material crash performance, material parameters based on uniaxial tensile and notched tensile tests are determined with varying consolidation areas. Especially evaluation methods based on the localized necking behaviour in tensile tests are investigated. The potential of local ductility characterisation is validated with results of Edge-Compression Tests (ECT) which applies load conditions that occur in actual crash events.

Amélioration des performances du procédé de soudage TIG sur un acier au carbone et un alliage d'aluminium par dépôt de silice

NASA Astrophysics Data System (ADS)

Sire, Stéphane; Marya, Surendar

This Note presents ways to improve the weld penetration potential of TIG process by optimising silica application around the joints in a plain carbon steel and an aluminium alloy 5086. Whereas for plain carbon steels, full coverage of joint improves penetration, the presence of a blank zone around the joint in the flux coating on aluminium 5086 using AC-TIG seems to be the best solution for cosmetic and deep welds. To cite this article: S. Sire, S. Marya, C. R. Mecanique 330 (2002) 83-89.

Zirconium behaviour during electrorefining of actinide-zirconium alloy in molten LiCl-KCl on aluminium cathodes

NASA Astrophysics Data System (ADS)

Meier, R.; Souček, P.; Malmbeck, R.; Krachler, M.; Rodrigues, A.; Claux, B.; Glatz, J.-P.; Fanghänel, Th.

2016-04-01

A pyrochemical electrorefining process for the recovery of actinides from metallic nuclear fuel based on actinide-zirconium alloys (An-Zr) in a molten salt is being investigated. In this process actinides are group-selectively recovered on solid aluminium cathodes as An-Al alloys using a LiCl-KCl eutectic melt at a temperature of 450 °C. In the present study the electrochemical behaviour of zirconium during electrorefining was investigated. The maximum amount of actinides that can be oxidised without anodic co-dissolution of zirconium was determined at a selected constant cathodic current density. The experiment consisted of three steps to assess the different stages of the electrorefining process, each of which employing a fresh aluminium cathode. The results indicate that almost a complete dissolution of the actinides without co-dissolution of zirconium is possible under the applied experimental conditions.

Wear Resistance Increase by Friction Stir Processing for Partial Magnesium Replacement in Aluminium Alloys

NASA Astrophysics Data System (ADS)

Balos, Sebastian; Labus Zlatanovic, Danka; Janjatovic, Petar; Dramicanin, Miroslav; Rajnovic, Dragan; Sidjanin, Leposava

2018-03-01

In this paper, the influence of friction stir processing (FSP) was evaluated as a way of increasing mechanical properties and a way of replacing the magnesium content in aluminium alloys. FSP was done on AA5754 H111 aluminium alloy, containing 3 % Mg, by using various types of tools and different welding speeds, rotational speeds and tilt angles. Wear test was done against SiC abrasive papers. SiC was used to simulate extreme abrasive wear conditions. The wear test was done on untreated AA5754 specimens, processed AA5754 specimens and untreated AA5083 H111 specimens, the latter containing 4.5 % Mg. AA5083 was chosen as an alternative to AA5754, but with a significantly higher Mg content. Base material microhardness was 60 HV1 and 80 HV1 for AA5754 and AA5083 alloys respectively. To find the effect of FSP on AA5754 alloy, microstructures were studied, mainly grain size in the stir zone. It was found, that an elevated processing and rotational speed, without tilt angle and the tool without a reservoir resulted in an increase in hardness of the AA5754 to 70 HV1, but with the occurrence of tunneling defect and the wear rate of 79.3 mg. Lower FSP parameters and a tilted tool with a reservoir resulted in microhardness of 68 HV1 and wear rate of 68.2 mg without tunneling. These wear values are lower than those obtained with unmodified Al-alloys: AA5754 97.2 mg and AA5083 86.3 mg. An increased wear resistance can be attributed to the combined effect of grain boundary strengthening mechanism and solid solution strengthening, versus only the latter in untreated alloys.

Foaming of aluminium-silicon alloy using concentrated solar energy

DOE Office of Scientific and Technical Information (OSTI.GOV)

Cambronero, L.E.G.; Ruiz-Roman, J.M.; Canadas, I.

2010-06-15

Solar energy is used for the work reported here as a nonconventional heating system to produce aluminium foam from Al-Si alloy precursors produced by powder metallurgy. A commercial precursor in cylindrical bars enclosed in a stainless-steel mould was heated under concentrated solar radiation in a solar furnace with varied heating conditions (heating rate, time, and temperature). Concentrated solar energy close to 300 W/cm{sup 2} on the mould is high enough to achieve complete foaming after heating for only 200 s. Under these conditions, the density and pore distribution in the foam change depending on the solar heating parameters and mouldmore » design. (author)« less

Delamination properity of 2060 aluminium lithium alloy laminate

NASA Astrophysics Data System (ADS)

Guo, Xiang; Huang, Yi; Tong, Dihua; Ma, Shaojun

2018-03-01

Delamination is an significant property of aluminium lithium alloy laminate for damage tolerance design. Double Crack Lap Shear specimens of "2/1" structure are used for testing delamination properity. Experiments of 2 stress ratio conditions R=0.06, 0.5 are conducted, and 5 stress levels for each stress ratio. Delamination growth data b-N are obtained from 4 crack tips’ locations. The energy release rate, Gd, of the "2/1" structure laminate are calculated. Alderliesten modelis used for describing delamination growth db/dN and energy release rate Gd. Parameters Cd and nd in Alderliesten model are determined for R=0.06 and R=0.5 by linear fitting. An analysis is made by comparing the results of different stress ratio conditons.

Investigation of Selective Laser Melting Surface Alloyed Aluminium Metal Matrix Dispersive Reinforced Layers

NASA Astrophysics Data System (ADS)

Kamburov, V. V.; Dimitrova, R. B.; Kandeva, M. K.; Sofronov, Y. P.

2018-01-01

The aim of the paper is to investigate the improvement of mechanical properties and in particular wear resistance of laser surface alloyed dispersive reinforced thin layers produced by selective laser melting (SLM) technology. The wear resistance investigation of aluminium matrix composite layers in the conditions of dry friction surface with abrasive particles and nanoindentation tests were carried out. The process parameters (as scan speed) and their impact on the wear resistant layers have been evaluated. The alloyed layers containing metalized SiC particles were studied by Optical and Scanning Electron Microscopy (SEM) and Energy Dispersive X-ray microanalysis (EDX). The obtained experimental results of the laser alloyed thin layers show significant development of their wear resistance and nanohardness due to the incorporated reinforced phase of electroless nickel coated SiC particles.

Direct chill casting of aluminium alloys under electromagnetic interaction by permanent magnet assembly

NASA Astrophysics Data System (ADS)

Bojarevičs, Andris; Kaldre, Imants; Milgrāvis, Mikus; Beinerts, Toms

2018-05-01

Direct chill casting is one of the methods used in industry to obtain good microstructure and properties of aluminium alloys. Nevertheless, for some alloys grain structure is not optimal. In this study, we offer the use of electromagnetic interaction to modify melt convection near the solidification interface. Solidification under various electromagnetic interactions has been widely studied, but usually at low solidification velocity and high thermal gradient. This type of interaction may succeed fragmentation of dendrite arms and transport of solidification nuclei thus leading to improved material structure and properties. Realization of experimental small-scale crystallizer and electromagnetic system has been described in this article.

Regarding to the Variance Analysis of Regression Equation of the Surface Roughness obtained by End Milling process of 7136 Aluminium Alloy

NASA Astrophysics Data System (ADS)

POP, A. B.; ȚÎȚU, M. A.

2016-11-01

In the metal cutting process, surface quality is intrinsically related to the cutting parameters and to the cutting tool geometry. At the same time, metal cutting processes are closely related to the machining costs. The purpose of this paper is to reduce manufacturing costs and processing time. A study was made, based on the mathematical modelling of the average of the absolute value deviation (Ra) resulting from the end milling process on 7136 aluminium alloy, depending on cutting process parameters. The novel element brought by this paper is the 7136 aluminium alloy type, chosen to conduct the experiments, which is a material developed and patented by Universal Alloy Corporation. This aluminium alloy is used in the aircraft industry to make parts from extruded profiles, and it has not been studied for the proposed research direction. Based on this research, a mathematical model of surface roughness Ra was established according to the cutting parameters studied in a set experimental field. A regression analysis was performed, which identified the quantitative relationships between cutting parameters and the surface roughness. Using the variance analysis ANOVA, the degree of confidence for the achieved results by the regression equation was determined, and the suitability of this equation at every point of the experimental field.

Steam assisted oxide growth on aluminium alloys using oxidative chemistries: Part I Microstructural investigation

NASA Astrophysics Data System (ADS)

Din, Rameez Ud; Piotrowska, Kamila; Gudla, Visweswara Chakravarthy; Jellesen, Morten Stendahl; Ambat, Rajan

2015-11-01

The surface treatment of aluminium alloys under steam containing KMnO4 and HNO3 resulted in the formation of an oxide layer having a thickness of up to 825 nm. The use of KMnO4 and HNO3 in the steam resulted in incorporation of the respective chemical species into the oxide layer. Steam treatment with solution containing HNO3 caused dissolution of Cu and Si from the intermetallic particles in the aluminium substrate. The growth rate of oxide layer was observed to be a function of MnO4- and NO3- ions present in the aqueous solution. The NO3- ions exhibit higher affinity towards the intermetallic particles resulting in poor coverage by the steam generated oxide layer compared to the coating formed using MnO4- ions. Further, increase in the concentration of NO3- ions in the solution retards precipitation of the steam generated aluminium hydroxide layer.

Formation of A Non-detachable Welded Titanium-aluminium Compound by Laser Action

NASA Astrophysics Data System (ADS)

Murzin, Serguei P.

2018-01-01

Progressive in the welding of dissimilar materials is the use of laser technology. With the use of the ROFIN StarWeld Manual Performance laser, an aluminium alloy AK4 and a titanium alloy VT5-1 were welded. Processing regimes have been determined, the realization of which during melting of materials in the zone of thermal influence makes it possible to obtain a homogeneous structure without voids and shells, which indicates a potential sufficiently high serviceability of the welded joint. To create the required power density distribution in the cross section of the laser beam, it is expedient to use diffractive optical elements.

Frictional conditions between alloy AA6060 aluminium and tool steel

DOE Office of Scientific and Technical Information (OSTI.GOV)

Wideroee, Fredrik; Welo, Torgeir

The frictional conditions in the new process of screw extrusion of aluminium have been investigated. The contact behaviour between the aluminum alloy and the tool steel in the extruder is vital for understanding the extrusion process. Using a compressive-rotational method for frictional measurements the conditions for unlubricated sticking friction between aluminum alloy AA6060 and tool steel at different combinations of temperatures and pressures have been investigated. In this method the samples in the form of disks are put under hydrostatic pressure while simultaneously being rotated at one end. Pins made from contrast material have been inserted into the samples tomore » measure the deformation introduced. This approach along with 3D simulations form a method for determining the frictional conditions. The paper describes the test method and the results. It was found that the necessary pressure for sticking to occur between the aluminum AA6060 and the different parts of the extruder is heavily influenced by the temperature.« less

AE Monitoring of Diamond Turned Rapidly Soldified Aluminium 443

NASA Astrophysics Data System (ADS)

Onwuka, G.; Abou-El-Hossein, K.; Mkoko, Z.

2017-05-01

The fast replacement of conventional aluminium with rapidly solidified aluminium alloys has become a noticeable trend in the current manufacturing industries involved in the production of optics and optical molding inserts. This is as a result of the improved performance and durability of rapidly solidified aluminium alloys when compared to conventional aluminium. Melt spinning process is vital for manufacturing rapidly solidified aluminium alloys like RSA 905, RSA 6061 and RSA 443 which are common in the industries today. RSA 443 is a newly developed alloy with few research findings and huge research potential. There is no available literature focused on monitoring the machining of RSA 443 alloys. In this research, Acoustic Emission sensing technique was applied to monitor the single point diamond turning of RSA 443 on an ultrahigh precision lathe machine. The machining process was carried out after careful selection of feed, speed and depths of cut. The monitoring process was achieved with a high sampling data acquisition system using different tools while concurrent measurement of the surface roughness and tool wear were initiated after covering a total feed distance of 13km. An increasing trend of raw AE spikes and peak to peak signal were observed with an increase in the surface roughness and tool wear values. Hence, acoustic emission sensing technique proves to be an effective monitoring method for the machining of RSA 443 alloy.

Hot-crack test for aluminium alloys welds using TIG process

NASA Astrophysics Data System (ADS)

Niel, A.; Deschaux-Beaume, F.; Bordreuil, C.; Fras, G.

2010-06-01

Hot cracking is a critical defect frequently observed during welding of aluminium alloys. In order to better understand the interaction between cracking phenomenon, process parameters, mechanical factors and microstructures resulting from solidification after welding, an original hot-cracking test during welding is developed. According to in-situ observations and post mortem analyses, hot cracking mechanisms are investigated, taking into account the interaction between microstructural parameters, depending on the thermal cycles, and mechanical parameters, depending on geometry and clamping conditions of the samples and on the thermal field on the sample. Finally, a process map indicating the limit between cracking and non-cracking zones according to welding parameters is presented.

Enhancing elevated temperature strength of copper containing aluminium alloys by forming L12 Al3Zr precipitates and nucleating θ″ precipitates on them.

PubMed

Kumar Makineni, Surendra; Sugathan, Sandeep; Meher, Subhashish; Banerjee, Rajarshi; Bhattacharya, Saswata; Kumar, Subodh; Chattopadhyay, Kamanio

2017-09-11

Strengthening by precipitation of second phase is the guiding principle for the development of a host of high strength structural alloys, in particular, aluminium alloys for transportation sector. Higher efficiency and lower emission demands use of alloys at higher operating temperatures (200 °C-250 °C) and stresses, especially in applications for engine parts. Unfortunately, most of the precipitation hardened aluminium alloys that are currently available can withstand maximum temperatures ranging from 150-200 °C. This limit is set by the onset of the rapid coarsening of the precipitates and consequent loss of mechanical properties. In this communication, we present a new approach in designing an Al-based alloy through solid state precipitation route that provides a synergistic coupling of two different types of precipitates that has enabled us to develop coarsening resistant high-temperature alloys that are stable in the temperature range of 250-300 °C with strength in excess of 260 MPa at 250 °C.

Optimization of Aluminium-to-Magnesium Ultrasonic Spot Welding

NASA Astrophysics Data System (ADS)

Panteli, A.; Chen, Y.-C.; Strong, D.; Zhang, Xiaoyun; Prangnell, P. B.

2012-03-01

The ability to join dissimilar materials in the automotive industry will result in more efficient multimaterial structures. However, welding of aluminium (Al) to magnesium (Mg) alloys is problematic because of the rapid formation of brittle intermetallic phases at the weld interface. Ultrasonic welding (USW) is a solid-state joining technology that may offer a potential solution, but USW of Al to Mg is currently not well understood. Here, we have investigated the effect of process variables and energy input on joint formation between Al-6111 and Mg-AZ31 alloys, and we report on the optimum welding conditions, heat generation, and the formation of a significant intermetallic reaction layer. Furthermore, the factors influencing the interface reaction rate and the advantages of precoating the Mg with Al are discussed.

Aluminum-lithium alloys in helicopters

DOE Office of Scientific and Technical Information (OSTI.GOV)

Smith, A.F.

1997-10-01

Aluminium-lithium alloys are widely applied on the EH101 helicopter, designed and built jointly by GKN Westland Helicopters of England and Agusta S.p.A. of Italy. With the exception of the powder metallurgy alloy AA 5091, all the current commercially available aluminum-lithium alloys are produced by direct-chill casting, and require a precipitation-aging heat treatment to achieve the required properties. In aluminum-lithium alloys containing greater than 1.3% (by weight) of lithium, the intermetallic phase {delta}{prime}-Al{sub 3}Li precipitates upon natural or artificial aging, but the associated strengthening effect is insufficient to meet the medium or high strength levels usually required (the damage tolerant tempermore » in AA 8090 is an exception).« less

The effect of strain rate on the evolution of microstructure in aluminium alloys.

PubMed

Leszczyńska-Madej, B; Richert, M

2010-03-01

Intensive deformations influence strongly microstructure. The very well-known phenomenon is the diminishing dimension of grain size by the severe plastic deformation (SPD) methods. The nanometric features of microstructure were discovered after the SPD deformation of various materials, such as aluminium alloys, iron and others. The observed changes depended on the kind of the deformed material, amount of deformation, strain rate, existence of different phases and stacking fault energy. The influence of the strain and strain rate on the microstructure is commonly investigated nowadays. It was found that the high strain rates activate deformation in shear bands, microbands and adiabatic shear bands. It was observed that bands were places of the nucleation of nanograins in the material deformed by SPD methods. In the work, the refinement of microstructure of the aluminium alloys influenced by the high strain rate was investigated. The samples were compressed by a specially designed hammer to the deformation of phi= 0/0.62 with the strain rate in the range of [Formula in text]. The highest reduction of microbands width with the increase of the strain was found in the AlCu4Zr alloy. The influence of the strain rate on the microstructure refinement indicated that the increase of the strain rate caused the reduction of the microbands width in the all investigated materials (Al99.5, AlCu4Zr, AlMg5, AlZn6Mg2.5CuZr). A characteristic feature of the microstructure of the compressed material was large density of the shear bands and microbands. It was found that the microbands show a large misorientation to the surrounds and, except Al99.5, the large density of dislocation.

Investigation of the aluminium-aluminium oxide reversible transformation as observed by hot stage electron microscopy.

NASA Technical Reports Server (NTRS)

Grove, C. A.; Judd, G.; Ansell, G. S.

1972-01-01

Thin foils of high purity aluminium and an Al-Al2O3 SAP type of alloy were oxidised in a specially designed hot stage specimen chamber in an electron microscope. Below 450 C, amorphous aluminium oxide formed on the foil surface and was first detectable at foil edges, holes, and pits. Islands of aluminium then nucleated in this amorphous oxide. The aluminium islands displayed either a lateral growth with eventual coalescence with other islands, or a reoxidation process which caused the islands to disappear. The aluminium island formation was determined to be related to the presence of the electron beam. A mechanism based upon electron charging due to the electron beam was proposed to explain the nucleation, growth, coalescence, disappearance, and geometry of the aluminium islands.

Friction stir welding of T joints of dissimilar aluminum alloy: A review

NASA Astrophysics Data System (ADS)

Thakare, Shrikant B.; Kalyankar, Vivek D.

2018-04-01

Aluminum alloys are preferred in the mechanical design due to their advantages like high strength, good corrosion resistance, low density and good weldability. In various industrial applications T joints configuration of aluminum alloys are used. In different fields, T joints having skin (horizontal sheet) strengthen by stringers (vertical sheets) were used to increase the strength of structure without increasing the weight. T joints are usually carried out by fusion welding which has limitations in joining of aluminum alloy due to significant distortion and metallurgical defects. Some aluminum alloys are even non weldable by fusion welding. The friction stir welding (FSW) has an excellent replacement of conventional fusion welding for T joints. In this article, FSW of T joints is reviewed by considering aluminum alloy and various joint geometries for defect analysis. The previous experiments carried out on T joints shows the factors such as tool geometry, fixturing device and joint configurations plays significant role in defect free joints. It is essential to investigate the material flow during FSW to know joining mechanism and the formation of joint. In this study the defect occurred in the FSW are studied for various joint configurations and parameters. Also the effect of the parameters and defects occurs on the tensile strength are studied. It is concluded that the T-joints of different joint configurations can be pretended successfully. Comparing to base metal some loss in tensile strength was observed in the weldments as well as overall reduction of the hardness in the thermos mechanically affected zone also observed.

Isoelectronic substitutions and aluminium alloying in the Ta-Nb-Hf-Zr-Ti high-entropy alloy superconductor

NASA Astrophysics Data System (ADS)

von Rohr, Fabian O.; Cava, Robert J.

2018-03-01

High-entropy alloys (HEAs) are a new class of materials constructed from multiple principal elements statistically arranged on simple crystallographic lattices. Due to the large amount of disorder present, they are excellent model systems for investigating the properties of materials intermediate between crystalline and amorphous states. Here we report the effects of systematic isoelectronic replacements, using Mo-Y, Mo-Sc, and Cr-Sc mixtures, for the valence electron count 4 and 5 elements in the body-centered cubic (BCC) Ta-Nb-Zr-Hf-Ti high-entropy alloy (HEA) superconductor. We find that the superconducting transition temperature Tc strongly depends on the elemental makeup of the alloy, and not exclusively its electron count. The replacement of niobium or tantalum by an isoelectronic mixture lowers the transition temperature by more than 60%, while the isoelectronic replacement of hafnium, zirconium, or titanium has a limited impact on Tc. We further explore the alloying of aluminium into the nearly optimal electron count [TaNb] 0.67(ZrHfTi) 0.33 HEA superconductor. The electron count dependence of the superconducting Tc for (HEA)Al x is found to be more crystallinelike than for the [TaNb] 1 -x(ZrHfTi) x HEA solid solution. For an aluminum content of x =0.4 the high-entropy stabilization of the simple BCC lattice breaks down. This material crystallizes in the tetragonal β -uranium structure type and superconductivity is not observed above 1.8 K.

Thermomechanical treatment of welded joints of aluminum-lithium alloys modified by scandium

NASA Astrophysics Data System (ADS)

Malikov, A. G.

2017-12-01

At present, the aeronautical equipment manufacture involves up-to-date high-strength aluminum alloys of decreased density resulting from the lithium admixture. Various technologies of fusible welding of these alloys are being developed. The paper presents experimental investigations of the optimization of the laser welding of aluminum alloys with the scandium-modified welded joint after thermomechanical treatment. The effect of scandium on the micro- and macrostructure is studied along with strength characteristics of the welded joint. It is found that thermomechanical treatment allows us to obtain the strength of the welded joint 0.89 for the Al-Mg-Li system and 0.99 for the Al-Cu-Li system with the welded joint modified by scandium in comparison with the base alloy after treatment.

Friction Stir Welding of Magnesium Alloy Type AZ 31

NASA Astrophysics Data System (ADS)

Kupec, Tomáš; Behúlová, Mária; Turňa, Milan; Sahul, Miroslav

The paper deals with welding of Mg alloy of the type AZ 31 by Friction Stir Welding technology (FSW). The FSW technology is at present predominantly used for welding light metals and alloys, as aluminium, magnesium and their alloys. Experimental part consists of performing the simulation and fabrication of welded joints on a new-installed welding equipment available at the Welding Research Institute — Industrial Institute of SR Bratislava. Welding tools made of tool steel type H 13 were used for welding experiments. Geometry of welding tools was designed on the base of literature knowledge. Suitable welding parameters and conditions were determined using numerical simulation. Main emphasis was laid upon the tool revolutions, welding speed and tool bevel angle. The effect of welding parameters on the quality of welded joints was assessed. Assessment of welded joints was carried out by radiography, light microscopy, hardness measurement and EDX microanalysis. Static tensile test was employed for mechanical testing.

Evaluating stress corrosion cracking behaviour of high strength AA7075-T651 aluminium alloy

NASA Astrophysics Data System (ADS)

Prabhuraj, P.; Rajakumar, S.; Lakshminarayanan, A. K.; Balasubramanian, V.

2017-12-01

The objective of the present study is to determine the threshold stress level of stress corrosion cracking (SCC) in AA7075-T651 aluminium alloy by suitable experimentation. The test was carried out using a circumferential notch specimen in a horizontal-type constant load SCC setup in a 3.5 wt.% NaCl solution. The time to failure by SCC was determined at various loading conditions. The threshold stress of AA7075-T651 alloy was found to be 242 MPa in a 3.5 wt.% NaCl solution. The various regions of the fractured surface specimen such as machined notch, SCC region and final overload fracture area were examined using scanning electron microscopy (SEM) in order to identify the SCC mechanism.

Numerical modelling in friction lap joining of aluminium alloy and carbon-fiber-reinforced-plastic sheets

NASA Astrophysics Data System (ADS)

Das, A.; Bang, H. S.; Bang, H. S.

2018-05-01

Multi-material combinations of aluminium alloy and carbon-fiber-reinforced-plastics (CFRP) have gained attention in automotive and aerospace industries to enhance fuel efficiency and strength-to-weight ratio of components. Various limitations of laser beam welding, adhesive bonding and mechanical fasteners make these processes inefficient to join metal and CFRP sheets. Friction lap joining is an alternative choice for the same. Comprehensive studies in friction lap joining of aluminium to CFRP sheets are essential and scare in the literature. The present work reports a combined theoretical and experimental study in joining of AA5052 and CFRP sheets using friction lap joining process. A three-dimensional finite element based heat transfer model is developed to compute the temperature fields and thermal cycles. The computed results are validated extensively with the corresponding experimentally measured results.

Properties of welded joints in laser welding of aeronautic aluminum-lithium alloys

NASA Astrophysics Data System (ADS)

Malikov, A. G.; Orishich, A. M.

2017-01-01

The work presents the experimental investigation of the laser welding of the aluminum-lithium alloys (system Al-Mg-Li) and aluminum alloy (system Al-Cu-Li) doped with Sc. The influence of the nano-structuring of the surface layer welded joint by the cold plastic deformation method on the strength properties of the welded joint is determined. It is founded that, regarding the deformation degree over the thickness, the varying value of the welded joint strength is different for these aluminum alloys.

Study of twin-roll cast Aluminium alloys subjected to severe plastic deformation by equal channel angular pressing

NASA Astrophysics Data System (ADS)

Poková, M.; Cieslar, M.

2014-08-01

Aluminium alloys prepared by twin-roll casting method become widely used in industry applications. Their high solid solution supersaturation and finer grains ensure better mechanical properties when compared with the direct-chill cast ones. One of the possibilities how to enhance their thermal stability is the addition of zirconium. After heat treatment Al3Zr precipitates form and these pin moving grain boundaries when the material is exposed to higher temperatures. In the present work twin-roll cast aluminium alloys based on AA3003 with and without Zr addition were annealed for 8 hours at 450 °C to enable precipitation of Al3Zr phase. Afterwards they were subjected to severe plastic deformation by equal channel angular pressing, which led to the reduction of average grain size under 1 μm. During subsequent isochronal annealing recovery and recrystallization took place. These processes were monitored by microhardness measurements, light optical microscopy and in-situ transmission electron microscopy. The addition of Zr stabilizes the grain size and increases the recrystallization temperature by 100 °C.

Weldability of Aluminium Alloys for Automotive Applications

NASA Astrophysics Data System (ADS)

Löveborn, D.; Larsson, J. K.; Persson, K.-A.

Restrictions in CO2-emissions have caused increased demands on decreased weight and increased use of lightweight materials in the automotive industry. Aluminium has shown to be of great interest due to its beneficial weight to strength ratio, and are suitable for hang-on parts such as roof, doors etc. However, the use of aluminium requires reliable joining techniques. This project has been focusing on laser welding of aluminium. It have been reported earlier that hot cracks and porosity are common defects while joining aluminium with laser welding. The aim with this project has been to produce crack free laser welds while joining thin aluminium sheets. Two different optics have been used in this project, oscillating- and triple-spot optics. The results from the experiments show that both the oscillating optics and the triple-spot optics can produce crack free welds. The amount of pores is shown to be low for both cases. The results do also show that the amount of pores in the welds increases with the weld length while the flange length is of minor impact. The mechanical properties are similar for the both optics. The oscillation specimens receive a higher tensile strength while the triple-spot specimens receive a larger elongation at break value.

The effects of alloying elements on microstructures and mechanical properties of tungsten inert gas welded AZ80 magnesium alloys joint

NASA Astrophysics Data System (ADS)

Li, Hui; Zhang, Jiansheng; Ding, Rongrong

2017-11-01

The effects of alloying elements on the macrostructures, microstructures and tensile strength of AZ80 Mg alloy weldments were studied in the present study. The results indicate that with the decrease of Al element content of filler wire, the welding defects of seam are gradually eliminated and the β-Mg17Al12 phases at α-Mg boundaries are refined and become discontinuous, which are beneficial to the improvement of tensile strength. With AZ31 Mg alloy filler wire, the maximum tensile strength of AZ80 weldment is 220 MPa and fracture occurs at the welding seam of joint. It is experimentally proved that robust AZ80 Mg alloy joints can be obtained by tungsten inert gas (TIG) welding process with AZ31 Mg alloy filler wire. However, further study is required to improve the microstructures and reduce welding defects of joint in order to further improve the joining strength of AZ80 Mg alloy joint.

Properties of experimental copper-aluminium-nickel alloys for dental post-and-core applications.

PubMed

Rittapai, Apiwat; Urapepon, Somchai; Kajornchaiyakul, Julathep; Harniratisai, Choltacha

2014-06-01

This study aimed to develop a copper-aluminium-nickel alloy which has properties comparable to that of dental alloys used for dental post and core applications with the reasonable cost. Sixteen groups of experimental copper alloys with variants of 3, 6, 9, 12 wt% Al and 0, 2, 4, 6 wt% Ni were prepared and casted. Their properties were tested and evaluated. The data of thermal, physical, and mechanical properties were analyzed using the two-way ANOVA and Tukey's test (α=0.05). The alloy toxicity was evaluated according to the ISO standard. The solidus and liquidus points of experimental alloys ranged from 1023℃ to 1113℃ and increased as the nickel content increased. The highest ultimate tensile strength (595.9 ± 14.2 MPa) was shown in the Cu-12Al-4Ni alloy. The tensile strength was increased as the both elements increased. Alloys with 3-6 wt% Al exhibited a small amount of 0.2% proof strength. Accordingly, the Cu-9Al-2Ni and Cu-9Al-4Ni alloys not only demonstrated an appropriate modulus of elasticity (113.9 ± 8.0 and 122.8 ± 11.3 GPa, respectively), but also had a value of 0.2% proof strength (190.8 ± 4.8 and 198.2 ± 3.4 MPa, respectively), which complied with the ISO standard requirement (>180 MPa). Alloys with the highest contents of nickel (6 wt% Ni) revealed a widespread decolourisation zone (5.0-5.9 mm), which correspondingly produced the largest cell response, equating positive control. The copper alloys fused with 9 wt% Al and 2-4 wt% Ni can be considered for a potential use as dental post and core applications.

Complex deformation routes for direct recycling aluminium alloy scrap via industrial hot extrusion

NASA Astrophysics Data System (ADS)

Paraskevas, Dimos; Kellens, Karel; Kampen, Carlos; Mohammadi, Amirahmad; Duflou, Joost R.

2018-05-01

This paper presents the final results of an industrial project, aiming for direct hot extrusion of wrought aluminium alloy scrap at an industrial scale. Two types of complex deformation/extrusion routes were tested for the production of the same profile, starting from AA6060 scrap in form of machining chips. More specifically scrap-based billets were extruded through: a 2-porthole and a 4-porthole die-set, modified for enhanced scrap consolidation and grain refinement. For comparison reasons, cast billets of the same alloy were extruded through the modified 2-porthole die set. The tensile testing results as well as microstructural investigations show that the 4-porthole extrusion route further improves scrap consolidation compared to the 2-porthole die output. The successful implementation of solid state recycling, directly at industrial level, indicates the technological readiness level of this research.

Effects of various tool pin profiles on mechanical and metallurgical properties of friction stir welded joints of cryorolled AA2219 aluminium alloy

NASA Astrophysics Data System (ADS)

Kamal Babu, Karupannan; Panneerselvam, Kavan; Sathiya, Paulraj; Noorul Haq, Abdul Haq; Sundarrajan, Srinivasan; Mastanaiah, Potta; Srinivasa Murthy, Chunduri Venkata

2018-02-01

Friction stir welding (FSW) process was conducted on cryorolled (CR) AA2219 plate using different tool pin profiles such as cylindrical pin, threaded cylindrical pin, square pin and hexagonal pin profiles. The FSW was carried out with pairs of 6 mm thick CR aluminium plates with different tool pin profiles. The different tool pin profile weld portions' behaviors like mechanical (tensile strength, impact and hardness) and metallurgical characteristics were analyzed. The results of the mechanical analysis revealed that the joint made by the hexagonal pin tool had good strength compared to other pin profiles. This was due to the pulsating action and material flow of the tool resulting in dynamic recrystallization in the weld zone. This was confirmed by the ultra fine grain structure formation in Weld Nugget (WN) of hexagonal pin tool joint with a higher percentage of precipitate dissolution. The fractograph of the hexagonal tool pin weld portion confirmed the finer dimple structure morphology without having any interior defect compared to other tool pin profiles. The lowest weld joint strength was obtained from cylindrical pin profile weld joint due to insufficient material flow during welding. The Transmission Electron Microscope and EDX analysis showed the dissolution of the metastable θ″, θ' (Al2Cu) partial precipitates in the WN and proved the influence of metastable precipitates on enhancement of mechanical behavior of weld. The XRD results also confirmed the Al2Cu precipitation dissolution in the weld zone.

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. Copyright © 2014 Elsevier B.V. All rights reserved.

Thermal analysis of laser additive manufacturing of aluminium alloys: Experiment and simulation

NASA Astrophysics Data System (ADS)

Bock, Frederic E.; Froend, Martin; Herrnring, Jan; Enz, Josephin; Kashaev, Nikolai; Klusemann, Benjamin

2018-05-01

Laser additive manufacturing (LAM) has become increasingly popular in industry in recent decades because it enables exceptional degrees of freedom regarding the structural design of lightweight components compared to subtractive manufacturing techniques. Laser metal deposition (LMD) of wire-fed material shows in particular the advantages such as high process velocity and efficient use of material compared to other LAM processes. During wire-based LMD, the material is deposited onto a substrate and supplemented by successive layers allowing a layer-wise production of complex three-dimensional structures. Despite the increased productivity of LMD, regarding the ability to process aluminium alloys, there is still a lack in quality and reproducibility due to the inhomogeneous temperature distribution during the process, leading to undesired residual stresses, distortions and inconsistent layer geometries and poor microstructures. In this study, the aluminium alloy AA5087 as wire and AA5754 as substrate material were utilized for LMD. In order to obtain information about the temperature field during LMD, thermocouple and thermography measurements were performed during the process. The temperature measurements were used to validate a finite element model regarding the heat distribution, which will be further used to investigate the temperature field evolution over time. To consider the continuous addition of material within the FE-model, an inactive/active element approach was chosen, where initially deactivated elements are activated corresponding to the deposition of material. The first results of the simulation and the experiments show good agreement. Therefore, the model can be used in the future for LMD process optimization, e.g., in terms of minimizing local variations of the thermal load for each layer.

Finite element simulations of the Portevin Le Chatelier effect in aluminium alloy

NASA Astrophysics Data System (ADS)

Hopperstad, O. S.; Børvik, T.; Berstad, T.; Benallal, A.

2006-08-01

Finite element simulations of the Portevin-Le Chatelier effect in aluminium alloy 5083-H116 are presented and evaluated against existing experimental results. The constitutive model of McCormick (1988) for materials exhibiting negative steady-state strain-rate sensitivity is incorporated into an elastic-viscoplastic model for large plastic deformations and implemented in LS-DYNA for use with the explicit or implicit solver. Axisymmetric tensile specimens loaded at different strain rates are studied numerically, and it is shown that the model predicts the experimental behaviour with reasonable accuracy; including serrated yielding and propagating bands of localized plastic deformation along the gauge length of the specimen at intermediate strain rates.

Characterising ductility of 6xxx-series aluminium sheet alloys at combined loading conditions

NASA Astrophysics Data System (ADS)

Henn, Philipp; Liewald, Mathias; Sindel, Manfred

2017-10-01

This paper presents a new approach to characterise material ductility when combined, three dimensional loading conditions occurring during vehicle crash are applied. So called "axial crush test" of closed hat sections is simplified by reducing it down to a two-dimensional testing procedure. This newly developed edge-compression test (ECT) provides the opportunity to investigate a defined characteristic axial folding behaviour of a profile edge. The potential to quantify and to differentiate crashworthiness of material by use of new edge-compression test is investigated by carrying out experimental studies with two different 6xxx-aluminium sheet alloys.

3D study of intermetallics and their effect on the corrosion morphology of rheocast aluminium alloy

DOE Office of Scientific and Technical Information (OSTI.GOV)

Mingo, B.; Arrabal, R., E-mail: rarrabal@ucm.es; Pardo, A.

In the present study, the effect of heat treatment T6.1 on the microstructure and corrosion behaviour of rheocast aluminium alloy A356 is investigated on the basis of 2D/3D characterization techniques and electrochemical and SKPFM measurements. Heat treatment strengthens the α-Al matrix, modifies the intermetallic particles and spheroidizes eutectic Si. These changes do not modify significantly the corrosion behaviour of the alloy. 3D SEM-Tomography clearly shows that the corrosion advances in the shape of narrow paths between closely spaced intermetallics without a major influence of eutectic Si. - Highlights: • T6.1 spheroidizes Si, strengthens the matrix and modifies the intermetallics. •more » Electrochemical behaviour of untreated and heat-treated alloys is similar. • 3D SEM-Tomography provides additional information on the corrosion morphology. • Corrosion advances as paths between intermetallics with little influence of Si.« less

New Light Alloys (Les Nouveaux Alliages Legers)

DTIC Science & Technology

1990-09-01

Authors/Speakers iv Reference Introduction I by IGA P.Costa The Development of Aluminium Lithium Alloys: An Overview I by C. J.Peel The Microstructure...Magnesium Alloys 7 by DJ.Bray V 1 INTRODUCTION by Paul Costa Materials Department, Head, ONERA BP 72 F92322 Chatillon Cedex France The last fifteen years... INTRODUCTION For the last decade the aluminium industry has been redeveloping aluminium-lithium alloys for aerospace use. Whilst not new in concept or

Effect of 1.0% Ni on high-temperature impression creep and hardness of recycled aluminium alloy with high Fe content

NASA Astrophysics Data System (ADS)

Faisal, M.; Mazni, Noor; Prasada Rao, A. K.

2018-03-01

Reported work focusses on the effect of 1.0% Ni addition on the microstructure, high- temperature impression creep and thereby the hardness of recycled Al-alloy containing >2wt% Fe, obtained from automotive scrap. Present studies have shown that the addition of 1.0% Ni have supress the formation of α-phase (Al5FeSi) by supressing the peritectic transformation of β-phase (Al8Fe2Si). Such suppression is found to improve the hardness and high-temperature impression creep of the recycled aluminium alloy.

Study of strength properties of semi-finished products from economically alloyed high-strength aluminium-scandium alloys for application in automobile transport and shipbuilding

NASA Astrophysics Data System (ADS)

Baranov, Vladimir; Sidelnikov, Sergey; Zenkin, Evgeny; Frolov, Viktor; Voroshilov, Denis; Yakivyuk, Olga; Konstantinov, Igor; Sokolov, Ruslan; Belokonova, Irina

2018-04-01

The results of a study on the strength of rolled products from aluminium alloys doped with scandium under various processing conditions of hot and cold rolling are presented. The regularities of metal flow and the level of strength of deformed semi-finished products from aluminum-scandium alloys are established, depending on the total degree of deformation and the various modes of single reduction during rolling. It is shown that when using one heating of a cast billet to obtain high-quality semi-finished products, the temperature during the rolling process should not be lower than 350-370°, and the total degree of deformation does not exceed 50-60%. It was found that the semi-finished products from alloys with a content of scandium in the range 0.11-0.12% in the deformed state had elevated values of ultimate tensile strength and yield strength of the metal, which allows them to be recommended for industrial production of sheet metal products.

Non-destructive and three-dimensional measurement of local strain development during tensile deformation in an aluminium alloy

NASA Astrophysics Data System (ADS)

Kobayashi, M.; Miura, H.; Toda, H.

2015-08-01

Anisotropy of mechanical responses depending on crystallographic orientation causes inhomogeneous deformation on the mesoscopic scale (grain size scale). Investigation of the local plastic strain development is important for discussing recrystallization mechanisms, because the sites with higher local plastic strain may act as potential nucleation sites for recrystallization. Recently, high-resolution X-ray tomography, which is non-destructive inspection method, has been utilized for observation of the materials structure. In synchrotron radiation X-ray tomography, more than 10,000 microstructural features, like precipitates, dispersions, compounds and hydrogen pores, can be observed in aluminium alloys. We have proposed employing these microstructural features as marker gauges to measure local strains, and then have developed a method to calculate the three-dimensional strain distribution by tracking the microstructural features. In this study, we report the development of local plastic strain as a function of the grain microstructure in an aluminium alloy by means of this three-dimensional strain measurement technique. Strongly heterogeneous strain development was observed during tensile loading to 30%. In other words, some parts of the sample deform little whereas another deforms a lot. However, strain in the whole specimen was keeping harmony. Comparing the microstructure with the strain concentration that is obtained by this method has a potential to reveal potential nucleation sites of recrystallization.

Fatigue Strength Estimation Based on Local Mechanical Properties for Aluminum Alloy FSW Joints

PubMed Central

Sillapasa, Kittima; Mutoh, Yoshiharu; Miyashita, Yukio; Seo, Nobushiro

2017-01-01

Overall fatigue strengths and hardness distributions of the aluminum alloy similar and dissimilar friction stir welding (FSW) joints were determined. The local fatigue strengths as well as local tensile strengths were also obtained by using small round bar specimens extracted from specific locations, such as the stir zone, heat affected zone, and base metal. It was found from the results that fatigue fracture of the FSW joint plate specimen occurred at the location of the lowest local fatigue strength as well as the lowest hardness, regardless of microstructural evolution. To estimate the fatigue strengths of aluminum alloy FSW joints from the hardness measurements, the relationship between fatigue strength and hardness for aluminum alloys was investigated based on the present experimental results and the available wide range of data from the references. It was found as: σa (R = −1) = 1.68 HV (σa is in MPa and HV has no unit). It was also confirmed that the estimated fatigue strengths were in good agreement with the experimental results for aluminum alloy FSW joints. PMID:28772543

Fatigue Strength Estimation Based on Local Mechanical Properties for Aluminum Alloy FSW Joints.

PubMed

Sillapasa, Kittima; Mutoh, Yoshiharu; Miyashita, Yukio; Seo, Nobushiro

2017-02-15

Overall fatigue strengths and hardness distributions of the aluminum alloy similar and dissimilar friction stir welding (FSW) joints were determined. The local fatigue strengths as well as local tensile strengths were also obtained by using small round bar specimens extracted from specific locations, such as the stir zone, heat affected zone, and base metal. It was found from the results that fatigue fracture of the FSW joint plate specimen occurred at the location of the lowest local fatigue strength as well as the lowest hardness, regardless of microstructural evolution. To estimate the fatigue strengths of aluminum alloy FSW joints from the hardness measurements, the relationship between fatigue strength and hardness for aluminum alloys was investigated based on the present experimental results and the available wide range of data from the references. It was found as: σ a ( R = -1) = 1.68 HV ( σ a is in MPa and HV has no unit). It was also confirmed that the estimated fatigue strengths were in good agreement with the experimental results for aluminum alloy FSW joints.

Evaluation of Mechanical Properties of MWCNT / Nanoclay Reinforced Aluminium alloy Metal Matrix Composite

NASA Astrophysics Data System (ADS)

Ratna Kumar, P. S. Samuel; Robinson Smart, D. S.; Alexis, S. John

2018-04-01

Aluminium alloy 5083 (AA5083) is a widely used material in aerospace, marine, defence and structural applications were mechanical and corrosion resistance property plays a vital role. For the present work, MWCNT / Nanoclay (montmorillonite (MMT) K10) mixed with AA5083 for different composition in weight percentage to enhance the mechanical property. Semi-solid state casting method (Compo-casting) was used to fabricate the composite materials. By using Field-emission scanning electron microscope (FESEM) the uniform dispersion of the reinforcement and microstructure were studied. Finally, the addition of Nanoclay shows decrease in tensile strength compared to the AA5083 / MWCNT composites and hardness value of the composites (AA5083 / MWCNT and AA5083 / Nanoclay) was found to increase significantly.

Two-Scale Modelling of Effects of Microstructure and Thermomechanical Properties on Dynamic Performance of an Aluminium Alloy

DTIC Science & Technology

2010-09-01

effects of crystallographic texture on the high-rate shear response of a Ti - 6Al - 4V alloy. Schoenfeld and Kad (2002) found that lattice orientations affect...shear response in Ti - 6Al - 4V plates’, Int. J. Plasticity, Vol. 18, pp.461–486. Starink, M.J., Wang, P., Sinclair, I. and Gregson, P.J. (1999... porosity and ceramic inclusions. Rezvanian et al. (2006) studied evolution of dislocation cells in aluminium undergoing severe plastic deformation using

Monomolecular Silane Coatings on Magnesium/Aluminium Fuels

DTIC Science & Technology

1991-07-01

iii SUMMARY The aim of this project was to investigate the curing reaction between CTBN and magnesium/aluminium ailoy surfaces. A dispersion of...performing rheoloqacai experiments with these coated magnesium particles and CTBN . Surface analysis ot the alloys show a nigh percentage of magnesium...Rheoloq’cai analysis of these alloys dispersed 40% w/w in CTBN show increasing rates of change in viscosity with time for each alloy with increasing nominal

Application of laser in seam welding of dissimilar steel to aluminium joints for thick structural components

NASA Astrophysics Data System (ADS)

Meco, S.; Pardal, G.; Ganguly, S.; Williams, S.; McPherson, N.

2015-04-01

Laser welding-brazing technique, using a continuous wave (CW) fibre laser with 8000 W of maximum power, was applied in conduction mode to join 2 mm thick steel (XF350) to 6 mm thick aluminium (AA5083-H22), in a lap joint configuration with steel on the top. The steel surface was irradiated by the laser and the heat was conducted through the steel plate to the steel-aluminium interface, where the aluminium melts and wets the steel surface. The welded samples were defect free and the weld micrographs revealed presence of a brittle intermetallic compounds (IMC) layer resulting from reaction of Fe and Al atoms. Energy Dispersive Spectroscopy (EDS) analysis indicated the stoichiometry of the IMC as Fe2Al5 and FeAl3, the former with maximum microhardness measured of 1145 HV 0.025/10. The IMC layer thickness varied between 4 to 21 μm depending upon the laser processing parameters. The IMC layer showed an exponential growth pattern with the applied specific point energy (Esp) at a constant power density (PD). Higher PD values accelerate the IMC layer growth. The mechanical shear strength showed a narrow band of variation in all the samples (with the maximum value registered at 31.3 kN), with a marginal increase in the applied Esp. This could be explained by the fact that increasing the Esp results into an increase in the wetting and thereby the bonded area in the steel-aluminium interface.

Corrosion characterization of in-situ titanium diboride (TiB2) reinforced aluminium-copper (Al-Cu) alloy by two methods: Salts spray fog and linear polarization resistance (LPR)

NASA Astrophysics Data System (ADS)

Rosmamuhamadani, R.; Talari, M. K.; Yahaya, Sabrina M.; Sulaiman, S.; Ismail, M. I. S.; Hanim, M. A. Azmah

2018-05-01

Aluminium-copper (Al-Cu) alloys is the one of most Metal Matrix Composites (MMCs) have important high-strength Al alloys. The aluminium (Al) casting alloys, based on the Al-Cu system are widely used in light-weight constructions and transport applications requiring a combination of high strength and ductility. In this research, Al-Cu master alloy was reinforced with 3 and 6wt.% titanium diboride (TiB2) that obtained from salts route reactions. The salts used were were potassium hexafluorotitanate (K2TiF6) and potassium tetrafluoroborate (KBF4). The salts route reaction process were done at 800 °C. The Al-Cu alloy then has characterized on the mechanical properties and microstructure characterization. Salts spray fog test and Gamry-electrode potentiometer instruments were used to determine the corrosion rate of this alloys. From results obtained, the increasement of 3wt.%TiB2 contents will decrease the value of the corrosion rate. In corrosion test that conducted both of salt spray fog and Gamry-electrode potentiometer, the addition of 3wt.%TiB2 gave the good properties in corrosion characterization compare to Al-Cu-6wt.%TiB2 and Al-Cu cast alloy itself. As a comparison, Al-Cu with 3wt.%TiB2 gave the lowest value of corrosion rate, which means alloy has good properties in corrosion characterization. The results obtained show that in-situ Al-Cu alloy composites containing the different weight of TiB2 phase were synthesized successfully by the salt-metal reaction method.

Interfacial morphology of low-voltage anodic aluminium oxide

DOE Office of Scientific and Technical Information (OSTI.GOV)

Hu, Naiping; Dongcinn, Xuecheng; He, Xueying

X-ray reflectivity (XRR) and neutron reflectivity (NR), as well as ultra-smallangle X-ray scattering (USAXS), are used to examine the in-plane and surfacenormal structure of anodic films formed on aluminium alloy AA2024 and pure aluminium. Aluminium and alloy films up to 3500 A thick were deposited on Si wafers by electron beam evaporation of ingots. Porous anodic aluminium oxide (AAO) films are formed by polarizing at constant voltage up to 20 V noble to the open circuit potential. The voltage sweet spot (5 V) appropriate for constant-voltage anodization of such thin films was determined for both alloy and pure Al. Inmore » addition, a new concurrent voltage- and current-control protocol was developed to prepare films with larger pores (voltages higher than 5 V), but formed at a controlled current so that pore growth is slow enough to avoid stripping the aluminium substrate layer. USAXS shows that the pore size and interpore spacing are fixed in the first 10 s after initiation of anodization. Pores then grow linearly in time, at constant radius and interpore spacing. Using a combination of XRR and NR, the film density and degree of hydration of the films were determined from the ratio of scattering length densities. Assuming a chemical formula Al2O3xH2O, it was found that x varies from 0.29 for the native oxide to 1.29 for AAO grown at 20 V under concurrent voltage and current control. The average AAO film density of the porous film at the air surface is 2.45 (20) g cm3. The density of the barrier layer at the metal interface is 2.9 (4) g cm3, which indicates that this layer is also quite porous« less

Distribution of trace elements in a modified and grain refined aluminium-silicon hypoeutectic alloy.

PubMed

Faraji, M; Katgerman, L

2010-08-01

The influence of modifier and grain refiner on the nucleation process of a commercial hypoeutectic Al-Si foundry alloy (A356) was investigated using optical microscopy, scanning electron microscopy (SEM) and electron probe microanalysis technique (EPMA). Filtering was used to improve the casting quality; however, it compromised the modification of silicon. Effect of filtering on strontium loss was also studied using the afore-mentioned techniques. EPMA was used to trace the modifying and grain refining agents inside matrix and eutectic Si. This was to help understanding mechanisms of nucleation and modification in this alloy. Using EPMA, the negative interaction of Sr and Al3TiB was closely examined. In modified structure, it was found that the maximum point of Sr concentration was in line with peak of silicon; however, in case of just 0.1wt% added Ti, the peak of Ti concentration was not in line with aluminium, (but it was close to Si peak). Furthermore, EPMA results showed that using filter during casting process lowered the strontium content, although produced a cleaner melt. (c) 2010 Elsevier Ltd. All rights reserved.

In temperature forming of friction stir lap welds in aluminium alloys

NASA Astrophysics Data System (ADS)

Bruni, Carlo; Cabibbo, Marcello; Greco, Luciano; Pieralisi, Massimiliano

2018-05-01

The objective of such investigation is the study in depth of the forming phase of welds realized on three sheet metal blanks in aluminium alloys by friction stir lap welding. Such forming phase was performed by upsetting at different constant forming temperatures varying from 200°C to 350°C with constant ram velocities of 0.01 and 0.1 mm/s. The temperature values were obtained by the use of heating strips applied on the upper tool and on the lower tool. It was observed an increase in the friction factor, acting at the upsetting tool-workpiece interface, with increasing temperature that is very useful in producing the required localized deformation with which to improve the weld. It was also confirmed that the forming phase allows to realize a required thickness in the weld area allowing to neglect the surficial perturbation produced by the friction stir welding tool shoulder. The obtained thickness could be subjected to springback when too low temperatures are considered.

