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Showing papers on "Aluminium alloy published in 2001"


Journal ArticleDOI
TL;DR: A review of available information on factors which contribute to poor wetting between ceramic phases, and liquid metals is presented in this article, focusing on aluminium, a common MMC matrix material.

327 citations


Journal ArticleDOI
TL;DR: In this paper, a three-step manufacturing process to fabricate complex shaped components can be envisaged: cast sheet or hot-pressed powder metallurgy sheet + friction stir processing + superplastic forging or forming.
Abstract: Friction stir processing is a new thermo-mechanical processing technique that leads to a microstructure amenable for high strain rate superplasticity in commercial aluminum alloys. Friction stirring produces a combination of very fine grain size and high grain boundary misorientation angles. Preliminary results on a 7075 Al demonstrate high strain rate superplasticity in the temperature range of 430-510 °C. For example, an elongation of >1000 % was observed at 490 °C and 1 × 10 -2 s -1 . This demonstrates a new possibility to economically obtain a superplastic microstructure in commercial aluminum alloys. Based on these results, a three-step manufacturing process to fabricate complex shaped components can be envisaged: cast sheet or hot-pressed powder metallurgy sheet + friction stir processing + superplastic forging or forming.

256 citations


Journal ArticleDOI
TL;DR: In this article, the effects of volume fraction, Al 2 O 3 particle size and porosity in the composites on the abrasive wear resistance of compo-casting Al alloy MMCs have been studied for different abrasive conditions.

219 citations


Journal ArticleDOI
TL;DR: In this paper, the effects of Ca addition on the microstructure and mechanical properties of AZ91 magnesium alloy have been studied, and the results show that the Ca addition can refine the micro-structure, reduce the quantity of Mg17Al12 phase, and form new Al2Ca phase.
Abstract: The effects of Ca addition on the microstructure and mechanical properties of AZ91 magnesium alloy have been studied The results show that the Ca addition can refine the microstructure, reduce the quantity of Mg17Al12 phase, and form new Al2Ca phase in AZ91 magnesium alloy With the Ca addition, the tensile strength and elongation of AZ91magnesium alloy at ambient temperature are reduced, whereas Ca addition confers elevated temperature strengthening on AZ91 magnesium alloy The tensile strength at 150°C increases with increasing Ca content The impact toughness of AZ91magnesium alloy increases, and then declines as the Ca content increases The tensile and impact fractographs exhibit intergranular fracture features, Ca addition changes the pattern and quantity of tearing ridge, with radial or parallel tearing ridge increasing, tensile strength, elongation and impact toughness reduce

193 citations


Journal ArticleDOI
TL;DR: Anodizing of binary Mg-Al alloys and intermetallic Mg17Al12 was studied in a solution containing 3 M KOH+0.6 M KF+ 0.21 M Na3PO4, with and without addition of 0.4 M and 1.1 M aluminate as mentioned in this paper.

179 citations


Journal ArticleDOI
TL;DR: In this paper, the growth morphology of the Al3Sc primary particles formed in a slightly hypereutectic Al 0.7Sc alloy has been studied for a range of cooling rates in a FEG-SEM, using extracted particles, and in the TEM.

148 citations


Journal ArticleDOI
TL;DR: In this paper, the effect of machining parameters (discharge current, pulse-on-time, pulseoff time, voltage) on the machining feed rate and surface roughness during wire electrical discharge machining (WEDM) of metal matrix composite AlSi7Mg/SiC and AlSi 7mg/Al2O3 composites are investigated.

126 citations


Journal ArticleDOI
TL;DR: In this paper, the production of net shape SiC particle reinforced AA6061 aluminium alloy components by a conventional powder metallurgical processing technique, involving the uniaxial cold pressing and sintering of composite powders, was investigated.
Abstract: The machining difficulties and processing costs related to particle reinforced aluminium matrix composites have limited the application range of these advanced materials. The present investigation deals with the production of net shape SiC particle reinforced AA6061 aluminium alloy components by a conventional powder metallurgical processing technique, involving the uniaxial cold pressing and sintering of composite powders. Three aluminium alloy powder sizes were combined with three SiC particle sizes in various volume fractions of up to 20% SiC, and processed to produce net shape tensile test samples. The tensile test results and the morphological analysis of the fracture surfaces show that this process may be used to produce well sintered, small-to-medium sized net shape aluminium composite components exhibiting ultimate tensile strength (UTS) of up to 324 MPa. The successful production of these aluminium powder based components is affected strongly by the aluminium powder size, SiC volume fraction and the SiC particle size. It is also linked to the penetration of the aluminium powder oxide layer by the hard SiC particles, which occurs during cold compaction. Based on the present investigations, a number of processing improvements are suggested, which should further advance the usefulness of this technically uncomplicated net shape processing method for the production of aluminium matrix composites.

126 citations


Journal ArticleDOI
TL;DR: In this article, three alloys of the above types (nano-Sn, AlSi0.1 and Li4.4Sn) were studied by electrochemical impedance spectroscopy (EIS) to determine their electrochemical kinetics and intrinsic resistance during initial lithium insertion-extraction.