Inhibitory effect of konjac glucomanan on pitting corrosion of AA5052 aluminium alloy in NaCl solution.

PubMed

Zhang, Kegui; Yang, Wenzhong; Xu, Bin; Chen, Yun; Yin, Xiaoshuang; Liu, Ying; Zuo, Huanzhen

2018-05-01

A natural carbohydrate polymer, konjac glucomanan, has been extracted from commercial product and studied as a green corrosion inhibitor for AA5052 aluminium alloy in 3.5 wt% NaCl solution by high-performance gel permeation chromatography (GPC), thermo gravimetric analysis (TGA), Fourier-transform infrared (FT-IR) spectra, electrochemical measurement and surface characterization techniques. The results of GPC measurements suggest the weight-average molecular weight and the number-average molecular weight of KGM with 98.2% purity are 1.61 × 10 5  g/mol and 1.54 × 10 5  g/mol, respectively. Potentiodynamic polarization curves show konjac glucomanan behaves as a mixed-type inhibitor with dominant anodic effect and that its maximum efficiency at 200 ppm is 94%. Electrochemical impedance spectroscopy (EIS) studies reveal the resistance of oxide film is approximately two orders of magnitude greater than the resistance of adsorbed inhibitor layer and that they both increase with KGM concentration. Moreover, in-situ electrochemical noise (EN) detection demonstrates that the growth and propagation stages of the pitting corrosion germinating on metal surface are blocked by polysaccharide additive, which is confirmed by the surface analysis of aluminium alloy using scanning electron microscope (SEM), energy dispersive spectroscopy (EDS) and Raman spectroscopy. At last, it is found that the addition of KGM makes it harder for water droplet containing NaCl to wet the metallic substrate. Copyright © 2018 Elsevier Inc. All rights reserved.

Corrosion behavior in high-temperature pressurized water of Zircaloy-4 joints brazed with Zr-Cu-based amorphous filler alloys

NASA Astrophysics Data System (ADS)

Lee, Jung Gu; Lee, Gyoung-Ja; Park, Jin-Ju; Lee, Min-Ku

2017-05-01

The compositional effects of ternary Zr-Cu-X (X: Al, Fe) amorphous filler alloys on galvanic corrosion susceptibility in high-temperature pressurized water were investigated for Zircaloy-4 brazed joints. Through an Al-induced microgalvanic reaction that deteriorated the overall nobility of the joint, application of the Zr-Cu-Al filler alloy caused galvanic coupling to develop readily between the Al-bearing joint and the Al-free base metal, finally leading to massive localized corrosion of the joint. Contrastingly, joints prepared with a Zr-Cu-Fe filler alloy showed excellent corrosion resistance comparable to that of the Zircaloy-4 base metal, since the Cu and Fe elements forming fine intermetallic particles with Zr did not influence the electrochemical stability of the resultant joints. The present results demonstrate that Fe is a more suitable alloying element than Al for brazing filler alloys subjected to high-temperature corrosive environments.

A Study on Tooling and Its Effect on Heat Generation and Mechanical Properties of Welded Joints in Friction Stir Welding

NASA Astrophysics Data System (ADS)

Tikader, Sujoy; Biswas, Pankaj; Puri, Asit Baran

2018-04-01

Friction stir welding (FSW) has been the most attracting solid state welding process as it serves numerous advantages like good mechanical, metallurgical properties etc. Non weldable aluminium alloys like 5XXX, 7XXX series can be simply joined by this process. In this present study a mathematical model has been developed and experiments were successfully performed to evaluate mechanical properties of FSW on similar aluminium alloys i.e. AA1100 for different process parameters and mainly two kind of tool geometry (straight cylindrical and conical or cylindrical tapered shaped pin with flat shoulder). Tensile strength and micro hardness for different process parameters are reported of the welded plate sample. It was noticed that in FSW of similar alloy with tool made of SS-310 tool steel, friction is the major contributor for the heat generation. It was seen that tool geometry, tool rotational speed, plunging force by the tool and traverse speed have significant effect on tensile strength and hardness of friction stir welded joints.

The effect of re-ageing on a novel thermomechanical treatment for improving the mechanical properties of AA2139 aerospace aluminium alloys

NASA Astrophysics Data System (ADS)

Ragkousis, A.; Bakare, F.; Babalola, M. I.

2017-11-01

This study presents the effects of a novel thermomechanical treatment on the mechanical properties of the AA2139 aerospace aluminium alloys. The novel treatment, which is comprised of a combination of under-aging, cold-rolling, and re-aging, was successfully employed by Wang et al (2014 Mater. Sci. Eng. A 607 313-7) to enhance the mechanical and microstructure properties of 6000 series aluminium alloys. The influence of under-ageing and re-aging parameters of the treatment on the AA2139 properties has been examined by tensile and hardness testing, differential scanning calorimetry, and thermoelectric power measurements. It was determined that a higher temperature under-ageing, combined with lower temperature and long duration re-ageing resulted in the most attractive mechanical properties, which significantly exceeded those of other traditional treatments. More specifically, a 175 °C/1.5 h under-ageing treatment, followed by a cold rolling reduction of 75% and a 110 °C/96 h re-ageing resulted in a yield strength of 554 MPa, an ultimate tensile strength of 618 MPa, and an elongation of 7.5%, far exceeding the strength requirements and 5% acceptable elongation for applications in the aerospace industry. These results, in conjunction with the results of the parallel study focusing on the effects of the cold-rolling component of the treatment (Bakare et al 2017 Mater. Res. Express 4) further reinforce the position that the treatment employed is superior to conventional ones for the 2139 alloy.

Study on aluminium-based single films.

PubMed

Vinod Kumar, G S; García-Moreno, F; Babcsán, N; Brothers, A H; Murty, B S; Banhart, J

2007-12-28

In the present paper the authors studied isolated metallic films made from the same material used for making metallic foams, and then characterised their properties. Metal films were made from a liquid aluminium alloy reinforced with ceramic particles of known concentration. Melts without such particles were also investigated. It is shown that stable films could not be made from Al-Si alloy having no particles, and just extremely thin and fragile films could be made from commercially-pure Al. In contrast, aluminium alloys containing particles such as SiC and TiB(2) allowed pulling thin, stable films, which did not rupture. Significant thinning of films was observed when the particle concentration in the melt decreased. By in situ X-ray monitoring of liquid films during pulling, film thickness and drainage effects within the liquid film could be studied. The morphology and microstructure of films was characterised after solidification. Our work shows that the question of how foams are stabilised can be studied using a simplified system such as a film, instead of having to deal with the multitude of different structural elements present in a foam.

Effects of surface treatment of aluminium alloy 1050 on the adhesion and anticorrosion properties of the epoxy coating

NASA Astrophysics Data System (ADS)

Sharifi Golru, S.; Attar, M. M.; Ramezanzadeh, B.

2015-08-01

The objective of this work is to investigate the effects of zirconium-based (Zr) conversion coating on the adhesion properties and corrosion resistance of an epoxy/polyamide coating applied on the aluminium alloy 1050 (AA1050). Field emission scanning electron microscope (FE-SEM), energy dispersive X-ray spectrum (EDS), atomic force microscope (AFM) and contact angle measuring device were employed in order to characterize the surface characteristics of the Zr treated AA1050 samples. The epoxy/polyamide coating was applied on the untreated and Zr treated samples. The epoxy coating adhesion to the aluminium substrate was evaluated by pull-off test before and after 30 days immersion in 3.5% w/w NaCl solution. In addition, the electrochemical impedance spectroscopy (EIS) and salt spray tests were employed to characterize the corrosion protection properties of the epoxy coating applied on the AA1050 samples. Results revealed that the surface treatment of AA1050 by zirconium conversion coating resulted in the increase of surface free energy and surface roughness. The dry and recovery (adhesion strength after 30 days immersion in the 3.5 wt% NaCl solution) adhesion strengths of the coatings applied on the Zr treated aluminium samples were greater than untreated sample. In addition, the adhesion loss of the coating applied on the Zr treated aluminium substrate was lower than other samples. Also, the results obtained from EIS and salt spray test clearly revealed that the Zr conversion coating could enhance the corrosion protective performance of the epoxy coating significantly.

Tribological Properties of Aluminium Alloy Composites Reinforced with Multi-Layer Graphene—The Influence of Spark Plasma Texturing Process

PubMed Central

Kostecki, Marek; Woźniak, Jarosław; Cygan, Tomasz; Petrus, Mateusz; Olszyna, Andrzej

2017-01-01

Self-lubricating composites are designed to obtain materials that reduce energy consumption, improve heat dissipation between moving bodies, and eliminate the need for external lubricants. The use of a solid lubricant in bulk composite material always involves a significant reduction in its mechanical properties, which is usually not an optimal solution. The growing interest in multilayer graphene (MLG), characterised by interesting properties as a component of composites, encouraged the authors to use it as an alternative solid lubricant in aluminium matrix composites instead of graphite. Aluminium alloy 6061 matrix composite reinforced with 2–15 vol % of MLG were synthesised by the spark plasma sintering process (SPS) and its modification, spark plasma texturing (SPT), involving deformation of the pre-sintered body in a larger diameter matrix. It was found that the application of the SPT method improves the density and hardness of the composites, resulting in improved tribological properties, particularly in the higher load regime. PMID:28796172

Characterisation of Ga-coated and Ga-brazed aluminium

DOE Office of Scientific and Technical Information (OSTI.GOV)

Ferchaud, E.; Christien, F., E-mail: frederic.christien@univ-nantes.fr; Barnier, V.

This work is devoted to the brazing of aluminium using liquid gallium. Gallium was deposited on aluminium samples at {approx} 50 Degree-Sign C using a liquid gallium 'polishing' technique. Brazing was undertaken for 30 min at 500 Degree-Sign C in air. EDS (Energy Dispersive X-ray Spectroscopy) and AES (Auger Electron Spectroscopy) characterisation of Ga-coated samples has shown that the Ga surface layer thickness is of ten (or a few tens of) nanometres. Furthermore, aluminium oxide layer (Al{sub 2}O{sub 3}) was shown to be 'descaled' during Ga deposition, which ensures good conditions for further brazing. Cross-section examination of Ga-coated samples showsmore » that liquid gallium penetrates into the aluminium grain boundaries during deposition. The thickness of the grain boundary gallium film was measured using an original EDS technique and is found to be of a few tens of nanometres. The depth of gallium grain boundary penetration is about 300 {mu}m at the deposition temperature. The fracture stress of the brazed joints was measured from tensile tests and was determined to be 33 MPa. Cross-section examination of brazed joints shows that gallium has fully dissolved into the bulk and that the joint is really autogenous. - Highlights: Black-Right-Pointing-Pointer Aluminium can be brazed using liquid gallium deposited by a 'polishing' technique. Black-Right-Pointing-Pointer The aluminium oxide layer is 'descaled' during liquid Ga 'polishing' deposition. Black-Right-Pointing-Pointer EDS can be used for determination of surface and grain boundary Ga film thickness. Black-Right-Pointing-Pointer The surface and grain boundary Ga film thickness is of a few tens of nm. Black-Right-Pointing-Pointer Surface and grain boundary gallium dissolves in the bulk during brazing.« less

Lithium/aluminium alloys. A problem material for biological monitoring.

PubMed

Bencze, K; Pelikan, C; Bahemann-Hoffmeister, A; Kronseder, A

1991-01-01

Investigations on aqueous and nonaqueous media have shown that the dust particles of lithium/aluminium alloy are readily soluble in blood serum. Concentration of 10 mg A1 and 3 mg Li in 1 l serum constitute the saturation values in human blood serum at 20 degrees C. Further observations are intended to clarify the danger at the workplace. With a short-term exposure, the change in concentration of Li and Al was followed in the working environment and in the staff. Both elements (Li and Al) were determined in the working air, in the urine, the blood serum and on human skin with electrothermal AAS. On human skin, microerosions arise owing to hydrolytic destruction of the epidermis after long-term contact. The intensive irritant action of Li/Al dust is most relevant for preventive measures. It must also be considered that the Al values in the blood serum are raised by up to 50% in the presence of Li. The resorption and/or the bioavailability of Al is altered by Li. In the presence of Li up to a Li content of 2.5% in Al dust, a MAK (biological tolerance value, threshold limit value) of 1 mg Al/m3 room air (for the total dust) is recommended.

Effect of severe plastic deformation on microstructure and mechanical properties of magnesium and aluminium alloys in wide range of strain rates

NASA Astrophysics Data System (ADS)

Skripnyak, Vladimir; Skripnyak, Evgeniya; Skripnyak, Vladimir; Vaganova, Irina; Skripnyak, Nataliya

2013-06-01

Results of researches testify that a grain size have a strong influence on the mechanical behavior of metals and alloys. Ultrafine grained HCP and FCC metal alloys present higher values of the spall strength than a corresponding coarse grained counterparts. In the present study we investigate the effect of grain size distribution on the flow stress and strength under dynamic compression and tension of aluminium and magnesium alloys. Microstructure and grain size distribution in alloys were varied by carrying out severe plastic deformation during the multiple-pass equal channel angular pressing, cyclic constrained groove pressing, and surface mechanical attrition treatment. Tests were performed using a VHS-Instron servo-hydraulic machine. Ultra high speed camera Phantom V710 was used for photo registration of deformation and fracture of specimens in range of strain rates from 0,01 to 1000 1/s. In dynamic regime UFG alloys exhibit a stronger decrease in ductility compared to the coarse grained material. The plastic flow of UFG alloys with a bimodal grain size distribution was highly localized. Shear bands and shear crack nucleation and growth were recorded using high speed photography.

Analysis Of The Surface Roughness Obtained During The Dry Turning Of UNS A97050-T7 Aluminium Alloys

NASA Astrophysics Data System (ADS)

de Agustina, B.; Rubio, E. M.; Villeta, M.; Sebastián, M. A.

2009-11-01

Currently, in the aeronautical, aerospace and automotive industries there is high demand of materials such as the aluminium alloys that have high resistance even at high temperatures as well as a low density. For this reason, these alloys are widely used for the production of different elements that compose aircraft and aerospace vehicles. Nevertheless, in spite of the important role these materials have from the competitive point of view, they can commonly show problems of machinability associated with the tool wear. That has made that traditionally cutting fluids had been used in machining processes. However, they can contain environmentally harmful constituents and increase considerably the total cost of the process. Therefore, researches have been focused on the development of cleaner production technologies applications as dry machining. This leads to the search for combinations of cutting parameters and type of tools (types of coatings and different geometries) that could improve the machining under such conditions. The aim of this study is to analyse the relationship between the surface roughness obtained during the dry turning of aluminium UNS A97050-T7 bars and the cutting parameters (cutting speed and feed) using three different tools. As a first conclusion it could be affirmed that the feed was the cutting parameter more influential on the surface roughness and to a lesser extend the cutting speed, the type of tool and the interaction between the type of tool and the feed.

The effect of pre-straining and pre-ageing on a novel thermomechanical treatment for improving the mechanical properties of AA2139 aerospace aluminium alloys

NASA Astrophysics Data System (ADS)

Bakare, F.; Alsubhi, Y.; Ragkousis, A.; Ebomwonyi, O.; Damisa, J.; Okunzuwa, S.

2017-07-01

The novel thermomechanical treatment employed by Wang Z et al (2014 Mater. Sci. Eng. A 607 313-7) in enhancing the mechanical and microstructure properties of 6000 series aluminium alloys has been replicated for AA2139 aerospace aluminium alloys. The novel route which involves under-ageing, cold-rolling reductions and re-ageing at a fixed temperature has been carried out focusing on the effect of pre-straining and pre-ageing on the alloy properties. The influence of varying cold-rolling reductions and pre-ageing has been examined by tensile testing, hardness testing, differential scanning calorimetry, thermoelectric power measurements and scanning electron microscope (SEM). Further analyses were conducted with DSC and TEP measurements to check for precipitation sequence and solute retention respectively. On comparing the hardness and strength of the non pre-aged to the pre-aged samples, there is a remarkable increase in the hardness and strength of the aerospace alloy showing the huge influence of both pre-ageing and pre-straining stage of the novel thermomechanical treatment as observed in the 6000 series alloy, albeit at a higher rate. The treatments that exhibited the most promising mechanical properties (hardness, yield and ultimate tensile strength, elongation to failure) were found to be at a pre-ageing temperature of 175 °C for 1.5 h, 40% cold-rolling and re-ageing at 150 °C. The material was found to have yield strength of 590 MPa and 8.1% uniform elongation, which is well above the 5% acceptable value for structural applications and with strength levels adaptable for aerospace industries. The presence of higher volume fraction of well dispersed precipitates observed in the SEM further shows that intermediate cold-rolling reductions combines well with pre-ageing to give the best mechanical properties in this alloy.

Microstructure and Mechanical Properties of C/C Composite/TC17 Joints with Ag-Cu-Ti Brazing Alloy

NASA Astrophysics Data System (ADS)

Cao, Xiujie; Zhu, Ying; Guo, Wei; Peng, Peng; Ma, Kaituo

2017-12-01

Carbon/Carbon composite(C/C) was vacuum brazed to titanium alloy (TC17) using Ag-Cu-Ti brazing alloy. The effects of brazing temperature on the interfacial microstructure and joint properties were investigated by energy dispersive spectrometer (EDS), a scanning electron microscope (SEM), X-ray diffraction (XRD) and Gleeble1500D testing machine. Results show that C/C composite and TC17 were successfully brazed using AgCuTi brazing alloy. Various phases including TiC, Ag(s, s), Cu(s, s), Ti3Cu4, TiCu, and Ti2Cu were formed in the brazed joint. The maximum shear strength of the brazed joints with AgCuTi brazing alloy was 24±1 MPa when brazed at 860°C for 15 min.

Corrosion of dental aluminium bronze in neutral saline and saline lactic acid.

PubMed

Tibballs, J E; Erimescu, Raluca

2006-09-01

To compare the corrosion behaviours of two aluminium bronze, dental casting alloys during a standard immersion test and for immersion in neutral saline. Cast specimens of aluminium bronzes with 1.4 wt% Fe (G) and 4 wt% Fe (N) were subject to progressively longer periods (up to in total 7 days) immersed in 0.1 M saline, 0.1 M lactic acid solutions and examined by scanning electron microscopy with EDX analysis. Immersion in 0.1M neutral saline was for 7 days. In the acidic solution, exposed interdendritic volumes in alloy N corroded completely away in 7 days with dissolution of Ni-enriched precipitate species as well as the copper-rich matrix. Alloy G begins to corrode more slowly but by a similar mechanism. The number density of an Fe-enriched species is insufficient to maintain a continuous galvanic potential to the copper matrix, and dissolution becomes imperceptible. In neutral saline solution, galvanic action alone caused pit-etching, without the dissolution of either precipitate species. The upper limit for the total dissolution of metallic ions in the standard immersion test can be set at 200 microg cm(-2). Aluminium bronze dental alloys can be expected to release both copper and nickel ions into an acidic oral environment.

Assessment of the Sensitivity of Welded Joints of Al -Mg - Si Alloys to Liquation Cracks Under Laser Welding

NASA Astrophysics Data System (ADS)

Ivanov, S. Yu.; Karkhin, V. A.; Mikhailov, V. G.; Martikainen, J.; Hiltunen, E.

2018-03-01

The microstructure and the distribution of chemical elements in laser-welded joints of Al - Mg - Si alloy 6005-T6 are studied. Segregations of chemical elements are detected over grain boundaries in the heat-affected zones of the welded joints. The joints fracture by the intergrain mechanism. A Gleeble 3800 device is used to determine the temperature dependences of the mechanical properties of the alloy with allowance for the special features of the welding cycle. Amethod for evaluating the sensitivity of welded joints of aluminum alloys to formation of liquation cracks with allowance for the local properties of the metal, the welding conditions, and the rigidity of the construction is suggested.

Influence of scandium on the microstructure and strength properties of the welded joint at the laser welding of aluminum-lithium alloys

NASA Astrophysics Data System (ADS)

Malikov, A. G.; Golyshev, A. A.; Ivanova, M. Yu.

2017-10-01

Today, aeronautical equipment manufacture involves up-to-date high-strength aluminum alloys of decreased density resulting from lithium admixture. Various technologies of fusible welding of these alloys are being developed. Serious demands are imposed to the welded joints of aluminum alloys in respect to their strength characteristics. The paper presents experimental investigations of the optimization of the laser welding of aluminum alloys with the scandium-modified welded joint. The effect of scandium on the micro-and macro-structure has been studied as well as the strength characteristics of the welded joint. It has been found that scandium under in the laser welding process increases the welded joint elasticity for the system Al-Mg-Li, aluminum alloy 1420 by 20 %, and almost doubles the same for the system Al-Cu-Li, aluminum alloy 1441.

Effect of Shielding Gas on the Properties of AW 5083 Aluminum Alloy Laser Weld Joints

NASA Astrophysics Data System (ADS)

Vyskoč, Maroš; Sahul, Miroslav; Sahul, Martin

2018-04-01

The paper deals with the evaluation of the shielding gas influence on the properties of AW 5083 aluminum alloy weld joints produced with disk laser. Butt weld joints were produced under different shielding gas types, namely Ar, He, Ar + 5 vol.% He, Ar + 30 vol.% He and without shielding weld pool. Light and electron microscopy, computed tomography, microhardness measurements and tensile testing were used for evaluation of weld joint properties. He-shielded weld joints were the narrowest ones. On the other hand, Ar-shielded weld joints exhibited largest weld width. The choice of shielding gas had significant influence on the porosity level of welds. The lowest porosity was observed in weld joint produced in Ar with the addition of 5 vol.% He shielding atmosphere (only 0.03%), while the highest level of porosity was detected in weld joint produced in pure He (0.24%). Except unshielded aluminum alloy weld joint, the lowest tensile strength was recorded in He-shielded weld joints. On the contrary, the highest average microhardness was measured in He-shielded weld joints.

Spall fracture in aluminium alloy at high strain rates

NASA Astrophysics Data System (ADS)

Joshi, K. D.; Rav, Amit; Sur, Amit; Kaushik, T. C.; Gupta, Satish C.

2016-05-01

Spall fracture strength and dynamic yield strength has been measured in 8mm thick target plates of aluminium alloy Al2024-T4 at high strain rates generated in three plate impact experiments carried out at impact velocities of 180 m/s, 370 m/s and 560m/s, respectively, using single stage gas gun facility. In each experiment, the free surface velocity history of the Al2024-T4 sample plate measured employing velocity interferometer system for any reflector (VISAR) is used to determine the spall strength and dynamic yield strength of this material. The spall strength of 1.11 GPa, 1.16 GPa and 1.43 GPa, determined from measured free surface velocity history of sample material in three experiments performed at impact velocity of 180 m/s, 370 m/s and 560 m/s, respectively, are higher than the quasi static value of 0.469 GPa and display almost linearly increasing trend with increasing impact velocity or equivalently with increasing strain rates. The average strain rates just ahead of the spall fracture are determined to be 1.9×10 4/s, 2.0×104/s and 2.5×104/s, respectively. The dynamic yield strength determined in the three experiments range from 0.383 GPa to 0.407 GPa, which is higher than the quasi static value of 0.324GPa.

The improvement of the surface hardness of stainless steel and aluminium alloy by ultrasonic cavitation peening

NASA Astrophysics Data System (ADS)

Janka, Styková; Miloš, Müller; Jan, Hujer

This article presents first results of the experimental investigation of the influence of the cavitation shot less peening process on the properties of stainless steel and aluminium alloy specimens. The cavitation field was generated by an ultrasonic horn submerged in water and operated by an ultrasonic generator. The temperature of the water was controlled by thermometer and adjusted by separate water cooling system. The mass loss, the mass loss rate and the modification of the surface hardness are evaluated for different cavitation exposure intervals. The mass loss was measured by micro weighing scale and the surface hardness by the micro-hardness meter. The presented results indicates the significant improvement in the surface hardness for both tested materials.

Optimization of process parameters in CNC turning of aluminium alloy using hybrid RSM cum TLBO approach

NASA Astrophysics Data System (ADS)

Rudrapati, R.; Sahoo, P.; Bandyopadhyay, A.

2016-09-01

The main aim of the present work is to analyse the significance of turning parameters on surface roughness in computer numerically controlled (CNC) turning operation while machining of aluminium alloy material. Spindle speed, feed rate and depth of cut have been considered as machining parameters. Experimental runs have been conducted as per Box-Behnken design method. After experimentation, surface roughness is measured by using stylus profile meter. Factor effects have been studied through analysis of variance. Mathematical modelling has been done by response surface methodology, to made relationships between the input parameters and output response. Finally, process optimization has been made by teaching learning based optimization (TLBO) algorithm. Predicted turning condition has been validated through confirmatory experiment.

Synergistic effects of carboxymethyl cellulose and ZnO as alkaline electrolyte additives for aluminium anodes with a view towards Al-air batteries

NASA Astrophysics Data System (ADS)

Liu, Jie; Wang, Dapeng; Zhang, Daquan; Gao, Lixin; Lin, Tong

2016-12-01

The synergistic effects of carboxymethyl cellulose (CMC) and zinc oxide (ZnO) have been investigated as alkaline electrolyte additives for the AA5052 aluminium alloy anode in aluminium-air battery by the hydrogen evolution test, the electrochemical measurements and the surface analysis method. The combination of CMC and ZnO effectively retards the self-corrosion of AA5052 alloy in 4 M NaOH solution. A complex film is formed via the interaction between CMC and Zn2+ ions on the alloy surface. The carboxyl groups adsorbed on the surface of aluminium make the protective film more stable. The cathodic reaction process is mainly suppressed significantly. AA5052 alloy electrode has a good discharge performance in the applied electrolyte containing the composite CMC/ZnO additives.

Numerical simulation of the laser welding process for the prediction of temperature distribution on welded aluminium aircraft components

NASA Astrophysics Data System (ADS)

Tsirkas, S. A.

2018-03-01

The present investigation is focused to the modelling of the temperature field in aluminium aircraft components welded by a CO2 laser. A three-dimensional finite element model has been developed to simulate the laser welding process and predict the temperature distribution in T-joint laser welded plates with fillet material. The simulation of the laser beam welding process was performed using a nonlinear heat transfer analysis, based on a keyhole formation model analysis. The model employs the technique of element ;birth and death; in order to simulate the weld fillet. Various phenomena associated with welding like temperature dependent material properties and heat losses through convection and radiation were accounted for in the model. The materials considered were 6056-T78 and 6013-T4 aluminium alloys, commonly used for aircraft components. The temperature distribution during laser welding process has been calculated numerically and validated by experimental measurements on different locations of the welded structure. The numerical results are in good agreement with the experimental measurements.

Life cycle assessment of metal alloys for structural applications

NASA Astrophysics Data System (ADS)

Malovrh Rebec, K.; Markoli, B.; Leskovar, B.

2018-03-01

The study compared environmental footprints of two types of Al-alloys: well-known 5083 aluminium alloy with magnesium and traces of manganese and chromium in its composition. This material is highly resistant to seawater corrosion and the influence of industrial chemicals. Furthermore, it retains exceptional strength after welding. The comparisons were made to an innovative alloy where the aluminium based matrix is reinforced by metastable quasicrystals (QC), thus avoiding magnesium in its composition. Furthermore, we checked other aluminium ingots’ footprints and compared European average and Germany country specific production data. Environmental footprints were assessed via cradle to gate life cycle assessment. Our findings normalized to 1 m2 plate suggest, that newly proposed alloy could save around 50 % in value of parameters abiotic resources depletion of fossil fuels, acidification, eutrophication, global warming potential and photochemical ozone creation potential if we compare Qc5 to 6 mm 5083 alloy plate. Only abiotic resources depletion of elements and ozone depletion parameters increase for Qc5 compared to 6 mm 5083 alloy plate.

Microstructure Evolution and Mechanical Properties of High-Speed Friction Stir Welded Aluminum Alloy Thin Plate Joints

NASA Astrophysics Data System (ADS)

Liu, Fenjun; Fu, Li; Chen, Haiyan

2018-06-01

Sound friction stir welded (FSW) joints of 6061-T6 aluminum alloy sheets with an 0.8 mm thickness were obtained at conventional speed (2000 rpm, 300 mm/min) and high speed (11,000 rpm, 1500 mm/min). The recrystallization mechanism, precipitate evolution, mechanical properties and fracture behavior were investigated in detail. Microstructure analyses revealed that the grain structure evolution in the nugget zone (NZ) was dominated by continuous dynamic recrystallization. In the process of FSW, high speed facilitates the formation of finer equiaxed recrystallized grains, higher density of dislocations and substructures, and a larger number of precipitates in the NZ compared to the conventional speed, which further significantly improves the hardness and tensile strength of the joints. The maximum tensile strength was obtained with 292.6 MPa, 83.2% for the 6061-T6 aluminum alloy and 122.6% for the conventional-speed FSW joints. This work provides an effective method for preparing FSW aluminum alloy thin plate joints with excellent mechanical properties.

Eutectic structures in friction spot welding joint of aluminum alloy to copper

NASA Astrophysics Data System (ADS)

Shen, Junjun; Suhuddin, Uceu F. H.; Cardillo, Maria E. B.; dos Santos, Jorge F.

2014-05-01

A dissimilar joint of AA5083 Al alloy and copper was produced by friction spot welding. The Al-MgCuAl2 eutectic in both coupled and divorced manners were found in the weld. At a relatively high temperature, mass transport of Cu due to plastic deformation, material flow, and atomic diffusion, combined with the alloy system of AA5083 are responsible for the ternary eutectic melting.

Ductile fracture mechanism of low-temperature In-48Sn alloy joint under high strain rate loading.

PubMed

Kim, Jong-Woong; Jung, Seung-Boo

2012-04-01

The failure behaviors of In-48Sn solder ball joints under various strain rate loadings were investigated with both experimental and finite element modeling study. The bonding force of In-48Sn solder on an Ni plated Cu pad increased with increasing shear speed, mainly due to the high strain-rate sensitivity of the solder alloy. In contrast to the cases of Sn-based Pb-free solder joints, the transition of the fracture mode from a ductile mode to a brittle mode was not observed in this solder joint system due to the soft nature of the In-48Sn alloy. This result is discussed in terms of the relationship between the strain-rate of the solder alloy, the work-hardening effect and the resulting stress concentration at the interfacial regions.

Shock induced spall fracture in aluminium alloy "Al2014-T4"

NASA Astrophysics Data System (ADS)

Joshi, K. D.; Rav, Amit; Sur, Amit; Das, P. C.; Gupta, Satish C.

2015-06-01

The plate impact experiments have been carried out on 8mm thick target plates of aluminium alloy Al2014-T4 at impact velocities of 180 m/s, 290 m/s and 500m/s, respectively, using single stage gas gun facility. In each experiment, the of free surface velocity history of the sample plate is measured using VISAR instrument and utilized to determine the spall strength and dynamic yield strength of this material. The spall strength of 0.87 GPa, 0.97 GPa and 1.11 GPa, respectively, measured for impact velocities of 180 m/s, 290 m/s and 500 m/s with corresponding average strain rates varying from 1.36×104/s to 2.41×14/s has been found to display nearly linear dependence upon the strain rates. The dynamic yield strength with its value ranging from 0.395 GPa to 0.400 GPa, though, is higher than the quasi static value of 0.355GPa, appears to be relatively independent of impact velocities up to at least 500 m/s or equivalently strain rates up to ˜ 9.4×104/s.

The effects of additives to SnAgCu alloys on microstructure and drop impact reliability of solder joints

NASA Astrophysics Data System (ADS)

Liu, Weiping; Lee, Ning-Cheng

2007-07-01

The impact reliability of solder joints in electronic packages is critical to the lifetime of electronic products, especially those portable devices using area array packages such as ball-grid array (BGA) and chip-scale packages (CSP). Currently, SnAgCu (SAC) solders are most widely used for lead-free applications. However, BGA and CSP solder joints using SAC alloys are fragile and prone to premature interfacial failure, especially under shock loading. To further enhance impact reliability, a family of SAC alloys doped with a small amount of additives such as Mn, Ce, Ti, Bi, and Y was developed. The effects of doping elements on drop test performance, creep resistance, and microstructure of the solder joints were investigated, and the solder joints made with the modified alloys exhibited significantly higher impact reliability.

Eutectic structures in friction spot welding joint of aluminum alloy to copper

DOE Office of Scientific and Technical Information (OSTI.GOV)

Shen, Junjun, E-mail: junjun.shen@hzg.de; Suhuddin, Uceu F. H.; Cardillo, Maria E. B.

2014-05-12

A dissimilar joint of AA5083 Al alloy and copper was produced by friction spot welding. The Al-MgCuAl{sub 2} eutectic in both coupled and divorced manners were found in the weld. At a relatively high temperature, mass transport of Cu due to plastic deformation, material flow, and atomic diffusion, combined with the alloy system of AA5083 are responsible for the ternary eutectic melting.

Localised anodic oxidation of aluminium material using a continuous electrolyte jet

NASA Astrophysics Data System (ADS)

Kuhn, D.; Martin, A.; Eckart, C.; Sieber, M.; Morgenstern, R.; Hackert-Oschätzchen, M.; Lampke, T.; Schubert, A.

2017-03-01

Anodic oxidation of aluminium and its alloys is often used as protection against material wearout and corrosion. Therefore, anodic oxidation of aluminium is applied to produce functional oxide layers. The structure and properties of the oxide layers can be influenced by various factors. These factors include for example the properties of the substrate material, like alloy elements and heat treatment or process parameters, like operating temperature, electric parameters or the type of the used electrolyte. In order to avoid damage to the work-piece surface caused by covering materials in masking applications, to minimize the use of resources and to modify the surface in a targeted manner, the anodic oxidation has to be localised to partial areas. Within this study a proper alternative without preparing the substrate by a mask is investigated for generating locally limited anodic oxidation by using a continuous electrolyte jet. Therefore aluminium material EN AW 7075 is machined by applying a continuous electrolyte jet of oxalic acid. Experiments were carried out by varying process parameters like voltage or processing time. The realised oxide spots on the aluminium surface were investigated by optical microscopy, SEM and EDX line scanning. Furthermore, the dependencies of the oxide layer properties from the process parameters are shown.

Residual stresses in shape memory alloy fiber reinforced aluminium matrix composite

NASA Astrophysics Data System (ADS)

Tsz Loong, Tang; Jamian, Saifulnizan; Ismail, Al Emran; Nur, Nik Hisyammudin Muhd; Watanabe, Yoshimi

2017-01-01

Process-induced residual stress in shape memory alloy (SMA) fiber reinforced aluminum (Al) matrix composite was simulated by ANSYS APDL. The manufacturing process of the composite named as NiTi/Al is start with loading and unloading process of nickel titanium (NiTi) wire as SMA to generate a residual plastic strain. Then, this plastic deformed NiTi wire would be embedded into Al to become a composite. Lastly, the composite is heated form 289 K to 363 K and then cooled back to 300 K. Residual stress is generated in composite because of shape memory effect of NiTi and mismatch of thermal coefficient between NiTi wire and Al matrix of composite. ANSYS APDL has been used to simulate the distribution of residual stress and strain in this process. A sensitivity test has been done to determine the optimum number of nodes and elements used. Hence, the number of nodes and elements used are 15680 and 13680, respectively. Furthermore, the distribution of residual stress and strain of nickel fiber reinforced aluminium matrix composite (Ni/Al) and titanium fiber reinforced aluminium matrix composite (Ti/Al) under same simulation process also has been simulated by ANSYS APDL as comparison to NiTi/Al. The simulation results show that compressive residual stress is generated on Al matrix of Ni/Al, Ti/Al and NiTi/Al during heating and cooling process. Besides that, they also have similar trend of residual stress distribution but difference in term of value. For Ni/Al and Ti/Al, they are 0.4% difference on their maximum compressive residual stress at 363K. At same circumstance, NiTi/Al has higher residual stress value which is about 425% higher than Ni/Al and Ti/Al composite. This implies that shape memory effect of NiTi fiber reinforced in composite able to generated higher compressive residual stress in Al matrix, hence able to enhance tensile property of the composite.

A 3D printed superconducting aluminium microwave cavity

DOE Office of Scientific and Technical Information (OSTI.GOV)

Creedon, Daniel L.; Goryachev, Maxim; Kostylev, Nikita

3D printing of plastics, ceramics, and metals has existed for several decades and has revolutionized many areas of manufacturing and science. Printing of metals, in particular, has found a number of applications in fields as diverse as customized medical implants, jet engine bearings, and rapid prototyping in the automotive industry. Although many techniques are used for 3D printing metals, they commonly rely on computer controlled melting or sintering of a metal alloy powder using a laser or electron beam. The mechanical properties of parts produced in such a way have been well studied, but little attention has been paid tomore » their electrical properties. Here we show that a microwave cavity (resonant frequencies 9.9 and 11.2 GHz) 3D printed using an Al-12Si alloy exhibits superconductivity when cooled below the critical temperature of aluminium (1.2 K), with a performance comparable with the common 6061 alloy of aluminium. Superconducting cavities find application in numerous areas of physics, from particle accelerators to cavity quantum electrodynamics experiments. The result is achieved even with a very large concentration of non-superconducting silicon in the alloy of 12.18%, compared with Al-6061, which has between 0.4% and 0.8%. Our results may pave the way for the possibility of 3D printing superconducting cavity configurations that are otherwise impossible to machine.« less

A 3D printed superconducting aluminium microwave cavity

NASA Astrophysics Data System (ADS)

Creedon, Daniel L.; Goryachev, Maxim; Kostylev, Nikita; Sercombe, Timothy B.; Tobar, Michael E.

2016-07-01

3D printing of plastics, ceramics, and metals has existed for several decades and has revolutionized many areas of manufacturing and science. Printing of metals, in particular, has found a number of applications in fields as diverse as customized medical implants, jet engine bearings, and rapid prototyping in the automotive industry. Although many techniques are used for 3D printing metals, they commonly rely on computer controlled melting or sintering of a metal alloy powder using a laser or electron beam. The mechanical properties of parts produced in such a way have been well studied, but little attention has been paid to their electrical properties. Here we show that a microwave cavity (resonant frequencies 9.9 and 11.2 GHz) 3D printed using an Al-12Si alloy exhibits superconductivity when cooled below the critical temperature of aluminium (1.2 K), with a performance comparable with the common 6061 alloy of aluminium. Superconducting cavities find application in numerous areas of physics, from particle accelerators to cavity quantum electrodynamics experiments. The result is achieved even with a very large concentration of non-superconducting silicon in the alloy of 12.18%, compared with Al-6061, which has between 0.4% and 0.8%. Our results may pave the way for the possibility of 3D printing superconducting cavity configurations that are otherwise impossible to machine.

Structure and Corrosion Resistance of Welded Joints of Alloy 1151 in Marine Atmosphere

NASA Astrophysics Data System (ADS)

Bakulo, A. V.; Yakushin, B. F.; Puchkov, Yu. A.

2017-07-01

The corrosion behavior of joints formed by TIG and IMIG welding from clad sheets of heat-hardenable aluminum alloy 1151 of the Al - Cu - Mg system is studied. The corrosion tests are performed in an aqueous solution of NaCl in a salt-spray chamber. The welded joints are subjected to a metallographic analysis.

[Comporison Sduty of Microstructure by Metallographicalk on the Polarized Light and Texture by XRD of CC 5083 and CC 5182 Aluminium Alloy after Cold Rolling and Recrystallization].

PubMed

Chen, Ming-biao; Li, Yong-wei; Tan, Yuan-biao; Ma, Min; Wang, Xue-min; Liu, Wen-chang

2015-03-01

At present the study of relation between microstructure, texture and performance of CC 5083 aluminium alloy after cold tolling and recrystallization processes is still finitude. So that the use of the CC 5083 aluminium alloy be influenced. Be cased into electrical furnace, hot up with unlimited speed followed the furnace hot up to different temperature and annealed 2h respectively, and be cased into salt-beth furnace, hot up quickly to different temperature and annealed 30 min respectively for CC 5083 and CC 5182 aluminum alloy after cold roling with 91.5% reduction. The microstructure be watched use metallographic microscope, the texture be inspected by XRD. The start temperature of recrystallization and grain grow up temperature within annealing in the electric furnace of CC 5083 aluminum alloy board is 343 degrees C, and the shap of grain after grow up with long strip (the innovation point ); The start temperature of recrystallization within annealling in the salt bath furnace of CC 5083 is 343 degrees C. The start temperature and end temperature of recrystallization within annealling of CC 5083 and CC 5182 aluminum alloy is 371 degrees C. The grain grow up outstanding of cold rooled CC 5152 aluminum alloy after annealed with 454 degrees C in the electric furnace and salt bath furnace. The start temperature of grain grow up of CC 5083 alluminurn alloy annealed in the electric furnace and salt bath furnace respectively is higher than the start temperature of grain grow up of CC 5182 alluminum alloy annealed in the electric furnace and salt bath furnace respectively. The strat temperature of recrystallization grain grow up is higher than which annealled with other three manner annealing process. The recrystallization temperature of CC 5182 annealed in the salt bath furnace is higher than which annealed in the electric furnace. The recrystallization temperature of the surface layer of CC 5083 and CC 5182 aluminum alloy is higher than the inner layer (the innovation

Butt Welding Joint of Aluminum Alloy by Space GHTA Welding Process in Vacuum

NASA Astrophysics Data System (ADS)

Suita, Yoshikazu; Shinike, Shuhei; Ekuni, Tomohide; Terajima, Noboru; Tsukuda, Yoshiyuki; Imagawa, Kichiro

Aluminum alloys have been used widely in constructing various space structures including the International Space Station (ISS) and launch vehicles. For space applications, welding experiments on aluminum alloy were performed using the GHTA (Gas Hollow Tungsten Arc) welding process using a filler wire feeder in a vacuum. We investigated the melting phenomenon of the base metal and filler wire, bead formation, and the effects of wire feed speed on melting characteristics. The melting mechanism in the base metal during the bead on a plate with wire feed was similar to that for the melt run without wire feed. We clarified the effects of wire feed speed on bead sizes and configurations. Furthermore, the butt welded joint welded using the optimum wire feed speed, and the joint tensile strengths were evaluated. The tensile strength of the square butt joint welded by the pulsed DC GHTA welding with wire feed in a vacuum is nearly equal to that of the same joint welded by conventional GTA (Gas Tungsten Arc) welding in air.

Small Crack Growth and Fatigue Life Predictions for High-Strength Aluminium Alloys. Part 1; Experimental and Fracture Mechanics Analysis

NASA Technical Reports Server (NTRS)

Wu, X. R.; Newman, J. C.; Zhao, W.; Swain, M. H.; Ding, C. F.; Phillips, E. P.

1998-01-01

The small crack effect was investigated in two high-strength aluminium alloys: 7075-T6 bare and LC9cs clad alloy. Both experimental and analytical investigations were conducted to study crack initiation and growth of small cracks. In the experimental program, fatigue tests, small crack and large crack tests A,ere conducted under constant amplitude and Mini-TWIST spectrum loading conditions. A pronounced small crack effect was observed in both materials, especially for the negative stress ratios. For all loading conditions, most of the fatigue life of the SENT specimens was shown to be crack propagation from initial material defects or from the cladding layer. In the analysis program, three-dimensional finite element and A weight function methods were used to determine stress intensity factors and to develop SIF equations for surface and corner cracks at the notch in the SENT specimens. A plastisity-induced crack-closure model was used to correlate small and large crack data, and to make fatigue life predictions, Predicted crack-growth rates and fatigue lives agreed well with experiments. A total fatigue life prediction method for the aluminum alloys was developed and demonstrated using the crack-closure model.

Effects of vacuum and ageing on Zr4/Cr3 based conversion coatings on aluminium alloys

NASA Astrophysics Data System (ADS)

Thirupathi, Kalaivanan; Bárczy, Pál; Vad, Kálmán; Csik, Attila; Somosvári, Béla Márton

2018-05-01

In this study, we investigate the impact of ageing and high vacuum on existing environmentally friendly Zr4/Cr3-based conversion coatings. The freshly formed coating undergoes several changes during ageing and exposure to high vacuum. Based on the present data, we propose that the coating formed over AA6082 and AA7075 alloys is sol-gel in nature, confirmed by secondary neutral mass spectroscopy (SNMS) using the depth profiling technique. Our findings reveal that there are elemental level changes that result in shrinkage of the coating. Most Zr ions in the coating are in the solute form, with lesser number of Cr and Al ions that disappear under high vacuum over a certain period of time. The remaining Cr, Zr and O atoms exist in a gelatinous state. During ageing, there is a continuous transition of ions from solute to gelatinous state. In addition, the deposition of coating ions is directly influenced by the substrates and their constituents. The extent of dissolution of aluminium in the conversion bath determines both Zr and Cr ion deposition. For a highly alloyed metal like AA7075, the dissolution rate is disturbed by copper and zinc.

Al and Si Alloying Effect on Solder Joint Reliability in Sn-0.5Cu for Automotive Electronics

NASA Astrophysics Data System (ADS)

Hong, Won Sik; Oh, Chulmin; Kim, Mi-Song; Lee, Young Woo; Kim, Hui Joong; Hong, Sung Jae; Moon, Jeong Tak

2016-12-01

To suppress the bonding strength degradation of solder joints in automotive electronics, we proposed a mid-temperature quaternary Pb-free Sn-0.5Cu solder alloy with minor Pd, Al, Si and Ge alloying elements. We manufactured powders and solder pastes of Sn-0.5Cu-(0.01,0.03)Al-0.005Si-(0.006-0.007)Ge alloys ( T m = 230°C), and vehicle electronic control units used for a flame-retardant-4 printed circuit board with an organic solderability preservative finish were assembled by a reflow soldering process. To investigate the degradation properties of solder joints used in engine compartments, thermal cycling tests were conducted from -40°C to 125°C (10 min dwell) for 1500 cycles. We also measured the shear strength of the solder joints in various components and observed the microstructural evolution of the solder joints. Based on these results, intermetallic compound (IMC) growth at the solder joints was suppressed by minor Pd, Al and Si additions to the Sn-0.5Cu alloy. After 1500 thermal cycles, IMC layers thicknesses for 100 parts per million (ppm) and 300 ppm Al alloy additions were 6.7 μm and 10 μm, compared to the as-reflowed bonding thicknesses of 6 μm and 7 μm, respectively. Furthermore, shear strength degradation rates for 100 ppm and 300 ppm Al(Si) alloy additions were at least 19.5%-26.2%. The cause of the improvement in thermal cycling reliability was analyzed using the (Al,Cu)-Sn, Si-Sn and Al-Sn phases dispersed around the Cu6Sn5 intermetallic at the solder matrix and bonding interfaces. From these results, we propose the possibility of a mid-temperature Sn-0.5Cu(Pd)-Al(Si)-Ge Pb-free solder for automotive engine compartment electronics.

Effect of the layer of anodized 7075-T6 aluminium corrosion properties

NASA Astrophysics Data System (ADS)

Montoya Z, R. D.; L, E. Vera; Pineda T, Y.; Cedeño, M. L.

2017-01-01

Aluminium alloys are widely used in various sectors of industry. The 7075-T6 alloy corresponding to an Al-Zn T6, is mostly used as structural component in the aviation industry, due to the good relationship between weight and mechanical properties. However, the negative point of this alloys is the resistance to corrosion, which is why they need to be coated with an anodic film. Different surface treatments, such as anodizing, are used to improve corrosion resistance. Anodizing is an electrolytic process by which a protective layer on aluminium known as “alumina” is formed, this is formed by the passage of an electric current in an acidic electrolyte. This investigation presents a study of the effect of the thickness of layers of alumina deposited by anodized method, in the corrosion resistance of 7075-T6 aluminium. This study was performed by using in a solution of tartaric acid - sulfuric acid and an inorganic salt. To evaluate the influence alumina layer thickness on the corrosion properties some tests were carried out by using the electrochemical spectroscopy impedances (EIS) technique and Tafel polarization curves. It was found that the grown of the thickness of film favourably influences in the corrosion resistance.

The study of aluminium anodes for high power density Al/air batteries with brine electrolytes

NASA Astrophysics Data System (ADS)

Nestoridi, Maria; Pletcher, Derek; Wood, Robert J. K.; Wang, Shuncai; Jones, Richard L.; Stokes, Keith R.; Wilcock, Ian

Aluminium alloys containing small additions of both tin (∼0.1 wt%) and gallium (∼0.05 wt%) are shown to dissolve anodically at high rates in sodium chloride media at room temperatures; current densities >0.2 A cm -2 can be obtained at potentials close to the open circuit potential, ∼-1500 mV versus SCE. The tin exists in the alloys as a second phase, typically as ∼1 μm inclusions (precipitates) distributed throughout the aluminium structure, and anodic dissolution occurs to form pits around the tin inclusions. Although the distribution of the gallium in the alloy could not be established, it is also shown to be critical in the formation of these pits as well as maintaining their activity. The stability of the alloys to open circuit corrosion and the overpotential for high rate dissolution, both critical to battery performance, are shown to depend on factors in addition to elemental composition; both heat treatment and mechanical working influence the performance of the alloy. The correlation between alloy performance and their microstructure has been investigated.

Study on erosion behaviour of hybrid aluminium composite

NASA Astrophysics Data System (ADS)

Vishwas, D. K.; Chandrappa, C. N.; Venkatesh, Shreyas

2018-04-01

The origin of the light metals, as compared to other metals in this century, is noticeable and an exciting area of expansion for innovation. Light metals, are need of the day in engineering, among them application of aluminium and its alloys is enormous. we observe that these metals tend to have a progressive loss of metal from having contact surface with other metals. Erosion is one such wear process, where damage occurs by the repeated application of high localised stresses. Erosion due to impact of solid particle, is a significant problem. In the present work, the erosion behaviour of hybrid aluminium composite is studied. AL 6061 is used as the base alloy. AL 6061 alloy has excellent corrosion resistance but poor wear resistance. So, in order to have improved properties, it is reinforced with Tungsten Chromium Nickel powder in varied proportions by the method of stir casting. The results are compared with the as-cast Al-alloy to determine the improvement in mechanical properties. The tests were conducted in ASTM G76 setup, to determine solid particle erosion behaviour and the results of the hybrid composite were compared with that of as-cast AL 6061 alloy. It was evident that mass loss was maximum at 300 inclinations, which is a characteristic of ductile materials. It was observed that upon increasing the percentages of reinforcement (wt.%), the wear resistance of the hybrid composite increased significantly. It was also observed that the inclusion of tungsten-chromium-nickel powder increased the hardness of the hybrid composite significantly.

Influence of groove size and reinforcements addition on mechanical properties and microstructure of friction stir welded joints

NASA Astrophysics Data System (ADS)

Reddy Baridula, Ravinder; Ibrahim, Abdullah Bin; Yahya, Che Ku Mohammad Faizal Bin Che Ku; Kulkarni, Ratnakar; Varma Ramaraju, Ramgopal

2018-03-01

The butt joints fabricated by friction stir welding were found to have more strength than the joints obtained by conventional joining process. The important outcome of this process is the successful fabrication of surface composites with improved properties. Thus in order to further enhance the strength of the dissimilar alloy joints the reinforcements can be deposited in to the aluminium matrix during the process of friction stir welding. In the present study the multi-walled carbon nanotubes were embedded in to the groove by varying the width during joining of dissimilar alloys AA2024 and AA7075. Four widths were selected with constant depth and optimum process parameters were selected to fabricate the sound welded joints. The results show that the mechanical properties of the fabricated butt joints were influenced by the size of the groove, due to variation in the deposition of reinforcement in the stir zone. The microstructural study and identification of the elements of the welded joints show that the reinforcements deposition is influenced by the size of the groove. It has also been observed that the groove with minimum width is more effective than higher width. The mechanical properties are found to be improved due to the pinning of grain boundaries.

Mechanical Properties and Microstructure of TIG and FSW Joints of a New Al-Mg-Mn-Sc-Zr Alloy

NASA Astrophysics Data System (ADS)

Xu, Guofu; Qian, Jian; Xiao, Dan; Deng, Ying; Lu, Liying; Yin, Zhimin

2016-04-01

A new Al-5.8%Mg-0.4%Mn-0.25%Sc-0.10%Zr (wt.%) alloy was successfully welded by tungsten inert gas (TIG) and friction stir welding (FSW) techniques, respectively. The mechanical properties and microstructure of the welded joints were investigated by microhardness measurements, tensile tests, and microscopy methods. The results show that the ultimate tensile strength, yield strength, and elongation to failure are 358, 234 MPa, and 27.6% for TIG welded joint, and 376, 245 MPa and 31.9% for FSW joint, respectively, showing high strength and superior ductility. The TIG welded joint fails in the heat-affected zone and the fracture of FSW joint is located in stirred zone. Al-Mg-Mn-Sc-Zr alloy is characterized by lots of dislocation tangles and secondary coherent Al3(Sc,Zr) particles. The superior mechanical properties of the TIG and FSW joints are mainly derived from the Orowan strengthening and grain boundary strengthening caused by secondary coherent Al3(Sc,Zr) nano-particles (20-40 nm). For new Al-Mg-Mn-Sc-Zr alloy, the positive effect from secondary Al3(Sc, Zr) particles in the base metal can be better preserved in FSW joint than in TIG welded joint.

Effect of linear energy on the properties of an AL alloy in DPMIG welding

NASA Astrophysics Data System (ADS)

Liao, Tianfa; Jin, Li; Xue, Jiaxiang

2018-01-01

The effect of different linear energy parameters on the DPMIG welding performance of AA1060 aluminium alloy is studied in this paper. The stability of the welding process is verified with a Labview electrical signal acquisition system, and the microstructure and tensile properties of the welded joint are studied via optical microscopy, scanning electron microscopy and electrical tensile tests. The test results show that the welding process for the DPMIG methods stable and that the weld beads appear as scales. Tensile strength results indicate that, with increasing linear energy, the tensile strength first increases and then decreases. The tensile strength of the joint is maximized when the linear energy is 120.5 J / mm-1.

XAFS studies on a modified Al-Si hypoeutectic alloy

NASA Astrophysics Data System (ADS)

Srirangam, V. S. Prakash; Chattopadhyay, S.; Shibata, T.; Kaduk, J. A.; Miller, J. T.; Segre, C. U.; Shankar, S.

2009-11-01

To understand the role of Sr in doped aluminium-silicon alloys, we have conducted for the first time, Sr- K edge XAFS measurements on Al-3%Si-0.04%Sr. Aluminium-Silicon alloys are widely used in automobile and aerospace applications. Modification of these alloys with addition of trace levels of Sr (200-400 ppm) results in changing the morphology of Si eutectic from "plate" like structure to "fibrous" structure. Several theories have been proposed to understand the mechanism of modification of eutectic phases with Sr addition in these alloys, but there is no conclusive evidence in support of these theories. From our XAFS analysis, we suggest Sr-Si bonds and Sr-Sr correlations may be responsible for the morphological transformation observed in the alloy.

Aluminium surface treatment with ceramic phases using diode laser

NASA Astrophysics Data System (ADS)

Labisz, K.; Tański, T.; Brytan, Z.; Pakieła, W.; Wiśniowski, M.

2016-07-01

Ceramic particles powder feeding into surface layer of engineering metal alloy is a well-known and widely used technique. New approach into the topic is to obtain finely distributed nano-sized particles involved in the aluminium matrix using the traditional laser technology. In this paper are presented results of microstructure investigation of cast aluminium-silicon-copper alloys surface layer after heat treatment and alloying with ceramic carbides of WC and ZrO2 using high-power diode laser. The surface layer was specially prepared for the reason of reducing the reflectivity, which is the main problem in the up-to-date metal matrix composites production. With scanning electron microscopy, it was possible to determine the deformation process and distribution of WC and ZrO2 ceramic powder phase. Structure of the surface after laser treatment changes, revealing three zones—remelting zone, heat-affected zone and transition zone placed over the Al substrate. The structural changes of ceramic powder, its distribution and morphology as well as microstructure of the matrix material influence on functional properties, especially wear resistance and hardness of the achieved layer, were investigated.

Structure and Mechanical Properties of Friction Stir Weld Joints of Magnesium Alloy AZ31

NASA Astrophysics Data System (ADS)

Nagasawa, T.; Otsuka, M.; Yokota, T.; Ueki, T.

The applicability of friction stir welding to hot rolled sheet of commercial magnesium alloy AZ31 plates has been investigated. Friction stir weld joint showed mechanical strength comparable to that of base material, though the ductility remained at one half of that of the latter. The results are consistent with the microstructure which is characterized by a fine grained bond layer bounded by-intermediate grained base metals. It is found that both anodizing treatment and insertion of aluminum foil between batting faces do not degrade the joint properties at all. The results suggest that friction stir welding can be potentially applied to magnesium alloy.

Experimental characterisation and modelling of deformation- induced microstructure in an A6061 aluminium alloy

NASA Astrophysics Data System (ADS)

Kreyca, J. F.; Falahati, A.; Kozeschnik, E.

2016-03-01

For industry, the mechanical properties of a material in form of flow curves are essential input data for finite element simulations. Current practice is to obtain flow curves experimentally and to apply fitting procedures to obtain constitutive equations that describe the material response to external loading as a function of temperature and strain rate. Unfortunately, the experimental procedure for characterizing flow curves is complex and expensive, which is why the prediction of flow-curves by computer modelling becomes increasingly important. In the present work, we introduce a state parameter based model that is capable of predicting the flow curves of an A6061 aluminium alloy in different heat-treatment conditions. The model is implemented in the thermo-kinetic software package MatCalc and takes into account precipitation kinetics, subgrain formation, dynamic recovery by spontaneous annihilation and dislocation climb. To validate the simulation results, a series of compression tests is performed on the thermo-mechanical simulator Gleeble 1500.

Modelling Dynamic Behaviour and Spall Failure of Aluminium Alloy AA7010

NASA Astrophysics Data System (ADS)

Ma'at, N.; Nor, M. K. Mohd; Ismail, A. E.; Kamarudin, K. A.; Jamian, S.; Ibrahim, M. N.; Awang, M. K.

2017-10-01

A finite strain constitutive model to predict the dynamic deformation behaviour of Aluminium Alloy 7010 including shockwaves and spall failure is developed in this work. The important feature of this newly hyperelastic-plastic constitutive formulation is a new Mandel stress tensor formulated using new generalized orthotropic pressure. This tensor is combined with a shock equation of state (EOS) and Grady spall failure. The Hill’s yield criterion is adopted to characterize plastic orthotropy by means of the evolving structural tensors that is defined in the isoclinic configuration. This material model was developed and integration into elastic and plastic parts. The elastic anisotropy is taken into account through the newly stress tensor decomposition of a generalized orthotropic pressure. Plastic anisotropy is considered through yield surface and an isotropic hardening defined in a unique alignment of deviatoric plane within the stress space. To test its ability to describe shockwave propagation and spall failure, the new material model was implemented into the LLNL-DYNA3D code of UTHM’s. The capability of this newly constitutive model were compared against published experimental data of Plate Impact Test at 234m/s, 450m/s and 895m/s impact velocities. A good agreement is obtained between experimental and simulation in each test.

Treatment of highly concentrated tannery wastewater using electrocoagulation: Influence of the quality of aluminium used for the electrode.

PubMed

Elabbas, S; Ouazzani, N; Mandi, L; Berrekhis, F; Perdicakis, M; Pontvianne, S; Pons, M-N; Lapicque, F; Leclerc, J-P

2016-12-05

This paper deals with the ability of electrocoagulation (EC) to remove simultaneously COD and chromium from a real chrome tanning wastewater in a batch stirred electro-coagulation cell provided with two aluminium-based electrodes (aluminium/copper/magnesium alloy and pure aluminium). Effects of operating time, current density and initial concentration of Cr(III) and COD have been investigated. The concentrations of pollutants have been successfully reduced to environmentally acceptable levels even if the concentrated effluent requires a long time of treatment of around 6h with a 400A/m(2) current density. The aluminium alloy was found to be more efficient than pure aluminium for removal of COD and chromium. Dilution of the waste has been tested for treatment: high abatement levels could be obtained with shorter time of treatment and lower current densities. Energy consumption of the electrocoagulation process was also discussed. The dilution by half of the concentrated waste leads to a higher abatement performance of both COD and chromium with the best energy efficiency. Copyright © 2016 Elsevier B.V. All rights reserved.

Modelling of Local Necking and Fracture in Aluminium Alloys

DOE Office of Scientific and Technical Information (OSTI.GOV)

Achani, D.; Eriksson, M.; Hopperstad, O. S.

2007-05-17

Non-linear Finite Element simulations are extensively used in forming and crashworthiness studies of automotive components and structures in which fracture need to be controlled. For thin-walled ductile materials, the fracture-related phenomena that must be properly represented are thinning instability, ductile fracture and through-thickness shear instability. Proper representation of the fracture process relies on the accuracy of constitutive and fracture models and their parameters that need to be calibrated through well defined experiments. The present study focuses on local necking and fracture which is of high industrial importance, and uses a phenomenological criterion for modelling fracture in aluminium alloys. As anmore » accurate description of plastic anisotropy is important, advanced phenomenological constitutive equations based on the yield criterion YLD2000/YLD2003 are used. Uniaxial tensile tests and disc compression tests are performed for identification of the constitutive model parameters. Ductile fracture is described by the Cockcroft-Latham fracture criterion and an in-plane shear tests is performed to identify the fracture parameter. The reason is that in a well designed in-plane shear test no thinning instability should occur and it thus gives more direct information about the phenomenon of ductile fracture. Numerical simulations have been performed using a user-defined material model implemented in the general-purpose non-linear FE code LS-DYNA. The applicability of the model is demonstrated by correlating the predicted and experimental response in the in-plane shear tests and additional plane strain tension tests.« less

Experiment-based modelling of grain boundary β-phase (Mg2Al3) evolution during sensitisation of aluminium alloy AA5083.

PubMed

Zhang, R; Steiner, M A; Agnew, S R; Kairy, S K; Davies, C H J; Birbilis, N

2017-06-07

An empirical model for the evolution of β-phase (Mg 2 Al 3 ) along grain boundaries in aluminium alloy AA5083 (Al-Mg-Mn) during isothermal exposures is proposed herein. Developing a quantitative understanding of grain boundary precipitation is important to interpreting intergranular corrosion and stress corrosion cracking in this alloy system. To date, complete ab initio models for grain boundary precipitation based upon fundamental principles of thermodynamics and kinetics are not available, despite the critical role that such precipitates play in dictating intergranular corrosion phenomena. Empirical models can therefore serve an important role in advancing the understanding of grain boundary precipitation kinetics, which is an approach applicable beyond the present context. High resolution scanning electron microscopy was to quantify the size and distribution of β-phase precipitates on Ga-embrittled intergranular fracture surfaces of AA5083. The results are compared with the degree of sensitisation (DoS) as judged by nitric acid mass loss testing (ASTM-G67-04), and discussed with models for sensitisation in 5xxx series Al-alloys. The work herein allows sensitisation to be quantified from an unambiguous microstructural perspective.

Effect of Mg and Cu on mechanical properties of high-strength welded joints of aluminum alloys obtained by laser welding

NASA Astrophysics Data System (ADS)

Annin, B. D.; Fomin, V. M.; Karpov, E. V.; Malikov, A. G.; Orishich, A. M.

2017-09-01

Results of experimental investigations of welded joints of high-strength aluminum-lithium alloys of the Al-Cu-Li and Al-Mg-Li systems are reported. The welded joints are obtained by means of laser welding and are subjected to various types of processing for obtaining high-strength welded joints. A microstructural analysis is performed. The phase composition and mechanical properties of the welded joints before and after heat treatment are studied. It is found that combined heat treatment of the welded joint (annealing, quenching, and artificial ageing) increases the joint strength, but appreciably decreases the alloy strength outside the region thermally affected by the welding process.

Microstructural characterisation of friction stir welding joints of mild steel to Ni-based alloy 625

DOE Office of Scientific and Technical Information (OSTI.GOV)

Rodriguez, J.; University of Campinas; Ramirez, A.J., E-mail: ramirezlondono.1@osu.edu

2015-12-15

In this study, 6-mm-thick mild steel and Ni-based alloy 625 plates were friction stir welded using a tool rotational speed of 300 rpm and a travel speed of 100 mm·min{sup −1}. A microstructural characterisation of the dissimilar butt joint was performed using optical microscopy, scanning and transmission electron microscopy, and energy dispersive X-ray spectroscopy (XEDS). Six different weld zones were found. In the steel, the heat-affected zone (HAZ) was divided into three zones and was composed of ferrite, pearlite colonies with different morphologies, degenerated regions of pearlite and allotriomorphic and Widmanstätten ferrite. The stir zone (SZ) of the steel showedmore » a coarse microstructure consisting of allotriomorphic and Widmanstätten ferrite, degenerate pearlite and MA constituents. In the Ni-based alloy 625, the thermo-mechanically affected zone (TMAZ) showed deformed grains and redistribution of precipitates. In the SZ, the high deformation and temperature produced a recrystallised microstructure, as well as fracture and redistribution of MC precipitates. The M{sub 23}C{sub 6} precipitates, present in the base material, were also redistributed in the stir zone of the Ni-based alloy. TMAZ in the steel and HAZ in the Ni-based alloy could not be identified. The main restorative mechanisms were discontinuous dynamic recrystallisation in the steel, and discontinuous and continuous dynamic recrystallisation in the Ni-based alloy. The interface region between the steel and the Ni-based alloy showed a fcc microstructure with NbC carbides and an average length of 2.0 μm. - Highlights: • Comprehensive microstructural characterisation of dissimilar joints of mild steel to Ni-based alloy • Friction stir welding of joints of mild steel to Ni-based alloy 625 produces sound welds. • The interface region showed deformed and recrystallised fcc grains with NbC carbides and a length of 2.0 μm.« less

Increasing Ti-6Al-4V brazed joint strength equal to the base metal by Ti and Zr amorphous filler alloys

DOE Office of Scientific and Technical Information (OSTI.GOV)

Ganjeh, E., E-mail: navidganjehie@sina.kntu.ac.ir; Sarkhosh, H.; Bajgholi, M.E.

Microstructural features developed along with mechanical properties in furnace brazing of Ti-6Al-4V alloy using STEMET 1228 (Ti-26.8Zr-13Ni-13.9Cu, wt.%) and STEMET 1406 (Zr-9.7Ti-12.4Ni-11.2Cu, wt.%) amorphous filler alloys. Brazing temperatures employed were 900-950 Degree-Sign C for the titanium-based filler and 900-990 Degree-Sign C for the zirconium-based filler alloys, respectively. The brazing time durations were 600, 1200 and 1800 s. The brazed joints were evaluated by ultrasonic test, and their microstructures and phase constitutions analyzed by metallography, scanning electron microscopy and X-ray diffraction analysis. Since microstructural evolution across the furnace brazed joints primarily depends on their alloying elements such as Cu, Ni andmore » Zr along the joint. Accordingly, existence of Zr{sub 2}Cu, Ti{sub 2}Cu and (Ti,Zr){sub 2}Ni intermetallic compounds was identified in the brazed joints. The chemical composition of segregation region in the center of brazed joints was identical to virgin filler alloy content which greatly deteriorated the shear strength of the joints. Adequate brazing time (1800 s) and/or temperature (950 Degree-Sign C for Ti-based and 990 Degree-Sign C for Zr-based) resulted in an acicular Widmanstaetten microstructure throughout the entire joint section due to eutectoid reaction. This microstructure increased the shear strength of the brazed joints up to the Ti-6Al-4V tensile strength level. Consequently, Ti-6Al-4V can be furnace brazed by Ti and Zr base foils produced excellent joint strengths. - Highlights: Black-Right-Pointing-Pointer Temperature or time was the main factors of controlling braze joint strength. Black-Right-Pointing-Pointer Developing a Widmanstaetten microstructure generates equal strength to base metal. Black-Right-Pointing-Pointer Brittle intermetallic compounds like (Ti,Zr){sub 2}Ni/Cu deteriorate shear strength. Black-Right-Pointing-Pointer Ti and Zr base filler alloys were the best choice for

Iron aluminide alloy coatings and joints, and methods of forming

DOEpatents

Wright, Richard N.; Wright, Julie K.; Moore, Glenn A.

1994-01-01

A method of joining two bodies together, at least one of the bodies being predominantly composed of metal, the two bodies each having a respective joint surface for joining with the joint surface of the other body, the two bodies having a respective melting point, includes the following steps: a) providing aluminum metal and iron metal on at least one of the joint surfaces of the two bodies; b) after providing the aluminum metal and iron metal on the one joint surface, positioning the joint surfaces of the two bodies in juxtaposition against one another with the aluminum and iron positioned therebetween; c) heating the aluminum and iron on the juxtaposed bodies to a temperature from greater than or equal to 600.degree. C. to less than the melting point of the lower melting point body; d) applying pressure on the juxtaposed surfaces; and e) maintaining the pressure and the temperature for a time period effective to form the aluminum and iron into an iron aluminide alloy joint which bonds the juxtaposed surfaces and correspondingly the two bodies together. The method can also effectively be used to coat a body with an iron aluminide coating.

Iron aluminide alloy coatings and joints, and methods of forming

DOEpatents

Wright, R.N.; Wright, J.K.; Moore, G.A.

1994-09-27

Disclosed is a method of joining two bodies together, at least one of the bodies being predominantly composed of metal, the two bodies each having a respective joint surface for joining with the joint surface of the other body, the two bodies having a respective melting point, includes the following steps: (a) providing aluminum metal and iron metal on at least one of the joint surfaces of the two bodies; (b) after providing the aluminum metal and iron metal on the one joint surface, positioning the joint surfaces of the two bodies in juxtaposition against one another with the aluminum and iron positioned therebetween; (c) heating the aluminum and iron on the juxtaposed bodies to a temperature from greater than or equal to 600 C to less than the melting point of the lower melting point body; (d) applying pressure on the juxtaposed surfaces; and (e) maintaining the pressure and the temperature for a time period effective to form the aluminum and iron into an iron aluminide alloy joint which bonds the juxtaposed surfaces and correspondingly the two bodies together. The method can also effectively be used to coat a body with an iron aluminide coating.

Tensile Properties of Friction Stir Welded Joints of AA 2024-T6 Alloy at Different Welding Speeds

NASA Astrophysics Data System (ADS)

Avula, Dhananjayulu; Devuri, Venkateswarlu; Cheepu, Muralimohan; Dwivedi, Dheerendra Kumar

2018-03-01

The influence of welding speed on the friction stir welded joint properties of hardness, tensile properties, defects and microstructure characterization are studied in the present study. The friction stir welding was conducted on AA2014-T6 heat treated alloy with 5 mm thickness plate in butt joint configuration. The welding speed was varied from 8 mm/min to 120 mm/min at the fixed travel speed and load conditions. It is observed that the welding speeds at higher rate with wide range can be possible to weld this alloy at higher rates of tool revolution suggesting that the inherent capability of friction stir welding technique for aluminum 2014 alloys. The strength of the joints gradually increases with enhancing of welding speed. The micro structural observations exhibited the formation of equiaxed grains in the stir zone and slightly in the thermo-mechanically affected zone. In addition, the size of the grains decreases with increase in welding speed owing to the presence of low heat input. Hence the hardness of the joints slightly increased in the stir zones over the other zones of the weld nugget. The joint strength initially increases with the welding speed and starts to decreases after reaching to the maximum value. The relationship between the welding conditions and friction stir welded joint properties has been discussed.

Aluminium. II - A review of deformation properties of high purity aluminium and dilute aluminium alloys.

NASA Technical Reports Server (NTRS)

Reed, R. P.

1972-01-01

The elastic and plastic deformation behavior of high-purity aluminum and of dilute aluminum alloys is reviewed. Reliable property data, including elastic moduli, elastic coefficients, tensile, creep, fatigue, hardness, and impact are presented. Single crystal tensile results are discussed. Rather comprehensive reference lists, containing publications of the past 20 years, are included for each of the above categories. Defect structures and mechanisms responsible for mechanical behavior are presented. Strengthening techniques (alloys, cold work, irradiation, quenching, composites) and recovery are briefly reviewed.

Use of Nitrocarburizing for Strengthening Threaded Joints of Drill Pipes from Medium-Carbon Alloy Steels

NASA Astrophysics Data System (ADS)

Priymak, E. Yu.; Stepanchukova, A. V.; Yakovleva, I. L.; Tereshchenko, N. A.

2015-05-01

Nitrocarburizing is tested at the Drill Equipment Plant for reinforcing threaded joints of drill pipes for units with retrievable core receiver (RCR). The effect of the nitrocarburizing on the mechanical properties of steels of different alloying systems is considered. Steels for the production of threaded joints of drill pipes are recommended.

Subminiature eddy-current transducers designed to study welded joints of titanium alloys

NASA Astrophysics Data System (ADS)

Malikov, V. N.; Dmitriev, S. F.; Katasonov, A. O.; Sagalakov, A. M.; Ishkov, A. V.

2017-12-01

Eddy current transducers (ECT) are used to construct a sensor for investigating titanium sheets connected by a welded joint. The paper provides key technical information about the eddy current transducer used and describes the procedure of measurements that makes it possible to control defects in welded joints of titanium alloys. It is capable of automatically changing the filtering cutoff frequency and operating frequency of the device. Experiments were conducted on welded VT1-0 titanium plates. The paper contains the results of these measurements. The dependence data facilitates the assessment of the quality of the welded joints and helps make an educated conclusion about welding quality.

Improved TIG weld joint strength in aluminum alloy 2219-T87 by filler metal substitution

NASA Technical Reports Server (NTRS)

Poorman, R. M.; Lovoy, C. V.

1972-01-01

The results of an investigation on weld joint characteristics of aluminum alloy 2219-T87 are given. Five different alloys were utilized as filler material. The mechanical properties of the joints were determined at ambient and cryogenic temperatures for weldments in the as-welded condition and also, for weldments after elevated temperature exposures. Other evaluations included hardness surveys, stress corrosion susceptibility, and to a limited extent, the internal metallurgical weld structures. The overall results indicate that M-943 filler weldments are superior in strength to weldments containing either the standard 2319 filler or fillers 2014, 2020, and a dual wire feed consisting of three parts 2319 and one part 5652. In addition, no deficiencies were evident in M-934 filler weldments with regard to ductility, joint strength after elevated temperature exposure, weld hardness, metallographic structures, or stress corrosion susceptibility.

Microstructure and Properties of Lap Joint Between Aluminum Alloy and Galvanized Steel by CMT

NASA Astrophysics Data System (ADS)

Niu, Song; Chen, Su; Dong, Honggang; Zhao, Dongsheng; Zhang, Xiaosheng; Guo, Xin; Wang, Guoqiang

2016-05-01

Lap joining of 1-mm-thick Novelist AC 170 PX aluminum alloy to 1.2-mm-thick ST06 Z galvanized steel sheets for automotive applications was conducted by cold metal transfer advanced welding process with ER4043 and ER4047 filler wires. Under the optimized welding parameters with ER4043 filler wire, the tensile shear strength of joint was 189 MPa, reaching 89% of the aluminum alloy base metal. Microstructure and elemental distribution were characterized by optical metalloscope and electron probe microanalysis. The lap joints with ER4043 filler wire had smaller wetting angle and longer bonded line length with better wettability than with ER4047 filler wire during welding with same parameters. The needle-like Al-Fe-Si intermetallic compounds (IMCs) were spalled into the weld and brought negative effect to the tensile strength of joints. With increasing welding current, the needle-like IMCs grew longer and spread further into the weld, which would deteriorate the tensile shear strength.

Mechanical and interfacial characterization of laser welded Co-Cr alloy with different joint configurations

PubMed Central

Kokolis, John; Chakmakchi, Makdad; Theocharopoulos, Antonios; Prombonas, Anthony

2015-01-01

PURPOSE The mechanical and interfacial characterization of laser welded Co-Cr alloy with two different joint designs. MATERIALS AND METHODS Dumbbell cast specimens (n=30) were divided into 3 groups (R, I, K, n=10). Group R consisted of intact specimens, group I of specimens sectioned with a straight cut, and group K of specimens with a 45° bevel made at the one welding edge. The microstructure and the elemental distributions of alloy and welding regions were examined by an SEM/EDX analysis and then specimens were loaded in tension up to fracture. The tensile strength (TS) and elongation (ε) were determined and statistically compared among groups employing 1-way ANOVA, SNK multiple comparison test (α=.05) and Weibull analysis where Weibull modulus m and characteristic strength σο were identified. Fractured surfaces were imaged by a SEM. RESULTS SEM/EDX analysis showed that cast alloy consists of two phases with differences in mean atomic number contrast, while no mean atomic number was identified for welded regions. EDX analysis revealed an increased Cr and Mo content at the alloy-joint interface. All mechanical properties of group I (TS, ε, m and σο) were found inferior to R while group K showed intermediated values without significant differences to R and I, apart from elongation with group R. The fractured surfaces of all groups showed extensive dendritic pattern although with a finer structure in the case of welded groups. CONCLUSION The K shape joint configuration should be preferred over the I, as it demonstrates improved mechanical strength and survival probability. PMID:25722836

A Study on Effect of Graphite Particles on Tensile, Hardness and Machinability of Aluminium 8011 Matrix Material

NASA Astrophysics Data System (ADS)

Latha Shankar, B.; Anil, K. C.; Karabasappagol, Prasann J.

2016-09-01

Industrial application point of view, metal matrix composites in general and Aluminium alloy matrix composites in particular are ideal candidates because of their favourable engineering properties. Being lightweight Aluminium matrix composites are widely used in aircraft, defence and automotive industries. In this work Aluminium 8011 metal matrix was reinforced with fine Graphite particles of 50 μm. developed by two-step Stir casting method. Graphite weight %was varied in the range 2, 4, 6 and 8%. Uniform dispersion of graphite particle is examined under optical microscope. Tensile test coupons were prepared as per standard to determine % of elongation and tensile strength for various % of graphite particle. Hardness of developed composite for various % of graphite particle and Machinability parameters were also studied for effect on surface finish. It was observed that with increase of weight percentage of Graphite particles up to 8% in Aluminium 8011 alloy matrix there was increase in tensile strength, decrease in % of elongation with increase in hardness. Machinability study revealed that, there was decrease in surface roughness with increase in Graphite content.

Finite Element Simulation of Aluminium/GFRP Fibre Metal Laminate under Tensile Loading

NASA Astrophysics Data System (ADS)

Merzuki, M. N. M.; Rejab, M. R. M.; Romli, N. K.; Bachtiar, D.; Siregar, J.; Rani, M. F.; Salleh, Salwani Mohd

2018-03-01

The response of a fibre metal laminate (FML) model to the tensile loading is predicted through a computational approach. The FML consisted with layers of aluminum alloy and embedded with one layer of composite material, Glass fibre Reinforced Plastic (GFRP). The glass fibre and aluminium alloy 2024-0 was laminated by using thermoset epoxy. A compression moulding technique was used in the process of a FML fabrication. The aluminium has been roughen by a metal sanding method which to improve the bonding between the fibre and metal layer. The main objective of this paper is to determine the failure behaviour of the FML under the tensile loading. The responses on the FML under the tensile loading were numerically performed. The FML was modelled and analysed by using Abaqus/CAE 6.13 version. Based on the experimental and FE data of the tensile, the ultimate tensile stress is 120 MPa where delamination and fibre breakage happened. A numerical model was developed and agreed well with the experimental results. The laminate has an inelastic respond to increase the tensile loads which due to the plasticity of the aluminium layers.

Investigation on wear and corrosion behavior of equal channel angular pressed aluminium 2014 alloy

NASA Astrophysics Data System (ADS)

Divya, S. P.; Yoganandan, G.; Balaraju, J. N.; Srinivasan, S. A.; Nagaraj, M.; Ravisankar, B.

2018-02-01

Aluminium 2014 alloy solutionized at 495°C, aged at 195°C was subjected to Equal Channel Angular Pressing (ECAP). Dry sliding wear tests were conducted using pin on disc tribometer system under nominal loads of 10N and 30N with constant speed 2m/s for 2000m in order to investigate their wear behavior after ECAP. The Co-efficient of friction and loss in volume were decreased after ECAP. The dominant wear mechanism observed was adhesion, delamination in addition to these wear mechanisms, oxidation and transfer of Fe from the counter surface to the Al 2014 pin were observed at higher loading condition. The corrosion behavior was evaluated by potentiodynamic polarization (PDP) and electrochemical impedance spectroscopy (EIS) in 3.5% NaCl solution. The results obtained from PDP showed higher corrosion potential and lower corrosion density after ECAP than base. Electrochemical impedance spectroscopy (EIS) showed higher charge transfer resistance after ECAP. Surface morphology showed decreased pit size and increased oxygen content in ECAP sample than base after PDP.

Strain Measurement in Aluminium Alloy during the Solidification Process Using Embedded Fibre Bragg Gratings.

PubMed

Weraneck, Klaus; Heilmeier, Florian; Lindner, Markus; Graf, Moritz; Jakobi, Martin; Volk, Wolfram; Roths, Johannes; Koch, Alexander W

2016-11-04

In recent years, the observation of the behaviour of components during the production process and over their life cycle is of increasing importance. Structural health monitoring, for example of carbon composites, is state-of-the-art research. The usage of Fibre Bragg Gratings (FBGs) in this field is of major advantage. Another possible area of application is in foundries. The internal state of melts during the solidification process is of particular interest. By using embedded FBGs, temperature and stress can be monitored during the process. In this work, FBGs were embedded in aluminium alloys in order to observe the occurring strain. Two different FBG positions were chosen in the mould in order to compare its dependence. It was shown that FBGs can withstand the solidification process, although a compression in the range of one percent was measured, which is in agreement with the literature value. Furthermore, different lengths of the gratings were applied, and it was shown that shorter gratings result in more accurate measurements. The obtained results prove that FBGs are applicable as sensors for temperatures up to 740 °C.

Special Features of Induction Annealing of Friction Stir Welded Joints of Medium-Alloy Steels

NASA Astrophysics Data System (ADS)

Priymak, E. Yu.; Stepanchukova, A. V.; Bashirova, E. V.; Fot, A. P.; Firsova, N. V.

2018-01-01

Welded joints of medium-alloy steels XJY750 and 40KhN2MA are studied in the initial condition and after different variants of annealing. Special features of the phase transformations occurring in the welded steels are determined. Optimum modes of annealing are recommended for the studied welded joints of drill pipes, which provide a high level of mechanical properties including the case of impact loading.

Volatilisation and oxidation of aluminium scraps fed into incineration furnaces

DOE Office of Scientific and Technical Information (OSTI.GOV)

Biganzoli, Laura, E-mail: laura.biganzoli@mail.polimi.it; Gorla, Leopoldo; Nessi, Simone

Highlights: Black-Right-Pointing-Pointer Aluminium packaging partitioning in MSW incineration residues is evaluated. Black-Right-Pointing-Pointer The amount of aluminium packaging recoverable from the bottom ashes is evaluated. Black-Right-Pointing-Pointer Aluminium packaging oxidation rate in the residues of MSW incineration is evaluated. Black-Right-Pointing-Pointer 80% of aluminium cans, 51% of trays and 27% of foils can be recovered from bottom ashes. - Abstract: Ferrous and non-ferrous metal scraps are increasingly recovered from municipal solid waste incineration bottom ash and used in the production of secondary steel and aluminium. However, during the incineration process, metal scraps contained in the waste undergo volatilisation and oxidation processes, which determinemore » a loss of their recoverable mass. The present paper evaluates the behaviour of different types of aluminium packaging materials in a full-scale waste to energy plant during standard operation. Their partitioning and oxidation level in the residues of the incineration process are evaluated, together with the amount of potentially recoverable aluminium. About 80% of post-consumer cans, 51% of trays and 27% of foils can be recovered through an advanced treatment of bottom ash combined with a melting process in the saline furnace for the production of secondary aluminium. The residual amount of aluminium concentrates in the fly ash or in the fine fraction of the bottom ash and its recovery is virtually impossible using the current eddy current separation technology. The average oxidation levels of the aluminium in the residues of the incineration process is equal to 9.2% for cans, 17.4% for trays and 58.8% for foils. The differences between the tested packaging materials are related to their thickness, mechanical strength and to the alloy.« less

The influence of laser alloying on the structure and mechanical properties of AlMg5Si2Mn surface layers

NASA Astrophysics Data System (ADS)

Pakieła, W.; Tański, T.; Brytan, Z.; Labisz, K.

2016-04-01

The goal of this paper was focused on investigation of microstructure and properties of surface layer produced during laser surface treatment of aluminium alloy by high-power fibre laser. The performed laser treatment involves remelting and feeding of Inconel 625 powder into the aluminium surface. As a base metal was used aluminium alloy AlMg5Si2Mn. The Inconel powder was injected into the melt pool and delivered by a vacuum feeder at a constant rate of 4.5 g/min. The size of Inconel alloying powder was in the range 60-130 µm. In order to remelt the aluminium alloy surface, the fibre laser of 3 kW laser beam power has been used. The linear laser scan rate of the beam was set 0.5 m/min. Based on performed investigations, it was possible to obtain the layer consisting of heat-affected zone, transition zone and remelted zone, without cracks and defects having much higher hardness value compared to the non-alloyed material.

Mechanical Properties of Aluminum-Based Dissimilar Alloy Joints by Power Beams, Arc and FSW Processes

NASA Astrophysics Data System (ADS)

Okubo, Michinori; Kon, Tomokuni; Abe, Nobuyuki

Dissimilar smart joints are useful. In this research, welded quality of dissimilar aluminum alloys of 3 mm thickness by various welding processes and process parameters have been investigated by hardness and tensile tests, and observation of imperfection and microstructure. Base metals used in this study are A1050-H24, A2017-T3, A5083-O, A6061-T6 and A7075-T651. Welding processes used are YAG laser beam, electron beam, metal inert gas arc, tungsten inert gas arc and friction stir welding. The properties of weld zones are affected by welding processes, welding parameters and combination of base metals. Properties of high strength aluminum alloy joints are improved by friction stir welding.

Finite element simulations and experimental investigations on ductile fracture in cold forging of aluminum alloy

NASA Astrophysics Data System (ADS)

Amiri, Amir; Nikpour, Amin; Saraeian, Payam

2018-05-01

Forging is one of the manufacturing processes of aluminium parts which has two major categories: called hot and cold forging. In the cold forging, the dimensional and geometrical accuracy of final part is high. However, fracture may occur in some aluminium alloys during the process because of less workability. Fracture in cold forging can be in the form of ductile, brittle or combination of both depending on the alloy type. There are several criteria for predicting fracture in cold forging. In this study, cold forging process of 6063 aluminium alloy for three different parts is simulated in order to predict fracture. The results of numerical simulations of Freudenthal criterion is in conformity with experimental tests.

Fracture Toughness and Shear Strength of the Bonded Interface Between an Aluminium Alloy Skin and a FRP Patch

NASA Astrophysics Data System (ADS)

Kumar, Prashant; Shinde, Prakash Sonyabapu; Bhoyar, Gaurav

2018-05-01

The existing techniques to determine the fracture properties such as critical energy release rate in mode I (GIc) and mode II (GIIc) of an interface between two sheets of same material were modified to determine these properties between the sheets of dissimilar materials and thickness. In addition, the interface shear strength (ISS) was also determined. Experiments were carried out on the specimens made of a pre-cracked thin aluminium alloy skin and a Fiber reinforced polymer (FRP) patch. Two kinds of surface preparation of the aluminium skin were employed; (i) emery-paper roughened surface (ERS) and (ii) Sodium Hydroxide (NaOH) treated surface (NTS). GIc of ERS specimen was found to be 36.1 J/m2, while it was found to be much higher for NTS specimens, that is, 87.3 J/m2. GIIc was found to be 282.4 J/m2 for ERS specimens and much higher as 734.5 J/m2 for NTS specimens. ISS was determined as 32.6 MPa for ERS specimen and significantly higher for NTS specimen, that is, 44.5 MPa. The micrographs obtained from a field emission-scanning electron microscope (FE-SEM) and the surface roughness test showed that the NTS was significantly rougher than the ERS, explaining the higher values of all the three kinds of NTS specimens.

Dietary exposure to aluminium in the popular Chinese fried bread youtiao.

PubMed

Li, Ge; Zhao, Xue; Wu, Shimin; Hua, Hongying; Wang, Qiang; Zhang, Zhiheng

2017-06-01

Youtiao is a typical, traditional and widely consumed fried food in China. Fermentation of youtiao involves the use of aluminium potassium sulphate (alum). There are health concerns related to the levels of aluminium in food; therefore, we aimed to determine the aluminium concentrations of youtiao from various locations, and to estimate the dietary exposure by different age groups in southern and northern China. The aluminium content of youtiao samples varied considerably (range = 4.46-852.69 mg kg -1 ). Both the mean and median aluminium contents of youtiao exceeded 100 mg kg -1 , which is the China National Standard (GB) 2760-2014 National Food Safety for Standards for food additives. However, the median and 97.5th percentile of weekly dietary exposure to aluminium from youtiao, estimated using Monte Carlo simulation, did not exceed the provisional tolerable weekly intake (PTWI) set by the joint FAO/WHO Expert Committee on Food Additives (JECFA) for children, adolescents, adults and seniors. The weekly dietary exposure to aluminium would exceed the PTWI if children, adolescents, adults and seniors consumed 134.47, 260.98, 327.10 or 320.41 g of youtiao per week, respectively.

A Brief Research Review for Improvement Methods the Wettability between Ceramic Reinforcement Particulate and Aluminium Matrix Composites

NASA Astrophysics Data System (ADS)

Razzaq, Alaa Mohammed; Majid, Dayang Laila Abang Abdul; Ishak, M. R.; B, Uday M.

2017-05-01

The development of new methods for addition fine ceramic powders to Al aluminium alloy melts, which would lead to more uniform distribution and effective incorporation of the reinforcement particles into the aluminium matrix alloy. Recently the materials engineering research has moved to composite materials from monolithic, adapting to the global need for lightweight, low cost, quality, and high performance advanced materials. Among the different methods, stir casting is one of the simplest ways of making aluminium matrix composites. However, it suffers from poor distribution and combination of the reinforcement ceramic particles in the metal matrix. These problems become significantly effect to reduce reinforcement size, more agglomeration and tendency with less wettability for the ceramic particles in the melt process. Many researchers have carried out different studies on the wettability between the metal matrix and dispersion phase, which includes added wettability agents, fluxes, preheating the reinforcement particles, coating the reinforcement particles, and use composting techniques. The enhancement of wettability of ceramic particles by the molten matrix alloy and the reinforcement particles distribution improvement in the solidified matrix is the main objective for many studies that will be discussed in this paper.

Thermal migration of alloying agents in aluminium

NASA Astrophysics Data System (ADS)

Cooil, S. P.; Mørtsell, E. A.; Mazzola, F.; Jorge, M.; Wenner, S.; Edmonds, M. T.; Thomsen, L.; Klemm, H. W.; Peschel, G.; Fuhrich, A.; Prieto, M.; Schmidt, Th; Miwa, J. A.; Holmestad, R.; Wells, J. W.

2016-11-01

The in situ thermal migration of alloying agents in an Al-Mg-Si-Li alloy is studied using surface sensitive photo-electron and electron diffraction/imaging techniques. Starting with the preparation of an almost oxide free surface (oxide thickness = 0.1 nm), the relative abundance of alloying agents (Mg, Li and Si) at the surface are recorded at various stages of thermal annealing, from room temperature to melting (which is observed at 550 ◦C). Prior to annealing, the surface abundances are below the detection limit ≪1%, in agreement with their bulk concentrations of 0.423% Si, 0.322% Mg and 0.101% Li (atomic %). At elevated temperatures, all three alloying agents appear at drastically increased concentrations (13.3% Si, 19.7% Mg and 45.3% Li), but decrease again with further elevation of the annealing temperature or after melting. The temperature at which the migration occurs is species dependent, with Li migration occurring at significantly higher temperatures than Si and Mg. The mechanism of migration also appears to be species dependent with Li migration occurring all over the surface but Mg migration being restricted to grain boundaries.

Ratcheting fatigue behaviour of Al-7075 T6 alloy: Influence of stress parameters

NASA Astrophysics Data System (ADS)

Amarnath, Lala; Bhattacharjee, Antara; Dutta, K.

2016-02-01

The use of aluminium and aluminium based alloys are increasing rapidly on account of its high formability, good thermal and electrical conductivity, high strength and lightness. Aluminium alloys are extensively used in aerospace, automobile, marine and space research industries and are also put into structural applications where chances of fatigue damage cannot be ruled out. In the current work, it is intended to study the ratcheting fatigue behavior of 7075-T6 aluminium alloy at room temperature. This Al alloy is potentially used in aviation, marine and automotive components as well as in bicycle parts, rock mounting equipment and parts of ammunition where there is every chance of failure of the parts due to deformation caused by ratcheting. Ratcheting is the process of accruement of plastic stain produced when a component is subjected to asymmetric cyclic loading under the influence of low cycle fatigue. To accomplish the requirements of the projected research, stress-controlled cyclic loading experiments were done using a ±250 kN servo-hydraulic universal testing machine (Instron: 8800R). The effect of stress parameters such as mean stress and stress amplitude were investigated on the ratcheting behavior of the selected aluminium alloy. It was observed that, ratcheting strain increased with increase in the value of stress amplitude at any constant mean stress while a saturation in strain accumulation attained in the investigated material after around 10-20 cycles, under all test conditions. The analyses of hysteresis loop generated during cyclic loading indicate that the material exhibits cyclic hardening in the initial fifty cycles which gets softened in further loading up to about 70-80 cycles and finally attains a steady state. The increase in the ratcheting strain value with stress parameters happens owing to increased deformation domain during cycling. The cyclic hardening accompanied by softening is correlated with characteristic precipitation features of

Tensile strength and corrosion resistance of brazed and laser-welded cobalt-chromium alloy joints.

PubMed

Zupancic, Rok; Legat, Andraz; Funduk, Nenad

2006-10-01

The longevity of prosthodontic restorations is often limited due to the mechanical or corrosive failure occurring at the sites where segments of a metal framework are joined together. The purpose of this study was to determine which joining method offers the best properties to cobalt-chromium alloy frameworks. Brazed and 2 types of laser-welded joints were compared for their mechanical and corrosion characteristics. Sixty-eight cylindrical cobalt-chromium dental alloy specimens, 35 mm long and 2 mm in diameter, were cast. Sixteen specimens were selected for electrochemical measurements in an artificial saliva solution and divided into 4 groups (n=4). In the intact group, the specimens were left as cast. The specimens of the remaining 3 groups were sectioned at the center, perpendicular to the long-axis, and were subsequently rejoined by brazing (brazing group) or laser welding using an X- or I-shaped joint design (X laser and I laser groups, respectively). Another 16 specimens were selected for electrochemical measurements in a more acidic artificial saliva solution. These specimens were also divided into 4 groups (n=4) as described above. Electrochemical impedance spectroscopy and potentiodynamic polarization were used to assess corrosion potentials, breakdown potentials, corrosion current densities, total impedances at lowest frequency, and polarization charge-transfer resistances. The remaining 36 specimens were used for tensile testing. They were divided into 3 groups in which specimen pairs (n=6) were joined by brazing or laser welding to form 70-mm-long cylindrical rods. The tensile strength (MPa) was measured using a universal testing machine. Differences between groups were analyzed using 1-way analysis of variance (alpha=.05). The fracture surfaces and corrosion defects were examined with a scanning electron microscope. The average tensile strength of brazed joints was 792 MPa and was significantly greater (P<.05) than the tensile strength of both types of

Metal transfer and V-I transients in GMAW of aluminium

DOE Office of Scientific and Technical Information (OSTI.GOV)

Pandey, S.; Rao, U.R.K.; Aghakhani, M.

1996-12-31

The mode of metal transfer in arc welding significantly affects the positional weldability; particularly the overhead welding, the chemical composition and properties of weld metal, metallurgy of weld metal, weld pool stability, arc stability, spatter losses, and weld bead geometry. The mode of metal transfer is affected mainly by the type of the arc, welding current, electrode polarity, arc voltage, contact tube to plate distance (CTPD)/Stand-off, type and flow rate of the shielding gas, torch angle and alloying elements in GMAW of aluminium and its alloys.

The microstructure and precipitation effects in Inconel alloy 690

NASA Astrophysics Data System (ADS)

Smith, Alan J.

Failure of Alloy 600 steam generator tubing in Pressurised Water Reactors (PWRs) has prompted the investigation of alloy 690 as an alternative material. Six commercially produced tubes and ten experimentally produced alloys have been examined with varying amounts of carbon, aluminium and titanium. Alloy compositions have been selected to investigate the individual and combined effects of these elements on the microstructure and corrosion behaviour in the environments of corrosion tests and simulated PWR conditions. Alloys were subjected to simulated mill annealing treatments at varied temperatures. Microstructural characterisation using optical and electron microscopy has demonstrated the effects of composition and thermal treatment in controlling grain size and carbide precipitation together with the interdependence between these structural details. Stress corrosion resistance of selected alloy 690 tubes has been examined with samples in an autoclave at fixed temperatures with environments based on pure water, sodium hydroxide and sodium hydroxide + sodium sulphate solutions. Susceptibility to intergranular attack has been related to aluminium contents of the alloy and to thermal treatments given. Results suggest a decreased resistance to IGA when aluminium is increased. Thermal treatments given to the samples appear not to be very significant to the amounts of IGA. The compositions and heat treatments used in the corrosion study were further examined on a dedicated scanning transmission electron microscope in order to correlate the effects of, chromium depletion, nickel enrichment and impurity segregation at grain boundaries, with corrosion characteristics. These results have shown the effect of varying the special thermal treatment temperature and time on the degree of enrichment / depletion / segregation and the corrosion resistance of the alloy. The mechanism of protection afforded by the special thermal treatment can thus be elucidated.

Low-cost high-quality Fe-based shape memory alloys suitable for pipe joints

NASA Astrophysics Data System (ADS)

Kajiwara, Setsuo; Baruj, Albert L.; Kikuchi, Takehiko; Shinya, Norio

2003-08-01

By addition of small amount of Nb and C to the conventional Fe-Mn-Si based shape memory alloys, shape memory properties are greatly improved in such an extent that the costly 'training' heat treatment is no more necessary. The key to this remarkable improvement of shape memory effect is to produce small NbC precipitates of about several nm in size in austenite. In order to generate such very small NbC particles, the sample is firstly rolled at 870 K and then aged at 1070 K. An example of Fe-28Mn-6Si-5Cr-0.53Nb-0.06C (mass %) alloy is shown; 95% shape recovery for initial strain of 4% is obtained and the shape recovery stress of about 300 MPa is attained for the sample pre-rolled 14%, which is well above the criterion for industry application of pipe jointing. A pipe jointing with this material is demonstrated.

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.

Design and Analysis of Wind Turbine Blade Hub using Aluminium Alloy AA 6061-T6

NASA Astrophysics Data System (ADS)

Ravikumar, S.; Jaswanthvenkatram, V.; Sai kumar, Y. J. N. V.; Sohaib, S. Md.

2017-05-01

This work presents the design and analysis of horizontal axis wind turbine blade hub using different material. The hub is very crucial part of the wind turbine, which experience the loads from the blades and the loads were transmitted to the main shaft. At present wind turbine is more expensive and weights more than a million pounds, with the nacelle, rotor hub and blades accounting for most of the weight. In this work Spheroidal graphite cast iron GGG 40.3 is replaced by aluminium alloy 6061-T6 to enhance the casting properties and also to improve the strength-weight ratio. This transition of material leads to reduction in weight of the wind turbine. All the loads caused by wind and extreme loads on the blades are transferred to the hub. Considering the IEC 61400-1 standard for defining extreme loads on the hub the stress and deflection were calculated on the hub by using Finite element Analysis. Result obtained from ANSYS is compared and discussed with the existing design.

Process Simulation of Aluminium Sheet Metal Deep Drawing at Elevated Temperatures

DOE Office of Scientific and Technical Information (OSTI.GOV)

Winklhofer, Johannes; Trattnig, Gernot; Lind, Christoph

Lightweight design is essential for an economic and environmentally friendly vehicle. Aluminium sheet metal is well known for its ability to improve the strength to weight ratio of lightweight structures. One disadvantage of aluminium is that it is less formable than steel. Therefore complex part geometries can only be realized by expensive multi-step production processes. One method for overcoming this disadvantage is deep drawing at elevated temperatures. In this way the formability of aluminium sheet metal can be improved significantly, and the number of necessary production steps can thereby be reduced. This paper introduces deep drawing of aluminium sheet metalmore » at elevated temperatures, a corresponding simulation method, a characteristic process and its optimization. The temperature and strain rate dependent material properties of a 5xxx series alloy and their modelling are discussed. A three dimensional thermomechanically coupled finite element deep drawing simulation model and its validation are presented. Based on the validated simulation model an optimised process strategy regarding formability, time and cost is introduced.« less

Aluminium plasmonics

DOE Office of Scientific and Technical Information (OSTI.GOV)

Gerard, Davy; Gray, Stephen K.

In this study, we present an overview of 'aluminium plasmonics', i.e. the study of both fundamental and practical aspects of surface plasmon excitations in aluminium structures, in particular thin films and metal nanoparticles. After a brief introduction noting both some recent and historical contributions to aluminium plasmonics, we discuss the optical properties of aluminium and aluminium nanostructures and highlight a few selected studies in a host of areas ranging from fluorescence to data storage.

Aluminium plasmonics

DOE PAGES

Gerard, Davy; Gray, Stephen K.

2014-12-15

In this study, we present an overview of 'aluminium plasmonics', i.e. the study of both fundamental and practical aspects of surface plasmon excitations in aluminium structures, in particular thin films and metal nanoparticles. After a brief introduction noting both some recent and historical contributions to aluminium plasmonics, we discuss the optical properties of aluminium and aluminium nanostructures and highlight a few selected studies in a host of areas ranging from fluorescence to data storage.

Thermal treatment, grain boundary composition and intergranular attack resistance of Alloy 690

DOE Office of Scientific and Technical Information (OSTI.GOV)

Smith, A.J.; Stratton, R.P.

1992-12-31

Commercial Alloy 690 PWR steam generator tubes and experimentally produced alloys with varying amounts of carbon, aluminium and titanium have been examined. After simulated mill annealing and thermal treatment, the microstructure and corrosion behaviour in corrosion tests have been investigated. Stress corrosion resistance of selected alloy 690 tubes and experimental alloys has been examined with environments based on pure water, sodium hydroxide and sodium hydroxide + sodium sulphate solutions. Effects of aluminium content and the thermal treatments on the susceptibility to intergranular attack have been examined, although they appear not to be very significant to the amounts of IGA. Samplesmore » used in thermal treatments have been further examined with a dedicated scanning transmission electron microscope to show compositional changes at grain boundaries.« less

Crashworthiness of Aluminium Tubes; Part 2: Improvement of Hydroforming Operation to Increase Absorption Energy

DOE Office of Scientific and Technical Information (OSTI.GOV)

D'Amours, Guillaume; Rahem, Ahmed; Mayer, Robert

2007-05-17

The motivation to reduce overall vehicle weight within the automotive sector drives the substitution of lightweight materials such as aluminium alloys for structural components. Such a substitution requires a significant amount of development to manufacture structurally parts such that the energy absorption characteristics are not sacrificed in the event of crash. The effects of the manufacturing processes on the crash performance of automotive structural components must be better understood to ensure improved crashworthiness. This paper presents results of an experimental and numerical investigation of the crash response and energy absorption properties of impacted hydroformed aluminium alloy tubes. Crash experiments onmore » hydroformed tubes were performed using a deceleration sled test at the General Motors Technical Center. Results from axial crush testing showed that an important parameter that influences the energy absorption characteristics during crash was the thickness reduction caused by circumferential expansion of the tube during hydroforming. It was found that that the energy absorption decreased as the corner radius decreased, which results because of increased thinning. Sensitivity studies of end feeding parameters, such as end feed level and profile, were carried out to evaluate their impact on the energy absorption of the aluminium tubes.« less

Crashworthiness of Aluminium Tubes; Part 2: Improvement of Hydroforming Operation to Increase Absorption Energy

NASA Astrophysics Data System (ADS)

D'Amours, Guillaume; Rahem, Ahmed; Mayer, Robert; Williams, Bruce; Worswick, Michael

2007-05-01

The motivation to reduce overall vehicle weight within the automotive sector drives the substitution of lightweight materials such as aluminium alloys for structural components. Such a substitution requires a significant amount of development to manufacture structurally parts such that the energy absorption characteristics are not sacrificed in the event of crash. The effects of the manufacturing processes on the crash performance of automotive structural components must be better understood to ensure improved crashworthiness. This paper presents results of an experimental and numerical investigation of the crash response and energy absorption properties of impacted hydroformed aluminium alloy tubes. Crash experiments on hydroformed tubes were performed using a deceleration sled test at the General Motors Technical Center. Results from axial crush testing showed that an important parameter that influences the energy absorption characteristics during crash was the thickness reduction caused by circumferential expansion of the tube during hydroforming. It was found that that the energy absorption decreased as the corner radius decreased, which results because of increased thinning. Sensitivity studies of end feeding parameters, such as end feed level and profile, were carried out to evaluate their impact on the energy absorption of the aluminium tubes.

The effect of welding parameters on surface quality of AA6351 aluminium alloy

NASA Astrophysics Data System (ADS)

Yacob, S.; MAli, M. A.; Ahsan, Q.; Ariffin, N.; Ali, R.; Arshad, A.; Wahab, M. I. A.; Ismail, S. A.; Roji, NS M.; Din, W. B. W.; Zakaria, M. H.; Abdullah, A.; Yusof, M. I.; Kamarulzaman, K. Z.; Mahyuddin, A.; Hamzah, M. N.; Roslan, R.

2015-12-01

In the present work, the effects of gas metal arc welding-cold metal transfer (GMAW-CMT) parameters on surface roughness are experimentally assessed. The purpose of this study is to develop a better understanding of the effects of welding speed, material thickness and contact tip to work distance on the surface roughness. Experiments are conducted using single pass gas metal arc welding-cold metal transfer (GMAW-CMT) welding technique to join the material. The material used in this experiment was AA6351 aluminum alloy with the thickness of 5mm and 6mm. A Mahr Marsuft XR 20 machine was used to measure the average roughness (Ra) of AA6351 joints. The main and interaction effect analysis was carried out to identify process parameters that affect the surface roughness. The results show that all the input process parameters affect the surface roughness of AA6351 joints. Additionally, the average roughness (Ra) results also show a decreasing trend with increased of welding speed. It is proven that gas metal arc welding-cold metal transfer (GMAW-CMT)welding process has been successful in term of providing weld joint of good surface quality for AA6351 based on the low value surface roughness condition obtained in this setup. The outcome of this experimental shall be valuable for future fabrication process in order to obtained high good quality weld.

Novel Dissimilar Joints Between Alloy 800H and 2.25%Cr and 1%Mo Steel

DOE Office of Scientific and Technical Information (OSTI.GOV)

DebRoy, Tarasankar

Dissimilar metal joints between ferritic steels and nickel base alloys are currently fabricated using conventional arc welding processes with selected filler metal combinations. The dissimilar metal joints contain abrupt changes in composition over a relatively small distance. Many years of service at elevated temperatures has shown that these welds are susceptible to creep and creep fatigue failures. The primary mechanism for these creep failures involves carbon diffusion from the ferritic steel to the nickel base alloy. As a result, a carbon depleted zone is created that contains very few stable carbides. This work used additive manufacturing (AM) technologies as amore » highly controllable means for reducing carbon migration through theoretically designed, compositionally graded transition joints guided by appropriate thermodynamic, kinetic and heat transfer and fluid flow modeling. The contents of the report include the objectives and tasks set forth by the PI and collaborators, major technical accomplishments throughout the research and additional details in the form of technical publications resulting from the NEUP grant and reports from the collaborating university and national laboratory.« less

Welding current and melting rate in GMAW of aluminium

DOE Office of Scientific and Technical Information (OSTI.GOV)

Pandey, S.; Rao, U.R.K.; Aghakhani, M.

1996-12-31

Studies on GMAW of aluminium and its alloy 5083, revealed that the welding current and melting rate were affected by any change in wire feed rate, arc voltage, nozzle to plate distance, welding speed and torch angle. Empirical models have been presented to determine accurately the welding current and melting rate for any set of these parameters. These results can be utilized for determining accurately the heat input into the workpiece from which reliable predictions can be made about the mechanical and the metallurgical properties of a welded joint. The analysis of the model also helps in providing a vitalmore » information about the static V-I characteristics of the welding power source. The models were developed using a two-level fractional factorial design. The adequacy of the model was tested by the use of analysis of variance technique and the significance of the coefficients was tested by the student`s t test. The estimated and observed values of the welding current and melting rate have been shown on a scatter diagram and the interaction effects of different parameters involved have been presented in graphical forms.« less

Influence of Welding Process and Post Weld Heat Treatment on Microstructure and Pitting Corrosion Behavior of Dissimilar Aluminium Alloy Welds

NASA Astrophysics Data System (ADS)

Venkata Ramana, V. S. N.; Mohammed, Raffi; Madhusudhan Reddy, G.; Srinivasa Rao, K.

2018-03-01

Welding of dissimilar Aluminum alloy welds is becoming important in aerospace, shipbuilding and defence applications. In the present work, an attempt has been made to weld dissimilar aluminium alloys using conventional gas tungsten arc welding (GTAW) and friction stir welding (FSW) processes. An attempt was also made to study the effect of post weld heat treatment (T4 condition) on microstructure and pitting corrosion behaviour of these welds. Results of the present investigation established the differences in microstructures of the base metals in T4 condition and in annealed conditions. It is evident that the thickness of the PMZ is relatively more on AA2014 side than that of AA6061 side. In FS welds, lamellar like shear bands are well noticed on the top of the stir zone. The concentration profile of dissimilar friction stir weld in T4 condition revealed that no diffusion has taken place at the interface. Poor Hardness is observed in all regions of FS welds compared to that of GTA welds. Pitting corrosion resistance of the dissimilar FS welds in all regions was improved by post weld heat treatment.

Effect of Stress Relief Annealing on Microstructure & Mechanical Properties of Welded Joints Between Low Alloy Carbon Steel and Stainless Steel

NASA Astrophysics Data System (ADS)

Nivas, R.; Das, G.; Das, S. K.; Mahato, B.; Kumar, S.; Sivaprasad, K.; Singh, P. K.; Ghosh, M.

2017-01-01

Two types of welded joints were prepared using low alloy carbon steel and austenitic stainless steel as base materials. In one variety, buttering material and weld metal were Inconel 82. In another type, buttering material and weld metal were Inconel 182. In case of Inconel 82, method of welding was GTAW. For Inconel 182, welding was done by SMAW technique. For one set of each joints after buttering, stress relief annealing was done at 923 K (650 °C) for 90 minutes before further joining with weld metal. Microstructural investigation and sub-size in situ tensile testing in scanning electron microscope were carried out for buttered-welded and buttered-stress relieved-welded specimens. Adjacent to fusion boundary, heat-affected zone of low alloy steel consisted of ferrite-pearlite phase combination. Immediately after fusion boundary in low alloy steel side, there was increase in matrix grain size. Same trend was observed in the region of austenitic stainless steel that was close to fusion boundary between weld metal-stainless steel. Close to interface between low alloy steel-buttering material, the region contained martensite, Type-I boundary and Type-II boundary. Peak hardness was obtained close to fusion boundary between low alloy steel and buttering material. In this respect, a minimum hardness was observed within buttering material. The peak hardness was shifted toward buttering material after stress relief annealing. During tensile testing no deformation occurred within low alloy steel and failure was completely through buttering material. Crack initiated near fusion boundary between low alloy steel-buttering material for welded specimens and the same shifted away from fusion boundary for stress relieved annealed specimens. This observation was at par with the characteristics of microhardness profile. In as welded condition, joints fabricated with Inconel 82 exhibited superior bond strength than the weld produced with Inconel 182. Stress relief annealing

Structural Phase Evolution in Ultrasonic-Assisted Friction Stir Welded 2195 Aluminum Alloy Joints

NASA Astrophysics Data System (ADS)

Eliseev, A. A.; Fortuna, S. V.; Kalashnikova, T. A.; Chumaevskii, A. V.; Kolubaev, E. A.

2017-10-01

The authors examined the structural and phase state of fixed joints produced by method of friction stir welding (FSW) and ultrasonic-assisted friction stir welding (UAFSW) from extruded profile of aluminum alloy AA2195. In order to identify the role of ultrasonic application in the course of welding, such characteristics, as volume fraction and average size of secondary particles are compared in the base material and stir zones of FSW and UAFSW joints. By applying the methods of SEM and TEM analysis, researchers established the complex character of phase transitions as a result of ultrasonic application.

Constant and variable amplitude ultrasonic fatigue of 2024-T351 aluminium alloy at different load ratios.

PubMed

Mayer, H; Fitzka, M; Schuller, R

2013-12-01

Ultrasonic fatigue testing equipment is presented that is capable of performing constant amplitude (CA) and variable amplitude (VA) experiments at different constant load ratios. This equipment is used to study cyclic properties of aluminium alloy 2024-T351 in the high cycle fatigue (HCF) and very high cycle fatigue (VHCF) regime at load ratios R=-1 and R=0.5. CA loading does not reveal a fatigue limit below 10¹⁰ cycles. Cracks leading to VHCF failure start at broken constituent particles. Specimens that survived more than 10¹⁰ cycles at R=-1 contain non-propagating cracks of lengths below grain size. Resonance frequency and nonlinearity parameter β(rel) show changes of vibration properties of specimens at low fractions of their VHCF lifetime. VA lifetimes are measured in the HCF and VHCF regime and compared with Miner calculations. Damage sums decrease with decreasing load (and increasing mean lifetimes) and are lower for R=0.5 than R=-1. Copyright © 2013 Elsevier B.V. All rights reserved.

Effect of welding process on the microstructure and properties of dissimilar weld joints between low alloy steel and duplex stainless steel

NASA Astrophysics Data System (ADS)

Wang, Jing; Lu, Min-xu; Zhang, Lei; Chang, Wei; Xu, Li-ning; Hu, Li-hua

2012-06-01

To obtain high-quality dissimilar weld joints, the processes of metal inert gas (MIG) welding and tungsten inert gas (TIG) welding for duplex stainless steel (DSS) and low alloy steel were compared in this paper. The microstructure and corrosion morphology of dissimilar weld joints were observed by scanning electron microscopy (SEM); the chemical compositions in different zones were detected by energy-dispersive spectroscopy (EDS); the mechanical properties were measured by microhardness test, tensile test, and impact test; the corrosion behavior was evaluated by polarization curves. Obvious concentration gradients of Ni and Cr exist between the fusion boundary and the type II boundary, where the hardness is much higher. The impact toughness of weld metal by MIG welding is higher than that by TIG welding. The corrosion current density of TIG weld metal is higher than that of MIG weld metal in a 3.5wt% NaCl solution. Galvanic corrosion happens between low alloy steel and weld metal, revealing the weakness of low alloy steel in industrial service. The quality of joints produced by MIG welding is better than that by TIG welding in mechanical performance and corrosion resistance. MIG welding with the filler metal ER2009 is the suitable welding process for dissimilar metals jointing between UNS S31803 duplex stainless steel and low alloy steel in practical application.

Comparison of Extensive Thermal Cycling Effects on Microstructure Development in Micro-alloyed Sn-Ag-Cu Solder Joints

DOE Office of Scientific and Technical Information (OSTI.GOV)

Anderson, Iver E.; Boesenberg, Adam; Harringa, Joel

2011-09-28

Pb-free solder alloys based on the Sn-Ag-Cu (SAC) ternary eutectic have promise for widespread adoption across assembly conditions and operating environments, but enhanced microstructural control is needed. Micro-alloying with elements such as Zn was demonstrated for promoting a preferred solidification path and joint microstructure earlier in simple (Cu/Cu) solder joints studies for different cooling rates. This beneficial behavior now has been verified in reworked ball grid array (BGA) joints, using dissimilar SAC305 (Sn-3.0Ag-0.5Cu, wt.%) solder paste. After industrial assembly, BGA components joined with Sn-3.5Ag-0.74Cu-0.21Zn solder were tested in thermal cycling (-55 C/+125 C) along with baseline SAC305 BGA joints beyondmore » 3000 cycles with continuous failure monitoring. Weibull analysis of the results demonstrated that BGA components joined with SAC + Zn/SAC305 have less joint integrity than SAC305 joints, but their lifetime is sufficient for severe applications in consumer, defense, and avionics electronic product field environments. Failure analysis of the BGA joints revealed that cracking did not deviate from the typical top area (BGA component side) of each joint, in spite of different Ag3Sn blade content. Thus, SAC + Zn solder has not shown any advantage over SAC305 solder in these thermal cycling trials, but other characteristics of SAC + Zn solder may make it more attractive for use across the full range of harsh conditions of avionics or defense applications.« less

Recovery of actinides from actinide-aluminium alloys by chlorination: Part III - Chlorination with HCl(g)

NASA Astrophysics Data System (ADS)

Meier, Roland; Souček, Pavel; Walter, Olaf; Malmbeck, Rikard; Rodrigues, Alcide; Glatz, Jean-Paul; Fanghänel, Thomas

2018-01-01

Two steps of a pyrochemical route for the recovery of actinides from spent metallic nuclear fuel are being investigated at JRC-Karlsruhe. The first step consists in electrorefining the fuel in molten salt medium implying aluminium cathodes. The second step is a chlorination process for the separation of actinides (An) from An-Al alloys formed on the cathodes. The chlorination process, in turn, consists of three steps; the distillation of adhered salt (1), the chlorination of An-Al by HCl/Cl2 under formation of AlCl3 and An chlorides (2), and the subsequent sublimation of AlCl3 (3). In the present work UAl2, UAl3, NpAl2, and PuAl2 were chlorinated with HCl(g) in a temperature range between 300 and 400 °C forming UCl4, NpCl4 or PuCl3 as the major An containing phases, respectively. Thermodynamic calculations were carried out to support the experimental work. The results showed a high chlorination efficiency for all used starting materials and indicated that the sublimation step may not be necessary when using HCl(g).

Electromagnetic Gauge Study of Laser-Induced Shock Waves in Aluminium Alloys

NASA Astrophysics Data System (ADS)

Peyre, P.; Fabbro, R.

1995-12-01

The laser-shock behaviour of three industrial aluminum alloys has been analyzed with an Electromagnetic Gauge Method (EMV) for measuring the velocity of the back free surface of thin foils submitted to plane laser irradiation. Surface pressure, shock decay in depth and Hugoniot Elastic Limits (HEL) of the materials were investigated with increasing thicknesses of foils to be shocked. First, surface peak pressures values as a function of laser power density gave a good agreement with conventional piezoelectric quartz measurements. Therefore, comparison of experimental results with computer simulations, using a 1D hydrodynamic Lagrangian finite difference code, were also in good accordance. Lastly, HEL values were compared with static and dynamic compressive tests in order to estimate the effects of a very large range of strain rates (10^{-3} s^{-1} to 10^6 s^{-1}) on the mechanical properties of the alloys. Cet article fait la synthèse d'une étude récente sur la caractérisation du comportement sous choc-laser de trois alliages d'aluminium largement utilisés dans l'industrie à travers la méthode dite de la jauge électromagnétique. Cette méthode permet de mesurer les vitesses matérielles induites en face arrière de plaques d'épaisseurs variables par un impact laser. La mise en vitesse de plaques nous a permis, premièrement, de vérifier la validité des pressions d'impact superficielles obtenues en les comparant avec des résultats antérieurs obtenus par des mesures sur capteurs quartz. Sur des plaques d'épaisseurs croissantes, nous avons caractérisé l'atténuation des ondes de choc en profondeur dans les alliages étudiés et mesuré les limites d'élasticité sous choc (pressions d'Hugoniot) des alliages. Les résultats ont été comparés avec succès à des simulations numériques grâce à un code de calcul monodimensionnel Lagrangien. Enfin, les valeurs des pressions d'Hugoniot mesurées ont permis de tracer l'évolution des contraintes d

Grain refinement of Al-Si9.8-Cu3.4 alloy by novel Al-3.5FeNb-1.5C master alloy and its effect on mechanical properties

NASA Astrophysics Data System (ADS)

Apparao, K. Ch; Birru, Anil Kumar

2018-01-01

A novel Al-3.5FeNb-1.5C master alloy with uniform microstructure was prepared using a melt reaction process for this study. In the master alloy, basic intermetallic particles such as NbAl3, NbC act as heterogeneous nucleation substrates during the solidification of aluminium. The grain refining performance of the novel master alloy on Al-Si9.8-Cu3.4 alloy has also been investigated. It is observed that the addition of 0.1 wt.% of Al-3.5FeNb-1.5C master alloy can induce very effective grain refinement of the Al-Si9.8-Cu3.4 alloy. The average grain size of α-Al is reduced to 22.90 μm from about 61.22 μm and most importantly, the inoculation of Al-Si9.8-Cu3.4 alloy with FeNb-C is not characterised by any visible poisoning effect, which is the drawback of using commercial Al-Ti-B master alloys on aluminium cast alloys. Therefore, the mechanical properties of the Al-Si9.8-Cu3.4 alloy have been improved obviously by the addition of the 0.1 wt.% of Al-3.5FeNb-1.5C master alloy, including the yield strength and elongation.

Microstructure Analysis on 6061 Aluminum Alloy after Casting and Diffuses Annealing Process

NASA Astrophysics Data System (ADS)

Wang, H. Q.; Sun, W. L.; Xing, Y. Q.

One factory using semi-continuous casting process produce the ф200×6000 mm 6061 aluminium alloy barstock, and then rotary forged for car wheels. 6061 distorting aluminium alloy is an forged aluminum alloy, and mainly containing Mg, Si, Cu and other alloying elements. The main strengthening phase is Mg2Si, and also has few phase of (FeMn) 3Si2Al15. In order to eliminate the segregation and separation which present in the crystal boundary, and make the distortion to be uniform, and does not present ear and fracture defects after the forging. So the 6061 distorting aluminium alloy adopt the diffusion annealing heat treatment before the forging process.According to the current conditions, we use the diffusion annealing which have the different heating temperature and different holding time.The best process we can obtain from the test which can improve the production efficiency and reduce the material waste, improve the mechanical properties, and eliminate the overheated film on the surface.Then,we using OM,SEM and EDS to analyse the microstructure and the chemical composition of compound between the surface and centre. The result shows that the amount of segregation were different in the surface and in the center, and the different diffusion annealing can cause the phase change in the surface and the center.

Microstructure and critical strain of dynamic recrystallization of 6082 aluminum alloy in thermal deformation

NASA Astrophysics Data System (ADS)

Ren, W. W.; Xu, C. G.; Chen, X. L.; Qin, S. X.

2018-05-01

Using high temperature compression experiments, true stress true strain curve of 6082 aluminium alloy were obtained at the temperature 460°C-560°C and the strain rate 0.01 s-1-10 s-1. The effects of deformation temperature and strain rate on the microstructure are investigated; (‑∂lnθ/∂ε) ‑ ε curves are plotted based on σ-ε curve. Critical strains of dynamic recrystallization of 6082 aluminium alloy model were obtained. The results showed lower strain rates were beneficial to increase the volume fraction of recrystallization, the average recrystallized grain size was coarse; High strain rates are beneficial to refine average grain size, the volume fraction of dynamic recrystallized grain is less than that by using low strain rates. High temperature reduced the dislocation density and provided less driving force for recrystallization so that coarse grains remained. Dynamic recrystallization critical strain model and thermal experiment results can effectively predict recrystallization critical point of 6082 aluminium alloy during thermal deformation.

The porosity formation mechanism in the laser-MIG hybrid welded joint of Invar alloy

NASA Astrophysics Data System (ADS)

Zhan, Xiaohong; Gao, Qiyu; Gu, Cheng; Sun, Weihua; Chen, Jicheng; Wei, Yanhong

2017-10-01

The porosity formation mechanism in the laser-metal inter gas (MIG) multi-layer hybrid welded (HW) joint of 19.05 mm thick Invar alloy is investigated. The microstructure characteristics and energy dispersive spectroscopy (EDS) are analyzed. The phase identification was conducted by the X-ray diffractometer (XRD). Experimental results show that the generation of porosity is caused by the relatively low laser power in the root pass and low current in the cover pass. It is also indicated that the microstructures of the welded joints are mainly observed to be columnar crystal and equiaxial crystal, which are closely related to the porosity formation. The EDS results show that oxygen content is significantly high in the inner wall of the porosity. The XRD results indicate that the BM and the WB of laser-MIG HW all are composed of Fe0.64Ni0.36 and γ-(Fe,Ni). When the weld pool is cooled quickly, [NiO] [FeO] and [MnO] are formed that react on C to generate CO/CO2 gases. The porosity of laser-MIG HW for Invar alloy is oxygen pore. The root source of metallurgy porosity formation is that the dissolved gases are hard to escape sufficiently and thus exist in the weld pool. Furthermore, 99.99% pure Argon is recommended as protective gas in the laser-MIG HW of Invar alloy.

The Joint Strength and Fracture Mechanisms of TC4/TC4 and TA0/TA0 Brazed with Ti-25Cu-15Ni Braze Alloy

NASA Astrophysics Data System (ADS)

Zou, Zhihuan; Zeng, Fanhao; Wu, Haobo; Liu, Jian; Li, Yi; Gu, Yi; Yuan, Tiechui; Zhang, Fuqin

2017-05-01

In this paper, Ti-25Cu-15Ni (mass ratio) braze alloys were prepared by vacuum arc melting. Additionally, the TA0 pure titanium and TC4 titanium alloy were brazed with the Ti-25Cu-15Ni braze alloy at 960, 980, 1000, 1020, and 1040 °C. The effects of the braze temperature on the tensile strength of the TA0 and TC4 joints and their fracture mechanisms were studied. The maximum tensile strength of the TA0 joints of 219.9 ± 0.1 MPa was achieved at a brazing temperature of 980 °C, and the maximum tensile strength of the TC4 joints of 832.9 ± 0.1 MPa was achieved at the same brazing temperature. These results indicate that their ideal joint strength is comparable. According to the fractography results of the TA0 joints, a mixed fracture morphology is indicated. The TA0 fracture surface is dominated by cleavage fracture with a small contribution from ductile fracture. The TC4 joint fracture arises from cleavage.

BRAZING ALLOYS

DOEpatents

Donnelly, R.G.; Gilliland, R.G.; Slaughter, G.M.

1963-02-26

A brazing alloy which, in the molten state, is characterized by excellent wettability and flowability, said alloy being capable of forming a corrosion resistant brazed joint wherein at least one component of said joint is graphite and the other component is a corrosion resistant refractory metal, said alloy consisting essentially of 20 to 50 per cent by weight of gold, 20 to 50 per cent by weight of nickel, and 15 to 45 per cent by weight of molybdenum. (AEC)

The chemical phenol extraction of intermetallic particles from casting AlSi5Cu1Mg alloy.

PubMed

Mrówka-Nowotnik, G; Sieniawski, J; Nowotnik, A

2010-03-01

This paper presents a chemical extraction technique for determination of intermetallic phases formed in the casting AlSi5Cu1Mg aluminium alloy. Commercial aluminium alloys contain a wide range of intermetallic particles that are formed during casting, homogenization and thermomechanical processing. During solidification, particles of intermetallics are dispersed in interdendritic spaces as fine primary phases. Coarse intermetallic compounds that are formed in this aluminium alloy are characterized by unique atomic arrangement (crystallographic structure), morphology, stability, physical and mechanical properties. The volume fraction, chemistry and morphology of the intermetallics significantly affect properties and material behaviour during thermomechanical processing. Therefore, accurate determination of intermetallics is essential to understand and control microstructural evolution in Al alloys. Thus, in this paper it is shown that chemical phenol extraction method can be applied for precise qualitative evaluation. The results of optical light microscopy LOM, scanning electron microscopy SEM and X-ray diffraction XRD analysis reveal that as-cast AlSi5Cu1Mg alloy contains a wide range of intermetallic phases such as Al(4)Fe, gamma- Al(3)FeSi, alpha-Al(8)Fe(2)Si, beta-Al(5)FeSi, Al(12)FeMnSi.

Influences of post weld heat treatment on tensile strength and microstructure characteristics of friction stir welded butt joints of AA2014-T6 aluminum alloy

NASA Astrophysics Data System (ADS)

Rajendran, C.; Srinivasan, K.; Balasubramanian, V.; Balaji, H.; Selvaraj, P.

2016-08-01

Friction stir welded (FSWed) joints of aluminum alloys exhibited a hardness drop in both the advancing side (AS) and retreating side (RS) of the thermo-mechanically affected zone (TMAZ) due to the thermal cycle involved in the FSW process. In this investigation, an attempt has been made to overcome this problem by post weld heat treatment (PWHT) methods. FSW butt (FSWB) joints of Al-Cu (AA2014-T6) alloy were PWHT by two methods such as simple artificial aging (AA) and solution treatment followed by artificial aging (STA). Of these two treatments, STA was found to be more beneficial than the simple aging treatment to improve the tensile properties of the FSW joints of AA2014 aluminum alloy.

The effect of surface pre-conditioning treatments on the local composition of Zr-based conversion coatings formed on aluminium alloys

NASA Astrophysics Data System (ADS)

Cerezo, J.; Vandendael, I.; Posner, R.; de Wit, J. H. W.; Mol, J. M. C.; Terryn, H.

2016-03-01

This study investigates the effect of different alkaline, acidic and thermal pre-conditioning treatments applied to different Al alloy surfaces. The obtained results are compared to the characteristics of Zr-based conversion coatings that were subsequently generated on top of these substrates. Focus is laid on typical elemental distributions on the sample surfaces, in particular on the amount of precipitated functional additives such as Cu species that are present in the substrate matrix as well as in the conversion bath solutions. To this aim, Field Emission Auger Electron spectra, depth profiles and surface maps with superior local resolution were acquired and compared to scanning electron microscopy images of the sample. The results show how de-alloying processes, which occur at and around intermetallic particles in the Al matrix during typical industrial alkaline or acidic cleaning procedures, provide a significant source of crystallization cores for any following coating processes. This is in particular due for Cu-species, as the resulting local Cu structures on the surface strongly affect the film formation and compositions of state-of-the-art Zr-based films. The findings are highly relevant for industrial treatments of aluminium surfaces, especially for those that undergo corrosion protection and painting process steps prior to usage.

Microstructure and Mechanical Properties of Dissimilar Joints of Al-Mg2Si and 5052 Aluminum Alloy by Friction Stir Welding

NASA Astrophysics Data System (ADS)

Huang, B. W.; Qin, Q. D.; Zhang, D. H.; Wu, Y. J.; Su, X. D.

2018-03-01

Al-Mg2Si alloy and 5052 Al alloy were welded successfully by friction stir welding (FSW) in this study. The results show that the alloy consists of three distinct zones after FSW: the base material zone (BMZ), the transitional zone, and the weld nugget (WN). The morphologies of the primary Mg2Si phases are identified as coarse equiaxed crystals for Al-Mg2Si alloys in the BMZ. The WN is a mixture of rich Al-Mg2Si and rich 5052 alloy, and a banded structure is formed in the zone. Interestingly, in the WN, the equiaxed crystals changed to polygonal particles with substantially reduced sizes in the rich Al-Mg2Si zone. However, in addition to the white rich Mg phase appearing in the rich 5052 zone near the interface, the 5052 alloy does not show obvious changes. The hardness gradually increases from the BMZ of the 5052 to the welded joint to the Al-Mg2Si BMZ. In addition, the ultimate tensile strength (UTS) of the welded joint is higher than that of the base material of the Al-Mg2Si, whereas it is lower than that of the 5052 base alloy. The results of the elongation are similar to the UTS results. The fracture mechanism is also investigated.

Crack Resistance of Welded Joints of Pipe Steels of Strength Class K60 of Different Alloying Systems

NASA Astrophysics Data System (ADS)

Tabatchikova, T. I.; Tereshchenko, N. A.; Yakovleva, I. L.; Makovetskii, A. N.; Shander, S. V.

2018-03-01

The crack resistance of welded joints of pipe steels of strength class K60 and different alloying systems is studied. The parameter of the crack tip opening displacement (CTOD) is shown to be dependent on the size of the austenite grains and on the morphology of bainite in the superheated region of the heat-affected zone of the weld. The crack resistance is shown to be controllable due to optimization of the alloying system.

Numerical Simulation of Tension Properties for Al-Cu Alloy Friction Stir-Welded Joints with GTN Damage Model

NASA Astrophysics Data System (ADS)

Sun, Guo-Qin; Sun, Feng-Yang; Cao, Fang-Li; Chen, Shu-Jun; Barkey, Mark E.

2015-11-01

The numerical simulation of tensile fracture behavior on Al-Cu alloy friction stir-welded joint was performed with the Gurson-Tvergaard-Needleman (GTN) damage model. The parameters of the GTN model were studied in each region of the friction stir-welded joint by means of inverse identification. Based on the obtained parameters, the finite element model of the welded joint was built to predict the fracture behavior and tension properties. Good agreement can be found between the numerical and experimental results in the location of the tensile fracture and the mechanical properties.

Effects of joint configuration for the arc welding of cast Ti-6Al-4V alloy rods in argon.

PubMed

Taylor, J C; Hondrum, S O; Prasad, A; Brodersen, C A

1998-03-01

Titanium and its alloys are more commonly used in prosthodontics and welding has become the most common modality for their joining. Studies on the welding of titanium and its alloys have not quantified this value, though its importance has been suggested. This study compared the strength and properties of the joint achieved at various butt joint gaps by the arc-welding of cast Ti-6Al-4V alloy tensile bars in an argon atmosphere. Forty of 50 specimens were sectioned and welded at four gaps. All specimens underwent tensile testing to determine ultimate tensile strength and percentage elongation, then oxygen analysis and scanning electron microscopy. As no more than 3 samples in any group of 10 actually fractured in the weld itself, a secondary analysis that involved fracture location was initiated. There were no differences in ultimate tensile strength or percentage elongation between specimens with weld gaps of 0.25, 0.50, 0.75, and 1.00 mm and the as-cast specimens. There were no differences in ultimate tensile strength between specimens fracturing in the weld and those fracturing in the gauge in welded specimens; however, as-cast specimens demonstrated a higher ultimate tensile strength than welded specimens that fractured in the weld. Specimens that fractured in the weld site demonstrated less ductility than those that fractured in the gauge in both welded and as-cast specimens, as confirmed by scanning electron microscopy examination. The weld wire showed an oxygen scavenging effect from the as-cast parent alloy. The effects of the joint gap were not significant, whereas the characteristics of the joint itself were, which displayed slightly lower strength and significantly lower ductility (and thus decreased toughness). The arc-welding of cast titanium alloy in argon atmosphere appears to be a reliable and efficient prosthodontic laboratory modality producing predictable results, although titanium casting and joining procedures must be closely controlled to

The effect of zinc (Zn) content to cell potential value and efficiency aluminium sacrificial anode in 0.2 M sulphuric acid environment

NASA Astrophysics Data System (ADS)

Akranata, Ahmad Ridho; Sulistijono, Awali, Jatmoko

2018-04-01

Sacrificial anode is sacirifial component that used to protect steel from corrosion. Generally, the component are made of aluminium and zinc in water environment. Sacrificial anode change the protected metal structure become cathodic with giving current. The advantages of aluminium is corrosion resistance, non toxicity and easy forming. Zinc generally used for coating in steel to prevent steel from corrosion. This research was conducted to analyze the effect of zinc content to the value of cell potential and efficiency aluminium sacrificial anode with sand casting method in 0.2 M sulphuric acid environment. The sacrificial anode fabrication made with alloying aluminium and zinc metals with variation composition of alloy with pure Al, Al-3Zn, Al-6Zn, and Al-9Zn with open die sand casting process. The component installed with ASTM A36 steel. After the research has been done the result showed that addition of zinc content increase the cell potential, protection efficiency, and anode efficiency from steel plate. Cell potential value measurement and weight loss measurement showed that addition of zinc content increase the cell potential value into more positive that can protected the ASTM A36 steel more efficiently that showed in weight loss measurement where the protection efficiency and anodic efficiency of Al-9Zn sacrificial anode is better than protection efficiency and anodic efficiency of pure Al. The highest protection efficiency gotten by Al-9Zn alloy

In situ monitoring of corrosion mechanisms and phosphate inhibitor surface deposition during corrosion of zinc-magnesium-aluminium (ZMA) alloys using novel time-lapse microscopy.

PubMed

Sullivan, James; Cooze, Nathan; Gallagher, Callum; Lewis, Tom; Prosek, Tomas; Thierry, Dominique

2015-01-01

In situ time-lapse optical microscopy was used to examine the microstructural corrosion mechanisms in three zinc-magnesium-aluminium (ZMA) alloy coated steels immersed in 1% NaCl pH 7. Preferential corrosion of MgZn(2) lamellae within the eutectic phases was observed in all the ZMA alloys followed by subsequent dissolution of Zn rich phases. The total extent and rate of corrosion, measured using time-lapse image analysis and scanning vibrating electrode technique (SVET) estimated mass loss, decreased as Mg and Al alloying additions were increased up to a level of 3 wt% Mg and 3.7 wt% Al. This was probably due to the increased presence of MgO and Al(2)O(3) at the alloy surface retarding the kinetics of cathodic oxygen reduction. The addition of 1 × 10(-2) mol dm(-3) Na(3)PO(4) to 1% NaCl pH 7 had a dramatic influence on the corrosion mechanism for a ZMA with passivation of anodic sites through phosphate precipitation observed using time-lapse image analysis. Intriguing rapid precipitation of filamentous phosphate was also observed and it is postulated that these filaments nucleate and grow due to super saturation effects. Polarisation experiments showed that the addition of 1 × 10(-2) mol dm(-3) Na(3)PO(4) to the 1% NaCl electrolyte promoted an anodic shift of 50 mV in open circuit potential for the ZMA alloy with a reduction in anodic current of 2.5 orders of magnitude suggesting that it was acting primarily as an anodic inhibitor supporting the inferences from the time-lapse investigations. These phosphate additions resulted in a 98% reduction in estimated mass loss as measured by SVET demonstrating the effectiveness of phosphate inhibitors for this alloy system.

Effect of Initial Microstructure on the Microstructural Evolution and Joint Efficiency of a WE43 Alloy During Friction Stir Welding

DTIC Science & Technology

2013-04-01

to maximize joint efficiency. 15. SUBJECT TERMS friction stir welding, strain rate, dynamic recrystallization , joint efficiency, stir zone (SZ...stir welding, Strain rate, Dynamic recrystallization , Joint efficiency, Stir Zone (SZ) Abstract The initial microstructure plays an important role in... eutectic Mg17Al12 phase. Park et al. [7] demonstrated the importance of texture and related it to the mechanical properties of an AZ61 alloy

Improving Joint Formation and Tensile Properties of Dissimilar Friction Stir Welding of Aluminum and Magnesium Alloys by Solving the Pin Adhesion Problem

NASA Astrophysics Data System (ADS)

Liu, Zhenlei; Ji, Shude; Meng, Xiangchen

2018-03-01

Friction stir welding (FSW), as a solid-state welding technology invented by TWI in 1991, has potential to join dissimilar Al/Mg alloys. In this study, the pin adhesion phenomenon affecting joint quality during FSW of 6061-T6 aluminum and AZ31B magnesium alloys was investigated. The adhesion phenomenon induced by higher heat input easily transformed the tapered-and-screwed pin into a tapered pin, which greatly reduced the tool's ability to drive the plasticized materials and further deteriorated joint formation. Under the condition without the pin adhesion, the complex intercalated interlayer at the bottom of stir zone was beneficial to mechanical interlocking of Al/Mg alloys, improving tensile properties. However, the formation of intermetallic compounds was still the main reason of the joint fracture, significantly deteriorating tensile properties. Under the welding speed of 60 mm/min without the pin adhesion phenomenon, the maximum tensile strength of 107 MPa and elongation of 1.2% were achieved.

Improvement in Fatigue Performance of Aluminium Alloy Welded Joints by Laser Shock Peening in a Dynamic Strain Aging Temperature Regime.

PubMed

Su, Chun; Zhou, Jianzhong; Meng, Xiankai; Huang, Shu

2016-09-26

As a new treatment process after welding, the process parameters of laser shock peening (LSP) in dynamic strain aging (DSA) temperature regimes can be precisely controlled, and the process is a non-contact one. The effects of LSP at elevated temperatures on the distribution of the surface residual stress of AA6061-T6 welded joints were investigated by using X-ray diffraction technology with the sin² ϕ method and Abaqus software. The fatigue life of the welded joints was estimated by performing tensile fatigue tests. The microstructural evolution in surface and fatigue fractures of the welded joints was presented by means of surface integrity and fracture surface testing. In the DSA temperature regime of AA6061-T6 welded joints, the residual compressive stress was distributed more stably than that of LSP at room temperature. The thermal corrosion resistance and fatigue properties of the welded joints were also improved. The experimental results and numerical analysis were in mutual agreement.

Improvement in Fatigue Performance of Aluminium Alloy Welded Joints by Laser Shock Peening in a Dynamic Strain Aging Temperature Regime

PubMed Central

Su, Chun; Zhou, Jianzhong; Meng, Xiankai; Huang, Shu

2016-01-01

As a new treatment process after welding, the process parameters of laser shock peening (LSP) in dynamic strain aging (DSA) temperature regimes can be precisely controlled, and the process is a non-contact one. The effects of LSP at elevated temperatures on the distribution of the surface residual stress of AA6061-T6 welded joints were investigated by using X-ray diffraction technology with the sin2ϕ method and Abaqus software. The fatigue life of the welded joints was estimated by performing tensile fatigue tests. The microstructural evolution in surface and fatigue fractures of the welded joints was presented by means of surface integrity and fracture surface testing. In the DSA temperature regime of AA6061-T6 welded joints, the residual compressive stress was distributed more stably than that of LSP at room temperature. The thermal corrosion resistance and fatigue properties of the welded joints were also improved. The experimental results and numerical analysis were in mutual agreement. PMID:28773920

Factors affecting the aluminium content of human femoral head and neck.

PubMed

Zioła-Frankowska, Anetta; Dąbrowski, Mikołaj; Kubaszewski, Łukasz; Rogala, Piotr; Frankowski, Marcin

2015-11-01

Tissues for the study were obtained intraoperatively during hip replacement procedures from 96 patients. In all the cases, the indication for this treatment was primary or secondary degenerative changes in the hip joint. The subject of the study was the head and neck of the femur, resected in situ. Aluminium concentrations measured in femoral head and neck samples from patients aged between 25 and 91 were varied. Statistical methods were applied to determine the variations in relation to the parameters from the background survey. Significant differences in the aluminium content of femoral head samples were observed between patients under and over 60 years of age. Based on the results, it was confirmed that the aluminium accumulates in bones over a lifetime. The study showed that the content of aluminium in the head and neck of the femur depends on the factors such as: type of medicines taken, contact with chemicals at work, differences in body anatomy and sex. The study on the levels of aluminium in bones and the factors affecting its concentration is a valuable source of information for further research on the role of aluminium in bone diseases. Based on the investigations, it was found that the GF-AAS technique is the best analytical tool for routine analysis of aluminium in complex matrix samples. The use of femoral heads in the investigations was approved by the Bioethics Committee of the University of Medical Sciences in Poznań (Poland). Copyright © 2015 Elsevier Inc. All rights reserved.

Special Features of the Structure of Laser-Welded Joints of Dissimilar Alloys Based on Titanium and Aluminum

NASA Astrophysics Data System (ADS)

Nikulina, A. A.; Smirnov, A. I.; Turichin, G. A.; Klimova-Korsmik, O. G.; Babkin, K. D.

2017-11-01

The structure of laser-welded joints of parts having different thicknesses fabricated from alloys based on aluminum and titanium has been studied. Results of transmission and scanning electron microscopy measurements and x-ray diffraction analysis show that the diffusion interaction of microvolumes of two alloys in the weld leads to the formation of two interlayers: (i) a continuous intermetallic TiAl layer with thickness below 1 μm adjacent to the titanium alloy and (ii) a layer consisting of TiAl3 intermetallic dendrites with thickness of 2 - 6 μm adjacent to the TiAl layer. The average microhardness of the intermetallic layer is about 490 HV.

Structure-Property Relations in Aluminum-Lithium Alloys

DTIC Science & Technology

1989-01-01

adsorbed ( Mughrabi et al , 1983). Such dislocations could not re-enter the grain during the reverse cycle of stress and the associated slip would be...ASTM STP 601, ASTM, 33 Mughrabi , H., Wang, R., Differt, D., Essmann, U. (1983) ASTM STP 811, ASTM, 5 Muller, W. et al (1986) Aluminium-Lithium Alloys...behaviour of Al -Li-Cu-Mg-Zr alloys ...... 34 2.4 Mechanical behaviour ......................................... 35 2.4.1 Elastic modulus

Electrochemical Codeposition of Al-Li-Mg Alloys at Solid Aluminum Electrode from LiCl-KCl-MgCl2 Molten Salt System

NASA Astrophysics Data System (ADS)

Ye, Ke; Zhang, Mi Lin; Chen, Ye; Han, Wei; de Yan, Yong; Cao, Peng

2010-06-01

The electrochemical codeposition of Mg and Li at an aluminium electrode in LiCl-KCl (50:50 wt pct) melts containing different concentrations of MgCl2 at 893 K (620 °C) to form Al-Li-Mg alloys was investigated. Cyclic voltammograms showed that the potential of Li metal deposition at an Al electrode, before the addition of MgCl2, is more positive than that of Li metal deposition at an Mo electrode, which indicated the formation of an Al-Li alloy. The underpotential deposition of magnesium at an aluminium electrode leads to the formation of Al-Mg alloys, and the succeeding underpotential deposition of lithium on predeposited Al-Mg alloys leads to the formation of Al-Li-Mg alloys. Chronopotentiometric measurements indicated that the codeposition of Mg and Li occurs at current densities lower than -0.668 A cm-2 in LiCl-KCl-MgCl2 (8 wt pct) melts at an aluminium electrode. The chronoamperometric studies indicated that the onset potential for the codeposition of Mg and Li is -2.000 V, and the codeposition of Mg and Li at an aluminium electrode is formed into Al-Li-Mg alloys when the applied potentials are more negative than -2.000 V. X-ray diffraction and inductively coupled plasma analysis indicated that Al-Li-Mg alloys with different lithium and magnesium contents were prepared via potentiostatic and galvanostatic electrolysis. The microstructure of typical dual phases of the Al-Li-Mg alloy was characterized by an optical microscope and by scanning electron microscopy. The analysis of energy dispersive spectrometry showed that the elements of Al and Mg distribute homogeneously in the Al-Li-Mg alloy. The lithium and magnesium contents of Al-Li-Mg alloys can be controlled by MgCl2 concentrations and by electrolytic parameters.

Mechanical properties of dissimilar metal joints composed of DP 980 steel and AA 7075-T6

DOE PAGES

Squires, Lile; Lim, Yong Chae; Miles, Michael; ...

2015-03-18

In this study, a solid state joining process, called friction bit joining, was used to spot weld aluminium alloy 7075-T6 to dual phase 980 steel. Lap shear failure loads for specimens without adhesive averaged ~10kN, while cross-tension specimens averaged 2·8 kN. Addition of adhesive with a thickness up to 500 μm provided a gain of ~50% to lap shear failure loads, while a much thinner layer of adhesive increased cross-tension failure loads by 20%. Microstructures of the welds were martensitic, but the hardness of the joining bit portion was greater than that of the DP 980, owing to its highermore » alloy content. Softening in the heat affected zone of a welded joint appeared to be relatively small, though it was enough to cause nugget pullout failures in some lap shear tension specimens. Finally, other failures in lap shear tension were interfacial, while all of the failures in cross-tension were interfacial.« less

Determination of trace and minor elements in alloys by atomic-absorption spectroscopy using an induction-heated graphite-well furnace as atom source-II.

PubMed

Ashy, M A; Headridge, J B; Sowerbutts, A

1974-06-01

Results are presented for the atomic-absorption spectrophotometric determination of zinc in aluminium and aluminium-silicon alloys, and aluminium, antimony and tin in steels, by means of solid samples dropped into an induction-heated graphite-well furnace to produce the atomic vapour.

Aluminium in human sweat.

PubMed

Minshall, Clare; Nadal, Jodie; Exley, Christopher

2014-01-01

It is of burgeoning importance that the human body burden of aluminium is understood and is measured. There are surprisingly few data to describe human excretion of systemic aluminium and almost no reliable data which relate to aluminium in sweat. We have measured the aluminium content of sweat in 20 healthy volunteers following mild exercise. The concentration of aluminium ranged from 329 to 5329μg/L. These data equate to a daily excretion of between 234 and 7192μg aluminium and they strongly suggest that perspiration is the major route of excretion of systemic aluminium in humans. Copyright © 2013 Elsevier GmbH. All rights reserved.

A new lead alloy for automotive batteries operating under high-temperature conditions

NASA Astrophysics Data System (ADS)

Albert, L.; Goguelin, A.; Jullian, E.

The operating conditions of automotive and some industrial batteries are involving increasingly higher temperatures and heavier duty cycles. These place stress on the positive-grid materials which are presently not sufficiently resistant to corrosion and to creep. Conventional lead-calcium-tin-aluminium alloys can usually be optimized by a proper choice of calcium and tin contents for each specific manufacturing technology. With the new requirements of customers and the typical behaviour of these conventional alloys, however, there is no more room for improvement without searching for additional alloying elements. The work reported here shows how the doping of conventional lead-calcium-tin-aluminium alloys with barium improves mechanical properties (tensile strength and creep resistance) and increases corrosion resistance at temperatures between 50 and 75°C. Grid materials prepared by two manufacturing technologies (gravity cast; continuous cast followed by expansion) are investigated. Both the mechanical properties and the corrosion behaviour of the resulting grids are evaluated.

Effect of water-cooling treatment times on properties of friction stir welded joints of 7N01-T4 aluminum alloy

NASA Astrophysics Data System (ADS)

Zhang, T. H.; Wang, Y.; Fang, X. F.; Liang, P.; Zhao, Y.; Li, Y. H.; Liu, X. M.

2018-02-01

Due to the deformation caused by residual stress in the welding process, welded components need treatment to reduce welding distortion. In this paper, several different times of flame-heating and water-cooling treatment were subjected to the friction stir welding joints of 15mm thick 7N01P-T4 aluminum alloy sheets to study the microstructure variation of friction stir welding joints of 7N01P-T4 aluminum alloy, and to analyze the effect on micro-hardness, tensile and fracture mechanical properties. This investigation will be helpful to optimize treatment methods and provide instruction on industrial production.

Fatigue Properties of Butt Welded Aluminum Alloy and Carbon Steel Joints by Friction Stirring

NASA Astrophysics Data System (ADS)

Okane, M.; Shitaka, T.; Ishida, M.; Chaki, T.; Yasui, T.; Fukumoto, M.

2017-05-01

The butt dissimilar joints of Al-Mg-Si alloy JIS A6063 and carbon steel JIS S45C by means of friction stir welding were prepared for investigating fatigue properties of the joints. The joining tool used has cemented carbide thread probe and a shoulder made of alloy tool steel. All the fatigue tests were carried out under a load-controlled condition with a load ratio R=0.1 in air at room temperature. From the experimental results, it was found that hardness near the interface in A6063 was lower than that of base material. Three types of fatigue fracture occurred even in case of same welding condition. The first one was fracture at boundary between the lower hardness region and base material in A6063, the second type was initiated in the stir zone by FSW process and the last one was fracture at interface. Fatigue strength in case of the second one was lower than others. Furthermore, to investigate the effect of heat treatment on fatigue properties of the dissimilar joints, fatigue tests were also carried out with using the specimens which were heat treated under the same condition to aging process in T6 treatment. Fatigue fracture was initiated at interface between A6063 and S45C in case of the heat treated specimen, but fatigue strength was improved approximately 25% as compared with that of the non-heat treated specimen.

Improving Mechanical Properties of PVPPA Welded Joints of 7075 Aluminum Alloy by PWHT

PubMed Central

Li, Guowei; Chen, Furong; Han, Yongquan; Liang, Yahong

2018-01-01

In this study, 7075 aluminum alloy with a thickness of 10 mm was successfully welded with no obvious defects by pulsed variable polarity plasma arc (PVPPA) welding. The mechanical properties of PVPPA welded joints have been researched by post weld heat treatment (PWHT). The results indicate that the heat treatment strongly affects the mechanical properties of the welded joints. The tensile strength and the microhardness of the welded joints gradually improved with the increase of the solution temperature. With the increase of the solution time, the tensile strength, and microhardness first dramatically increased and then decreased slightly. The best tensile strength of 537.5 MPa and the microhardness of 143.7 HV were obtained after 490 °C × 80 min + 120 °C × 24 h, and the strength was nearly 91.2% of that of the parent metal, and increased about 35% compared with as-welded. The improvement of strength and microhardness was mainly due to the precipitation of η′ phase. PMID:29510551

Simulation of thin aluminium-foil in the packaging industry

NASA Astrophysics Data System (ADS)

Eskil, Andreasson; Lindström, Tommy; Käck, Britta; Malmberg, Christoffer; Asp, Ann-Magret

2017-10-01

This work present an approach of how to account for the anisotropic mechanical material behaviour in the simulation models of the thin aluminium foil layer (≈10 µm) used in the Packaging Industry. Furthermore, the experimental results from uniaxial tensile tests are parameterised into an analytical expression and the slope of the hardening subsequently extended way beyond the experimental data points. This in order to accommodate the locally high stresses present in the experiments at the neck formation. An analytical expression, denominated Ramberg-Osgood, is used to describe the non-linear mechanical behaviour. Moreover it is possible with a direct method to translate the experimental uniaxial tensile test results into useful numerical material model parameters in Abaqus™. In addition to this the extended material behaviour including the plastic flow i.e. hardening, valid after onset of localisation, the described procedure can also capture the microscopic events, i.e. geometrical thinning, ongoing in the deformation of the aluminium foil. This method has earlier successfully been applied by Petri Mäkelä for paperboard material [1]. The engineering sound and parameterised description of the mechanical material behaviour facilitates an efficient categorisation of different aluminium foil alloys and aid the identification of the correct anisotropic (RD/TD/45°) mechanical material behaviour derived from the physical testing.

Aspects of ultra-high-precision diamond machining of RSA 443 optical aluminium

NASA Astrophysics Data System (ADS)

Mkoko, Z.; Abou-El-Hossein, K.

2015-08-01

Optical aluminium alloys such as 6061-T6 are traditionally used in ultra-high precision manufacturing for making optical mirrors for aerospace and other applications. However, the optics industry has recently witnessed the development of more advanced optical aluminium grades that are capable of addressing some of the issues encountered when turning with single-point natural monocrystalline diamond cutters. The advent of rapidly solidified aluminium (RSA) grades has generally opened up new possibilities for ultra-high precision manufacturing of optical components. In this study, experiments were conducted with single-point diamond cutters on rapidly solidified aluminium RSA 443 material. The objective of this study is to observe the effects of depth of cut and feed rate at a fixed rotational speed on the tool wear rate and resulting surface roughness of diamond turned specimens. This is done to gain further understanding of the rate of wear on the diamond cutters versus the surface texture generated on the RSA 443 material. The diamond machining experiments yielded machined surfaces which are less reflective but with consistent surface roughness values. Cutting tools were observed for wear through scanning microscopy; relatively low wear pattern was evident on the diamond tool edge. The highest tool wear were obtained at higher depth of cut and increased feed rate.

Characteristics of AZ31 Mg alloy joint using automatic TIG welding

NASA Astrophysics Data System (ADS)

Liu, Hong-tao; Zhou, Ji-xue; Zhao, Dong-qing; Liu, Yun-teng; Wu, Jian-hua; Yang, Yuan-sheng; Ma, Bai-chang; Zhuang, Hai-hua

2017-01-01

The automatic tungsten-inert gas welding (ATIGW) of AZ31 Mg alloys was performed using a six-axis robot. The evolution of the microstructure and texture of the AZ31 auto-welded joints was studied by optical microscopy, scanning electron microscopy, energy-dispersive X-ray spectroscopy, and electron backscatter diffraction. The ATIGW process resulted in coarse recrystallized grains in the heat affected zone (HAZ) and epitaxial growth of columnar grains in the fusion zone (FZ). Substantial changes of texture between the base material (BM) and the FZ were detected. The {0002} basal plane in the BM was largely parallel to the sheet rolling plane, whereas the c-axis of the crystal lattice in the FZ inclined approximately 25° with respect to the welding direction. The maximum pole density increased from 9.45 in the BM to 12.9 in the FZ. The microhardness distribution, tensile properties, and fracture features of the AZ31 auto-welded joints were also investigated.

Fabrication of ultra-fine grained aluminium tubes by RTES technique

DOE Office of Scientific and Technical Information (OSTI.GOV)

Jafarzadeh, H., E-mail: h.jafarzadeh@ut.ac.ir; Abrinia, K.

Recently, repetitive tube expansion and shrinking have been exploited as a means for producing ultra-fine grained and nano-crystalline microstructures for magnesium alloy tubes. This method includes two different half-cycles and was based on pressing a tubular part through an angular channel die with two shear zones. Since the aluminium alloys are the most widely used materials in industries, in this study, repetitive tube expansion and shrinking as a new severe plastic deformation technique was applied to commercially pure aluminium for fabricating ultra-fine grained aluminium tubes for the first time and the ability of this process in significant grain refinement ismore » determined even after single cycle. Transmission electron microscopy and X-ray diffraction were used to evaluate the microstructure of the repetitive tube expansion and shrinking processed materials and the examinations showed ultra-fine grains with the average grain size of 320 nm after one cycle of repetitive tube expansion and shrinking. The yield strength, ultimate tensile strength increased notably by the factor of 2.17 and 1.27 respectively, after one cycle of repetitive tube expansion and shrinking, whereas the elongation to failure as well as the uniform elongation decreased. Furthermore, micro-hardness distribution through the part's section proposed the hardness increasing to ~ 55 HV from the initial value of ~ 28 HV after one cycle of repetitive tube expansion and shrinking. - Highlights: • RTES was introduced for fabricating the UFGed AA1050 tubes for the first time. • Nano-grained AA1050 tube was obtained by RTES process. • Grain size of ~ 320 nm was obtained after two half-cycles of RTES process. • Yield and ultimate strength increased by the factor of 2.17 and 1.27 respectively. • The microhardness increased to ~ 55 HV from the initial value of ~ 28 HV.« less

Role of the primary silicon particle on the dry sliding wear of hypereutectic aluminium-silicon alloy A390

NASA Astrophysics Data System (ADS)

Lee, Jung-Moo; Kang, Suk-Bong; Yoon, Sang-Chul

1999-07-01

The wear behavior of hypereutectic aluminium-silicon alloy A390 was investigated using a pin-on-disc wear machine under dry sliding conditions. The wear tests were performed within a load range of 10 to 300N at a constant sliding velocity of 0.5 m/sec. The microstructural and compositional changes that took place during wear were characterized by scanning electron microscopy (SEM) equipped with an energy dispersive X-ray analysis (EDXA) system. Based on the metallographic observations the role of the primary silicon particles was suggested. In a low pressure region, primary silicon particles supported the applied load and wear occurred mainly in the matrix. Thus the wear loss did not show much variation with the applied load. In the mid-load range, primary silicon particles did not yet fracture and thus supported the applied load in part. Transition from oxidative to metallic wear occurs mainly in the matrix and the increase of wear loss becomes sharper than that in a low pressure region. In the high pressure region, the fractures of primary silicon Particles occurred and wear loss increased sharply.

Effects of stress concentration on the fatigue strength of 7003-T5 aluminum alloy butt joints with weld reinforcement

NASA Astrophysics Data System (ADS)

Zhu, Zongtao; Li, Yuanxing; Zhang, Mingyue; Hui, Chen

2015-03-01

7003-T5 Aluminum (Al) alloy plates with a thickness of 5 mm are welded by gas metal arc welding (GMAW) method in this work. In order to investigate the influence of stress concentration introduced by weld reinforcement on fatigue strength, the stress concentration factor of the butt joint is calculated. Microscopic and X-ray techniques were utilized to make sure there are no weld defects with large size in butt weld, which can induce extra stress concentration. The cyclic stress - number of cycles to failure (S-N) curves of the joints with and without the welder were obtained by fatigue testing, and the results show that the fatigue strength of 7003-T5 Al alloy butt joints with the weld reinforcement is 50 MPa, which is only 45% of the joints without the weld reinforcement. Fracture surface observation indicated that the fatigue source and propagation are dissimilar for the specimens with and without the welder due to the stress concentration at the weld root. The stress concentration with a factor of 1.7 has great effect on the fatigue strength, but little influence on the tensile strength.

BRAZING ALLOYS

DOEpatents

Donnelly, R.G.; Gilliland, R.G.; Slaughter, G.M.

1962-02-20

A brazing alloy is described which, in the molten state, is characterized by excellent wettability and flowability and is capable of forming a corrosion-resistant brazed joint. At least one component of said joint is graphite and the other component is a corrosion-resistant refractory metal. The brazing alloy consists essentially of 40 to 90 wt % of gold, 5 to 35 wt% of nickel, and 1 to 45 wt% of tantalum. (AEC)

Experiments and simulation for 6061-T6 aluminum alloy resistance spot welded lap joints

NASA Astrophysics Data System (ADS)

Florea, Radu Stefanel

This comprehensive study is the first to quantify the fatigue performance, failure loads, and microstructure of resistance spot welding (RSW) in 6061-T6 aluminum (Al) alloy according to welding parameters and process sensitivity. The extensive experimental, theoretical and simulated analyses will provide a framework to optimize the welding of lightweight structures for more fuel-efficient automotive and military applications. The research was executed in four primary components. The first section involved using electron back scatter diffraction (EBSD) scanning, tensile testing, laser beam profilometry (LBP) measurements, and optical microscopy(OM) images to experimentally investigate failure loads and deformation of the Al-alloy resistance spot welded joints. Three welding conditions, as well as nugget and microstructure characteristics, were quantified according to predefined process parameters. Quasi-static tensile tests were used to characterize the failure loads in specimens based upon these same process parameters. Profilometer results showed that increasing the applied welding current deepened the weld imprints. The EBSD scans revealed the strong dependency between the grain sizes and orientation function on the process parameters. For the second section, the fatigue behavior of the RSW'ed joints was experimentally investigated. The process optimization included consideration of the forces, currents, and times for both the main weld and post-heating. Load control cyclic tests were conducted on single weld lap-shear joint coupons to characterize the fatigue behavior in spot welded specimens. Results demonstrate that welding parameters do indeed significantly affect the microstructure and fatigue performance for these welds. The third section comprised residual strains of resistance spot welded joints measured in three different directions, denoted as in-plane longitudinal, in-plane transversal, and normal, and captured on the fusion zone, heat affected zone

Aluminium-gold reference material for the k0-standardisation of neutron activation analysis

NASA Astrophysics Data System (ADS)

Ingelbrecht, C.; Peetermans, F.; De Corte, F.; De Wispelaere, A.; Vandecasteele, C.; Courtijn, E.; D'Hondt, P.

1991-05-01

Gold is an excellent comparator material for the k0-standardisation of neutron activation analysis because of its convenient and well defined nuclear properties. The most suitable form for a reference material is a dilute aluminium-gold alloy, for which the self-shielding effect for neutrons is small. Castings of composition Al-0.1 wt.% Au were prepared by crucible-less levitation melting, which gives close control of ingot composition with minimal contamination of the melt. The alloy composition was checked using induction-coupled plasma source emission spectrometry. The homogeneity of the alloy was measured by neutron activation analysis and a relative standard deviation of the gold content of 0.30% was found (10 mg samples). Metallography revealed a homogeneous distribution of AuAl 2 particles. The alloy was certified as Reference Material CBNM-530, with certified gold mass fraction 0.100±0.002 wt.%.

A Study on 3-Body Abrasive Wear Behaviour of Aluminium 8011 / Graphite Metal Matrix Composite

NASA Astrophysics Data System (ADS)

Latha Shankar, B.; Anil, K. C.; Patil, Rahul

2016-09-01

Metals and alloys have found their vital role in many applications like structural, corrosive, tribological, etc., in engineering environment. The alloys/composites having high strength to low weight ratio have gained attention of many researchers recently. In this work, graphite reinforced Aluminium 8011 metal matrix composite was prepared by conventional stir casting route, by varying the weight % of reinforcement. Uniform distribution of Graphite in matrix alloy was confirmed by optical micrographs. Prepared composite specimens were subjected to 3-body abrasive testing by varying applied load and time, the silica particles of 400 grit size were used as abrasive particles. It was observed that with the increase of weight% of Graphite the wear resistance of composite was also increasing and on comparison it was found that reinforced composite gives good wear resistance than base alloy.

Plasma Electrolytic Oxidation (PEO) Coatings on an A356 Alloy for Improved Corrosion and Wear Resistance

NASA Astrophysics Data System (ADS)

Peng, Zhijing

Plasma electrolytic oxidizing (PEO) is an advanced technique that has been used to deposit thick and hard ceramic coatings on aluminium (Al) alloys. This work was however to use the PEO process to produce thin ceramic oxide coatings on an A356 Al alloy for improving corrosion and wear resistance of the alloy. Effects of current density and treatment time on surface morphologies and thickness of the PEO coatings were investigated. The improvement of galvanic corrosion properties of the coated A356 alloy vs. steel and carbon fibre were evaluated in E85 fuel or NaCl environments. Tribological properties of the coatings were studied with comparison to the uncoated A356 substrate and other commercially-used engine bore materials. The research results indicated that the PEO coatings could have excellent tribological and corrosion properties for aluminium engine applications.

The Relation between the Tensile Properties and Constitution of Aluminium-Rich Aluminium-Magnesium-Manganese-Zinc Alloys

DTIC Science & Technology

1946-08-01

magnesium and lljs of zinc in the fully heat treated condition were .37.0 tons/in»2, 40.1 tons/in.2 aid Gji respectively and for the alloy with 4>» of...heat treated condition were 37.0 tons/in.2,» 40.1 tons/in.2 and Gji respectively, and for the 4ilill alloy. 40.4 tons/in.2 44.5 tons/in.2 and 2J5

Human exposure to aluminium.

PubMed

Exley, Christopher

2013-10-01

Human activities have circumvented the efficient geochemical cycling of aluminium within the lithosphere and therewith opened a door, which was previously only ajar, onto the biotic cycle to instigate and promote the accumulation of aluminium in biota and especially humans. Neither these relatively recent activities nor the entry of aluminium into the living cycle are showing any signs of abating and it is thus now imperative that we understand as fully as possible how humans are exposed to aluminium and the future consequences of a burgeoning exposure and body burden. The aluminium age is upon us and there is now an urgent need to understand how to live safely and effectively with aluminium.

On the Possibility of using Alluminium-Magnesium Alloys with Improved Mechanical Characteristics for Body Elements of Zenit-2S Launch Vehicle Propellant Tanks

NASA Astrophysics Data System (ADS)

Sitalo, V.; Lytvyshko, T.

2002-01-01

Yuzhnoye SDO developed several generations of launch vehicles and spacecraft that are characterized by weight perfection, optimal cost, accuracy of output geometrical characteristics, stable strength characteristics, high tightness. The main structural material of launch vehicles are thermally welded non-strengthened aluminium- magnesium alloys. The aluminium-magnesium alloys in the annealed state have insufficiently high strength characteristics. Considerable increase of yield strength of sheets and plates can be reached by cold working but in this case, plasticity reduces. An effective way to improve strength of aluminium-magnesium alloys is their alloying with scandium. The alloying with scandium leads to modification of the structure of ingots (size reduction of cast grain) and formation of supersaturated solid solutions of scandium and aluminium during crystallization. During subsequent heatings (annealing of the ingots, heating for deformation) the solid solution disintegrates with the formation of disperse particles of Al3Sc type, that cause great strengthening of the alloy. High degree of dispersion and density of distribution in the matrix of secondary Al3Sc particles contribute to the considerable increase of the temperature of recrystallization of deformed intermediate products and to the formation of stable non-recrystallized structure. The alloying of alluminium-magnesium alloys with scandium increases their strength and operational characteristics, preserves their technological and corrosion properties, improves weldability. The alloys can be used within the temperature limits ­196-/+150 0C. The experimental structures of propellant tanks made of alluminium-magnesium alloys with scandium have been manufactured and tested. It was ascertained that the propellant tanks have higher margin of safety during loading with internal pressure and higher stability factor of the shrouds during loading with axial compression force which is caused by higher value

Effect of Bio char on Plant Growth and Aluminium Form of Soil under Aluminium Stress

NASA Astrophysics Data System (ADS)

Qian, Lianwen; Li, Qingbiao; Sun, Jingwei; Feng, Ying

2018-01-01

Aluminium-enriched acid red soils in South China easily cause aluminium toxicity to plants, but biochip can improve soils and eliminate soil contaminations. In this project, biochip was used in potted plant control test to study the effect of biochip on plant growth in soil under acid aluminium stress and the migration and conversion of aluminium in plant-soil system. The fin dings show that the application of biochip increases the pH value of soil under aluminium stress significantly, changes the existing form of aluminium ion in soil, reduces the plants’ absorption of aluminium, and alleviates the aluminium toxicity to plants, but too much biochip may inhibit the growth of plants. In this case, further study should be carried out as regards the volume and way of biochip input in practical applications as well as the timeliness of aluminium toxicity removal.

IR thermography for the assessment of the thermal conductivity of aluminum alloys

NASA Astrophysics Data System (ADS)

Nazarov, S.; Rossi, S.; Bison, P.; Calliari, I.

2017-05-01

Aluminium alloys are here considered as a structural material for aerospace applications, guaranteeing lightness and strength at the same time. As aluminium alone is not particularly performing from a mechanical point of view, in this experimental solution it is produced as an alloy with Lithium added at 6 % in weight. To increase furtherly the strength of the material, two new alloys are produced by adding 0.5 % in weight of the rare earth elements Neodymium (Nd) and Yttrium (Y). The improvement of the mechanical properties is measured by means of hardness tests. At the same time the thermophysical properties are measured as well, at various temperature, from 80 °C to 500 °C. Thermal diffusivity is measured by Laser Flash equipment in vacuum. One possible drawback of the Al-Li alloy produced at so high percentage of Li (6 %) is an essential anisotropy that is evaluated by IR thermography thank to its imaging properties that allows to measure simultaneously both the in-plane and through-depth thermal diffusivity.

Preparation and characterization of aluminium-silica metal matrix composite

NASA Astrophysics Data System (ADS)

Mallikarjuna, G. B.; Basavaraj, E.

2018-04-01

Aluminum alloys are widely used in aerospace and automobile industries due to their low density and good mechanical properties, better corrosion resistance and wear, low thermal coefficient of expansion as compared to conventional metals and alloys. The excellent properties of these materials and relatively low production cost make them a very attractive for a variety of applications. In this present work, Al alloy LM13-SiO2 composites were produced by stir casting method. The reinforcement SiO2 particle size used for preparation of composites are 106 µm, 150 µm, 250 µm and 355 µm with varying amount of 3 to 12 wt% in steps of 3. The prepared composite specimens were machined as per test standards. Effects of weight percentage of SiO2 particles on wear, tensile strength of Al alloy LM13-SiO2 composites have been investigated. The microstructures of the composites were studied to know the dispersion of the SiO2 particles in matrix. Experimental results shows that there is enhanced mechanical properties, when silica weighing 9% was added to the base aluminium alloy and also similar trend exists in all four different micron size of silica and also it has been observed that addition of SiO2 particles significantly improves wear resistance properties as compared with that of unreinforced matrix.

T-joints of Ti alloys with hybrid laser-MIG welding: macro-graphic and micro-hardness analyses

NASA Astrophysics Data System (ADS)

Spina, R.; Sorgente, D.; Palumbo, G.; Scintilla, L. D.; Brandizzi, M.; Satriano, A. A.; Tricarico, L.

2012-03-01

Titanium alloys are characterized by high mechanical properties and elevated corrosion resistance. The combination of laser welding with MIG/GMAW has proven to improve beneficial effects of both processes (keyhole, gap-bridging ability) while limiting their drawbacks (high thermal gradient, low mechanical resistance) In this paper, the hybrid Laser-GMAW welding of Ti-6Al-4V 3-mm thick sheets is investigated using a specific designed trailing shield. The joint geometry was the double fillet welded T-joint. Bead morphologies, microstructures and mechanical properties (micro-hardness) of welds were evaluated and compared to those achieved for the base metals.

Interfacial microstructure and shear strength of reactive air brazed oxygen transport membrane ceramic-metal alloy joints

NASA Astrophysics Data System (ADS)

FR, Wahid Muhamad; Yoon, Dang-Hyok; Raju, Kati; Kim, Seyoung; Song, Kwang-sup; Yu, Ji Haeng

2018-01-01

To fabricate a multi-layered structure for maximizing oxygen production, oxygen transport membrane (OTM) ceramics need to be joined or sealed hermetically metal supports for interfacing with the peripheral components of the system. Therefore, in this study, Ag-10 wt% CuO was evaluated as an effective filler material for the reactive air brazing of dense Ce0.9Gd0.1O2-δ-La0.7Sr0.3MnO3±δ (GDC-LSM) OTM ceramics. Thermal decomposition in air and wetting behavior of the braze filler was performed. Reactive air brazing was performed at 1050 °C for 30 min in air to join GDC-LSM with four different commercially available high temperature-resistant metal alloys, such as Crofer 22 APU, Inconel 600, Fecralloy, and AISI 310S. The microstructure and elemental distribution of the ceramic-ceramic and ceramic-metal interfaces were examined from polished cross-sections. The mechanical shear strength at room temperature for the as-brazed and isothermally aged (800 °C for 24 h) joints of all the samples was compared. The results showed that the strength of the ceramic-ceramic joints was decreased marginally by aging; however, in the case of metal-ceramic joints, different decreases in strengths were observed according to the metal alloy used, which was explained based on the formation of different oxide layers at the interfaces.

Investigations on Laser Beam Welding of Different Dissimilar Joints of Steel and Aluminum Alloys for Automotive Lightweight Construction

NASA Astrophysics Data System (ADS)

Seffer, Oliver; Pfeifer, Ronny; Springer, André; Kaierle, Stefan

Due to the enormous potential of weight saving, and the consequential reduction of pollutant emissions, the use of hybrid components made of steel and aluminum alloys is increasing steadily, especially concerning automotive lightweight construction. However, thermal joining of steel and aluminum is still being researched, due to a limited solubility of the binary system of iron and aluminum causing the formation of hard and brittle intermetallic phases, which decrease the strength and the formability of the dissimilar seam. The presented results show the investigation of laser beam welding for joining different dissimilar hybrid components of the steel materials HX220LAD+Z100, 22MnB5+AS150 and 1.4301, as well as the aluminum alloy AA6016-T4 as a lap joint. Among other things, the influences of the energy per unit length, the material grade, the sheet thickness t, the weld type (lap weld, fillet weld) and the arrangement of the base materials in a lap joint (aluminum-sided irradiation, steel-sided irradiation) on the achievable strengths are analyzed. The characterization of the dissimilar joints includes tensile shear tests and metallographic analyses, depending on the energy per unit length.

Investigation on bending failure to characterize crashworthiness of 6xxx-series aluminium sheet alloys with bending-tension test procedure

NASA Astrophysics Data System (ADS)

Henn, Philipp; Liewald, Mathias; Sindel, Manfred

2018-05-01

As lightweight design as well as crash performance are crucial to future car body design, exact material characterisation is important to use materials at their full potential and reach maximum efficiency. Within the scope of this paper, the potential of newly established bending-tension test procedure to characterise material crashworthiness is investigated. In this test setup for the determination of material failure, a buckling-bending test is coupled with a subsequent tensile test. If prior bending load is critical, tensile strength and elongation in the subsequent tensile test are dramatically reduced. The new test procedure therefore offers an applicable definition of failure as the incapacity of energy consumption in subsequent phases of the crash represents failure of a component. In addition to that, the correlation of loading condition with actual crash scenarios (buckling and free bending) is improved compared to three- point bending test. The potential of newly established bending-tension test procedure to characterise material crashworthiness is investigated in this experimental studys on two aluminium sheet alloys. Experimental results are validated with existing ductility characterisation from edge compression test.

Experimental investigation on the effects of cooling system on surface quality in high speed milling of an aluminium alloy

NASA Astrophysics Data System (ADS)

Chirita, B.; Tampu, N. C.; Brabie, G.; Radu, M. C.

2016-08-01

Surface quality is often an important feature of industrial products, not only from the impact it has on the aesthetic aspect but also for the functional role of the parts. High quality surface increases corrosion resistance, assures a longer life cycle for the product and lowers the wear. For a machined part, surface quality is influenced by a series of factors such as the material of the part, the process type, tool geometry, cutting parameters or the cooling system. The choice of the cooling system is especially important, taking into account that the proper conditions will not only assure a superior surface quality, but will also lower the costs and reduce the environmental impact and health risks. The present study aims to investigate the performance of the cooling system and the effect of the cutting parameters on the characteristics of the surfaces resulted from high speed face milling of some parts made of Al 7050-T7451 aluminium alloy. Dry cutting conditions and minimum quantity lubrication (MQL) where used. The results were analysed using analysis of variance (ANOVA).

Effects of beam offset on mechanical properties and corrosion resistance of Alloy 690-SUS 304L EBW joints for nuclear power plant

NASA Astrophysics Data System (ADS)

Lin, Yong-Ding; Lee, Hwa-Teng; Kuo, Tsung-Yuan; Jeng, Sheng-Long; Wu, Jia-Lin

2010-06-01

The current study investigates the effect of the beam offset (BOF) on the microstructure, mechanical properties, and the corrosion resistance of the fusion zone (FZ) of Alloy 690-SUS 304L stainless steel (SS) dissimilar metal butt joints formed by electron beam welding (EBW). The experimental results showed that as the value of the BOF increased from 0 to 0.30 mm, i.e. the electron beam shifted progressively toward the Alloy 690 base metal (BM), the tensile strength of the FZ fell from 582.1 to 541.2 MPa. However, the modified Huey test results indicated that the interdendritic corrosion resistance of the FZ was significantly enhanced. Pit nucleation potential value ( Enp) was raised from 385 to 1050 mV. An offset of 0.30 mm appears to be the optimal BOF setting when fabricating Alloy 690-SUS 304L SS dissimilar metal butt joints using the EBW technique.

Preparation of SiC based Aluminium metal matrix nano composites by high intensity ultrasonic cavitation process and evaluation of mechanical and tribological properties

NASA Astrophysics Data System (ADS)

Murthy, N. V.; Prasad Reddy, A.; Selvaraj, N.; Rao, C. S. P.

2016-09-01

Request augments on a worldwide scale for the new materials. The metal matrix nano composites can be used in numerous applications of helicopter structural parts, gas turbine exit guide vane's, space shuttle, and other structural applications. The key mailman to ameliorate performance of composite matrix in aluminium alloy metal reinforces nano particles in the matrix of alloy uniformly, which ameliorates composite properties without affecting limit of ductility. The ultrasonic assisted stir casting helped agitation was successfully used to fabricate Al 2219 metal matrix of alloy reinforced with (0.5, 1, 1.5 and 2) wt.% of nano silicon carbide (SiC) particles of different sizes 50nm and 150nm. The micrographs of scanning electron microscopy of nano composite were investigated it reveals that the uniform dispersion of nano particles silicon carbide in aluminium alloy 2219 matrix and with the low porosity. How the specific wear rate was vary with increasing weight percentage of nano particles at constant load and speed as shown in results and discussions. And the mechanical properties showed that the ultimate tensile strength and hardness of metal matrix nano composite AA 2219 / nano SiC of 50nm and 150nm lean to augment with increase weight percentage of silicon carbide content in the matrix alloy.

Numerical analysis of dynamic behavior of pre-stressed shape memory alloy concrete beam-column joints

NASA Astrophysics Data System (ADS)

Yan, S.; Xiao, Z. F.; Lin, M. Y.; Niu, J.

2018-04-01

Beam-column joints are important parts of a main frame structure. Mechanical properties of beam-column joints have a great influence on dynamic performances of the frame structure. Shape memory alloy (SMA) as a new type of intelligent metal materials has wide applications in civil engineering. The paper aims at proposing a novel beam-column joint reinforced with pre-stressed SMA tendons to increase its dynamic performance. Based on the finite element analysis (FEA) software ABAQUS, a numerical simulation for 6 beam-column scaled models considering different SMA reinforcement ratios and pre-stress levels was performed, focusing on bearing capacities, energy-dissipation and self-centering capacities, etc. These models were numerically tested under a pseudo-static load on the beam end, companying a constant vertical compressive load on the top of the column. The numerical results show that the proposed SMA-reinforced joint has a significantly increased bearing capacity and a good self-centering capability after unloading even though the energy-dissipation capacity becomes smaller due the less residual deformation. The concept and mechanism of the novel joint can be used as an important reference for civil engineering applications.

The Load Distribution in Bolted or Riveted Joints in Light-Alloy Structures

NASA Technical Reports Server (NTRS)

Vogt, F.

1947-01-01

This report contains a theoretical discussion of the load distribution in bolted or riveted joints in light-alloy structures which is applicable not only for loads below the limit of proportionality but also for loads above this limit. The theory is developed for double and single shear joints. The methods given are illustrated by numerical examples and the values assumed for the bolt (or rivet) stiffnesses are based partly on theory and partly on known experimental values. It is shown that the load distribution does not vary greatly with the bolt (or rivet) stiffnesses and that for design purposes it is usually sufficient to know their order of magnitude. The theory may also be directly used for spot-welded structures and, with small modifications, for seam-welded structures, The computational work involved in the methods described is simple and may be completed in a reasonable time for most practical problems. A summary of earlier theoretical and experimental investigations on the subject is included in the report.

New design for a rotatory joint actuator made with shape memory alloy contractile wire

NASA Astrophysics Data System (ADS)

Wang, Guoping; Shahinpoor, Mohsen

1996-05-01

A design approach for a rotatory joint actuator using a contractile shape memory alloy (SMA) wire is presented and an example design is followed. In this example, the output torque of the actuator is 18 Newton-meters, and its angular range is 30 degrees. Compared with a SMA spring type actuating component, a SMA wire type actuating component uses less SMA material and uses less electrical energy when it is electrically powered. On the other hand, a SMA wire type actuating component must have a large SMA wire length to produce a required amount of angular rotation of the joint. When pulleys are used to arrange a lengthy SMA wire in a small space, the friction between pulleys and pins is introduced and the performance of the joint actuator is degenerated to some degree. The investigated joint actuator provides a good chance for developing powered orthoses with SMA actuators for disabled individuals. It can relieve the weight concern with hydraulic and motor-powered orthoses and the safety concern with motor-powered orthoses. When electrically powered, a SMA actuator has the disadvantage of low energy efficiency.

Dual-beam laser welding of AZ31B magnesium alloy in zero-gap lap joint configuration

NASA Astrophysics Data System (ADS)

Harooni, Masoud; Carlson, Blair; Kovacevic, Radovan

2014-03-01

Porosity within laser welds of magnesium alloys is one of the main roadblocks to achieving high quality joints. One of the causes of pore formation is the presence of pre-existing coatings on the surface of magnesium alloy such as oxide or chromate layers. In this study, single-beam and dual-beam laser heat sources are investigated in relation to mitigation of pores resulting from the presence of the as-received oxide layer on the surface of AZ31B-H24 magnesium alloy during the laser welding process. A fiber laser with a power of up to 4 kW is used to weld samples in a zero-gap lap joint configuration. The effect of dual-beam laser welding with different beam energy ratios is studied on the quality of the weld bead. The purpose of this paper is to identify the beam ratio that best mitigates pore formation in the weld bead. The laser molten pool and the keyhole condition, as well as laser-induced plasma plume are monitored in real-time by use of a high speed charge-coupled device (CCD) camera assisted with a green laser as an illumination source. Tensile and microhardness tests were used to measure the mechanical properties of the laser welded samples. Results showed that a dual-beam laser configuration can effectively mitigate pore formation in the weld bead by a preheating-welding mechanism.

Aluminium Pneumoconiosis I. In Vitro Comparison of Stamped Aluminium Powders Containing Different Lubricating Agents and a Granular Aluminium Powder

PubMed Central

Corrin, B.

1963-01-01

The discrepancy in previous reports of the action of aluminium on the lung may be explained by differences between stamped and granular aluminium powders. A stamped powder of the variety causing pulmonary fibrosis showed a brisk reaction with water, but a granular powder was unreactive. This difference is primarily due to the granular particles being covered by inert aluminium oxide, the formation of which is partially prevented in the stamping process by stearine and mineral oil. The reactivity of the flake-like stamped particles is also dependent on their large surface area per unit volume. The appearance of aluminium pneumoconiosis in Britain is explained by the introduction of mineral oil into the stamping industry for, in contrast to stearine, mineral oil permits the powder to react with water. The lung damage is believed to be caused by a soluble form of aluminium. PMID:14072616

Investigation of effects of process parameters on properties of friction stir welded joints

NASA Astrophysics Data System (ADS)

Chauhan, Atul; Soota, Tarun; Rajput, S. K.

2018-03-01

This work deals with application of friction stir welding (FSW) using application of Taguchi orthogonal array. FSW procedure is used for joining the aluminium alloy AA6063-T0 plates in butt configuration with orthogonal combination of factors and their levels. The combination of factors involving tool rotation speed, tool travel speed and tool pin profile are used in three levels. Grey relational analysis (GRA) has been applied to select optimum level of factors for optimising UTS, ductility and hardness of joint. Experiments have been conducted with two different tool materials (HSS and HCHCr steel) with various factors level combinations for joining AA6063-T0. On the basis of grey relational grades at different levels of factors and analysis of variance (ANOVA) ideal combination of factors are determined. The influence of tool material is also studied.

The toxicity of aluminium in humans.

PubMed

Exley, C

2016-06-01

We are living in the 'aluminium age'. Human exposure to aluminium is inevitable and, perhaps, inestimable. Aluminium's free metal cation, Alaq(3+), is highly biologically reactive and biologically available aluminium is non-essential and essentially toxic. Biologically reactive aluminium is present throughout the human body and while, rarely, it can be acutely toxic, much less is understood about chronic aluminium intoxication. Herein the question is asked as to how to diagnose aluminium toxicity in an individual. While there are as yet, no unequivocal answers to this problem, there are procedures to follow to ascertain the nature of human exposure to aluminium. It is also important to recognise critical factors in exposure regimes and specifically that not all forms of aluminium are toxicologically equivalent and not all routes of exposure are equivalent in their delivery of aluminium to target sites. To ascertain if Alzheimer's disease is a symptom of chronic aluminium intoxication over decades or breast cancer is aggravated by the topical application of an aluminium salt or if autism could result from an immune cascade initiated by an aluminium adjuvant requires that each of these is considered independently and in the light of the most up to date scientific evidence. The aluminium age has taught us that there are no inevitabilities where chronic aluminium toxicity is concerned though there are clear possibilities and these require proving or discounting but not simply ignored. Copyright © 2016 Elsevier Masson SAS. All rights reserved.

Interfacial Characterization of Dissimilar Joints Between Al/Mg/Al-Trilayered Clad Sheet to High-Strength Low-Alloy Steel

NASA Astrophysics Data System (ADS)

Macwan, A.; Jiang, X. Q.; Chen, D. L.

2015-07-01

Magnesium (Mg) alloys are increasingly used in the automotive and aerospace sectors to reduce vehicle weight. Al/Mg/Al tri-layered clad sheets are deemed as a promising alternative to improve the corrosion resistance and formability of Mg alloys. The structural application of Al/Mg/Al tri-layered clad sheets inevitably involves welding and joining in the multi-material vehicle body manufacturing. This study aimed to characterize the bonding interface microstructure of the Al/Mg/Al-clad sheet to high-strength low-alloy steel with and without Zn coating using ultrasonic spot welding at different levels of welding energy. It was observed that the presence of Zn coating improved the bonding at the interface due to the formation of Al-Zn eutectic structure via enhanced diffusion. At a higher level of welding energy, characteristic flow patterns of Zn into Al-clad layer were observed with an extensive penetration mainly along some high angle grain boundaries. The dissimilar joints without Zn coating made at a high welding energy of 800 J failed partially from the Al/Fe weld interface and partially from the Al/Mg clad interface, while the joints with Zn coating failed from the Al/Mg clad interface due to the presence of brittle Al12Mg17 phase.

High-strength laser welding of aluminum-lithium scandium-doped alloys

NASA Astrophysics Data System (ADS)

Malikov, A. G.; Ivanova, M. Yu.

2016-11-01

The work presents the experimental investigation of laser welding of an aluminum alloy (system Al-Mg-Li) and aluminum alloy (system Al-Cu-Li) doped with Sc. The influence of nano-structuring of the surface layer welded joint by cold plastic deformation on the strength properties of the welded joint is determined. It is founded that, regarding the deformation degree over the thickness, the varying value of the welded joint strength is different for these aluminum alloys. The strength of the plastically deformed welded joint, aluminum alloys of the Al-Mg-Li and Al-Cu-Li systems reached 0.95 and 0.6 of the base alloy strength, respectively.

Corrosion of pure aluminium and aluminium alloy: a comparative study using a slow positron beam

NASA Astrophysics Data System (ADS)

Wu, Y. C.; Li, P. H.; Xue, X. D.; Wang, S. J.; Kallis, A.; Coleman, P. G.; Zhai, T.

2011-01-01

Corrosion-related defects in pure Al and AA 2037 Al alloy have been investigated by positron beam-based Doppler broadening energy spectroscopy. Defect profiles have been analyzed by measuring the S parameter as a function of incident positron energy up to 30 keV. When pure Al samples are immersed in 1M NaOH for various times, a significant increase in the S parameter near the surface is observed. This implies that the corrosion process involves the creation of defects and nanometer voids. In contrast, a significant decrease in the S parameter is observed after the corrosion of water-quenched Al alloy by the same method, which is interpreted as being a result of Cu enrichment near the metal-oxide interface layer.

Friction Stir Back Extrusion of Aluminium Alloys for Automotive Applications

NASA Astrophysics Data System (ADS)

Xu, Zeren

Since the invention of Friction Stir Welding in 1991 as a solid state joining technique, extensive scientific investigations have been carried out to understand fundamental aspects of material behaviors when processed by this technique, in order to optimize processing conditions as well as mechanical properties of the welds. Based on the basic principles of Friction Stir Welding, several derivatives have also been developed such as Friction Stir Processing, Friction Extrusion and Friction Stir Back Extrusion. Friction Stir Back Extrusion is a novel technique that is proposed recently and designed for fabricating tubes from lightweight alloys. Some preliminary results have been reported regarding microstructure and mechanical properties of Friction Stir Back Extrusion processed AZ31 magnesium alloy, however, systematic study and in-depth investigations are still needed to understand the materials behaviors and underlying mechanisms when subjected to Friction Stir Back Extrusion, especially for age-hardenable Al alloys. In the present study, Friction Stir Back Extrusion processed AA6063-T5 and AA7075-T6 alloys are analyzed with respect to grain structure evolution, micro-texture change, recrystallization mechanisms, precipitation sequence as well as mechanical properties. Optical Microscopy, Electron Backscatter Diffraction, Transmission Electron Microscopy, Vickers Hardness measurements and uniaxial tensile tests are carried out to characterize the microstructural change as well as micro and macro mechanical properties of the processed tubes. Special attention is paid to the micro-texture evolution across the entire tube and dynamic recrystallization mechanisms that are responsible for grain refinement. Significant grain refinement has been observed near the processing zone while the tube wall is characterized by inhomogeneous grain structure across the thickness for both alloys. Dissolution of existing precipitates is noticed under the thermal hysterias imposed by

Protection of Tempered Aluminum Alloy in Contact with the Environment

NASA Astrophysics Data System (ADS)

Araoyinbo, A. O.; Salleh, M. A. A. Mohd; Rahmat, A.; Azmi, A. I.; Rahim, W. M. F. Wan Abd; Perju, M. C.; Jin, T. S.

2018-06-01

In many service applications an increasing temperature or inadequate protections often give rise to localized forms of corrosion in an initially free and unprotected system. This research understudy the corrosion chemistry, the effect of chromium as the inhibitor, Vickers hardness test, and weight loss on tempered aluminium alloy 7075 in corrosive mediums. The tempers of the aluminium alloy used are T6 and T73 where obtained by solution heat treatment at 470°C and quenched before immersion test in acidic (pH3), and slightly alkaline (pH7.5) solutions. The results obtained were characterized by conventional weight loss process and morphology observation with a microscope. The surface morphology shows exfoliation form of corrosion and the weight loss analysis shows the as received sample experience more weight loss when compared with the other heat treated samples.

Ultrasonic-assisted soldering of Cu/Ti joints

NASA Astrophysics Data System (ADS)

Cui, Wei; Wang, Chunyu; Li, Yuhang; Zhong, Tongtong; Yang, Jianguo; Bao, Yefeng

2018-03-01

Cu/Ti joints are expected to be used in various applications, while reliable joining method is still to be developed. It is commonly not possible to solder Ti alloys using Sn-based solder alloys because of their poor wettability. In this study, Sn-Ag-Cu soldering filler metal was used to joining TC4 titanium alloy and pure copper using ultrasonic-assisted soldering. The influence of different temperature and different ultrasonic time on the welded joint is studied and explored. Microstructure of the joints was investigated. Shear strength of the joints reached the maximum value, i.e. 38.2MPa. Relationship between the sonication parameters and the microstructure and strength of the joints was discussed. Thus, it is verified that dissimilar metal brazing of TC4 and copper is suitable for low temperature soldering.

Analysis of microstructure and mechanical properties of aluminium-copper joints welded by FSW process

NASA Astrophysics Data System (ADS)

Iordache, M.; Sicoe, G.; Iacomi, D.; Niţu, E.; Ducu, C.

2017-08-01

The research conducted in this article aimed to check the quality of joining some dissimilar materials Al-Cu by determining the mechanical properties and microstructure analysis. For the experimental measurements there were used tin alloy Al - EN-AW-1050A with a thickness of 2 mm and Cu99 sheet with a thickness of 2 mm, joined by FSW weld overlay. The main welding parameters were: rotating speed of the rotating element 1400 rev/min, speed of the rotating element 50 mm/min. The experimental results were determined on samples specially prepared for metallographic analysis. In order to prepare samples for their characterization, there was designed and built a device that allowed simultaneous positioning and fixing for grinding. The characteristics analyzed in the joint welded samples were mictrostructure, microhardness and residual stresses. The techniques used to determine these characteristics were optical microscopy, electron microscopy with fluorescence radioactive elemental analysis (EDS), Vickers microhardness line - HV0.3 and X-ray diffractometry.

A Versatile Method for Nanostructuring Metals, Alloys and Metal Based Composites

NASA Astrophysics Data System (ADS)

Gurau, G.; Gurau, C.; Bujoreanu, L. G.; Sampath, V.

2017-06-01

A new severe plastic deformation method based on High Pressure Torsion is described. The method patented as High Speed High Pressure Torsion (HSHPT) shows a wide scope and excellent adaptability assuring large plastic deformation degree on metals, alloys even on hard to deform or brittle alloys. The paper present results obtained on aluminium, magnesium, titan, iron and coper alloys. In addition capability of HSHPT to process metallic composites is described. OM SEM, TEM, DSC, RDX and HV investigation methods were employed to confirm fine and ultrafine structure.

Structural study of VO {sub x} doped aluminium fluoride and aluminium oxide catalysts

DOE Office of Scientific and Technical Information (OSTI.GOV)

Scheurell, Kerstin; Scholz, Gudrun; Kemnitz, Erhard

The structural properties of vanadium doped aluminium oxyfluorides and aluminium oxides, prepared by a modified sol-gel synthesis route, were thoroughly investigated. The influence of the preparation technique and the calcination temperature on the coordination of vanadium, aluminium and fluorine was analysed by different spectroscopic methods such as Raman, MAS NMR and ESR spectroscopy. In all samples calcined at low temperatures (350 deg. C), vanadium coexists in two oxidation states V{sup IV} and V{sup V}, with V{sup IV} as dominating species in the vanadium doped aluminium oxyfluorides. In the fluoride containing solids aluminium as well as vanadium are coordinated by fluorinemore » and oxygen. Thermal annealing of 800 deg. C leads to an extensive reorganisation of the original matrices and to the oxidation of V{sup IV} to V{sup V} in both systems. - Graphical abstract: Structure model for VO {sub x} doped aluminium oxide.« less

Effect of Cr and Mn addition and heat treatment on AlSi3Mg casting alloy

DOE Office of Scientific and Technical Information (OSTI.GOV)

Tocci, Marialaura, E-mail: m.tocci@unibs.it

In the present paper the effect of heat treatment on an AlSi3Mg alloy with and without Cr and Mn addition was investigated. Beside the well-known modification of the morphology of Fe-containing intermetallics, it was found that Cr and Mn allowed the formation of dispersoids in the aluminium matrix after solution heat treatment at 545 °C, as shown by scanning transmission electron microscope observations. These particles were responsible of the enhanced Vickers microhardness of the aluminium matrix in comparison with the base alloy after solution treatment and quenching, according to dispersion hardening mechanism. The presence of these particles was not affectedmore » by ageing treatment, which instead allowed the precipitation of β-Mg{sub 2}Si, as shown by the elaboration of differential scanning calorimeter curves. The formation of dispersoids and the study of their effect on mechanical properties can represent an interesting development for applications at high temperatures of casting alloys due to their thermal stability compared to other strengthening phases as β-Mg{sub 2}Si. - Highlights: •Cr and Mn successfully modified the morphology of Fe-containing intermetallics. •Cr- and Mn-dispersoids formed in the aluminium matrix during solution treatment. •Dispersion hardening was detected after solution treatment for Cr-containing alloy. •The dispersion hardening effect was maintained after ageing treatment.« less

The prophylactic reduction of aluminium intake.

PubMed

Lione, A

1983-02-01

The use of modern analytical methods has demonstrated that aluminium salts can be absorbed from the gut and concentrated in various human tissues, including bone, the parathyroids and brain. The neurotoxicity of aluminium has been extensively characterized in rabbits and cats, and high concentrations of aluminium have been detected in the brain tissue of patients with Alzheimer's disease. Various reports have suggested that high aluminium intakes may be harmful to some patients with bone disease or renal impairment. Fatal aluminium-induced neuropathies have been reported in patients on renal dialysis. Since there are no demonstrable consequences of aluminium deprivation, the prophylactic reduction of aluminium intake by many patients would appear prudent. In this report, the major sources of aluminium in foods and non-prescription drugs are summarized and alternative products are described. The most common foods that contain substantial amounts of aluminium-containing additives include some processed cheeses, baking powders, cake mixes, frozen doughs, pancake mixes, self-raising flours and pickled vegetables. The aluminium-containing non-prescription drugs include some antacids, buffered aspirins, antidiarrhoeal products, douches and haemorrhoidal medications. The advisability of recommending a low aluminium diet for geriatric patients is discussed in detail.

Effect of adding powder on joint properties of laser penetration welding for dual phase steel and aluminum alloy

NASA Astrophysics Data System (ADS)

Zhou, D. W.; Liu, J. S.; Lu, Y. Z.; Xu, S. H.

2017-09-01

The experiments of laser penetration welding for dual phase steel and aluminum alloy were carried out, and the effect of adding Mn or Si powder on mechanical properties and microstructure of the weld was investigated. Some defects, such as spatter, inclusion, cracks and softening in heat affected zone (HAZ), can be avoided in welding joints, and the increased penetration depth is obtained by adding Mn or Si powder. The average tensile-shear strength of Si-added joint is 3.84% higher than that of Mn-added joint, and the strength of both joints exceeds that of no-added joint. In the case of adding Mn powder, small amount of liquid Al is mixed into steel molten pool, and the Al content increases in both sides of the weld, which leads to the increased weld width in aluminum molten pool. Thus, transverse area increases in jointing steel to aluminum, which is significant for the improved tensile-shear strength of joints. As far as adding Si powder is concerned, it is not the case, the enhancement of the joint properties benefits from improvement of metallurgical reaction.

Biological indicators of exposure to total and respirable aluminium dust fractions in a primary aluminium smelter.

PubMed Central

Röllin, H B; Theodorou, P; Cantrell, A C

1996-01-01

OBJECTIVES: The study attempts to define biological indicators of aluminium uptake and excretion in workers exposed to airborne aluminium compounds in a primary aluminium smelter. Also, this study defines the total and respirable aluminium dust fractions in two different potrooms, and correlates their concentrations with biological indicators in this group of workers. METHODS: Air was sampled at defined work sites. Non-destructive and conventional techniques were used to find total and respirable aluminium content of the dust. Blood and urine was collected from 84 volunteers employed at various work stations throughout the smelter and from two different cohorts of controls matched for sex, age, and socioeconomic status. Aluminium in serum samples and urine specimens was measured by flameless atomic absorption with a PE 4100 ZL spectrometer. RESULTS: The correlation of aluminium concentrations in serum and urine samples with the degree of exposure was assessed for three arbitrary exposure categories; low (0.036 mg Al/m3), medium (0.35 mg Al/m3) and high (1.47 mg Al/m3) as found in different areas of the smelter. At medium and high exposure, the ratio of respirable to total aluminium in the dust samples varied significantly. At high exposure, serum aluminium, although significantly raised, was still within the normal range of an unexposed population. The workers with low exposure excreted aluminium in urine at levels significantly higher than the controls, but still within the normal range of the population. However, potroom workers with medium and high exposure had significantly higher urinary aluminium than the normal range. CONCLUSIONS: It is concluded that only urinary aluminium constitutes a practical index of occupational exposure at or above 0.35 mg Al/m3, and that the respirable fraction of the dust may play a major role in the biological response to exposure to aluminium in a smelter environment. PMID:8758038

Characterisation of weld zone reactions in dissimilar glass-to-aluminium pulsed picosecond laser welds

DOE Office of Scientific and Technical Information (OSTI.GOV)

Ciuca, Octav P., E-mail: octav.ciuca@manchester.ac

Precision welded joints, produced between fused silica glass and aluminium by a newly-developed picosecond-pulse laser technique, have been analysed for the first time using a full range of electron microscopy methods. The welds were produced as lap joints by focusing a 1.2 μm diameter laser beam through the transparent glass top sheet, slightly below the surface of the metal bottom sheet. Despite the extremely short interaction time, extensive reaction was observed in the weld zone, which involved the formation of nanocrystalline silicon and at least two transitional alumina phases, γ- and δ-Al{sub 2}O{sub 3}. The weld formation process was foundmore » to be complex and involved: the formation of a constrained plasma cavity at the joint interface, non-linear absorption in the glass, and the creation of multiple secondary keyholes in the metal substrate by beam scattering. The joint area was found to expand outside of the main interaction volume, as the energy absorbed into the low conductivity and higher melting point silica glass sheet melted the aluminium surface across a wider contact area. The reasons for the appearance of nanocrystalline Si and transitional alumina reaction products within the welds are discussed. - Highlights: •Pulsed laser welding of dissimilar materials causes extensive chemical reactivity. •Metastable Al{sub 2}O{sub 3} phases form due to laser-induced highly-transient thermal regime. •Fused silica is reduced by Al to form nanocrystalline Si. •Mechanism of joint formation is discussed.« less

Separation of actinides from irradiated An-Zr based fuel by electrorefining on solid aluminium cathodes in molten LiCl-KCl

NASA Astrophysics Data System (ADS)

Souček, P.; Murakami, T.; Claux, B.; Meier, R.; Malmbeck, R.; Tsukada, T.; Glatz, J.-P.

2015-04-01

An electrorefining process for metallic spent nuclear fuel treatment is being investigated in ITU. Solid aluminium cathodes are used for homogeneous recovery of all actinides within the process carried out in molten LiCl-KCl eutectic salt at a temperature of 500 °C. As the selectivity, efficiency and performance of solid Al has been already shown using un-irradiated An-Zr alloy based test fuels, the present work was focused on laboratory-scale demonstration of the process using irradiated METAPHIX-1 fuel composed of U67-Pu19-Zr10-MA2-RE2 (wt.%, MA = Np, Am, Cm, RE = Nd, Ce, Gd, Y). Different electrorefining techniques, conditions and cathode geometries were used during the experiment yielding evaluation of separation factors, kinetic parameters of actinide-aluminium alloy formation, process efficiency and macro-structure characterisation of the deposits. The results confirmed an excellent separation and very high efficiency of the electrorefining process using solid Al cathodes.

The fatigue response of the aluminium-lithium alloy, 8090

NASA Technical Reports Server (NTRS)

Birt, M. J.; Beevers, C. J.

1989-01-01

The fatigue response of an Al-Li-Cu-Mg-Zr (8090) alloy has been studied at room temperature. The initiation and growth of small and long cracks has been examined at R = 0.1 and at a frequency of 100 Hz. Initiation was observed to occur dominantly at sub-grain boundaries. The growth of the small cracks was crystallographic in character and exhibited little evidence of retardation or arrest at the grain boundaries. The long crack data showed the alloy to have a high resistance to fatigue crack growth with underaging providing the optimum heat treatment for fatigue crack growth resistance. In general, this can be attributed to high levels of crack closure which resulted from the presence of extensive microstructurally related asperities.

Computational prediction of the refinement of oxide agglomerates in a physical conditioning process for molten aluminium alloy

NASA Astrophysics Data System (ADS)

Tong, M.; Jagarlapudi, S. C.; Patel, J. B.; Stone, I. C.; Fan, Z.; Browne, D. J.

2015-06-01

Physically conditioning molten scrap aluminium alloys using high shear processing (HSP) was recently found to be a promising technology for purification of contaminated alloys. HSP refines the solid oxide agglomerates in molten alloys, so that they can act as sites for the nucleation of Fe-rich intermetallic phases which can subsequently be removed by the downstream de-drossing process. In this paper, a computational modelling for predicting the evolution of size of oxide clusters during HSP is presented. We used CFD to predict the macroscopic flow features of the melt, and the resultant field predictions of temperature and melt shear rate were transferred to a population balance model (PBM) as its key inputs. The PBM is a macroscopic model that formulates the microscopic agglomeration and breakage of a population of a dispersed phase. Although it has been widely used to study conventional deoxidation of liquid metal, this is the first time that PBM has been used to simulate the melt conditioning process within a rotor/stator HSP device. We employed a method which discretizes the continuous profile of size of the dispersed phase into a collection of discrete bins of size, to solve the governing population balance equation for the size of agglomerates. A finite volume method was used to solve the continuity equation, the energy equation and the momentum equation. The overall computation was implemented mainly using the FLUENT module of ANSYS. The simulations showed that there is a relatively high melt shear rate between the stator and sweeping tips of the rotor blades. This high shear rate leads directly to significant fragmentation of the initially large oxide aggregates. Because the process of agglomeration is significantly slower than the breakage processes at the beginning of HSP, the mean size of oxide clusters decreases very rapidly. As the process of agglomeration gradually balances the process of breakage, the mean size of oxide clusters converges to a

Metal-ceramic joint assembly

DOEpatents

Li, Jian

2002-01-01

A metal-ceramic joint assembly in which a brazing alloy is situated between metallic and ceramic members. The metallic member is either an aluminum-containing stainless steel, a high chromium-content ferritic stainless steel or an iron nickel alloy with a corrosion protection coating. The brazing alloy, in turn, is either an Au-based or Ni-based alloy with a brazing temperature in the range of 9500 to 1200.degree. C.

X-ray online detection for laser welding T-joint of Al-Li alloy

NASA Astrophysics Data System (ADS)

Zhan, Xiaohong; Bu, Xing; Qin, Tao; Yu, Haisong; Chen, Jie; Wei, Yanhong

2017-05-01

In order to detect weld defects in laser welding T-joint of Al-Li alloy, a real-time X-ray image system is set up for quality inspection. Experiments on real-time radiography procedure of the weldment are conducted by using this system. Twin fillet welding seam radiographic arrangement is designed according to the structural characteristics of the weldment. The critical parameters including magnification times, focal length, tube current and tube voltage are studied to acquire high quality weld images. Through the theoretical and data analysis, optimum parameters are settled and expected digital images are captured, which is conductive to automatic defect detection.

Content and bioaccessibility of aluminium in duplicate diets from southern Spain.

PubMed

Cabrera-Vique, Carmen; Mesías, Marta

2013-08-01

Aluminium is found naturally in foods and beverages, but levels increase notably during processing, packaging, storage, and cooking, as a consequence of its presence in food additives and the wide use of aluminium utensils and vessels. Dietary intake of Al was estimated in 2 population groups in southern Spain (families and university students) in a duplicate diet sampling study. Diets were sampled for 7 consecutive days, and Al was determined in acid-mineralized samples with electrothermal atomization-atomic absorption spectrometry (ETA-AAS). Mean values for Al intake were 2.93 and 1.01 mg/d in families and students, respectively, ranging from 0.12 to 10.00 mg/d. Assuming an average adult weight of 60 kg, the mean dietary exposures to aluminium were 0.34 and 0.12 mg/kg body weight/week in these groups, which amounted to 17% and 6% of the 2 mg/kg body weight estimated as the tolerable weekly intake by the Joint FAO/WHO Expert Committee on Food Additives. Bioaccessibility of dietary Al tested with in vitro studies ranged from 0.30 to 17.26% (absorbable fraction). The highest aluminium intakes were observed in subjects consuming diets with a low adherence to the Mediterranean diet, which were associated to high consumption of processed and canned food. On the contrary, subjects consuming diets with a high adherence to the Mediterranean diet patterns showed the lowest Al intakes. The present findings are useful for giving both a reliable estimate of total aluminium dietary intake and tolerable intake levels according to usual dietary habits. © 2013 Institute of Food Technologists®

Analysis of aluminium in rat following administration of allergen immunotherapy using either aluminium or microcrystalline-tyrosine-based adjuvants.

PubMed

McDougall, Stuart A; Heath, Matthew D; Kramer, Matthias F; Skinner, Murray A

2016-03-01

Investigation into the absorption, distribution and elimination of aluminium in rat after subcutaneous aluminium adjuvant formulation administration using ICP-MS is described. Assays were verified under the principles of a tiered approach. There was no evidence of systemic exposure of aluminium, in brain or in kidney. Extensive and persistent retention of aluminium at the dose site was observed for at least 180 days after administration. This is the first published work that has quantified aluminium adjuvant retention based on the quantity of aluminium delivered in a typical allergy immunotherapy course. The results indicate that the repeated administration of aluminium-containing adjuvants will likely contribute directly and significantly to an individual's body burden of aluminium.

Influence of tool geometry and processing parameters on welding defects and mechanical properties for friction stir welding of 6061 Aluminium alloy

NASA Astrophysics Data System (ADS)

Daneji, A.; Ali, M.; Pervaiz, S.

2018-04-01

Friction stir welding (FSW) is a form of solid state welding process for joining metals, alloys, and selective composites. Over the years, FSW development has provided an improved way of producing welding joints, and consequently got accepted in numerous industries such as aerospace, automotive, rail and marine etc. In FSW, the base metal properties control the material’s plastic flow under the influence of a rotating tool whereas, the process and tool parameters play a vital role in the quality of weld. In the current investigation, an array of square butt joints of 6061 Aluminum alloy was to be welded under varying FSW process and tool geometry related parameters, after which the resulting weld was evaluated for the corresponding mechanical properties and welding defects. The study incorporates FSW process and tool parameters such as welding speed, pin height and pin thread pitch as input parameters. However, the weld quality related defects and mechanical properties were treated as output parameters. The experimentation paves way to investigate the correlation between the inputs and the outputs. The correlation between inputs and outputs were used as tool to predict the optimized FSW process and tool parameters for a desired weld output of the base metals under investigation. The study also provides reflection on the effect of said parameters on a welding defect such as wormhole.

Wear behavioral study of as cast and 7 hr homogenized Al25Mg2Si2Cu4Ni alloy at constant load

NASA Astrophysics Data System (ADS)

Harlapur, M. D.; Sondur, D. G.; Akkimardi, V. G.; Mallapur, D. G.

2018-04-01

In the current study, the wear behavior of as cast and 7 hr homogenized Al25Mg2Si2Cu4Ni alloy has been investigated. Microstructure, SEM and EDS results confirm the presence of different intermetallic and their effects on wear properties of Al25Mg2Si2Cu4Ni alloy in as cast as well as aged condition. Alloying main elements like Si, Cu, Mg and Ni partly dissolve in the primary α-Al matrix and to some amount present in the form of intermetallic phases. SEM structure of as cast alloy shows blocks of Mg2Si which is at random distributed in the aluminium matrix. Precipitates of Al2Cu in the form of Chinese script are also observed. Also `Q' phase (Al-Si-Cu-Mg) be distributed uniformly into the aluminium matrix. Few coarsened platelets of Ni are seen. In case of 7 hr homogenized samples blocks of Mg2Si get rounded at the corners, Platelets of Ni get fragmented and distributed uniformly in the aluminium matrix. Results show improved volumetric wear resistance and reduced coefficient of friction after homogenizing heat treatment.

The causes of high power diode laser brazed seams fractures of dissimilar materials

NASA Astrophysics Data System (ADS)

Adamiak, Marcin; Czupryński, Artur; Janicki, Damian; Górka, Jacek

2016-12-01

Presented in this article are the results of experiments carried out to determine the causes of braze cracking of dissimilar materials brazed with a ROFIN DL 020 high power diode laser with the use of additional powdered EN AW-1070A aluminium alloy to bond thin aluminium sheets with soft, low alloy DC04+ZE75/75 steel plate which was electrolytically coated with zinc on both sides. Presented are the results of metallographic, macroscopic, microscopic, diffractometric phase analyses of the weld joints. Metallurgical problems arising during processing as well as suggestions regarding technical aspects of laser brazing dissimilar materials in regards to their physical characteristics and chemical composition are explored.

Effect of welding speed on butt joint quality of Ti-6Al-4V alloy welded using a high-power Nd:YAG laser

NASA Astrophysics Data System (ADS)

Cao, X.; Jahazi, M.

2009-11-01

Annealed Ti-6Al-4V alloy sheets with 1 and 2 mm thickness are welded using a 4 kW Nd:YAG laser system. The effects of welding speed on surface morphology and shape, welding defects, microstructure, hardness and tensile properties are investigated. Weld joints without or with minor cracks, porosity and shape defects were obtained indicating that high-power Nd:YAG laser welding is a suitable method for Ti-6Al-4V alloy. The fusion zone consists mainly of acicular α' martensite leading to an increase of approximately 20% in hardness compared with that in the base metal. The heat-affected zone consists of a mixture of α' martensite and primary α phases. Significant gradients of microstructures and hardness are obtained over the narrow heat-affected zone. The laser welded joints have similar or slightly higher joint strength but there is a significant decrease in ductility. The loss of ductility is related to the presence of micropores and aluminum oxide inclusions.

Tuning the Hydrogen Storage in Magnesium Alloys

NASA Astrophysics Data System (ADS)

Er, Suleyman; de Wijs, Gilles A.; Brocks, Geert

2011-03-01

We investigate the hydrogen storage properties of promising magnesium alloys. Mg H2 (7.6 wt % H) would be a very useful storage material if the (de)hydrogenation kinetics can be improved and the desorption temperature is markedly lowered. Using first principles calculations, we show that hydrides of Mg-transition metal (TM) alloys adopt a structure that promotes faster (de)hydrogenation kinetics, as is also observed in experiment. Within the lightweight TMs, the most promising alloying element is titanium. Alloying Mg with Ti alone, however, is not sufficient to decrease the stability of the hydride phases, which is necessary to reduce the hydrogen desorption temperature. We find that adding aluminium or silicon markedly destabilizes Mg-Ti hydrides and stabilizes Mg-Ti alloys. Finally, we show that controlling the structure of Mg-Ti-Al(Si) system by growing it as multilayers, has a beneficial influence on the thermodynamic properties and makes it a stronger candidate for hydrogen storage.

Development of a persistent superconducting joint between Bi-2212/Ag-alloy multifilamentary round wires

NASA Astrophysics Data System (ADS)

Chen, Peng; Trociewitz, Ulf P.; Davis, Daniel S.; Bosque, Ernesto S.; Hilton, David K.; Kim, Youngjae; Abraimov, Dmytro V.; Starch, William L.; Jiang, Jianyi; Hellstrom, Eric E.; Larbalestier, David C.

2017-02-01

Superconducting joints are one of the key components needed to make Ag-alloy clad Bi2Sr2CaCu2O8+x (Bi-2212) superconducting round wire (RW) successful for high-field, high-homogeneity magnet applications, especially for nuclear magnetic resonance magnets in which persistent current mode operation is highly desired. In this study, a procedure for fabricating superconducting joints between Bi-2212 RWs during coil reaction was developed. Melting temperatures of Bi-2212 powder with different amounts of Ag addition were investigated by differential thermal analysis so as to provide information for selecting the proper joint matrix. Test joints of 1.3 mm dia. wires heat treated in 1 bar flowing oxygen using the typical partial melt Bi-2212 heat treatment (HT) had transport critical currents I c of ˜900 A at 4.2 K and self-field, decreasing to ˜480 A at 14 T evaluated at 0.1 μV cm-1 at 4.2 K. Compared to the I c of the open-ended short conductor samples with identical 1 bar HT, the I c values of the superconducting joint are ˜20% smaller than that of conductor samples measured in parallel field but ˜20% larger than conductor samples measured in perpendicular field. Microstructures examined by scanning electron microscopy clearly showed the formation of a superconducting Bi-2212 interface between the two Bi-2212 RWs. Furthermore, a Bi-2212 RW closed-loop solenoid with a superconducting joint heat treated in 1 bar flowing oxygen showed an estimated joint resistance below 5 × 10-12 Ω based on its field decay rate. This value is sufficiently low to demonstrate the potential for persistent operation of large inductance Bi-2212 coils.

Bone aluminium in haemodialysed patients and in rats injected with aluminium chloride: relationship to impaired bone mineralisation.

PubMed Central

Ellis, H A; McCarthy, J H; Herrington, J

1979-01-01

Iliac bone aluminium was determined by neutron activation analysis in 34 patients with chronic renal failure and in eight control subjects. In 17 patients treated by haemodialysis there was a significant increase in the amount of aluminium (mean +/- SE = 152 +/- 30 ppm bone ash). In eight patients treated by haemodialysis and subsequent renal transplantation, bone aluminium was still significantly increased (92 +/- 4.5 ppm bone ash) but was less than in the haemodialysed patients. In some patients aluminium persisted in bone for many years after successful renal transplantation. There was no relationship between hyperparathyroidism and bone aluminium. Although no statistically significant relationship was found between the mineralisation status of bone and bone aluminium, patients dialysed for the longest periods tended to be those with the highest levels of aluminium, osteomalacia, and dialysis encephalopathy. In 20 rats given daily intraperitoneal injections of aluminium chloride for periods of up to three months, there was accumulation of aluminium in bone (163 +/- 9 ppm ash) to levels comparable to those obtained in the dialysis patients, and after about eight weeks osteomalacia developed. The increased bone aluminium and osteomalacia persisted after injections had been stopped for up to 49 days, although endochondral ossification was restored to normal. As a working hypothesis it is suggested that aluminium retained in the bone of the dialysis patients and the experimental animals interferes with normal mineralisation. Images Fig. 5 Fig. 6 PMID:389958

Effects of as-cast and wrought Cobalt-Chrome-Molybdenum and Titanium-Aluminium-Vanadium alloys on cytokine gene expression and protein secretion in J774A.1 macrophages.

PubMed

Jakobsen, Stig S; Larsen, A; Stoltenberg, M; Bruun, J M; Soballe, K

2007-09-11

Insertion of metal implants is associated with a possible change in the delicate balance between pro- and anti-inflammatory proteins, probably leading to an unfavourable predominantly pro-inflammatory milieu. The most likely cause is an inappropriate activation of macrophages in close relation to the metal implant and wear-products. The aim of the present study was to compare surfaces of as-cast and wrought Cobalt-Chrome-Molybdenum (CoCrMo) alloys and Titanium-Aluminium-Vanadium (TiAlV) alloy when incubated with mouse macrophage J774A.1 cell cultures. Changes in pro- and anti-inflammatory cytokines (TNF-alpha, IL-6, IL-alpha, IL-1beta, IL-10) and proteins known to induce proliferation (M-CSF), chemotaxis (MCP-1) and osteogenesis (TGF-beta, OPG) were determined by ELISA and Real Time reverse transcriptase - PCR (Real Time rt-PCR). Lactate dehydrogenase (LDH) was measured in the medium to asses the cell viability. Surface properties of the discs were characterised with a profilometer and with energy dispersive X-ray spectroscopy. We here report, for the first time, that the prosthetic material surface (non-phagocytable) of as-cast high carbon CoCrMo reduces the pro-inflammatory cytokine IL-6 transcription, the chemokine MCP-1 secretion, and M-CSF secretion by 77%, 36%, and 62%, respectively. Furthermore, we found that reducing surface roughness did not affect this reduction. The results suggest that as-cast CoCrMo alloy is more inert than wrought CoCrMo and wrought TiAlV alloys and could prove to be a superior implant material generating less inflammation which might result in less osteolysis.

Parameter Design in Fusion Welding of AA 6061 Aluminium Alloy using Desirability Grey Relational Analysis (DGRA) Method

NASA Astrophysics Data System (ADS)

Adalarasan, R.; Santhanakumar, M.

2015-01-01

In the present work, yield strength, ultimate strength and micro-hardness of the lap joints formed with Al 6061 alloy sheets by using the processes of Tungsten Inert Gas (TIG) welding and Metal Inert Gas (MIG) welding were studied for various combinations of the welding parameters. The parameters taken for study include welding current, voltage, welding speed and inert gas flow rate. Taguchi's L9 orthogonal array was used to conduct the experiments and an integrated technique of desirability grey relational analysis was disclosed for optimizing the welding parameters. The ignored robustness in desirability approach is compensated by the grey relational approach to predict the optimal setting of input parameters for the TIG and MIG welding processes which were validated through the confirmation experiments.

Experimental Investigation and Finite Element Analysis on Fatigue Behavior of Aluminum Alloy 7050 Single-Lap Joints

NASA Astrophysics Data System (ADS)

Zhou, Bing; Cui, Hao; Liu, Haibo; Li, Yang; Liu, Gaofeng; Li, Shujun; Zhang, Shangzhou

2018-03-01

The fatigue behavior of single-lap four-riveted aluminum alloy 7050 joints was investigated by using high-frequency fatigue test and scanning electron microscope (SEM). Stress distributions obtained by finite element (FE) analysis help explain the fatigue performance. The fatigue test results showed that the fatigue lives of the joints depend on cold expansion and applied cyclic loads. FE analysis and fractography indicated that the improved fatigue lives can be attributed to the reduction in maximum stress and evolution of fatigue damage at the critical location. The beneficial effects of strengthening techniques result in tearing ridges or lamellar structure on fracture surface, decrease in fatigue striations spacing, delay of fatigue crack initiation, crack deflection in fatigue crack propagation and plasticity-induced crack closure.

Variation in aluminium patch test reactivity over time.

PubMed

Siemund, Ingrid; Mowitz, Martin; Zimerson, Erik; Bruze, Magnus; Hindsén, Monica

2017-11-01

Contact allergy to aluminium has been reported more frequently in recent years. It has been pointed out that positive patch test reactions to aluminium may not be reproducible on retesting. To investigate possible variations in patch test reactivity to aluminium over time. Twenty-one adults, who had previously reacted positively to aluminium, were patch tested with equimolar dilution series in pet. of aluminium chloride hexahydrate and aluminium lactate, four times over a period of 8 months. Thirty-six of 84 (43%) serial dilution tests with aluminium chloride hexahydrate and 49 of 84 (58%) serial dilution tests with aluminium lactate gave negative results. The range of reactivity varied between a negative reaction to aluminium chloride hexahydrate at 10% and/or to aluminium lactate at 12%, and a positive reaction to aluminium chloride hexahydrate at 0.1% and/or to aluminium lactate at 0.12%. The highest individual difference in test reactivity noticed was 320-fold when the two most divergent minimal eliciting concentrations were compared. The patch test reactivity to aluminium varies over time. Aluminium-allergic individuals may have false-negative reactions. Therefore, retesting with aluminium should be considered when there is a strong suspicion of aluminium contact allergy. © 2017 John Wiley & Sons A/S. Published by John Wiley & Sons Ltd.

Hydrogenated vacancies lock dislocations in aluminium

PubMed Central

Xie, Degang; Li, Suzhi; Li, Meng; Wang, Zhangjie; Gumbsch, Peter; Sun, Jun; Ma, Evan; Li, Ju; Shan, Zhiwei

2016-01-01

Due to its high diffusivity, hydrogen is often considered a weak inhibitor or even a promoter of dislocation movements in metals and alloys. By quantitative mechanical tests in an environmental transmission electron microscope, here we demonstrate that after exposing aluminium to hydrogen, mobile dislocations can lose mobility, with activating stress more than doubled. On degassing, the locked dislocations can be reactivated under cyclic loading to move in a stick-slip manner. However, relocking the dislocations thereafter requires a surprisingly long waiting time of ∼103 s, much longer than that expected from hydrogen interstitial diffusion. Both the observed slow relocking and strong locking strength can be attributed to superabundant hydrogenated vacancies, verified by our atomistic calculations. Vacancies therefore could be a key plastic flow localization agent as well as damage agent in hydrogen environment. PMID:27808099

Hydrogenated vacancies lock dislocations in aluminium

DOE Office of Scientific and Technical Information (OSTI.GOV)

Xie, Degang; Li, Suzhi; Li, Meng

Due to its high diffusivity, hydrogen is often considered a weak inhibitor or even a promoter of dislocation movements in metals and alloys. By quantitative mechanical tests in an environmental transmission electron microscope, here we demonstrate that after exposing aluminium to hydrogen, mobile dislocations can lose mobility, with activating stress more than doubled. On degassing, the locked dislocations can be reactivated under cyclic loading to move in a stick-slip manner. However, relocking the dislocations thereafter requires a surprisingly long waiting time of ~10 3 s, much longer than that expected from hydrogen interstitial diffusion. Both the observed slow relocking andmore » strong locking strength can be attributed to superabundant hydrogenated vacancies, verified by our atomistic calculations. In conclusion, vacancies therefore could be a key plastic flow localization agent as well as damage agent in hydrogen environment.« less

Hydrogenated vacancies lock dislocations in aluminium

DOE PAGES

Xie, Degang; Li, Suzhi; Li, Meng; ...

2016-11-03

Due to its high diffusivity, hydrogen is often considered a weak inhibitor or even a promoter of dislocation movements in metals and alloys. By quantitative mechanical tests in an environmental transmission electron microscope, here we demonstrate that after exposing aluminium to hydrogen, mobile dislocations can lose mobility, with activating stress more than doubled. On degassing, the locked dislocations can be reactivated under cyclic loading to move in a stick-slip manner. However, relocking the dislocations thereafter requires a surprisingly long waiting time of ~10 3 s, much longer than that expected from hydrogen interstitial diffusion. Both the observed slow relocking andmore » strong locking strength can be attributed to superabundant hydrogenated vacancies, verified by our atomistic calculations. In conclusion, vacancies therefore could be a key plastic flow localization agent as well as damage agent in hydrogen environment.« less

Microhardness variation and related microstructure in Al-Cu alloys prepared by HF induction melting and RF sputtering

NASA Astrophysics Data System (ADS)

Boukhris, N.; Lallouche, S.; Debili, M. Y.; Draissia, M.

2009-03-01

The materials under consideration are binary aluminium-copper alloys (10 at% to 90.3 at%Cu) produced by HF melting and RF magnetron sputtering. The resulting micro structures have been observed by standard metallographic techniques, X-ray powder diffraction, scanning electron microscopy and transmission electron microscopy. Vickers microhardness of bulk Al-Cu alloys reaches a maximum of 1800 MPa at 70.16 at%Cu. An unexpected metastable θ ' phase has been observed within aluminium grain in Al-37 at%Cu. The mechanical properties of a family of homogeneous Al{1-x}Cu{x} (0 < x < 0.92) thin films made by radiofrequency (13.56 MHz) cathodic magnetron sputtering from composite Al-Cu targets have been investigated. The as-deposited microstructures for all film compositions consisted of a mixture of the two expected face-centred-cubic (fcc) Al solid solution and tetragonal θ (Al{2}Cu) phases. The microhardness regularly increases and the grain size decreases both with copper concentration. This phenomenon of significant mechanical strengthening of aluminium by means of copper is essentially due to a combination between solid solution effects and grain size refinement. This paper reports some structural features of different Al-Cu alloys prepared by HF melting and RF magnetron on glass substrate sputtering.

Mechanical Properties of SiC, Al2O3 Reinforced Aluminium 6061-T6 Hybrid Matrix Composite

NASA Astrophysics Data System (ADS)

Murugan, S. Senthil; Jegan, V.; Velmurugan, M.

2018-04-01

This paper contains the investigation of tensile, compression and impact characterization of SiC, Al2O3 reinforced Aluminium 6061-T6 matrix hybrid composite. Hybrid matrix composite fabrication was done by stir casting method. An attempt has been made by keeping Al2O3 percentage (7%) constant and increasing SiC percentage (10, 15, and 20%). After fabricating, the samples were prepared and tested to find out the various mechanical properties like tensile, compressive, and impact strength of the developed composites of different weight % of silicon carbide and Alumina in Aluminium alloy. The main objective of the study is to compare the values obtained and choose the best composition of the hybrid matrix composite from the mechanical properties point of view.

The development and mechanical characterization of aluminium copper-carbon fiber metal matrix hybrid composite

NASA Astrophysics Data System (ADS)

Manzoor, M. U.; Feroze, M.; Ahmad, T.; Kamran, M.; Butt, M. T. Z.

2018-04-01

Metal matrix composites (MMCs) come under advanced materials that can be used for a wide range of industrial applications. MMCs contain a non-metallic reinforcement incorporated into a metallic matrix which can enhance properties over base metal alloys. Copper-Carbon fiber reinforced aluminium based hybrid composites were prepared by compo casting method. 4 weight % copper was used as alloying element with Al because of its precipitation hardened properties. Different weight compositions of composites were developed and characterized by mechanical testing. A significant improvement in tensile strength and micro hardness were found, before and after heat treatment of the composite. The SEM analysis of the fractured surfaces showed dispersed and embedded Carbon fibers within the network leading to the enhanced strength.

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.

The behavior of Aluminium Carbon/Epoxy fibre metal laminate under quasi-static loading

NASA Astrophysics Data System (ADS)

Romli, N. K.; Rejab, M. R. M.; Bachtiar, D.; Siregar, J.; Rani, M. F.; Harun, W. S. W.; Salleh, Salwani Mohd; Merzuki, M. N. M.

2017-10-01

One of major concerns that related to the flight safety is impact of birds. To minimize the risks, there is need to increase the impact resistance of aircraft by developing a new material and has the good structural design of aircraft structures. The hybrid laminates are potential candidate material to be applied for the aircraft structures susceptible to bird strikes. The fibre metal laminate was fabricated by a compression moulding technique. The carbon fibre and aluminium alloy 2024-0 was laminated by using thermoset epoxy. A compression moulding technique was used for the FML fabrication. The aluminium sheet metal has been roughening by a metal sanding method which to improve the bonding between the fibre and metal layer. The main objective of this paper is to determine the failure response of the laminate under five variations of the crosshead displacement in the quasi-static loading. The FML was modelled and analysed by using Explicit solver. Based on the experimental data of the quasi-static test, the result of 1 mm/min was 11.85 kN and higher than 5, 10, 50 and 100 mm/min which because of the aluminium ductility during the impact loading response. The numerical simulations were generally in good agreement with the experimental measurements.

Laser welding of NiTi shape memory alloy: Comparison of the similar and dissimilar joints to AISI 304 stainless steel

NASA Astrophysics Data System (ADS)

Mirshekari, G. R.; Saatchi, A.; Kermanpur, A.; Sadrnezhaad, S. K.

2013-12-01

The unique properties of NiTi alloy, such as its shape memory effect, super-elasticity and biocompatibility, make it ideal material for various applications such as aerospace, micro-electronics and medical device. In order to meet the requirement of increasing applications, great attention has been given to joining of this material to itself and to other materials during past few years. Laser welding has been known as a suitable joining technique for NiTi shape memory alloy. Hence, in this work, a comparative study on laser welding of NiTi wire to itself and to AISI 304 austenitic stainless steel wire has been made. Microstructures, mechanical properties and fracture morphologies of the laser joints were investigated using optical microscopy, scanning electron microscopy (SEM), energy dispersive spectroscopy (EDS), X-ray diffraction analysis (XRD), Vickers microhardness (HV0.2) and tensile testing techniques. The results showed that the NiTi-NiTi laser joint reached about 63% of the ultimate tensile strength of the as-received NiTi wire (i.e. 835 MPa) with rupture strain of about 16%. This joint also enabled the possibility to benefit from the pseudo-elastic properties of the NiTi component. However, tensile strength and ductility decreased significantly after dissimilar laser welding of NiTi to stainless steel due to the formation of brittle intermetallic compounds in the weld zone during laser welding. Therefore, a suitable modification process is required for improvement of the joint properties of the dissimilar welded wires.

Effect of inlet geometry on macrosegregation during the direct chill casting of 7050 alloy billets: experiments and computer modelling

NASA Astrophysics Data System (ADS)

Zhang, L.; Eskin, D. G.; Miroux, A.; Subroto, T.; Katgerman, L.

2012-07-01

Controlling macrosegregation is one of the major challenges in direct-chill (DC) casting of aluminium alloys. In this paper, the effect of the inlet geometry (which influences the melt distribution) on macrosegregation during the DC casting of 7050 alloy billets was studied experimentally and by using 2D computer modelling. The ALSIM model was used to determine the temperature and flow patterns during DC casting. The results from the computer simulations show that the sump profiles and flow patterns in the billet are strongly influenced by the melt flow distribution determined by the inlet geometry. These observations were correlated to the actual macrosegregation patterns found in the as-cast billets produced by having two different inlet geometries. The macrosegregation analysis presented here may assist in determining the critical parameters to consider for improving the casting of 7XXX aluminium alloys.

Fabrication of MEMS components using ultrafine-grained aluminium alloys

NASA Astrophysics Data System (ADS)

Qiao, Xiao Guang; Gao, Nong; Moktadir, Zakaria; Kraft, Michael; Starink, Marco J.

2010-04-01

A novel process for the fabrication of a microelectromechanical systems (MEMS) metallic component with features smaller than 10 µm and high thermal conductivity was investigated. This may be applied to new or improved microscale components, such as (micro-) heat exchangers. In the first stage of processing, equal channel angular pressing (ECAP) was employed to refine the grain size of commercial purity aluminium (Al-1050) to the ultrafine-grained (UFG) material. Embossing was conducted using a micro silicon mould fabricated by deep reactive ion etching (DRIE). Both cold embossing and hot embossing were performed on the coarse-grained and UFG Al-1050. Cold embossing on UFG Al-1050 led to a partially transferred pattern from the micro silicon mould and high failure rate of the mould. Hot embossing on UFG Al-1050 provided a smooth embossed surface with a fully transferred pattern and a low failure rate of the mould, while hot embossing on the coarse-grained Al-1050 resulted in a rougher surface with shear bands.

Aluminium, antiperspirants and breast cancer.

PubMed

Darbre, P D

2005-09-01

Aluminium salts are used as the active antiperspirant agent in underarm cosmetics, but the effects of widespread, long term and increasing use remain unknown, especially in relation to the breast, which is a local area of application. Clinical studies showing a disproportionately high incidence of breast cancer in the upper outer quadrant of the breast together with reports of genomic instability in outer quadrants of the breast provide supporting evidence for a role for locally applied cosmetic chemicals in the development of breast cancer. Aluminium is known to have a genotoxic profile, capable of causing both DNA alterations and epigenetic effects, and this would be consistent with a potential role in breast cancer if such effects occurred in breast cells. Oestrogen is a well established influence in breast cancer and its action, dependent on intracellular receptors which function as ligand-activated zinc finger transcription factors, suggests one possible point of interference from aluminium. Results reported here demonstrate that aluminium in the form of aluminium chloride or aluminium chlorhydrate can interfere with the function of oestrogen receptors of MCF7 human breast cancer cells both in terms of ligand binding and in terms of oestrogen-regulated reporter gene expression. This adds aluminium to the increasing list of metals capable of interfering with oestrogen action and termed metalloestrogens. Further studies are now needed to identify the molecular basis of this action, the longer term effects of aluminium exposure and whether aluminium can cause aberrations to other signalling pathways in breast cells. Given the wide exposure of the human population to antiperspirants, it will be important to establish dermal absorption in the local area of the breast and whether long term low level absorption could play a role in the increasing incidence of breast cancer.

Investigation of the dependence of deformation mechanisms on solute content in polycrystalline Mg–Al magnesium alloys by neutron diffraction and acoustic emission

DOE PAGES

Mathis, Kristian; Capek, J.; Clausen, Bjorn; ...

2015-04-20

Influence of aluminium content on the deformation mechanisms in Mg–Al binary alloys has been studied using in-situ neutron diffraction and acoustic emission technique. Here, it is shown that the addition of the solute increases the critical resolved shear stress for twinning. Further, the role of aluminium on the solid solution hardening of the basal plane and softening of non-basal planes are discussed using results of the convolutional multiple peak profile analysis of diffraction patterns. In conclusion, the results indicate that the density of both prismatic and pyramidal dislocations increases with increasing alloying content.

Tensile strength comparison of presoldered and postsoldered joints.

PubMed

Monday, J J; Asgar, K

1986-01-01

Twenty half-dumbbell shaped rods were cast in a silverless gold-palladium alloy that contained a minimum of 42% fresh alloy and the rest once-melted alloy. Each pair of half-dumbbells was assembled and either presoldered or postsoldered using a vacuum-oven and a torch-soldering technique. There was no significant difference in the ultimate tensile strength values between the presoldered and postsoldered joints within the same technique group, but the torch-soldered joints for the same solder were significantly stronger (p less than .01). It was believed that slow heating and cooling has deleterious effects on the ultimate tensile strength joints (UTS) possibly because of the microstructural changes and the highly oxidizable content of the postsolder used. Another 15 samples cast using once, twice, and three-times remelted parent alloy were presoldered and postsoldered with the torch only. In each of these groups, specimens joined by presolder showed significantly higher strength than those joined by postsolder (p less than .02). Remelting the parent alloy affected the strength differences between the presoldered and postsoldered joints. It was assumed that on remelting, the nature of the parent alloy is changed because some original elements are volatilized and newly formed oxides dissolved into it. Because it contains copper, the postsolder is more affected by this contamination than presolder. The UTS of the parent alloy, as well as that of the presolder and postsolder, were also determined. As expected, the parent alloy possessed the highest strength and the postsolder, the lowest.

Aluminium content of foods originating from aluminium-containing food additives.

PubMed

Ogimoto, Mami; Suzuki, Kumi; Haneishi, Nahoko; Kikuchi, Yuu; Takanashi, Mayu; Tomioka, Naoko; Uematsu, Yoko; Monma, Kimio

2016-09-01

Aluminium (Al) levels of 90 food samples were investigated. Nineteen samples contained Al levels exceeding the tolerable weekly intake (TWI) for young children [body weight (bw): 16 kg] when consuming two servings/week. These samples were purchased multiple times at specific intervals and were evaluated for Al levels. Al was detected in 27 of the 90 samples at levels ranging from 0.01 (limit of quantitation) to 1.06 mg/g. Of these, the Al intake levels in two samples (cookie and scone mix, 1.3 and 2 mg/kg bw/week, respectively) exceeded the TWI as established by European Food Safety Authority, although the level in the scone mix was equivalent to the provisional TWI (PTWI) as established by Joint Food and Agriculture Organization of the United Nations/World Health Organization Expert Committee on Food Additives. The Al levels markedly decreased in 14 of the 19 samples with initially high Al levels. These results indicated reductions in the Al levels to below the PTWI limits in all but two previously identified food samples.

Interstitial atoms enable joint twinning and transformation induced plasticity in strong and ductile high-entropy alloys

NASA Astrophysics Data System (ADS)

Li, Zhiming; Tasan, Cemal Cem; Springer, Hauke; Gault, Baptiste; Raabe, Dierk

2017-01-01

High-entropy alloys (HEAs) consisting of multiple principle elements provide an avenue for realizing exceptional mechanical, physical and chemical properties. We report a novel strategy for designing a new class of HEAs incorporating the additional interstitial element carbon. This results in joint activation of twinning- and transformation-induced plasticity (TWIP and TRIP) by tuning the matrix phase’s instability in a metastable TRIP-assisted dual-phase HEA. Besides TWIP and TRIP, such alloys benefit from massive substitutional and interstitial solid solution strengthening as well as from the composite effect associated with its dual-phase structure. Nanosize particle formation and grain size reduction are also utilized. The new interstitial TWIP-TRIP-HEA thus unifies all metallic strengthening mechanisms in one material, leading to twice the tensile strength compared to a single-phase HEA with similar composition, yet, at identical ductility.

Interstitial atoms enable joint twinning and transformation induced plasticity in strong and ductile high-entropy alloys.

PubMed

Li, Zhiming; Tasan, Cemal Cem; Springer, Hauke; Gault, Baptiste; Raabe, Dierk

2017-01-12

High-entropy alloys (HEAs) consisting of multiple principle elements provide an avenue for realizing exceptional mechanical, physical and chemical properties. We report a novel strategy for designing a new class of HEAs incorporating the additional interstitial element carbon. This results in joint activation of twinning- and transformation-induced plasticity (TWIP and TRIP) by tuning the matrix phase's instability in a metastable TRIP-assisted dual-phase HEA. Besides TWIP and TRIP, such alloys benefit from massive substitutional and interstitial solid solution strengthening as well as from the composite effect associated with its dual-phase structure. Nanosize particle formation and grain size reduction are also utilized. The new interstitial TWIP-TRIP-HEA thus unifies all metallic strengthening mechanisms in one material, leading to twice the tensile strength compared to a single-phase HEA with similar composition, yet, at identical ductility.

Comparative Investigation on Modal analysis of LM25 Aluminium alloy with other Aluminim alloys using Finite element analysis software

NASA Astrophysics Data System (ADS)

Arunkumar, S.; Baskaralal, V. P. M.; Muthuraman, V.

2017-03-01

The rudimentary steps of the modal analysis and simulation are carried out. The modal analysis is carried out on the different Aluminum Alloys cantilever beam. The cantilever beam is designed in the graphical environment of the ANSYS. The cantilever beam was fine-tuned on one end with all degree of liberation on this end were taken, beam cannot move and rotate. Mode shapes and natural frequencies are premeditated in platforms ANSYS with arithmetical formulation of the direct solver including the block Lanczos method. Aluminum alloys are widely utilized in much application due to their estimable weight to vigor property. Many examination works have been distributed out to make developments the mechanical properties of aluminum alloys. The composition of alloying elements plays a consequential role in deciding the properties of an alloy. In this study a numerical analysis implement i.e., finite element analysis (FEA) is utilized. The work obtainable in this paper is aimed at the study of effect of modal analysis of different aluminum alloys. The modeling and analysis is carried out utilizing ANSYS FEA software. A modal analysis is carried out to understand the modes of frequency demeanor of the material considered. The modal analysis play a vital role in the design of components subjected to high vibration.

Aluminium in foodstuffs and diets in Sweden.

PubMed

Jorhem, L; Haegglund, G

1992-01-01

The levels of aluminium have been determined in a number of individual foodstuffs on the Swedish market and in 24 h duplicate diets collected by women living in the Stockholm area. The results show that the levels in most foods are very low and that the level in vegetables can vary by a factor 10. Beverages from aluminium cans were found to have aluminium levels not markedly different from those in glass bottles. Based on the results of the analysis of individual foods, the average Swedish daily diet was calculated to contain about 0.6 mg aluminium, whereas the mean content of the collected duplicate diets was 13 mg. A cake made from a mix containing aluminium phosphate in the baking soda was identified as the most important contributor of aluminium to the duplicate diets. Tea and aluminium utensils were estimated to increase the aluminium content of the diets by approximately 4 and 2 mg/day, respectively. The results also indicate that a considerable amount of aluminium must be introduced from other sources.

The effect of postprocessing on tensile property and microstructure evolution of friction stir welding aluminum alloy joint

DOE Office of Scientific and Technical Information (OSTI.GOV)

Hu, Z.L., E-mail: zhilihuhit@163.com; State Key Laboratory of Advanced Welding and Joining, Harbin Institute of Technology, Harbin 150001; State Key Laboratory of Materials Processing and Die & Mould Technology, Huazhong University of Science and Technology

Friction stir welding is an efficient manufacturing method for joining aluminum alloy and can dramatically reduce grain size conferring excellent plastic deformation properties. Consequently, friction stir welding is used to manufacture tailor welded blanks to optimize weight or performance in the final component. In the study, the microstructural evolution and mechanical properties of friction stir welding joint during plastic forming and subsequent heat treatment were investigated. The microstructural characteristics of the friction stir welding joints were studied by Electron Backscattered Diffraction and Transmission Electron Microscopy. The mechanical properties were evaluated by tensile and microhardness tests. It is found that themore » tensile and yield strengths of friction stir welding joints are significantly improved after severe plastic deformation due to the grain refinement. Following heat treatment, the strength of the friction stir welding joints significantly decrease due to the obvious abnormal grain growth. Careful attention must be given to the processing route of any friction stir welding joint intended for plastic forming, especially the annealing between forming passes. Severe plastic deforming of the friction stir welding joint leads to a high level of stored energy/dislocation density, which causes the abnormal grain growth during subsequent heat treatment, and consequently reduce the mechanical properties of the friction stir welding joint. - Highlights: • Great changes are observed in the microstructure of FSW joint after postprocessing. • Postprocessing shows great effect on the microstructure stability of FSW joint. • The weld shows more significant decrease in strength than the BM due to the AGG. • Attention must be given to the processing route of FSW joint for plastic forming.« less

Emission of nanoparticles during friction stir welding (FSW) of aluminium alloys.

PubMed

Gomes, J F; Miranda, R M; Santos, T J; Carvalho, P A

2014-01-01

Friction stir welding (FSW) is now well established as a welding process capable of joining some different types of metallic materials, as it was (1) found to be a reliable and economical way of producing high quality welds, and (2) considered a "clean" welding process that does not involve fusion of metal, as is the case with other traditional welding processes. The aim of this study was to determine whether the emission of particles during FSW in the nanorange of the most commonly used aluminum (Al) alloys, AA 5083 and AA 6082, originated from the Al alloy itself due to friction of the welding tool against the item that was being welded. Another goal was to measure Al alloys in the alveolar deposited surface area during FSW. Nanoparticles dimensions were predominantly in the 40- and 70-nm range. This study demonstrated that microparticles were also emitted during FSW but due to tool wear. However, the biological relevance and toxic manifestations of these microparticles remain to be determined.

Computation material science of structural-phase transformation in casting aluminium alloys

NASA Astrophysics Data System (ADS)

Golod, V. M.; Dobosh, L. Yu

2017-04-01

Successive stages of computer simulation the formation of the casting microstructure under non-equilibrium conditions of crystallization of multicomponent aluminum alloys are presented. On the basis of computer thermodynamics and heat transfer during solidification of macroscale shaped castings are specified the boundary conditions of local heat exchange at mesoscale modeling of non-equilibrium formation the solid phase and of the component redistribution between phases during coalescence of secondary dendrite branches. Computer analysis of structural - phase transitions based on the principle of additive physico-chemical effect of the alloy components in the process of diffusional - capillary morphological evolution of the dendrite structure and the o of local dendrite heterogeneity which stochastic nature and extent are revealed under metallographic study and modeling by the Monte Carlo method. The integrated computational materials science tools at researches of alloys are focused and implemented on analysis the multiple-factor system of casting processes and prediction of casting microstructure.

Summary of Prior Work on Joining of Oxide Dispersion-Strengthened Alloys

DOE Office of Scientific and Technical Information (OSTI.GOV)

Wright, Ian G; Tatlock, Gordon J; Badairy, H.

2009-08-01

There is a range of joining techniques available for use with ODS alloys, but care should be exercised in matching the technique to the final duty requirements of the joint. The goal for joining ODS alloys is a joint with no local disruption of the distribution of the oxide dispersion, and no significant change in the size and orientation of the alloy microstructure. Not surprisingly, the fusion welding processes typically employed with wrought alloys produce the least satisfactory results with ODS alloys, but some versions, such as fusion spot welding, and the laser and electron-beam welding technologies, have demonstrated potentialmore » for producing sound joints. Welds made using solid-state spot welding reportedly have exhibited parent metal properties. Thus, it is possible to employ processes that result in significant disruption of the alloy microstructure, as long as the processing parameters are adjustment to minimize the extent of or influence of the changes in the alloy microstructure. Selection among these joining approaches largely depends on the particular application and component configuration, and an understanding of the relationships among processing, alloy microstructure, and final properties is key. Recent developments have resulted in friction welding evolving to be a prime method for joining ODS sheet products, and variants of brazing/diffusion bonding have shown excellent promise for use with tubes and pipes. The techniques that come closest to the goal defined above involve solid-state diffusion bonding and, in particular, it has been found that secondary recrystallization of joints made by pulsed plasma-assisted diffusion can produce the desired, continuous, large alloy grain structure through the joint. Such joints have exhibited creep rupture failure at >82% of the load needed to fail the monolithic parent alloy at 1000 C.« less

A numerical study on the influence of the Portevin Le Chatelier effect on necking in an aluminium alloy

NASA Astrophysics Data System (ADS)

Hopperstad, O. S.; Børvik, T.; Berstad, T.; Lademo, O.-G.; Benallal, A.

2007-10-01

The constitutive relation proposed by McCormick (1988 Acta Metall. 36 3061-7) for materials exhibiting negative steady-state strain-rate sensitivity and the Portevin-Le Chatelier (PLC) effect is incorporated into an elastic-viscoplastic model for metals with plastic anisotropy. The constitutive model is implemented in LS-DYNA for corotational shell elements. Plastic anisotropy is taken into account by use of the yield criterion Yld2000/Yld2003 proposed by Barlat et al (2003 J. Plast. 19 1297-319) and Aretz (2004 Modelling Simul. Mater. Sci. Eng. 12 491-509). The parameters of the constitutive equations are determined for a rolled aluminium alloy (AA5083-H116) exhibiting negative steady-state strain-rate sensitivity and serrated yielding. The parameter identification is based on existing experimental data. A numerical investigation is conducted to determine the influence of the PLC effect on the onset of necking in uniaxial and biaxial tension for different overall strain rates. The numerical simulations show that the PLC effect leads to significant reductions in the strain to necking for both uniaxial and biaxial stress states. Increased surface roughness with plastic deformation is predicted for strain rates giving serrated yielding in uniaxial tension. It is likely that this is an important reason for the reduced critical strains. The characteristics of the deformation bands (orientation, width, velocity and strain rate) are also studied.

High-rate aluminium yolk-shell nanoparticle anode for Li-ion battery with long cycle life and ultrahigh capacity

PubMed Central

Li, Sa; Niu, Junjie; Zhao, Yu Cheng; So, Kang Pyo; Wang, Chao; Wang, Chang An; Li, Ju

2015-01-01

Alloy-type anodes such as silicon and tin are gaining popularity in rechargeable Li-ion batteries, but their rate/cycling capabilities should be improved. Here by making yolk-shell nanocomposite of aluminium core (30 nm in diameter) and TiO2 shell (∼3 nm in thickness), with a tunable interspace, we achieve 10 C charge/discharge rate with reversible capacity exceeding 650 mAh g−1 after 500 cycles, with a 3 mg cm−2 loading. At 1 C, the capacity is approximately 1,200 mAh g−1 after 500 cycles. Our one-pot synthesis route is simple and industrially scalable. This result may reverse the lagging status of aluminium among high-theoretical-capacity anodes. PMID:26243004

Degradation of bioabsorbable Mg-based alloys: Assessment of the effects of insoluble corrosion products and joint effects of alloying components on mammalian cells.

PubMed

Grillo, Claudia A; Alvarez, Florencia; Fernández Lorenzo de Mele, Mónica A

2016-01-01

This work is focused on the processes occurring at the bioabsorbable metallic biomaterial/cell interfaces that may lead to toxicity. A critical analysis of the results obtained when degradable metal disks (pure Mg and rare earth-containing alloys (ZEK100 alloys)) are in direct contact with cell culture and those obtained with indirect methods such as the use of metal salts and extracts was made. Viability was assessed by Acridine Orange dye, neutral red and clonogenic assays. The effects of concentration of corrosion products and possible joint effects of the binary and ternary combinations of La, Zn and Mg ions, as constituents of ZEK alloys, were evaluated on a mammalian cell culture. In all cases more detrimental effects were found for pure Mg than for the alloys. Experiments with disks showed that gradual alterations in pH and in the amount of corrosion products were better tolerated by cells and resulted in higher viability than abrupt changes. In addition, viability was dependent on the distance from the source of ions. Experiments with extracts showed that the effect of insoluble degradation products was highly detrimental. Indirect tests with Zn ions revealed that harmful effects may be found at concentrations ≥ 150 μM and at ≥ 100 μM in mixtures with Mg. These mixtures lead to more deleterious effects than single ions. Results highlight the need to develop a battery of tests to evaluate the biocompatibility of bioabsorbable biomaterials. Copyright © 2015 Elsevier B.V. All rights reserved.

Effects of aging treatment and heat input on the microstructures and mechanical properties of TIG-welded 6061-T6 alloy joints

NASA Astrophysics Data System (ADS)

Peng, Dong; Shen, Jun; Tang, Qin; Wu, Cui-ping; Zhou, Yan-bing

2013-03-01

Aging treatment and various heat input conditions were adopted to investigate the microstructural evolution and mechanical properties of TIG welded 6061-T6 alloy joints by microstructural observations, microhardness tests, and tensile tests. With an increase in heat input, the width of the heat-affected zone (HAZ) increases and grains in the fusion zone (FZ) coarsen. Moreover, the hardness of the HAZ decreases, whereas that of the FZ decreases initially and then increases with an increase in heat input. Low heat input results in the low ultimate tensile strength of the welded joints due to the presence of partial penetrations and pores in the welded joints. After a simple artificial aging treatment at 175°C for 8 h, the microstructure of the welded joints changes slightly. The mechanical properties of the welded joints enhance significantly after the aging process as few precipitates distribute in the welded seam.

Bumblebee pupae contain high levels of aluminium.

PubMed

Exley, Christopher; Rotheray, Ellen; Goulson, David

2015-01-01

The causes of declines in bees and other pollinators remains an on-going debate. While recent attention has focussed upon pesticides, other environmental pollutants have largely been ignored. Aluminium is the most significant environmental contaminant of recent times and we speculated that it could be a factor in pollinator decline. Herein we have measured the content of aluminium in bumblebee pupae taken from naturally foraging colonies in the UK. Individual pupae were acid-digested in a microwave oven and their aluminium content determined using transversely heated graphite furnace atomic absorption spectrometry. Pupae were heavily contaminated with aluminium giving values between 13.4 and 193.4 μg/g dry wt. and a mean (SD) value of 51.0 (33.0) μg/g dry wt. for the 72 pupae tested. Mean aluminium content was shown to be a significant negative predictor of average pupal weight in colonies. While no other statistically significant relationships were found relating aluminium to bee or colony health, the actual content of aluminium in pupae are extremely high and demonstrate significant exposure to aluminium. Bees rely heavily on cognitive function and aluminium is a known neurotoxin with links, for example, to Alzheimer's disease in humans. The significant contamination of bumblebee pupae by aluminium raises the intriguing spectre of cognitive dysfunction playing a role in their population decline.

Bumblebee Pupae Contain High Levels of Aluminium

PubMed Central

Exley, Christopher; Rotheray, Ellen; Goulson, David

2015-01-01

The causes of declines in bees and other pollinators remains an on-going debate. While recent attention has focussed upon pesticides, other environmental pollutants have largely been ignored. Aluminium is the most significant environmental contaminant of recent times and we speculated that it could be a factor in pollinator decline. Herein we have measured the content of aluminium in bumblebee pupae taken from naturally foraging colonies in the UK. Individual pupae were acid-digested in a microwave oven and their aluminium content determined using transversely heated graphite furnace atomic absorption spectrometry. Pupae were heavily contaminated with aluminium giving values between 13.4 and 193.4 μg/g dry wt. and a mean (SD) value of 51.0 (33.0) μg/g dry wt. for the 72 pupae tested. Mean aluminium content was shown to be a significant negative predictor of average pupal weight in colonies. While no other statistically significant relationships were found relating aluminium to bee or colony health, the actual content of aluminium in pupae are extremely high and demonstrate significant exposure to aluminium. Bees rely heavily on cognitive function and aluminium is a known neurotoxin with links, for example, to Alzheimer’s disease in humans. The significant contamination of bumblebee pupae by aluminium raises the intriguing spectre of cognitive dysfunction playing a role in their population decline. PMID:26042788

Long-term effects of aluminium dust inhalation.

PubMed

Peters, Susan; Reid, Alison; Fritschi, Lin; de Klerk, Nicholas; Musk, A W Bill

2013-12-01

During the 1950s and 1960s, aluminium dust inhalation was used as a potential prophylaxis against silicosis in underground miners, including in Australia. We investigated the association between aluminium dust inhalation and cardiovascular, cerebrovascular and Alzheimer's diseases in a cohort of Australian male underground gold miners. We additionally looked at pneumoconiosis mortality to estimate the effect of the aluminium therapy. SMRs and 95% CI were calculated to compare mortality of the cohort members with that of the Western Australian male population (1961-2009). Internal comparisons on duration of aluminium dust inhalation were examined using Cox regression. Aluminium dust inhalation was reported for 647 out of 1894 underground gold miners. During 42 780 person-years of follow-up, 1577 deaths were observed. An indication of increased mortality of Alzheimer's disease among miners ever exposed to aluminium dust was found (SMR=1.38), although it was not statistically significant (95% CI 0.69 to 2.75). Rates for cardiovascular and cerebrovascular death were above population levels, but were similar for subjects with or without a history of aluminium dust inhalation. HRs suggested an increasing risk of cardiovascular disease with duration of aluminium dust inhalation (HR=1.02, 95% CI 1.00 to 1.04, per year of exposure). No difference in the association between duration of work underground and pneumoconiosis was observed between the groups with or without aluminium dust exposure. No protective effect against silicosis was observed from aluminium dust inhalation. Conversely, exposure to aluminium dust may possibly increase the risk of cardiovascular disease and dementia of the Alzheimer's type.

Experimental and Mathematical Modeling for Prediction of Tool Wear on the Machining of Aluminium 6061 Alloy by High Speed Steel Tools

NASA Astrophysics Data System (ADS)

Okokpujie, Imhade Princess; Ikumapayi, Omolayo M.; Okonkwo, Ugochukwu C.; Salawu, Enesi Y.; Afolalu, Sunday A.; Dirisu, Joseph O.; Nwoke, Obinna N.; Ajayi, Oluseyi O.

2017-12-01

In recent machining operation, tool life is one of the most demanding tasks in production process, especially in the automotive industry. The aim of this paper is to study tool wear on HSS in end milling of aluminium 6061 alloy. The experiments were carried out to investigate tool wear with the machined parameters and to developed mathematical model using response surface methodology. The various machining parameters selected for the experiment are spindle speed (N), feed rate (f), axial depth of cut (a) and radial depth of cut (r). The experiment was designed using central composite design (CCD) in which 31 samples were run on SIEG 3/10/0010 CNC end milling machine. After each experiment the cutting tool was measured using scanning electron microscope (SEM). The obtained optimum machining parameter combination are spindle speed of 2500 rpm, feed rate of 200 mm/min, axial depth of cut of 20 mm, and radial depth of cut 1.0mm was found out to achieved the minimum tool wear as 0.213 mm. The mathematical model developed predicted the tool wear with 99.7% which is within the acceptable accuracy range for tool wear prediction.

Determination of aluminium in groundwater samples by GF-AAS, ICP-AES, ICP-MS and modelling of inorganic aluminium complexes.

PubMed

Frankowski, Marcin; Zioła-Frankowska, Anetta; Kurzyca, Iwona; Novotný, Karel; Vaculovič, Tomas; Kanický, Viktor; Siepak, Marcin; Siepak, Jerzy

2011-11-01

The paper presents the results of aluminium determinations in ground water samples of the Miocene aquifer from the area of the city of Poznań (Poland). The determined aluminium content amounted from <0.0001 to 752.7 μg L(-1). The aluminium determinations were performed using three analytical techniques: graphite furnace atomic absorption spectrometry (GF-AAS), inductively coupled plasma atomic emission spectrometry (ICP-AES) and inductively coupled plasma mass spectrometry (ICP-MS). The results of aluminium determinations in groundwater samples for particular analytical techniques were compared. The results were used to identify the ascent of ground water from the Mesozoic aquifer to the Miocene aquifer in the area of the fault graben. Using the Mineql+ program, the modelling of the occurrence of aluminium and the following aluminium complexes: hydroxy, with fluorides and sulphates was performed. The paper presents the results of aluminium determinations in ground water using different analytical techniques as well as the chemical modelling in the Mineql+ program, which was performed for the first time and which enabled the identification of aluminium complexes in the investigated samples. The study confirms the occurrence of aluminium hydroxy complexes and aluminium fluoride complexes in the analysed groundwater samples. Despite the dominance of sulphates and organic matter in the sample, major participation of the complexes with these ligands was not stated based on the modelling.

Microstructural, mechanical and electrochemical behaviour of a 7017 Al–Zn–Mg alloy of different tempers

DOE Office of Scientific and Technical Information (OSTI.GOV)

Rout, Prasanta Kumar, E-mail: prasantonnet55@yahoo.com; Ghosh, M.M.; Ghosh, K.S., E-mail: ksghosh2001@yahoo.co.uk

2015-06-15

The aim of the investigation is to assess the microstructural features and associated physical, mechanical and electrochemical properties of a 7017 Al–Zn–Mg alloy of various tempers. A 7017 Al–Zn–Mg alloy was subjected to different ageing schedules to produce under-(T4), peak-(T6), over-(T7) and highly over-aged tempers. Optical microscopy, hardness measurement, electrical conductivity measurement, tensile testing and SEM fractographs, differential scanning calorimetry (DSC), transmission electron microscopy (TEM), and electrochemical polarization studies have been used to characterize the alloy tempers. Hardness measurement and tensile testing showed the characteristic age hardening phenomenon of aluminium alloys. Optical and TEM micrographs have revealed the variation inmore » size of matrix strengthening η′ (MgZn{sub 2}) and also the size and distribution of grain boundary η (MgZn{sub 2}) precipitate with ageing time. DSC thermograms exhibiting exothermic and endothermic peaks indicated the characteristic solid state reaction sequence of the 7017 alloy. Potentiodynamic polarization study of the 7017 alloy of various tempers in 3.5 wt.% NaCl solution at near neutral pH showed typical active metal dissolution behaviour, but at pH 12 an active–passive–transpassive transition behaviour has been observed. - Graphical abstract: TEM micrograph of the 7017 aluminium alloy of various tempers (a, b) under aged (T4), (c, d) peak aged (T6), (e, f) over aged (T7) and (g, h) highly over-aged. Display Omitted - Highlights: • 7017 Al-Zn-Mg alloy was subjected to different artificial ageing treatments. • Characterization of 7017 alloy tempers by hardness, tensile, DSC, TEM and electrochemical behaviour. • Structure-properties relationship of the 7017 Al-Zn-Mg alloy of various tempers.« less

Electroplating of aluminium microparticles with nickel to synthesise reactive core-shell structures for thermal joining applications

NASA Astrophysics Data System (ADS)

Schreiber, S.; Zaeh, M. F.

2018-06-01

Reactive particles represent a promising alternative for effectively joining components with freeform surfaces and different material properties. While the primary application of reactive systems is combustion synthesis for the production of high-performance alloys, the highly exothermic reaction can also be used to firmly bond thermosensitive joining partners. Core-shell structures are of special interest, since they function as separate microreactors. In this paper, a method to synthesise reactive nickel-aluminium core-shell structures via a two-step plating process is described. Based on an electroless process, the natural oxide layer of the aluminium particles is removed and substituted with a thin layer of nickel. Subsequently, the pre-treated particles are electroplated with nickel. The high reactivity of aluminium and the oxide layer play a significant role in adjusting the process parameters of the Watts bath. Additionally, the developed experimental set-up is introduced and the importance of process control is shown. In order to achieve reproducible results, the electroplating process was automated. Ignition tests with electromagnetic waves demonstrated that the particles undergo an exothermic reaction. Therefore, they can be used as a heat source in thermal joining applications.

Monitoring of Surface Roughness in Aluminium Turning Process

NASA Astrophysics Data System (ADS)

Chaijareenont, Atitaya; Tangjitsitcharoen, Somkiat

2018-01-01

As the turning process is one of the most necessary process. The surface roughness has been considered for the quality of workpiece. There are many factors which affect the surface roughness. Hence, the objective of this research is to monitor the relation between the surface roughness and the cutting forces in aluminium turning process with a wide range of cutting conditions. The coated carbide tool and aluminium alloy (Al 6063) are used for this experiment. The cutting parameters are investigated to analyze the effects of them on the surface roughness which are the cutting speed, the feed rate, the tool nose radius and the depth of cut. In the case of this research, the dynamometer is installed in the turret of CNC turning machine to generate a signal while turning. The relation between dynamic cutting forces and the surface roughness profile is examined by applying the Fast Fourier Transform (FFT). The experimentally obtained results showed that the cutting force depends on the cutting condition. The surface roughness can be improved when increasing the cutting speed and the tool nose radius in contrast to the feed rate and the depth of cut. The relation between the cutting parameters and the surface roughness can be explained by the in-process cutting forces. It is understood that the in-process cutting forces are able to predict the surface roughness in the further research.

Thin-film diffusion brazing of titanium alloys

NASA Technical Reports Server (NTRS)

Mikus, E. B.

1972-01-01

A thin film diffusion brazing technique for joining titanium alloys by use of a Cu intermediate is described. The method has been characterized in terms of static and dynamic mechanical properties on Ti-6Al-4V alloy. These include tensile, fracture toughness, stress corrosion, shear, corrosion fatigue, mechanical fatigue and acoustic fatigue. Most of the properties of titanium joints formed by thin film diffusion brazing are equal or exceed base metal properties. The advantages of thin film diffusion brazing over solid state diffusion bonding and brazing with conventional braze alloys are discussed. The producibility advantages of this process over others provide the potential for producing high efficiency joints in structural components of titanium alloys for the minimum cost.

Experimental Research on Fatigue Failure for 2219-T6 Aluminum Alloy Friction Stir-Welded Joints

NASA Astrophysics Data System (ADS)

Sun, Guo-Qin; Niu, Jiang-Pei; Chen, Ya-Jing; Sun, Feng-Yang; Shang, De-Guang; Chen, Shu-Jun

2017-08-01

The fatigue experiment was executed for the 2219-T6 aluminum alloy friction stir-welded joints at the rotation speed of 800 r/min and the welding velocity of 150 mm/min. Most fatigue failures occurred in the weld nugget zone (WNZ), the thermo-mechanical affected zone and the nearby areas. The experimental results demonstrated that the sudden hardness gradient increases sites corresponding to the fatigue failure locations. The high-angle grain boundaries with the highest concentration were scattered within the WNZ. The microcracks initiated at the intersection of the soft grains. More than one crack initiation site was observed within the WNZ and the thermo-mechanical affected zone, when the fracture occurred in these areas. The rough surface of the welding area should be one of the main reasons for the fatigue failure occurrence. The fatigue crack growth rate in the WNZ at the first stage was fastest in comparison with the fatigue crack growth rate in the other areas of the joint.

Electromigration in solder joints and solder lines

NASA Astrophysics Data System (ADS)

Gan, H.; Choi, W. J.; Xu, G.; Tu, K. N.

2002-06-01

Electromigration may affect the reliability of flip-chip solder joints. Eutectic solder is a two-phase alloy, so its electromigration behavior is different from that in aluminum or copper interconnects. In addition, a flipchip solder joint has a built-in currentcrowding configuration to enhance electromigration failure. To better understand electromigration in SnPb and lead-free solder alloys, the authors prepared solder lines in v-grooves etched on Si (001). This article discusses the results of those tests and compares the electromigration failure modes of eutectic SnPb and SnAgCu flip-chip solder joints along with the mean-timeto-failure.

The effect of aluminium on the creep behavior of titanium aluminide alloys

DOE Office of Scientific and Technical Information (OSTI.GOV)

Nandy, T.K.; Mishra, R.S.; Gogia, A.K.

Small increases in the Al content of Ti{sub 3}Al-Nb alloys are known to improve creep resistance at the expense of the room temperature ductility. Though considerable work has been done on the creep behavior of titanium aluminide alloys, a systematic investigation involving the role of Al on the creep of aluminides is lacking. In the present study the authors have therefore carried out a complete investigation on stress and temperature effects on two alloys with differing Al contents, Ti-24Al-15Nb and Ti-26Al-15Nb (nominal composition in at%) in order to understand the effect of Al in terms of power law creep behavior.more » The following conclusions are made: (1) A strong Al effect on the creep resistance of O phase alloys in the Ti-Al-Nb systems has been confirmed, through a study of stress and temperature effects on the creep behavior of the Ti-24Al-15Nb and the Ti-26Al-15Nb compositions. (2) It has been shown, however, that the small differences in Al do not affect either the activation energies for creep ({approximately}370 kJ/mole) or the creep mechanism (climb controlled creep with a stress exponent of 4). The activation energies and stress exponents are similar to that observed in single phase O alloys. (3) It is suggested that Al influences creep strength through an intrinsic effect on the pre-exponential term AD{sub o} in the power law creep equation. It is possible that this effect is related to a higher ordering energy of the O phase with increasing Al content.« less

An electrochemical investigation of TMJ implant metal alloys in an artificial joint fluid environment: the influence of pH variation.

PubMed

Royhman, Dmitry; Radhakrishnan, Rashmi; Yuan, Judy Chia-Chun; Mathew, Mathew T; Mercuri, Louis G; Sukotjo, Cortino

2014-10-01

To investigate the corrosion behaviour of commonly used TMJ implants alloys (CoCrMo and Ti6Al4V) under simulated physiological conditions. Corrosion behaviour was evaluated using standard electrochemical corrosion techniques and galvanic corrosion techniques as per ASTM standards. Standard electrochemical tests (E(corr), I(corr), R(p) and C(f)) were conducted in bovine calf serum (BCS), as a function of alloys type and different pHs. Galvanic corrosion tests were conducted in BCS at a pH of 7.6. Alloy surfaces were characterized using white-light interferometry (WLI) and scanning electron microscopy (SEM). The potentiodynamic test results exhibited the enhanced passive layer growth and a better corrosion resistance of Ti6Al4V compared to CoCrMo. Electrochemical impedance spectroscopy measurements demonstrated the influence of protein as a function of pH on corrosion mechanisms/kinetics. Galvanic coupling was not a major contributor to corrosion. SEM and WLI images demonstrated a significantly higher in surface roughness in CoCrMo after corrosion. The results of this study suggest that Ti6Al4V shows superior corrosion behaviour to CoCrMo due to its strong passive layer, simulated joint fluid components can affect the electrochemical nature of the metal/electrolyte interface as a function of pH, and the galvanic effect of coupling CoCrMo and Ti6Al4V in a single joint is weak. Published by Elsevier Ltd.

Fires in storages of LFO: Analysis of hazard of structural collapse of steel-aluminium containers.

PubMed

Rebec, A; Kolšek, J; Plešec, P

2016-04-05

Pool fires of light fuel oil (LFO) in above-ground storages with steel-aluminium containers are discussed. A model is developed for assessments of risks of between-tank fire spread. Radiative effects of the flame body are accounted for by a solid flame radiation model. Thermal profiles evolved due to fire in the adjacent tanks and their consequential structural response is pursued in an exact (materially and geometrically non-linear) manner. The model's derivation is demonstrated on the LFO tank storage located near the Port of Koper (Slovenia). In support of the model, data from literature are adopted where appropriate. Analytical expressions are derived correspondingly for calculations of emissive characteristics of LFO pool fires. Additional data are collected from experiments. Fire experiments conducted on 300cm diameter LFO pans and at different wind speeds and high-temperature uniaxial tension tests of the analysed aluminium alloys types 3xxx and 6xxx are presented. The model is of an immediate fire engineering practical value (risk analyses) or can be used for further research purposes (e.g. sensitivity and parametric studies). The latter use is demonstrated in the final part of the paper discussing possible effects of high-temperature creep of 3xxx aluminium. Copyright © 2015 Elsevier B.V. All rights reserved.

Failure Behaviour of Aluminium/CFRP Laminates with Varying Fibre Orientation in Quasi-static Indentation Test

NASA Astrophysics Data System (ADS)

Romli, N. K.; Rejab, M. R. M.; Bachtiar, D.; Siregar, J.; Rani, M. F.; Salleh, Salwani Mohd; Merzuki, M. N. M.

2018-03-01

The response of the aluminium/carbon laminate was examined by an experimental work. The investigation on fibre metal laminate behaviour was done through an indentation test in a quasi-static loading. The hybrid laminate was fabricated by a compression moulding technique and used two types of carbon fibre orientations; plain weave and unidirectional. The plain weave orientation is dry fibre, and unidirectional orientation is prepreg type fibre. The plain weave carbon fibre and aluminium alloy 2024-0 was laminated by using thermoset epoxy while the unidirectional carbon fibre was pressed by using a hot press machine and cured under a specific temperature and pressure. A compression moulding technique was used for the FML fabrication. The aluminium sheet metal has been roughening by a metal sanding method which to improve the bonding between the fibre and metal layer. The main objective of this paper is to determine the failure response of the laminate under five variation of the crosshead speeds in the quasi-static loading. Based on the experimental data of the test, the result of 1 mm/min in the plain weave CFRP has lower loading than unidirectional fibre which the value of both was 4.11 kN and 4.69 kN, respectively.

Rate dependent strengths of some solder joints

NASA Astrophysics Data System (ADS)

Williamson, D. M.; Field, J. E.; Palmer, S. J. P.; Siviour, C. R.

2007-08-01

The shear strengths of three lead-free solder joints have been measured over the range of loading rates 10-3 to ~105 mm min-1. Binary (SnAg), ternary (SnAgCu) and quaternary (Castin: SnAgCuSb) alloys have been compared to a conventional binary SnPb solder alloy. Results show that at loading rates from 10-3 to 102 mm min-1, all four materials exhibit a linear relationship between the shear strength and the loading rate when the data are plotted on a log-log plot. At the highest loading rate of 105 mm min-1, the strengths of the binary alloys were in agreement with extrapolations made from the lower loading rate data. In contrast, the strengths of the higher order alloys were found to be significantly lower than those predicted by extrapolation. This is explained by a change in failure mechanism on the part of the higher order alloys. Similar behaviour was found in measurements of the tensile strengths of solder joints using a novel high-rate loading tensile test. Optical and electron microscopy were used to examine the microstructures of interest in conjunction with energy dispersive x-ray analysis for elemental identification. The effect of artificial aging and reflow of the solder joints is also reported.

Investigation into the Origin of Magnetic Properties of Amorphous Metallic Alloys.

DTIC Science & Technology

1981-10-01

Luborsky, F.E., J.L. Walter, and D. LeGrand. "Cold Rolling and Annealing of Amor- phous Ribbons," IEEE Trans. Magn. Mag-12, 1976, p. 930. Reprint 8011 ...curve. Iiii) For Fe-B-Al they lie significantly below. The differences between the T, for the three different aluminium containing alloys is not

Nano Precipitation and Hardening of Die-Quenched 6061 Aluminum Alloy.

PubMed

Utsunomiya, Hiroshi; Tada, Koki; Matsumoto, Ryo; Watanabe, Katsumi; Matsuda, Kenji

2018-03-01

Die quenching is applied to an age-hardenable aluminium alloys to obtain super-saturated solid solution. The application is advantageous because it can reduce number of manufacturing processes, and may increase strength by strain aging. If die quenching is realized in forging as well as sheet forming, it may widen industrial applicability further. In this study, Al-Mg-Si alloy AA6061 8 mm-thick billets were reduced 50% in height without cracks by die-quench forging. Supersaturated solid solution was successfully obtained. The die-quenched specimen shows higher hardness with nano precipitates at shorter aging time than the conventional water-quenched specimen.

Influence of Laser Power on the Microstructure and Mechanical Properties of a Laser Welded-Brazed Mg Alloy/Ni-Coated Steel Dissimilar Joint

NASA Astrophysics Data System (ADS)

Tan, Caiwang; Xiao, Liyuan; Liu, Fuyun; Chen, Bo; Song, Xiaoguo; Li, Liqun; Feng, Jicai

2017-05-01

In this work, we describe a method to improve the bonding of an immiscible Mg/steel system using Ni as an interlayer by coating it on the steel surface. Laser welding-brazing of AZ31B Mg alloy to Ni-coated Q235 steel using Mg-based filler was performed in a lap configuration. The influence of laser power on the weld characteristics, including joint appearance, formation of interfacial reaction layers and mechanical properties was investigated. The results indicated that the presence of the Ni-coating promoted the wetting of the liquid filler metal on the steel surface. A thermal gradient along the interface led to the formation of heterogeneous interfacial reaction layers. When using a low laser power of 1600 W, the reaction products were an FeAl phase in the direct laser irradiation zone, an AlNi phase close to the intermediate zone and mixtures of AlNi phase and an (α-Mg + Mg2Ni) eutectic structure near the interface at the seam head zone. For high powers of more than 2000 W, the FeAl phase grew thicker in the direct laser irradiation zone and a new Fe(Ni) transition layer formed at the interface of the intermediate zone and the seam head zone. However, the AlNi phase and (α-Mg + Mg2Ni) eutectic structure were scattered at the Mg seam. All the joints fractured at the fusion zone, indicating that the improved interface was not the weakest joint region. The maximum tensile-shear strength of the Mg/Ni-coated steel joint reached 190 N/mm, and the joint efficiency was 70% with respect to the Mg alloy base metal.

Laser welding of a cobalt-chromium removable partial denture alloy.

PubMed

NaBadalung, D P; Nicholls, J I

1998-03-01

The electric alloy brazed joints of removable partial denture alloys have failed frequently after routine usage. A technique providing higher joint strengths was investigated. This investigation compared the tensile strengths of electric-brazed and laser-welded joints for a cobalt-chromium removable partial denture alloy. Twenty-four cobalt-chromium standard tensile testing rods were prepared and divided into three groups of eight. All specimens in the control group (group 1) were left in the as-cast condition. Groups 2 and 3 were the test specimens, which were sectioned at the center of the rod. Eight specimens were joined by using electric brazing, and the remaining specimens were joined by using laser welding. After joining, each joint was ground to a uniform diameter, then tested to tensile failure on an Instron universal testing machine. Failure loads were recorded and fracture stress calculated. Statistical analysis was applied. The student-Newman-Keuls test showed a highly significant difference between the joint strengths of the as-cast control specimens, the electric-brazed and laser-welded joints. The tensile strengths of the as-cast joints were higher than those for the laser-welded joints, and both were higher than the electric-brazed joint strengths.

The effect of aluminium on mechanical properties and deformation mechanisms of hadfield steel single crystals

NASA Astrophysics Data System (ADS)

Zakharova, E. G.; Kireeva, I. V.; Chumlyakov, Y. I.; Shul'Mina, A. A.; Sehitoglu, H.; Karaman, I.

2004-06-01

On single crystals of Hadfield steel (Fe-13Mn-1.3C, Fe-13Mn-2.7Al-1.3C, wt.%) the systematical investigations of deformation mechanisms - slip and twinning, stages of plastic flow, strain hardening coefficient depending on orientation of tensile axis have been carried out by methods of optical and electron microscopy, x-ray analysis. Is has been shown that the combination of low stacking fault energy (γ{SF}=0.03J/m^2) with high concentration of carbon atoms in aluminium-free steel results in development of the mechanical twinning at room temperature in all crystal orientations. The new type of twinning with formation of extrinsic stacking fault has been found out in [001] single crystals. Experimentally it has been established that alloying with aluminium leads to increase of stacking fault energy of Hadfield steel and suppresses twinning in all orientations of crystals at preservation of high values of strain-hardening coefficients θ.

46 CFR 56.30-30 - Brazed joints.

Code of Federal Regulations, 2010 CFR

2010-10-01

....75). Brazed socket-type joints shall be made with suitable brazing alloys. The minimum socket depth shall be sufficient for the intended service. Brazing alloy shall either be end-fed into the socket or shall be provided in the form of a preinserted ring in a groove in the socket. The brazing alloy shall...

46 CFR 56.30-30 - Brazed joints.

Code of Federal Regulations, 2013 CFR

2013-10-01

....75). Brazed socket-type joints shall be made with suitable brazing alloys. The minimum socket depth shall be sufficient for the intended service. Brazing alloy shall either be end-fed into the socket or shall be provided in the form of a preinserted ring in a groove in the socket. The brazing alloy shall...

46 CFR 56.30-30 - Brazed joints.

Code of Federal Regulations, 2011 CFR

2011-10-01

....75). Brazed socket-type joints shall be made with suitable brazing alloys. The minimum socket depth shall be sufficient for the intended service. Brazing alloy shall either be end-fed into the socket or shall be provided in the form of a preinserted ring in a groove in the socket. The brazing alloy shall...

46 CFR 56.30-30 - Brazed joints.

Code of Federal Regulations, 2014 CFR

2014-10-01

....75). Brazed socket-type joints shall be made with suitable brazing alloys. The minimum socket depth shall be sufficient for the intended service. Brazing alloy shall either be end-fed into the socket or shall be provided in the form of a preinserted ring in a groove in the socket. The brazing alloy shall...

46 CFR 56.30-30 - Brazed joints.

Code of Federal Regulations, 2012 CFR

2012-10-01

....75). Brazed socket-type joints shall be made with suitable brazing alloys. The minimum socket depth shall be sufficient for the intended service. Brazing alloy shall either be end-fed into the socket or shall be provided in the form of a preinserted ring in a groove in the socket. The brazing alloy shall...

Aluminium in brain tissue in familial Alzheimer's disease.

PubMed

Mirza, Ambreen; King, Andrew; Troakes, Claire; Exley, Christopher

2017-03-01

The genetic predispositions which describe a diagnosis of familial Alzheimer's disease can be considered as cornerstones of the amyloid cascade hypothesis. Essentially they place the expression and metabolism of the amyloid precursor protein as the main tenet of disease aetiology. However, we do not know the cause of Alzheimer's disease and environmental factors may yet be shown to contribute towards its onset and progression. One such environmental factor is human exposure to aluminium and aluminium has been shown to be present in brain tissue in sporadic Alzheimer's disease. We have made the first ever measurements of aluminium in brain tissue from 12 donors diagnosed with familial Alzheimer's disease. The concentrations of aluminium were extremely high, for example, there were values in excess of 10μg/g tissue dry wt. in 5 of the 12 individuals. Overall, the concentrations were higher than all previous measurements of brain aluminium except cases of known aluminium-induced encephalopathy. We have supported our quantitative analyses using a novel method of aluminium-selective fluorescence microscopy to visualise aluminium in all lobes of every brain investigated. The unique quantitative data and the stunning images of aluminium in familial Alzheimer's disease brain tissue raise the spectre of aluminium's role in this devastating disease. Copyright © 2016 The Authors. Published by Elsevier GmbH.. All rights reserved.

A simple pre-treatment of aluminium cookware to minimize aluminium transfer to food.

PubMed

Karbouj, Rim; Desloges, I; Nortier, P

2009-03-01

In this work, we studied aluminium leaching from cookware to food under the effect of citric acid that is commonly found in foods and beverages. The authors showed that boiling the cookware in water prior to cooking is suitable for the decrease of aluminium leaching into food by a factor up to sixty (with a corresponding decrease of the aluminium intake by consumers). The effect of the pre-treatment has been studied by scanning electron microscopy and X-Ray diffraction and the effect has been attributed to changes in the structure and morphology of the passivation layer, from an initial heterogeneous layer to a surface uniformly covered with fine needles of Boehmite (alpha-AlOOH).

Design, Static Analysis And Fabrication Of Composite Joints

NASA Astrophysics Data System (ADS)

Mathiselvan, G.; Gobinath, R.; Yuvaraja, S.; Raja, T.

2017-05-01

The Bonded joints will be having one of the important issues in the composite technology is the repairing of aging in aircraft applications. In these applications and also for joining various composite material parts together, the composite materials fastened together either using adhesives or mechanical fasteners. In this paper, we have carried out design, static analysis of 3-D models and fabrication of the composite joints (bonded, riveted and hybrid). The 3-D model of the composite structure will be fabricated by using the materials such as epoxy resin, glass fibre material and aluminium rivet for preparing the joints. The static analysis was carried out with different joint by using ANSYS software. After fabrication, parametric study was also conducted to compare the performance of the hybrid joint with varying adherent width, adhesive thickness and overlap length. Different joint and its materials tensile test result have compared.

Lactobacillus plantarum CCFM639 alleviates aluminium toxicity.

PubMed

Yu, Leilei; Zhai, Qixiao; Liu, Xiaoming; Wang, Gang; Zhang, Qiuxiang; Zhao, Jianxin; Narbad, Arjan; Zhang, Hao; Tian, Fengwei; Chen, Wei

2016-02-01

Aluminium (Al) is the most abundant metal in the earth's crust. Al exposure can cause a variety of adverse physiological effects in humans and animals. Our aim was to demonstrate that specific probiotic bacteria can play a special physiologically functional role in protection against Al toxicity in mice. Thirty strains of lactic acid bacteria (LAB) were tested for their aluminium-binding ability, aluminium tolerance, their antioxidative capacity, and their ability to survive the exposure to artificial gastrointestinal (GI) juices. Lactobacillus plantarum CCFM639 was selected for animal experiments because of its excellent performance in vitro. Forty mice were divided into four groups: control, Al only, Al plus CCFM639, and Al plus deferiprone (DFP). CCFM639 was administered at 10(9) CFU once daily for 10 days, followed by a single oral dose of aluminium chloride hexahydrate at 5.14 mg aluminium (LD50) for each mouse. The results showed that CCFM639 treatment led to a significant reduction in the mortality rates with corresponding decrease in intestinal aluminium absorption and in accumulation of aluminium in the tissues and amelioration of hepatic histopathological damage. This probiotic treatment also resulted in alleviation of hepatic, renal, and cerebral oxidative stress. The treatment of L. plantarum CCFM639 has potential as a therapeutic dietary strategy against acute aluminium toxicity.

Mechanical Characteristics of Welded Joints of Aluminum Alloy 6061 T6 Formed by Arc and Friction Stir Welding

NASA Astrophysics Data System (ADS)

Astarita, A.; Squillace, A.; Nele, L.

2016-01-01

Butt welds formed by arc welding in inert gas with nonconsumable electrode (tungsten inert gas (TIG) welding) and by friction stir welding (FSW) from aluminum alloy AA6061 T6 are studied. Comparative analysis of the structures and mechanical properties of the welded joints is performed using the results of optical and electron microscopy, tensile tests, tests for residual bending ductility, and measurements of microhardness. The changes in the microstructure in different zones and the degrees of degradation of the mechanical properties after the welding are determined. It is shown that the size of the tool for the friction stir welding affects the properties of the welds. Quantitative results showing the relation between the microscopic behavior of the alloy and the welding-induced changes in the microstructure are obtained. Friction stir welding is shown to provide higher properties of the welds.

A Novel Process for Joining Ti Alloy and Al Alloy using Two-Stage Sintering Powder Metallurgy

NASA Astrophysics Data System (ADS)

Long, Luping; Liu, Wensheng; Ma, Yunzhu; Wu, Lei; Liu, Chao

2018-04-01

The major challenges for conventional diffusion bonding of joining Ti alloy and Al alloy are the undesirable interfacial reaction, low matrixes and joint strength. To avoid the problem in diffusion bonding, a novel two-stage sintering powder metallurgy process is developed. In the present work, the interface characterization and joint performance of the bonds obtained by powder metallurgy bonding are investigated and are compared with the diffusion bonded Ti/Al joints obtained with the same and the optimized process parameters. The results show that no intermetallic compound is visible in the Ti/Al joint obtained by powder metallurgy bonding, while a new layer formed at the joint diffusion bonded with the same parameters. The maximum tensile strength of joint obtained by diffusion bonding is 58 MPa, while a higher tensile strength reaching 111 MPa for a bond made by powder metallurgy bonding. Brittle fractures occur at all the bonds. It is shown that the powder metallurgy bonding of Ti/Al is better than diffusion bonding. The results of this study should benefit the bonding quality.

Characterization of an Additive Manufactured TiAl Alloy-Steel Joint Produced by Electron Beam Welding.

PubMed

Basile, Gloria; Baudana, Giorgio; Marchese, Giulio; Lorusso, Massimo; Lombardi, Mariangela; Ugues, Daniele; Fino, Paolo; Biamino, Sara

2018-01-17

In this work, the characterization of the assembly of a steel shaft into a γ-TiAl part for turbocharger application, obtained using Electron Beam Welding (EBW) technology with a Ni-based filler, was carried out. The Ti-48Al-2Nb-0.7Cr-0.3Si (at %) alloy part was produced by Electron Beam Melting (EBM). This additive manufacturing technology allows the production of a lightweight part with complex shapes. The replacement of Nickel-based superalloys with TiAl alloys in turbocharger automotive applications will lead to an improvement of the engine performance and a substantial reduction in fuel consumption and emission. The welding process allows a promising joint to be obtained, not affecting the TiAl microstructure. Nevertheless, it causes the formation of diffusive layers between the Ni-based filler and both steel and TiAl, with the latter side being characterized by a very complex microstructure, which was fully characterized in this paper by means of Scanning Electron Microscopy, Energy Dispersive X-ray Spectroscopy, and nanoindentation. The diffusive interface has a thickness of about 6 µm, and it is composed of several layers. Specifically, from the TiAl alloy side, we find a layer of Ti₃Al followed by Al₃NiTi₂ and AlNi₂Ti. Subsequently Ni becomes more predominant, with a first layer characterized by abundant carbide/boride precipitation, and a second layer characterized by Si-enrichment. Then, the chemical composition of the Ni-based filler is gradually reached.

Prevalence of beryllium sensitization among aluminium smelter workers

PubMed Central

Slade, M. D.; Cantley, L. F.; Kirsche, S. R.; Wesdock, J. C.; Cullen, M. R.

2010-01-01

Background Beryllium exposure occurs in aluminium smelters from natural contamination of bauxite, the principal source of aluminium. Aims To characterize beryllium exposure in aluminium smelters and determine the prevalence rate of beryllium sensitization (BeS) among aluminium smelter workers. Methods A population of 3185 workers from nine aluminium smelters owned by four different aluminium-producing companies were determined to have significant beryllium exposure. Of these, 1932 workers participated in medical surveillance programmes that included the serum beryllium lymphocyte proliferation test (BeLPT), confirmation of sensitization by at least two abnormal BeLPT test results and further evaluation for chronic beryllium disease in workers with BeS. Results Personal beryllium samples obtained from the nine aluminium smelters showed a range of <0.01–13.00 μg/m3 time-weighted average with an arithmetic mean of 0.25 μg/m3 and geometric mean of 0.06 μg/m3. Nine workers were diagnosed with BeS (prevalence rate of 0.47%, 95% confidence interval = 0.21–0.88%). Conclusions BeS can occur in aluminium smelter workers through natural beryllium contamination of the bauxite and further concentration during the refining and smelting processes. Exposure levels to beryllium observed in aluminium smelters are similar to those seen in other industries that utilize beryllium. However, compared with beryllium-exposed workers in other industries, the rate of BeS among aluminium smelter workers appears lower. This lower observed rate may be related to a more soluble form of beryllium found in the aluminium smelting work environment as well as the consistent use of respiratory protection. PMID:20610489

Co-extrusion of semi-finished aluminium-steel compounds

NASA Astrophysics Data System (ADS)

Thürer, S. E.; Uhe, J.; Golovko, O.; Bonk, C.; Bouguecha, A.; Klose, C.; Behrens, B.-A.; Maier, H. J.

2017-10-01

The combination of light metals and steels allows for new lightweight components with wear-resistant functional surfaces. Within the Collaborative Research Centre 1153 novel process chains are developed for the manufacture of such hybrid components. Here, the production process of a hybrid bearing bushing made of the aluminium alloy EN AW-6082 and the case-hardened steel 20MnCr5 is developed. Hybrid semi-finished products are an attractive alternative to conventional ones resulting from massive forming processes where the individual components are joined after the forming process. The actual hybrid semi-finished products were manufactured using a lateral angular co-extrusion (LACE) process. The bearing bushings are subsequently produced by die forging. In the present study, a tool concept for the LACE process is described, which renders the continuous joining of a steel rod with an aluminium tube possible. During the LACE process, the rod is fed into the extrusion die at an angle of approx. 90°. Metallographic analysis of the hybrid profile showed that the mechanical bonding between the different materials begins about 75 mm after the edge of the aluminium sheath. In order to improve the bonding strength, the steel rod is to be preheated during extrusion. Systematic investigations using a dilatometer, considering the maximum possible co-extrusion process parameters, were carried out. The variable parameters for the dilatometer experiments were determined by numerical simulation. In order to form a bond between the materials, the oxide layer needs to be disrupted during the co-extrusion process. In an attempt to better understand this effect, a modified sample geometry with chamfered steel was developed for the dilatometer experiments. The influence of the process parameters on the formation of the intermetallic phase at the interface was analysed by scanning electron microscopy and X-ray diffraction. This article, which was originally published online on 16

Aluminium in Biological Environments: A Computational Approach

PubMed Central

Mujika, Jon I; Rezabal, Elixabete; Mercero, Jose M; Ruipérez, Fernando; Costa, Dominique; Ugalde, Jesus M; Lopez, Xabier

2014-01-01

The increased availability of aluminium in biological environments, due to human intervention in the last century, raises concerns on the effects that this so far “excluded from biology” metal might have on living organisms. Consequently, the bioinorganic chemistry of aluminium has emerged as a very active field of research. This review will focus on our contributions to this field, based on computational studies that can yield an understanding of the aluminum biochemistry at a molecular level. Aluminium can interact and be stabilized in biological environments by complexing with both low molecular mass chelants and high molecular mass peptides. The speciation of the metal is, nonetheless, dictated by the hydrolytic species dominant in each case and which vary according to the pH condition of the medium. In blood, citrate and serum transferrin are identified as the main low molecular mass and high molecular mass molecules interacting with aluminium. The complexation of aluminium to citrate and the subsequent changes exerted on the deprotonation pathways of its tritable groups will be discussed along with the mechanisms for the intake and release of aluminium in serum transferrin at two pH conditions, physiological neutral and endosomatic acidic. Aluminium can substitute other metals, in particular magnesium, in protein buried sites and trigger conformational disorder and alteration of the protonation states of the protein's sidechains. A detailed account of the interaction of aluminium with proteic sidechains will be given. Finally, it will be described how alumnium can exert oxidative stress by stabilizing superoxide radicals either as mononuclear aluminium or clustered in boehmite. The possibility of promotion of Fenton reaction, and production of hydroxyl radicals will also be discussed. PMID:24757505

The mechanical behavior of metal alloys with grain size distribution in a wide range of strain rates

NASA Astrophysics Data System (ADS)

Skripnyak, V. A.; Skripnyak, V. V.; Skripnyak, E. G.

2017-12-01

The paper discusses a multiscale simulation approach for the construction of grain structure of metals and alloys, providing high tensile strength with ductility. This work compares the mechanical behavior of light alloys and the influence of the grain size distribution in a wide range of strain rates. The influence of the grain size distribution on the inelastic deformation and fracture of aluminium and magnesium alloys is investigated by computer simulations in a wide range of strain rates. It is shown that the yield stress depends on the logarithm of the normalized strain rate for light alloys with a bimodal grain distribution and coarse-grained structure.

Toxicity of dissolved and precipitated aluminium to marine diatoms.

PubMed

Gillmore, Megan L; Golding, Lisa A; Angel, Brad M; Adams, Merrin S; Jolley, Dianne F

2016-05-01

Localised aluminium contamination can lead to high concentrations in coastal waters, which have the potential for adverse effects on aquatic organisms. This research investigated the toxicity of 72-h exposures of aluminium to three marine diatoms (Ceratoneis closterium (formerly Nitzschia closterium), Minutocellus polymorphus and Phaeodactylum tricornutum) by measuring population growth rate inhibition and cell membrane damage (SYTOX Green) as endpoints. Toxicity was correlated to the time-averaged concentrations of different aluminium size-fractions, operationally defined as <0.025μm filtered, <0.45μm filtered (dissolved) and unfiltered (total) present in solution over the 72-h bioassay. The chronic population growth rate inhibition after aluminium exposure varied between diatom species. C. closterium was the most sensitive species (10% inhibition of growth rate (72-h IC10) of 80 (55-100)μg Al/L (95% confidence limits)) while M. polymorphus (540 (460-600)μg Al/L) and P. tricornutum (2100 (2000-2200)μg Al/L) were less sensitive (based on measured total aluminium). Dissolved aluminium was the primary contributor to toxicity in C. closterium, while a combination of dissolved and precipitated aluminium forms contributed to toxicity in M. polymorphus. In contrast, aluminium toxicity to the most tolerant diatom P. tricornutum was due predominantly to precipitated aluminium. Preliminary investigations revealed the sensitivity of C. closterium and M. polymorphus to aluminium was influenced by initial cell density with aluminium toxicity significantly (p<0.05) increasing with initial cell density from 10(3) to 10(5)cells/mL. No effects on plasma membrane permeability were observed for any of the three diatoms suggesting that mechanisms of aluminium toxicity to diatoms do not involve compromising the plasma membrane. These results indicate that marine diatoms have a broad range in sensitivity to aluminium with toxic mechanisms related to both dissolved and precipitated

Effect of thermal exposure on mechanical properties hypo eutectic aerospace grade aluminium-silicon alloy

NASA Astrophysics Data System (ADS)

Nagesh Kumar, R.; Ram Prabhu, T.; Siddaraju, C.

2016-09-01

The effect of thermal exposure on the mechanical properties of a C355.0 aerospace grade aluminum-silicon alloy (5% Si - 1.2% Cu - 0.5% Mg) was investigated in the present study. The alloy specimens were subjected to T6 (solution treatment and artificial ageing treatment) temper treatment to enhance the strength properties through precipitation hardening. The T6 temper treatment involved solution heat treatment at 520oC for 6h, followed by water quenching and ageing at 150oC. After the heat treatment, the specimens were exposed to various temperatures (50oC, 100oC, 150oC, 200oC and 250oC) for 5 and 10 h to study the structural applications of this alloy to the various Mach number military aircrafts. After the thermal exposure, specimens were tested for tensile, hardness and impact properties (Charpy). The microstructure of the thermal exposed specimens was examined in the optical microscopes and correlated with the mechanical properties results. In summary, an increase of exposure time has a different effect on the tensile and hardness properties of the alloy. For the exposure time 5h, the tensile and hardness properties increase upto 100oC and later decrease with an increase of temperature. In contrast, the tensile and hardness properties linearly decrease with an increase of temperature. Several factors such as matrix grain growth, diffusion rate, Si particles size and distribution, precipitate stability play a key role on deciding the tensile properties of the alloy. Comparing the relative effects of temperature and time, the temperature effects dominate more in deteriorating tensile properties of the alloy. There are no effects of exposure temperature and/or time on the impact properties of the alloy.

Numerical investigations on the lateral angular co-extrusion of aluminium and steel

NASA Astrophysics Data System (ADS)

Behrens, B.-A.; Klose, C.; Chugreev, A.; Thürer, S. E.; Uhe, J.

2018-05-01

In order to save weight and costs, different materials can be combined within one component. In the novel process chain being developed within the Collaborative Research Centre (CRC) 1153, joined semi-finished workpieces are used to produce hybrid solid components with locally adapted properties. Different materials are joined in an initial step before the forming process takes place. Hereby, the quality of the joining zone is improved by means of the thermo-mechanical treatment during the forming and machining processes. The lateral angular co-extrusion (LACE) approach is used to produce semi-finished workpieces because it allows for the production of coaxial semi-finished products consisting of aluminium and steel. In the further process chain, these semi-finished products are processed into hybrid bearing bushings with locally adapted properties by die forging. In the scope of this work, numerical investigations of the co-extrusion of aluminium-steel compounds were carried out using finite element (FE) simulation in order to examine the influence of the process parameters on the co-extrusion process. For this purpose, the relevant material properties of the aluminium alloy EN AW-6082 were determined experimentally and subsequently implemented in the numerical model. The obtained numerical model was used to study the impact of different ram speeds, press ratios and billet temperatures on the resulting extrusion forces and the material flow. The numerical results have been validated using force-time curves obtained from experimental extrusion tests carried out on a 2.5 MN laboratory extrusion press.

Liquid phase diffusion bonding of A1070 by using metal formate coated Zn sheet

NASA Astrophysics Data System (ADS)

Ozawa, K.; Koyama, S.; shohji, I.

2017-05-01

Aluminium alloy have high strength and easily recycle due to its low melting point. Therefore, aluminium is widely used in the manufacturing of cars and electronic devices. In recent years, the most common way for bonding aluminium alloy is brazing and friction stir welding. However, brazing requires positional accuracy and results in the formation of voids by the flax residue. Moreover, aluminium is an excellent heat radiating and electricity conducting material; therefore, it is difficult to bond together using other bonding methods. Because of these limitations, liquid phase diffusion bonding is considered to the suitable method for bonding aluminium at low temperature and low bonding pressure. In this study, the effect of metal formate coating processing of zinc surface on the bond strength of the liquid phase diffusion bonded interface of A1070 has been investigated by SEM observation of the interfacial microstructures and fractured surfaces after tensile test. Liquid phase diffusion bonding was carried out under a nitrogen gas atmosphere at a bonding temperature of 673 K and 713 K and a bonding load of 6 MPa (bonding time: 15 min). As a result of the metal formate coating processing, a joint having the ultimate tensile strength of the base aluminium was provided. It is hypothesized that this is because metallic zinc is generated as a result of thermal decomposition of formate in the bonded interface at lower bonding temperatures.

CHIP MORPHOLOGY AND HOLE SURFACE TEXTURE IN THE DRILLING OF CAST ALUMINUM ALLOYS. (R825370C057)

EPA Science Inventory

The effects of cutting fluid and other process variables on chip morphology when drilling cast aluminium alloys are investigated. The effects of workpiece material, speed, feed, hole depth, cutting-fluid presence and percentage oil concentration, workpiece temperature, drill t...

Estimating multivariate response surface model with data outliers, case study in enhancing surface layer properties of an aircraft aluminium alloy

NASA Astrophysics Data System (ADS)

Widodo, Edy; Kariyam

2017-03-01

To determine the input variable settings that create the optimal compromise in response variable used Response Surface Methodology (RSM). There are three primary steps in the RSM problem, namely data collection, modelling, and optimization. In this study focused on the establishment of response surface models, using the assumption that the data produced is correct. Usually the response surface model parameters are estimated by OLS. However, this method is highly sensitive to outliers. Outliers can generate substantial residual and often affect the estimator models. Estimator models produced can be biased and could lead to errors in the determination of the optimal point of fact, that the main purpose of RSM is not reached. Meanwhile, in real life, the collected data often contain some response variable and a set of independent variables. Treat each response separately and apply a single response procedures can result in the wrong interpretation. So we need a development model for the multi-response case. Therefore, it takes a multivariate model of the response surface that is resistant to outliers. As an alternative, in this study discussed on M-estimation as a parameter estimator in multivariate response surface models containing outliers. As an illustration presented a case study on the experimental results to the enhancement of the surface layer of aluminium alloy air by shot peening.

Wear mechanisms and improvements of wear resistance in cobalt-chromium alloy femoral components in artificial total knee joints

NASA Astrophysics Data System (ADS)

Que, Like

CrMo alloy surface roughness was higher than 0.022 mum Ra (surface roughness average), UHMWPE wear increased with increasing CoCrMo alloy surface roughness. Bone and poly(methyl methacrylate) (PMMA) bone cement abrasive particles created scratches on the alloy via a ploughing mechanism, and resulted in significantly rougher surfaces than controls without particles (P < 0.01). Solution treatments at 1230sp°C and 1245sp°C reduced the hardness and wear resistance of the as-cast F75 CoCrMo alloy. Aging at 700sp°C caused recrystallization of the forged F799 alloy and improved wear resistance. Thermo-mechanical treatments have the potential to increase the lifetime of artificial joints by increasing the wear resistance of CoCrMo components.

[Association between serum aluminium level and methylation of amyloid precursor protein gene in workers engaged in aluminium electrolysis].

PubMed

Yang, X J; Yuan, Y Z; Niu, Q

2016-04-20

To investigate the association between serum aluminium level and methylation of the promoter region of amyloid precursor protein (APP)gene in workers engaged in aluminium electrolysis. In 2012, 366 electrolysis workers in an aluminium factory were enrolled as exposure group (working years >10 and age >40 years)and divided into low-exposure group and high-exposure group based on the median serum aluminium level. Meanwhile, 102 workers in a cement plant not exposed to aluminium were enrolled as control group. Graphite furnace atomic absorption spectrometry was used to measure serum aluminium level, methylation specific PCR was used to measure the methylation rate of the promoter region of APP gene, and ELI-SA was used to measure the protein expression of APP in lymphocytes in peripheral blood. The exposure group had a significantly higher serum aluminium level than the control group (45.07 μg/L vs 30.51 μg/L, P< 0.01). The exposure group had a significantly lower methylation rate of the promoter region of APP gene than the control group (18.85% vs 25.49%, P=0.025), and the high-exposure group had a significantly lower methylation rate of the promoter region of APP gene than the low-exposure group (15.84% vs 21.85%, P<0.05). The exposure group had a significantly higher protein expression of APP in lymphocytes in peripheral blood than the control group (66.73 ng/ml vs 54.17 ng/ml, P<0.05); compared with the low-exposure group (65.39 ng/ml), the high-exposure group showed an increase in the protein expression of APP in lymphocytes in peripheral blood (67.22 ng/ml), but there was no significant difference between these two groups (P>0.05). The multivariate logistic regression analysis showed that with reference to the control group, low aluminium exposure (OR=1.86, 95% CI 1.67~3.52)and high aluminium exposure (OR=2.98, 95% CI 1.97~4.15)were risk factors for a reduced methylation rate of the promoter region of APP gene. Reduced methylation of the promoter region of APP

Study on Thermal Conductivity of Personal Computer Aluminum-Magnesium Alloy Casing

NASA Astrophysics Data System (ADS)

Liao, MeiHong

With the rapid development of computer technology, micro-state atoms by simulating the movement of material to analyze the nature of the macro-state have become an important subject. Materials, especially aluminium-magnesium alloy materials, often used in personal computer case, this article puts forward heat conduction model of the material, and numerical methods of heat transfer performance of the material.

Aluminium in allergen-specific subcutaneous immunotherapy--a German perspective.

PubMed

Kramer, Matthias F; Heath, Matthew D

2014-07-16

We are living in an "aluminium age" with increasing bioavailability of the metal for approximately 125 years, contributing significantly to the aluminium body burden of humans. Over the course of life, aluminium accumulates and is stored predominantly in the lungs, bones, liver, kidneys and brain. The toxicity of aluminium in humans is briefly summarised, highlighting links and possible causal relationships between a high aluminium body burden and a number of neurological disorders and disease states. Aluminium salts have been used as depot-adjuvants successfully in essential prophylactic vaccinations for almost 100 years, with a convincing positive benefit-risk assessment which remains unchanged. However, allergen-specific immunotherapy commonly consists of administering a long-course programme of subcutaneous injections using preparations of relevant allergens. Regulatory authorities currently set aluminium limits for vaccines per dose, rather than per treatment course. Unlike prophylactic vaccinations, numerous injections with higher proportions of aluminium-adjuvant per injection are applied in subcutaneous immunotherapy (SCIT) and will significantly contribute to a higher cumulative life dose of aluminium. While the human body may cope robustly with a daily aluminium overload from the environment, regulatory cumulative threshold values in immunotherapy need further addressing. Based on the current literature, predisposing an individual to an unusually high level of aluminium, such as through subcutaneous immunotherapy, has the potential to form focal accumulations in the body with the propensity to exert forms of toxicity. Particularly in relation to longer-term health effects, the safety of aluminium adjuvants in immunotherapy remains unchallenged by health authorities - evoking the need for more consideration, guidance, and transparency on what is known and not known about its safety in long-course therapy and what measures can be taken to prevent or

Infrared Brazing of Ti50Ni50 Shape Memory Alloy and Inconel 600 Alloy with Two Ag-Cu-Ti Active Braze Alloys

NASA Astrophysics Data System (ADS)

Shiue, Ren-Kae; Wu, Shyi-Kaan; Yang, Sheng-Hao

2017-02-01

Infrared brazing of Ti50Ni50 SMA and Inconel 600 alloy using Cusil-ABA and Ticusil filler metals has been investigated. The joints were dominated by Ag-Cu eutectic with proeutectic Cu in the Cusil-ABA brazed joint and with proeutectic Ag in the Ticusil one. A continuous curved belt composed of a Ni3Ti layer and a (Cu x Ni1- x )2Ti layer formed in the brazed Ti50Ni50/Ticusil/Inconel 600 joint. On the Ti50Ni50 SMA side, an intermetallic layer of (Cu x Ni1- x )2Ti formed in all joints, with x values around 0.81 and 0.47. Layers of (Cu x Ni1- x )2Ti, Ni3Ti, and mixed Ni3Ti and Ni2Cr intermetallics were observed next to the Inconel 600 substrate in the brazed Ti50Ni50/Cusil-ABA/Inconel 600 joint. The maximum shear strengths of the joints using the Cusil-ABA filler metal and the Ticusil filler metal were 324 and 300 MPa, respectively. In the Cusil-ABA brazed joint, cracks with cleavage-dominated fracture propagated along the (Cu x Ni1- x )2Ti interfacial layer next to the Ti50Ni50 SMA substrate. In the Ticusil brazed joint, ductile dimple fracture occurred in the Ag-rich matrix near the Inconel 600 alloy substrate. The absence of a detrimental Ti-Fe-(Cu) layer on the Inconel 600 substrate side can effectively improve the shear strength of the joint.

Formation of Gradient Structures in the Zone of Joining a Deformable Nickel Alloy and a Single-Crystal Intermetallic Alloy during Thermodiffusion Pressure Welding and Subsequent Heat Treatment

NASA Astrophysics Data System (ADS)

Povarova, K. B.; Valitov, V. A.; Drozdov, A. A.; Bazyleva, O. A.; Galieva, E. V.; Arginbaeva, E. G.

2018-01-01

The possibility of formation of a high-quality solid-phase joint of an Ni3Al-based single-crystal intermetallic VKNA-25 blade alloy with a high-temperature deformable EP975 disk alloy by pressure welding is studied to create high-performance one-piece blisk unit for the next-generation aviation gas turbine engines and to decrease the unit mass. The influence of the conditions of thermodiffusion pressure welding under the hightemperature superplasticity of the disk alloy and the influence of heat treatment of welded joints on the gradient structures in the welded joint zone and the structure at the periphery of the welded samples are investigated.

Interfacial Reaction During Dissimilar Joining of Aluminum Alloy to Magnesium and Titanium Alloys

NASA Astrophysics Data System (ADS)

Robson, J. D.; Panteli, A.; Zhang, C. Q.; Baptiste, D.; Cai, E.; Prangnell, P. B.

Ultrasonic welding (USW), a solid state joining process, has been used to produce welds between AA6111 aluminum alloy and AZ31 magnesium alloys or titanium alloy Ti-6Al-4V. The mechanical properties of the welds have been assessed and it has been shown that it is the nature and thickness of the intermetallic compounds (IMCs) at the joint line that are critical in determining joint strength and particularly fracture energy. Al-Mg welds suffer from a very low fracture energy, even when strength is comparable with that of similar metal Mg-Mg welds, due to a thick IMC layer always being formed. It is demonstrated that in USW of Al-Ti alloy the slow interdiffusion kinetics means that an IMC layer does not form during welding, and fracture energy is greater. A model has been developed to predict IMC formation during welding and provide an understanding of the critical factors that determine the IMC thickness. It is predicted that in Al-Mg welds, most of the lMC thickening occurs whilst the IMC regions grow as separate islands, prior to the formation of a continuous layer.

Quantitative characterization of brazing performance for Sn-plated silver alloy fillers

NASA Astrophysics Data System (ADS)

Wang, Xingxing; Peng, Jin; Cui, Datian

2017-12-01

Two types of AgCuZnSn fillers were prepared based on BAg50CuZn and BAg34CuZnSn alloy through a combinative process of electroplating and thermal diffusion. The models of wetting entropy and joint strength entropy of AgCuZnSn filler metals were established. The wetting entropy of the Sn-plated silver brazing alloys are lower than the traditional fillers, and its joint strength entropy value is slightly higher than the latter. The wetting entropy value of the Sn-plated brazing alloys and traditional filler metal are similar to the change trend of the wetting area. The trend of the joint strength entropy value with those fillers are consisted with the tensile strength of the stainless steel joints with the increase of Sn content.

Special issue on aluminium plasmonics

DOE PAGES

Gerard, Davy; Gray, Stephen K.

2015-04-08

Plasmonics is a rapidly growing field that takes advantage of the intense and confined electromagnetic fields that appear near metallic nanostructures illuminated at frequencies near their surface plasmon resonances. As plasmonics continues to develop, it faces the need to find new materials supporting well-defined surface plasmon resonances in different frequency ranges. In the visible and near-infrared ranges the noble metals, most typically gold and silver, exhibit relatively low losses. This is why they are quite ubiquitous in plasmonics literature. However it is somewhat ironic to see that a non-noble metal, aluminium, the metal upon which surface plasmons where first evidencedmore » in the 1950s, is now reappearing after fifty years of near oblivion as one of the 'hottest' materials for plasmonics. Several reasons explain the return of aluminium to the centre stage. First, aluminium exhibits good plasmonic properties in the ultraviolet and deep ultraviolet—a spectral range where gold and silver no longer behave as metals. Second, aluminium is cheap and widely available (Al is the third most abundant element in the earth's crust), criteria of paramount importance when discussing industry-related applications. It is furthermore compatible with complementary metal–oxide–semiconductor (CMOS) technology. In conclusion, this is why an ever-increasing number of papers report new advances on aluminium plasmonics.« less

Special issue on aluminium plasmonics

DOE Office of Scientific and Technical Information (OSTI.GOV)

Gerard, Davy; Gray, Stephen K.

Plasmonics is a rapidly growing field that takes advantage of the intense and confined electromagnetic fields that appear near metallic nanostructures illuminated at frequencies near their surface plasmon resonances. As plasmonics continues to develop, it faces the need to find new materials supporting well-defined surface plasmon resonances in different frequency ranges. In the visible and near-infrared ranges the noble metals, most typically gold and silver, exhibit relatively low losses. This is why they are quite ubiquitous in plasmonics literature. However it is somewhat ironic to see that a non-noble metal, aluminium, the metal upon which surface plasmons where first evidencedmore » in the 1950s, is now reappearing after fifty years of near oblivion as one of the 'hottest' materials for plasmonics. Several reasons explain the return of aluminium to the centre stage. First, aluminium exhibits good plasmonic properties in the ultraviolet and deep ultraviolet—a spectral range where gold and silver no longer behave as metals. Second, aluminium is cheap and widely available (Al is the third most abundant element in the earth's crust), criteria of paramount importance when discussing industry-related applications. It is furthermore compatible with complementary metal–oxide–semiconductor (CMOS) technology. In conclusion, this is why an ever-increasing number of papers report new advances on aluminium plasmonics.« less

Alveolar proteinosis associated with aluminium dust inhalation.

PubMed

Chew, R; Nigam, S; Sivakumaran, P

2016-08-01

Secondary alveolar proteinosis is a rare lung disease which may be triggered by a variety of inhaled particles. The diagnosis is made by detection of anti-granulocyte-macrophage colony-stimulating factor antibodies in bronchoalveolar lavage fluid, which appears milky white and contains lamellar bodies. Aluminium has been suggested as a possible cause, but there is little evidence in the literature to support this assertion. We report the case of a 46-year-old former boilermaker and boat builder who developed secondary alveolar proteinosis following sustained heavy aluminium exposure. The presence of aluminium was confirmed both by histological examination and metallurgical analysis of a mediastinal lymph node. Despite cessation of exposure to aluminium and treatment with whole-lung lavage which normally results in improvements in both symptoms and lung function, the outcome was poor and novel therapies are now being used for this patient. It may be that the natural history in aluminium-related alveolar proteinosis is different, with the metal playing a mediating role in the disease process. Our case further supports the link between aluminium and secondary alveolar proteinosis and highlights the need for measures to prevent excessive aluminium inhalation in relevant industries. © The Author 2016. Published by Oxford University Press on behalf of the Society of Occupational Medicine. All rights reserved. For Permissions, please email: journals.permissions@oup.com.

Properties- and applications of quasicrystals and complex metallic alloys.

PubMed

Dubois, Jean-Marie

2012-10-21

This article aims at an account of what is known about the potential for applications of quasicrystals and related compounds, the so-called family of Complex Metallic Alloys (CMAs‡). Attention is focused at aluminium-based CMAs, which comprise a large number of crystalline compounds and quasicrystals made of aluminium alloyed with transition metals (like Fe or Cu) or normal metals like Mg. Depending on composition, the structural complexity varies from a few atoms per unit cell up to thousands of atoms. Quasicrystals appear then as CMAs of ultimate complexity and exhibit a lattice that shows no periodicity anymore in the usual 3-dimensional space. Properties change dramatically with lattice complexity and turn the metal-type behaviour of simple Al-based crystals into a far more complex behaviour, with a fingerprint of semi-conductors that may be exploited in various applications, potential or realised. An account of the ones known to the author is given in the light of the relevant properties, namely light absorption, reduced adhesion and friction, heat insulation, reinforcement of composites for mechanical devices, and few more exotic ones. The role played by the search for applications of quasicrystals in the development of the field is briefly addressed in the concluding section.

Production of al-si alloy feedstocks using the solvent hot mixing method

NASA Astrophysics Data System (ADS)

Ni, J. Q.; Han, K. Q.; Yu, M. H.

2018-05-01

Powder injection molding is a promising low-cost technique for net shape processing of metal and ceramic components. This study aimed to investigate a new method for preparing aluminium (Al) – silicon (Si) alloy feedstock using the solvent hot mixing process. For this purpose, micron-sized Al-Si (20 wt. %) alloy powder was mixed with a binder consisting of 55 wt. % carnauba wax, 45 wt. % high-density polyethylene, and 3 wt. % stearic acid in a hot xylene bath. The scanning electron microscopy technique, thermogravimetric analysis, density measurement and torque measurements were used to verify the homogeneity of the feedstock. Moreover, the feedstock was chosen to perform the molding, debinding cycle and sintering. An Al-Si (20 wt. %) alloy part was successfully produced using this new method.

Effect of soldering techniques and gap distance on tensile strength of soldered Ni-Cr alloy joint.

PubMed

Lee, Sang-Yeob; Lee, Jong-Hyuk

2010-12-01

The present study was intended to evaluate the effect of soldering techniques with infrared ray and gas torch under different gap distances (0.3 mm and 0.5 mm) on the tensile strength and surface porosity formation in Ni-Cr base metal alloy. Thirty five dumbbell shaped Ni-Cr alloy specimens were prepared and assigned to 5 groups according to the soldering method and the gap distance. For the soldering methods, gas torch (G group) and infrared ray (IR group) were compared and each group was subdivided by corresponding gap distance (0.3 mm: G3 and IR3, 0.5 mm: G5, IR5). Specimens of the experimental groups were sectioned in the middle with a diamond disk and embedded in solder blocks according to the predetermined distance. As a control group, 7 specimens were prepared without sectioning or soldering. After the soldering procedure, a tensile strength test was performed using universal testing machine at a crosshead speed 1 mm/min. The proportions of porosity on the fractured surface were calculated on the images acquired through the scanning electronic microscope. Every specimen of G3, G5, IR3 and IR5 was fractured on the solder joint area. However, there was no significant difference between the test groups (P > .05). There was a negative correlation between porosity formation and tensile strength in all the specimens in the test groups (P < .05). There was no significant difference in ultimate tensile strength of joints and porosity formations between the gas-oxygen torch soldering and infrared ray soldering technique or between the gap distance of 0.3 mm and 0.5 mm.

Study of mechanical joint strength of aluminum alloy 7075-T6 and dual phase steel 980 welded by friction bit joining and weld-bonding under corrosion medium

DOE PAGES

Lim, Yong Chae; Squires, Lile; Pan, Tsung-Yu; ...

2014-12-30

We have employed a unique solid-sate joining process, called friction bit joining (FBJ), to spot weld aluminum alloy (AA) 7075-T6 and dual phase (DP) 980 steel. Static joint strength was studied in the lap shear tension configuration. In addition, weld-bonding (adhesive + FBJ) joints were studied in order to evaluate the ability of adhesive to mitigate the impact of corrosion on joint properties. Accelerated laboratory cyclic corrosion tests were carried out for both FBJ only and weld-bonding joints. Furthermore, the FBJ only joints that emerged from corrosion testing had lap shear failure loads that were significantly lower than freshly preparedmore » joints. However, weld-bonding specimens retained more than 80% of the lap shear failure load of the freshly prepared weld-bonding specimens. Moreover, examination of joint cross sections confirmed that the presence of adhesive in the weld-bonding joints mitigated the effect of the corrosion environment, compared to FBJ only joints.« less

Reinforcement with alumina particles at the interface region of AA6101-T6 and AA1350 alloys during friction stir welding

NASA Astrophysics Data System (ADS)

Ashok Kumar, R.; Thansekhar, M. R.

2018-04-01

This paper deals the combinational effect of friction stir welding and friction stir processing on dissimilar AA6101-T6 and AA1350 aluminium alloys. For that, alumina particles are reinforced at interface region of AA6101-T6 and AA1350 aluminium alloys. Friction Stir Welding and Friction Stir Processing are done simultaneously for various sizes of groove. To analyze the welding quality and surface modifications, mechanical, wear and microstructural tests are carried out. Among these, smallest groove of 0.5 mm width and 1 mm depth reveals highest tensile and bending strengths and largest groove of 2 mm width and 3 mm depth gives maximum hardness and wear resistance. Taguchi technique shows that groove width is most influencing parameter. Developed second order models with interaction predict the responses with minimum error.

Laser Brazing of High Temperature Braze Alloy

NASA Technical Reports Server (NTRS)

Gao, Y. P.; Seaman, R. F.; McQuillan, T. J.; Martiens, R. F.

2000-01-01

The Space Shuttle Main Engine (SSME) consists of 1080 conical tubes, which are furnace brazed themselves, manifolds, and surrounding structural jacket making almost four miles of braze joints. Subsequent furnace braze cycles are performed due to localized braze voids between the coolant tubes. SSME nozzle experiences extremely high heat flux (180 mW/sq m) during hot fire. Braze voids between coolant tubes may result in hot combustion gas escape causing jacket bulges. The nozzle can be disqualified for flight or result in mission failure if the braze voids exceed the limits. Localized braze processes were considered to eliminate braze voids, however, damage to the parent materials often prohibited use of such process. Being the only manned flight reusable rocket engine, it has stringent requirement on the braze process. Poor braze quality or damage to the parent materials limits the nozzle service life. The objective of this study was to develop a laser brazing process to provide quality, localized braze joints without adverse affect on the parent materials. Gold (Au-Cu-Ni-Pd-Mn) based high temperature braze alloys were used in both powder and wire form. Thin section iron base superalloy A286 tube was used as substrate materials. Different Laser Systems including CO2 (10.6 micrometers, 1kW), ND:YAG (1.06 micrometers, 4kW). and direct diode laser (808nm. 150W) were investigated for brazing process. The laser process variables including wavelength. laser power, travel speed and angle of inclination were optimized according to bead geometry and braze alloy wetting at minimum heat input level, The properties of laser brazing were compared to that of furnace brazing. Microhardness profiles were used for braze joint property comparison between laser and furnace brazing. The cooling rate of laser brazing was compared to furnace brazing based on secondary dendritic arm spacing, Both optical and Scanning Electron Microscope (SEM) were used to evaluate the microstructures of

The aluminium content of infant formulas remains too high.

PubMed

Chuchu, Nancy; Patel, Bhavini; Sebastian, Blaise; Exley, Christopher

2013-10-08

Recent research published in this journal highlighted the issue of the high content of aluminium in infant formulas. The expectation was that the findings would serve as a catalyst for manufacturers to address a significant problem of these, often necessary, components of infant nutrition. It is critically important that parents and other users have confidence in the safety of infant formulas and that they have reliable information to use in choosing a product with a lower content of aluminium. Herein, we have significantly extended the scope of the previous research and the aluminium content of 30 of the most widely available and often used infant formulas has been measured. Both ready-to-drink milks and milk powders were subjected to microwave digestion in the presence of 15.8 M HNO3 and 30% w/v H2O2 and the aluminium content of the digests was measured by TH GFAAS. Both ready-to-drink milks and milk powders were contaminated with aluminium. The concentration of aluminium across all milk products ranged from ca 100 to 430 μg/L. The concentration of aluminium in two soya-based milk products was 656 and 756 μg/L. The intake of aluminium from non-soya-based infant formulas varied from ca 100 to 300 μg per day. For soya-based milks it could be as high as 700 μg per day. All 30 infant formulas were contaminated with aluminium. There was no clear evidence that subsequent to the problem of aluminium being highlighted in a previous publication in this journal that contamination had been addressed and reduced. It is the opinion of the authors that regulatory and other non-voluntary methods are now required to reduce the aluminium content of infant formulas and thereby protect infants from chronic exposure to dietary aluminium.

Production and Compressive Characterization of Aluminium MMC Foam Manufactured Using Dual Foaming Agent

NASA Astrophysics Data System (ADS)

Haidar, S.; Ansary, S.; Rahman, A.

2016-02-01

Aluminium foams, produced by melting Aluminium alloy (LM6) containing blowing agent(s) and vigorous stirring. TiH2 is a known agent for this. As TiH2 begins to decompose into Ti and gaseous H2 when heated above about 465°C, large volumes of hydrogen gas are rapidly produced, creating bubbles that leads to a closed cell foam. A novel Strategy to enhance the mechanical properties of Al-MMC foams is discussed here, and it is demonstrated that titanium hydride (TiH2) in the form of 10-15 μm diameter particles can be pre-treated by selective oxidation to produce more uniform foams having better compressive properties (yield strength and energy absorption). It is found that the mechanical properties of the foams and the uniformity of cell size distribution is improved when the foam is blown with an optimized mixture of CaCO3 and pretreated TiH2. In order to define the relationship of mechanical properties with relative density of this material, correlations which uniquely defines the compressive behaviour of this modified Al- MMC foam has been developed.

Electrodeposition and characterisation of Al-W alloy films from ionic liquid

NASA Astrophysics Data System (ADS)

Höhlich, D.; Wachner, D.; Müller, M.; Scharf, I.; Lampke, T.

2018-06-01

Al–W alloy films were prepared by electrodeposition using anhydrous 1-ethyl-3-methylimidazolium chloride (EMIMCl) ionic-liquid solution with aluminium chloride in a ratio of 1:1.5. As a commercially available tungsten precursor, tungsten hexachloride was used. The metal is dissolved in the ionic liquid at concentrations up to 0.06 mol/l. The deposition took place outside the glove box with a continuous argon stream over the electrolyte at a temperature of 60 °C with a current density of 1 A/m2. Resulting alloys show a tungsten content higher than 20 wt% (3.5 at%). The phase composition of Al-W alloys was observed by X-ray diffraction (XRD), and the chemical composition was characterised by scanning electron microscopy (SEM) and inductively-coupled plasma optical emission spectroscopy (ICP-OES).

High Temperature Stability of Dissimilar Metal Joints in Fission Surface Power Systems

NASA Technical Reports Server (NTRS)

Locci, Ivan E.; Nesbitt, James A.; Ritzert, Frank J.; Bowman, Cheryl L.

2007-01-01

Future generations of power systems for spacecraft and lunar surface systems will likely require a strong dependence on nuclear power. The design of a space nuclear power plant involves integrating together major subsystems with varying materia1 requirements. Refractory alloys are repeatedly considered for major structural components in space power reactor designs because refractory alloys retain their strength at higher temperatures than other classes of metals. The relatively higher mass and lower ductility of the refractory alloys make them less attractive for lower temperature subsystems in the power plant such as the power conversion system. The power conversion system would consist more likely of intermediate temperature Ni-based superalloys. One of many unanswered questions about the use of refractory alloys in a space power plant is how to transition from the use of the structural refractory alloy to more traditional structural alloys. Because deleterious phases can form when complex alloys are joined and operated at elevated temperatures, dissimilar material diffusion analyses of refractory alloys and superalloys are needed to inform designers about options of joint temperature and operational lifetime. Combinations of four superalloys and six refractory alloys were bonded and annealed at 1150 K and 1300 K to examine diffusional interactions in this study. Joints formed through hot pressing and hot isostatic pressing were compared. Results on newer alloys compared favorably to historical data. Diffusional stability is promising for some combinations of Mo-Re alloys and superalloys at 1150 K, but it appears that lower joint temperatures would be required for other refractory alloy couples.

Serum aluminium levels of workers in the bauxite mines.

PubMed

de Kom, J F; Dissels, H M; van der Voet, G B; de Wolff, F A

1997-01-01

Aluminium is produced from the mineral bauxite. Occupational exposure is reported during the industrial processing of aluminium and is associated with pulmonary and neurotoxicity. However, data on exposure and toxicity of workers in the open bauxite mining industry do not exist. Therefore, a study was performed to explore aluminium exposure in employees involved in this bauxite mining process in a Surinam mine. A group of workers occupationally exposed to aluminium in an open bauxite mine were compared with a group of nonexposed wood processors. Serum aluminium was analyzed using atomic absorption spectrometry Data from the clinical chemistry of the blood and a questionnaire were used to explore determinants for aluminium exposure. No significant difference between serum aluminium in the exposed (4.4 +/- 2.0 micrograms/L, n = 27) and control group (5.1 +/- 1.5 micrograms/L, n = 27) was detected. For the serum concentration of the clinical chemical variables (calcium, citrate, and creatinine), a statistically significant difference was computed (p < or = 0.02) between the exposed and control group. All levels were slightly higher in the exposed group; no statistically significant correlations with serum aluminium were found. In this study, serum aluminium values were in the normal range, no significant difference between the groups could be detected despite long-term occupational exposure.

Design of splints based on the NiTi alloy for the correction of joint deformities in the fingers

PubMed Central

2010-01-01

Background The proximal interphalange joint (PIP) is fundamental for the functional nature of the hand. The contracture in flexion of the PIP, secondary to traumatisms or illnesses leads to an important functional loss. The use of correcting splints is the common procedure for treating this problem. Its functioning is based on the application of a small load and a prolonged stress which can be dynamic, static progressive or static serial. It is important that the therapist has a splint available which can release a constant and sufficient force to correct the contracture in flexion. Nowadays NiTi is commonly used in bio-engineering, due to its superelastical characteristics. The experience of the authors in the design of other devices based on the NiTi alloy, makes it possible to carry out a new design in this work - the production of a finger splint for the treatment of the contracture in flexion of the PIP joint. Methods Commercial orthosis have been characterized using a universal INSTRON 5565 machine. A computational simulation of the proposed design has been conducted, reproducing its performance and using a model "ad hoc" for the NiTi material. Once the parameters have been adjusted, the design is validated using the same type of test as those carried out on commercial orthosis. Results and Discussion For commercial splint the recovering force falls to excessively low values as the angle increases. Angle curves for different lengths and thicknesses of the proposed design have been obtained, with a practically constant recovering force value over a wide range of angles that vary between 30° and 150° in every case. Then the whole treatment is possible with only one splint, and without the need of progressive replacements as the joint recovers. Conclusions A new model of splint based on NiTi alloy has been designed, simulated and tested comparing its behaviour with two of the most regularly used splints. Its uses is recommended instead of other dynamic

Bond Strength of Gold Alloys Laser Welded to Cobalt-Chromium Alloy

PubMed Central

Watanabe, Ikuya; Wallace, Cameron

2008-01-01

The objective of this study was to investigate the joint properties between cast gold alloys and Co-Cr alloy laser-welded by Nd:YAG laser. Cast plates were fabricated from three types of gold alloys (Type IV, Type II and low-gold) and a Co-Cr alloy. Each gold alloy was laser-welded to Co-Cr using a dental laser-welding machine. Homogeneously-welded and non-welded control specimens were also prepared. Tensile testing was conducted and data were statistically analyzed using ANOVA. The homogeneously-welded groups showed inferior fracture load compared to corresponding control groups, except for Co-Cr. In the specimens welded heterogeneously to Co-Cr, Type IV was the greatest, followed by low-gold and Type II. There was no statistical difference (P<0.05) in fracture load between Type II control and that welded to Co-Cr. Higher elongations were obtained for Type II in all conditions, whereas the lowest elongation occurred for low-gold welded to Co-Cr. This study indicated that, of the three gold alloys tested, the Type IV gold alloy was the most suitable alloy for laser-welding to Co-Cr. PMID:19088892

What is the risk of aluminium as a neurotoxin?

PubMed

Exley, Christopher

2014-06-01

Aluminium is neurotoxic. Its free ion, Al(3+) (aq), is highly biologically reactive and uniquely equipped to do damage to essential cellular (neuronal) biochemistry. This unequivocal fact must be the starting point in examining the risk posed by aluminium as a neurotoxin in humans. Aluminium is present in the human brain and it accumulates with age. The most recent research demonstrates that a significant proportion of individuals older than 70 years of age have a potentially pathological accumulation of aluminium somewhere in their brain. What are the symptoms of chronic aluminium intoxication in humans? What if neurodegenerative diseases such as Alzheimer's disease are the manifestation of the risk of aluminium as a neurotoxin? How might such an (outrageous) hypothesis be tested?

Electrochemical behavior of lead alloys in sulfuric and phosphoric acid solutions

NASA Astrophysics Data System (ADS)

Paleska, I.; Pruszkowska-Drachal, R.; Kotowski, J.; Dziudzi, A.; Milewski, J. D.; Kopczyk, M.; Czerwiński, A.

The electrochemical behavior of lead, lead-antimony, and lead-calcium-aluminium-tin alloys has been studied in solutions containing various concentrations of sulfuric and phosphoric acids. The dependence of these electrode processes on some experimental conditions (mainly sweep rate and potential range) has been studied. The measurements were performed using a cyclic voltammetry technique. The study and the analysis of the morphology of alloys have been performed using a scanning electron microscope (SEM). Cyclic voltammograms of the lead-antimony alloy electrodes, similarly to pure lead electrode, also show the "anodic excursion" peak under some experimental conditions. Well defined current waves, corresponding to the oxidation and reduction processes of Sb, are observed, if the alloy surface is freshly abraded. The oxidation of antimony starts at potentials at which the formation of PbO takes place. The peak current of Sb oxidation reaction decreases during successive cycles, suggesting that Sb dissolves from the alloy surface during the first CV sweeps. Another explanation for this effect might be the formation of a PbSO 4 selective membrane.

The aluminium content of infant formulas remains too high

PubMed Central

2013-01-01

Background Recent research published in this journal highlighted the issue of the high content of aluminium in infant formulas. The expectation was that the findings would serve as a catalyst for manufacturers to address a significant problem of these, often necessary, components of infant nutrition. It is critically important that parents and other users have confidence in the safety of infant formulas and that they have reliable information to use in choosing a product with a lower content of aluminium. Herein, we have significantly extended the scope of the previous research and the aluminium content of 30 of the most widely available and often used infant formulas has been measured. Methods Both ready-to-drink milks and milk powders were subjected to microwave digestion in the presence of 15.8 M HNO3 and 30% w/v H2O2 and the aluminium content of the digests was measured by TH GFAAS. Results Both ready-to-drink milks and milk powders were contaminated with aluminium. The concentration of aluminium across all milk products ranged from ca 100 to 430 μg/L. The concentration of aluminium in two soya-based milk products was 656 and 756 μg/L. The intake of aluminium from non-soya-based infant formulas varied from ca 100 to 300 μg per day. For soya-based milks it could be as high as 700 μg per day. Conclusions All 30 infant formulas were contaminated with aluminium. There was no clear evidence that subsequent to the problem of aluminium being highlighted in a previous publication in this journal that contamination had been addressed and reduced. It is the opinion of the authors that regulatory and other non-voluntary methods are now required to reduce the aluminium content of infant formulas and thereby protect infants from chronic exposure to dietary aluminium. PMID:24103160

The effect of metallic oxide deposition on the electrochemical behaviour of Al-Zn-Mg-Sn alloy in natural tropical seawater

NASA Astrophysics Data System (ADS)

Din Yati, M. S.; Nazree Derman, Mohd; Isa, M. C.; Y Ahmad, M.; Yusoff, N. H. N.; Muhammad, M. M.; Nain, H.

2014-06-01

The potential of aluminium alloys as anode materials in cathodic protection system has been explored and a significant improvement has been achieved. However, for marine application, it is quite difficult to maintain continuous activation process due to passivation behavior of aluminum alloys. Therefore, to choose the best activation mechanism for aluminium alloy in marine environment, it has to be considered from various points such as alloy composition and surface treatment. This paper report the effect of metallic ruthenium oxide (RuO2) deposition on the surface of as-cast Al-Zn-Mg-Sn alloy and to study the effect of its presence on the electrochemical behavior using direct current (DC) electrochemical polarization and current capacity measurement. The morphology and topography of corroded surface were studied by the aid of scanning electron microscope (SEM) and confocal laser scanning microscope (CLSM) respectively. Results from this study showed that the presence of intermetallic compound (Mg2Sn) and also mixed metal oxide compound (Al2O3 and RuO2) on the alloy surface has been very useful in improving electrochemical reaction and charge transfer activities in chloride containing solution. This study also showed that RuO2 catalytic coating applied on the surface of Al-Zn-Mg-Sn alloy has slightly increased the corrosion current density compared to Al-Zn-Mg-Sn without RuO2. The corrosion morphology and topography of corroded surface of Al-Zn-Mg-Sn alloy deposited with RuO2 was found more uniform corrosion attack with the formation of porous and fibrous mud-like crack on outer layer. Based on surface morphology and 3D topographic studies, these features were believed to facilitate ionic species adsorption and diffusion through corrosion product layer at solution-alloy interface. Deposited RuO2 films also was found to increase of current efficiency by more than 10%.

Weld-brazing - a new joining process. [combination resistance spot welding and brazing of titanium alloys

NASA Technical Reports Server (NTRS)

Bales, T. T.; Royster, D. M.; Arnold, W. E., Jr.

1972-01-01

A joining process designated weld brazing which combines resistance spot welding and brazing has been developed. Resistance spot welding is used to position and align the parts as well as to establish a suitable faying surface gap for brazing. Fabrication is then completed by capillary flow of the braze alloy into the joint. The process has been used successfully to fabricate Ti-6Al-4V titanium alloy joints using 3003 aluminum braze alloy. Test results obtained on single overlap and hat-stiffened structural specimens show that weld brazed joints are superior in tensile shear, stress rupture, fatigue, and buckling than joint fabricated by spotwelding or brazing. Another attractive feature of the process is that the brazed joints is hermetically sealed by the braze material.

Fractographic Observations on the Mechanism of Fatigue Crack Growth in Aluminium Alloys

NASA Astrophysics Data System (ADS)

Alderliesten, R. C.; Schijve, J.; Krkoska, M.

Special load histories are adopted to obtain information about the behavior of the moving crack tip during the increasing and decreasing part of a load cycle. It is associated with the crack opening and closure of the crack tip. Secondly, modern SEM techniques are applied for observations on the morphology of the fractures surfaces of a fatigue crack. Information about the cross section profiles of striations are obtained. Corresponding locations of the upper and the lower fracture surface are also explored in view of the crack extension mechanism. Most experiments are carried out on sheet specimens of aluminum alloys 2024-T3, but 7050-T7451 specimens are also tested in view of a different ductility of the two alloys.

Microstructure and corrosion behavior of shielded metal arc-welded dissimilar joints comprising duplex stainless steel and low alloy steel

NASA Astrophysics Data System (ADS)

Srinivasan, P. Bala; Muthupandi, V.; Sivan, V.; Srinivasan, P. Bala; Dietzel, W.

2006-12-01

This work describes the results of an investigation on a dissimilar weld joint comprising a boiler-grade low alloy steel and duplex stainless steel (DSS). Welds produced by shielded metal arc-welding with two different electrodes (an austenitic and a duplex grade) were examined for their microstructural features and properties. The welds were found to have overmatching mechanical properties. Although the general corrosion resistance of the weld metals was good, their pitting resistance was found to be inferior when compared with the DSS base material.

Mechanical strength and microstructure of laser-welded Ti-6Al-7Nb alloy castings.

PubMed

Srimaneepong, Viritpon; Yoneyama, Takayuki; Kobayashi, Equo; Doi, Hisashi; Hanawa, Takao

2005-12-01

Mechanical properties of laser-welded castings of Ti-6Al-7Nb alloy, CP Ti, and Co-Cr alloy were investigated and compared to the unwelded castings using a tensile test. Dumbbell-shaped specimens were cut at the center, and two halves of the specimens were welded with an Nd:YAG laser welding machine at 220 or 260 V of laser voltage. The mechanical strength of 260 V groups was higher than that of 220 V groups for Ti-6Al-7Nb and Co-Cr alloys except for CP Ti. All 260 V laser-welded castings of Ti-6Al-7Nb alloy and CP Ti, which fractured outside the welded joints, exhibited ductile characteristics, while all laser-welded Co-Cr alloy castings, which fractured within the welded joints, showed brittle characteristics. This study proved that the mechanical strength of laser-welded Ti-6Al-7Nb alloy and CP Ti castings was as high as that of unwelded castings, while the mechanical properties of laser-welded alloy joints were influenced by microstructural changes.

Effect of soldering techniques and gap distance on tensile strength of soldered Ni-Cr alloy joint

PubMed Central

Lee, Sang-Yeob

2010-01-01

PURPOSE The present study was intended to evaluate the effect of soldering techniques with infrared ray and gas torch under different gap distances (0.3 mm and 0.5 mm) on the tensile strength and surface porosity formation in Ni-Cr base metal alloy. MATERIALS AND METHODS Thirty five dumbbell shaped Ni-Cr alloy specimens were prepared and assigned to 5 groups according to the soldering method and the gap distance. For the soldering methods, gas torch (G group) and infrared ray (IR group) were compared and each group was subdivided by corresponding gap distance (0.3 mm: G3 and IR3, 0.5 mm: G5, IR5). Specimens of the experimental groups were sectioned in the middle with a diamond disk and embedded in solder blocks according to the predetermined distance. As a control group, 7 specimens were prepared without sectioning or soldering. After the soldering procedure, a tensile strength test was performed using universal testing machine at a crosshead speed 1 mm/min. The proportions of porosity on the fractured surface were calculated on the images acquired through the scanning electronic microscope. RESULTS Every specimen of G3, G5, IR3 and IR5 was fractured on the solder joint area. However, there was no significant difference between the test groups (P > .05). There was a negative correlation between porosity formation and tensile strength in all the specimens in the test groups (P < .05). CONCLUSION There was no significant difference in ultimate tensile strength of joints and porosity formations between the gas-oxygen torch soldering and infrared ray soldering technique or between the gap distance of 0.3 mm and 0.5 mm. PMID:21264189

Human biomonitoring of aluminium after a single, controlled manual metal arc inert gas welding process of an aluminium-containing worksheet in nonwelders.

PubMed

Bertram, Jens; Brand, Peter; Hartmann, Laura; Schettgen, Thomas; Kossack, Veronika; Lenz, Klaus; Purrio, Ellwyn; Reisgen, Uwe; Kraus, Thomas

2015-10-01

Several existing field studies evaluate aluminium welding works but no thoroughly controlled exposure scenario for welding fume has been described yet. This study provides information about the uptake and elimination of aluminium from welding fumes under controlled conditions. In the Aachen Workplace Simulation Laboratory, we are able to generate welding fumes of a defined particle mass concentration. We exposed 12, until then occupationally unexposed participants with aluminium-containing welding fumes of a metal inert gas (MIG) welding process of a total dust mass concentration of 2.5 mg/m(3) for 6 h. Room air filter samples were collected, and the aluminium concentration in air derived. Urine and plasma samples were collected directly before and after the 6-h lasting exposure, as well as after 1 and 7 days. Human biomonitoring methods were used to determine the aluminium content of the samples with high-resolution continuum source atomic absorption spectrometry. Urinary aluminium concentrations showed significant changes after exposure compared to preexposure levels (mean t(1) (0 h) 13.5 µg/L; mean t(2) (6 h) 23.5 µg/L). Plasma results showed the same pattern but pre-post comparison did not reach significance. We were able to detect a significant increase of the internal aluminium burden of a single MIG aluminium welding process in urine, while plasma failed significance. Biphasic elimination kinetic can be observed. The German BAT of 60 µg/g creatinine was not exceeded, and urinary aluminium returned nearly to baseline concentrations after 7 days.

Real-time synchrotron x-ray observations of equiaxed solidification of aluminium alloys and implications for modelling

NASA Astrophysics Data System (ADS)

Prasad, A.; Liotti, E.; McDonald, S. D.; Nogita, K.; Yasuda, H.; Grant, P. S.; StJohn, D. H.

2015-06-01

Recently, in-situ observations were carried out by synchrotron X-ray radiography to observe the nucleation and growth in Al alloys during solidification. The nucleation and grain formation of a range of Al-Si and Al-Cu binary alloys were studied. When grain refiner was added to the alloys, the location of the nucleation events was readily observed. Once nucleation began it continued to occur in a wave of events with the movement of the temperature gradient across the field of view due to cooling. Other features observed were the settling of the primary phase grains in the Al-Si alloys and floating in the Al-Cu alloys, the effects of convection with marked fluctuation of the growth rate of the solid-liquid interface in the Al-Si alloys, and an absence of fragmentation. The microstructures are typical of those produced in the equiaxed zone of actual castings. These observations are compared with predictions arising from the Interdependence model. The results from this comparison have implications for further refinement of the model and simulation and modelling approaches in general. These implications will be discussed.

Effect of Pin Length on Hook Size and Joint Properties in Friction Stir Lap Welding of 7B04 Aluminum Alloy

NASA Astrophysics Data System (ADS)

Wang, Min; Zhang, Huijie; Zhang, Jingbao; Zhang, Xiao; Yang, Lei

2014-05-01

Friction stir lap welding of 7B04 aluminum alloy was conducted in the present paper, and the effect of pin length on hook size and joint properties was investigated in detail. It is found that for each given set of process parameters, the size of hook defect on the advancing side shows an "M" type evolution trend as the pin length is increased. The affecting characteristics of pin length on joint properties are dependent on the heat input levels. When the heat input is low, the fracture strength is firstly increased to a peak value and then shows a decrease. When the heat input is relatively high, the evolution trend of fracture strength tends to exhibit a "W" type with increasing the pin length.

Wear behaviour and morphology of stir cast aluminium/SiC nanocomposites

NASA Astrophysics Data System (ADS)

Tanwir Alam, Md; Arif, Sajjad; Husain Ansari, Akhter

2018-04-01

Wear and friction play a vital role in the service life of components. Aluminium matrix nanocomposites possess tremendous potential for a number of applications in addition to their present uses. It is valuable to the field of newer materials for better performance in tribological applications. In this work, dry sliding wear, friction coefficient and morphology of aluminium alloy (A356) reinforced with silicon carbide nanoparticles (SiCn) were investigated. A356/SiCn nanocomposites (AMNCs) containing 1–5 weight percentage of SiCn were prepared through two-step stir casting process via mechanical ball milling. The wear test was conducted on pin-on-disc test apparatus. Regression analysis was performed to develop mathematical functions to fit the experimental data points. Morphological studies of Al and SiCn as-received, wear debris and worn surfaces were further analysed by SEM along with EDS. The occurrence of oxide layers was observed on worn surfaces. Iron trace was identified by wear debris. It was found that the wear loss and friction coefficient were strongly influenced by mechanical milling and SiCn content. The results exhibited that the friction coefficient reduces with the addition of SiCn as well as with the increase in load. However, wear resistance increases as the reinforcement content increases because of the embedding and wettability effects.

Scanning and transmission electron microscopy study of the microstructural changes occurring in aluminium matrix composites reinforced with SiC particles during casting and welding: interface reactions

PubMed

Urena; Gomez De Salazar JM; Gil; Escalera; Baldonedo

1999-11-01

Processing of aluminium matrix composites (AMCs), especially those constituted by a reactive system such as Al-SiC, presents great difficulties which limit their potential applications. The interface reactivity between SiC and molten Al generates an aluminium carbide which degrades the composite properties. Scanning and transmission electron microscopes equipped with energy-dispersive X-ray spectroscopes are essential tools for determining the structure and chemistry of the Al-SiC interfaces in AMCs and changes occurring during casting and arc welding. In the present work, an aluminium-copper alloy (AA2014) reinforced with three different percentages of SiC particles was subjected to controlled remelting tests, at temperatures in the range 750-900 degrees C for 10 and 30 min. Arc welding tests using a tungsten intert gas with power inputs in the range 850-2000 W were also carried out. The results of these studies showed that during remelting there is preferential SiC particle consumption with formation of Al4C3 by interface reaction between the solid SiC particle and the molten aluminium matrix. The formation of Al4C3 by the same mechanism has also been detected in molten pools of arc welded composites. However, in this case there was formation of an almost continuous layer of Al4C3, which protects the particle against further consumption, and formation of aciculate aluminium carbide on the top weld. Both are formed by fusion and dissolution of the SiC in molten aluminium followed by reaction and precipitation of the Al4C3 during cooling.

Aluminium removal from water after defluoridation with the electrocoagulation process.

PubMed

Sinha, Richa; Mathur, Sanjay; Brighu, Urmila

2015-01-01

Fluoride is the most electronegative element and has a strong affinity for aluminium. Owing to this fact, most of the techniques used for fluoride removal utilized aluminium compounds, which results in high concentrations of aluminium in treated water. In the present paper, a new approach is presented to meet the WHO guideline for residual aluminium concentration as 0.2 mg/L. In the present work, the electrocoagulation (EC) process was used for fluoride removal. It was found that aluminium content in water increases with an increase in the energy input. Therefore, experiments were optimized for a minimum energy input to achieve the target value (0.7 mg/L) of fluoride in resultant water. These optimized sets were used for further investigations of aluminium control. The experimental investigations revealed that use of bentonite clay as coagulant in clariflocculation brings down the aluminium concentration of water below the WHO guideline. Bentonite dose of 2 g/L was found to be the best for efficient removal of aluminium.

Effect of joint design and welding type on the flexural strength and weld penetration of Ti-6Al-4V alloy bars.

PubMed

Simamoto Júnior, Paulo Cézar; Resende Novais, Veridiana; Rodrigues Machado, Asbel; Soares, Carlos José; Araújo Raposo, Luís Henrique

2015-05-01

Framework longevity is a key factor for the success of complete-arch prostheses and commonly depends on the welding methods. However, no consensus has been reached on the joint design and welding type for improving framework resistance. The purpose of this study was to assess the effect of different joint designs and welding methods with tungsten inert gas (TIG) or laser to join titanium alloy bars (Ti-6Al-4V). Seventy titanium alloy bar specimens were prepared (3.18 mm in diameter × 40.0 mm in length) and divided into 7 groups (n=10): the C-control group consisting of intact specimens without joints and the remaining 6 groups consisting of specimens sectioned perpendicular to the long-axis and rejoined using an I-, X30-, or X45-shaped joint design with TIG welding (TI, TX30, and TX45) or laser welding (LI, LX30, and LX45). The specimens were tested with 3-point bending. The fracture surfaces were first evaluated with stereomicroscopy to measure the weld penetration area and then analyzed with scanning electron microscopy (SEM). The data were statistically analyzed with 2-way ANOVA and the Tukey post hoc test, 1-way ANOVA and the Dunnett test, and the Pearson correlation test (α=.05). Specimens from the X30 and X45 groups showed higher flexural strength (P<.05) and welded area (P<.05) than specimens from the I groups, regardless of the welding type. TIG welded groups showed significantly higher flexural strength than the laser groups (P<.05), regardless of the joint design. TIG welding also resulted in higher welded areas than laser welding for the I-shaped specimens. No significant differences were found for the weld penetration area in the X45 group, either for laser or TIG welding. SEM analysis showed more pores at the fracture surfaces of the laser specimens. Fracture surfaces indicative of regions of increased ductility were detected for the TIG specimens. TIG welding resulted in higher flexural strength for the joined titanium specimens than laser welding

Microstructure and Fatigue Properties of Ultrasonic Spot Welded Joints of Aluminum 5754 Alloy

NASA Astrophysics Data System (ADS)

Mirza, F. A.; Macwan, A.; Bhole, S. D.; Chen, D. L.

2016-05-01

The purpose of this investigation was to evaluate the microstructural change, lap shear tensile load, and fatigue resistance of ultrasonic spot welded joints of aluminum 5754 alloy for automotive applications. A unique "necklace"-type structure with very fine equiaxed grains was observed to form along the weld line due to the mechanical interlocking coupled with the occurrence of dynamic recrystallization. The maximum lap shear tensile strength of 85 MPa and the fatigue limit of about 0.5 kN (at 1 × 107 cycles) were achieved. The tensile fracture occurred at the Al/Al interface in the case of lower energy inputs, and at the edge of nugget zone in the case of higher energy inputs. The maximum cyclic stress for the transition of fatigue fracture mode from the transverse through-thickness crack growth to the interfacial failure increased with increasing energy input. Fatigue crack propagation was mainly characterized by the formation of fatigue striations, which usually appeared perpendicular to the fatigue crack propagation.

Friction stir welding joint of dissimilar materials between AZ31B magnesium and 6061 aluminum alloys: Microstructure studies and mechanical characterizations

DOE Office of Scientific and Technical Information (OSTI.GOV)

Mohammadi, J.; Behnamian, Y.; Mostafaei, A., E-mail: amir.mostafaei@gmail.com

2015-03-15

Friction stir welding is an efficient manufacturing method for joining dissimilar alloys, which can dramatically reduce grain sizes and offer high mechanical joint efficiency. Lap FSW joints between dissimilar AZ31B and Al 6061 alloy sheets were made at various tool rotation and travel speeds. Rotation and travel speeds varied between 560–1400 r/min and 16–40 mm/min respectively, where the ratio between these parameters was such that nearly constant pitch distances were applied during welding. X-ray diffraction pattern (XRD), optical microscopy images (OM), electron probe microanalysis (EPMA) and scanning electron microscopy equipped with an energy-dispersive X-ray spectroscopy (SEM-EDS) were used to investigatemore » the microstructures of the joints welded. Intermetallic phases including Al{sub 12}Mg{sub 17} (γ) and Al{sub 3}Mg{sub 2} (β) were detected in the weld zone (WZ). For different tool rotation speeds, the morphology of the microstructure in the stir zone changed significantly with travel speed. Lap shear tensile test results indicated that by simultaneously increasing the tool rotation and travel speeds to 1400 r/min and 40 mm/min, the joint tensile strength and ductility reached a maximum. Microhardness measurements and tensile stress–strain curves indicated that mechanical properties were affected by FSW parameters and mainly depended on the formation of intermetallic compounds in the weld zone. In addition, a debonding failure mode in the Al/Mg dissimilar weld nugget was investigated by SEM and surface fracture studies indicated that the presence of intermetallic compounds in the weld zone controlled the failure mode. XRD analysis of the fracture surface indicated the presence of brittle intermetallic compounds including Al{sub 12}Mg{sub 17} (γ) and Al{sub 3}Mg{sub 2} (β). - Highlights: • Dissimilar Al/Mg joint was obtained by lap friction stir welding technique. • Effect of rotation and travel speeds on the formation of intermetallic

[Determination of aluminium in flour foods with photometric method].

PubMed

Ma, Lan; Zhao, Xin; Zhou, Shuang; Yang, Dajin

2012-05-01

To establish a determination method for aluminium in flour foods with photometric method. After samples being treated with microwave digestion and wet digestion, aluminium in staple flour foods was determined by photometric method. There was a good linearity of the result in the range of 0.25 - 5.0 microg/ml aluminium, r = 0.9998; limit of detection (LOD) : 2.3 ng/ml; limit of quantitation (LOQ) : 7 ng/ml. This method of determining aluminium in flour foods is simple, rapid and reliable.

Microstructural Influence on Mechanical Properties in Plasma Microwelding of Ti6Al4V Alloy

NASA Astrophysics Data System (ADS)

Baruah, M.; Bag, S.

2016-11-01

The complexity of joining Ti6Al4V alloy enhances with reduction in sheet thickness. The present work puts emphasis on microplasma arc welding (MPAW) of 500-μm-thick Ti6Al4V alloy in butt joint configuration. Using controlled and regulated arc current, the MPAW process is specifically designed to use in joining of thin sheet components over a wide range of process parameters. The weld quality is assessed by carefully controlling the process parameters and by reducing the formation of oxides. The combined effect of welding speed and current on the weld joint properties is evaluated for joining of Ti6Al4V alloy. The macro- and microstructural characterizations of the weldment by optical microscopy as well as the analysis of mechanical properties by microtensile and microhardness test have been performed. The weld joint quality is affected by specifically designed fixture that controls the oxidation of the joint and introduces high cooling rate. Hence, the solidified microstructure of welded specimen influences the mechanical properties of the joint. The butt joint of titanium alloy by MPAW at optimal process parameters is of very high quality, without any internal defects and with minimum residual distortion.

Pseudoplasticity of Propellant Slurry with Varied Aluminium Content for Castability Development

NASA Astrophysics Data System (ADS)

Restasari, A.; Budi, R. S.; Hartaya, K.

2018-04-01

The modification of the percentage of aluminium is necessary to obtain certain specific impulse. But, it affects the pseudoplasticity of propellant in elapsed time that is important in casting. Therefore, this research attempts to investigate the pseudoplasticity of propellant slurry with varied aluminium contents and as time elapsed, the range of percentage of aluminium and time that allows propellant slurry to be well processed. The methods include measuring the viscosity of propellant slurries that contain 6, 8, 10, 12, 14, 16 and 18% of aluminium at varied shear rates until 40 minutes after mixing by using Brookfield viscometer. The graphs of viscosity versus shear rate were made to determine pseudoplasticity index. After that, the graph volume fraction versus pseudoplasticity index were made to be investigated. It is concluded that the more aluminium contents, the slurries with 6 to 12% aluminium contents exhibit more pseudoplastic behaviour, but the slurries with 12 to 16% aluminium exhibit less pseudoplastic. While, slurry of 18% aluminium exhibit high pseudoplasticity. In the correlation with the time, the slurry compositions of 6, 8, 14, 16% aluminium become more pseudoplastic as time elapsed. While, for compositions of 10, 12 and 18% aluminium, the trend becomes contrary. Based on the pseudoplasticity index, propellant slurries that contain 10 and 14% of aluminium are suitable for pressure casting. While for slurries with 6, 8 and 16% of aluminium are also suitable for vacuum casting. All of those suitability are possesed until 40 minutes after mixing. While, the composition of slurries that contain 12 and 18% of aluminium need to be modified to enhanced its castability.