116 citations


Journal ArticleDOI
TL;DR: The application of ultrasonic frequency (20 kHz) loading to test fatigue and fracture mechanical properties of materials is briefly reviewed and recent investigations on high strength aluminium alloys are reported as mentioned in this paper.

108 citations


Journal ArticleDOI
TL;DR: In this paper, the effect of variation in the aluminium surface microstructure, caused by different surface pretreatment, on the performance of the deposited chromate conversion coating was investigated by means of measurements performed in aggressive and middle aggressive electrolytes.

Journal ArticleDOI
TL;DR: In this article, a cyclic four point bend (CPB) failure model was developed to predict the fatigue strength for each of the competing failure modes of face fatigue, core shear, and core indentation.

Journal ArticleDOI
TL;DR: In this paper, the binding energy (BE) of the C 1s photoelectron of adventitious hydrocarbon was found to be dependent on the thickness of the insulating AlN/Al2O3 surface layer.

Journal ArticleDOI
01 Oct 2001-Wear
TL;DR: In this paper, the wear properties of the aluminium alloy-Ni 3 Al composites and the monoliths were examined by dry sliding against an M2 steel counterface at 0.94m/s and a load in the range 42-140 n in a block-on-ring configuration.

Journal ArticleDOI
TL;DR: In this article, a minimum growth rate of a propagating crack of approximately 10 −10 m/cycle was found, whereas crack propagation rates may be as low as 10 −12 m/cycled in a vacuum.
Abstract: Fatigue investigations of AlZnMgCu1.5 aluminium alloy have been performed with conventional testing equipment (cyclic frequency 100 Hz) and with ultrasonic equipment (20 kHz). No statistically significant influence of cyclic frequency on lifetimes was found in the investigated regime, i.e. cycles to failure above 10 5 . Different heat treating influenced lifetimes and near threshold crack growth properties, and fatigue properties of AlZnMgCu1.5-T6 were superior to AlZnMgCu1.5-T66 and AlZnMgCu1.5-T64. Fatigue crack propagation in the range of approximately 10 −9 m/cycle and below measured at ultrasonic frequency is affected by air humidity, since growth rates are below the mean diffusion distance of hydrogen during one cycle. In ambient air, a minimum growth rate of a propagating crack of approximately 10 −10 m/cycle was found, whereas crack propagation rates may be as low as 10 −12 m/cycle in a vacuum. Threshold values of AlZnMgCu1.5-T6 in ambient air and in a vacuum are 1.5–1.55 MPa√m and 2.7–2.95 MPa√m, respectively.

Journal ArticleDOI
TL;DR: In this paper, the microstructure and texture of friction stir welded joints of hot mill stock 5754 and 5182 aluminium alloy sheets were examined after a commercial joining process, where the as received sheet was cut into two pieces, one piece was cold rolled with 20 reduction in thickness, whereas the other was subsequently aged at 230C for 100 h after the 20 prestrain.
Abstract: The microstructure and texture of friction stir welded joints of hot mill stock 5754 and 5182 aluminium alloy sheets were examined after a commercial joining process. The as received sheet was cut into two pieces, one piece was cold rolled with 20 reduction in thickness, whereas the other was subsequently aged at 230C for 100 h after the 20 prestrain. These two pieces with different thermal pretreatments were joined by friction stir welding FSW. On FSW, a uniform fine grained microstructure in the through thickness of the sheet having a width corresponding to the diameter of tool shoulder was observed in both the 5754 and 5182 joints. Moreover, the microhardness profile did not reveal a softened heat affected zone between the weld and the base metal. An X-ray pole figure study showed that the 5754 and 5182 weld zones were not highly textured and both comprised of similar texture components. The calculated average sheet formability of the weld zones predicts a more isotropic behaviour than that for...

Journal ArticleDOI
TL;DR: In this article, a glass matrix composites were obtained by mixing and sintering materials coming from municipal solid waste incinerators (MSWIs) and from one aluminium foundry.
Abstract: Glass matrix composites have been obtained by mixing and sintering “negative cost” materials coming from municipal solid waste incinerators (MSWIs) and from one aluminium foundry. The bottom ashes from two MSWIs were used to obtain the glass matrix and the solid wastes from an aluminium alloy industry were employed as a second phase. The bottom ashes were vitrified by heating at 1400°C without any additive. The vitrification process reduces the bottom ash initial volume by about 60%. The obtained glass has a Young modulus of 96 GPa and a Vickers hardness of 6 GPa. The composites were prepared in air by a low temperature pressure-less viscous phase sintering process (740–830°C) and were morphologically and mechanically characterised. The composites showed a bending strength up to 50 MPa at room temperature and could be proposed for applications in the field of tiles.

Journal ArticleDOI
TL;DR: In this paper, an oxide model was established to describe the oxidation procedure on the surface of the molten Mg-9Al-0.5Zn−0.3Be alloy.
Abstract: Excellent ignition proof performance was obtained during the melting of Mg–9Al–0.5Zn–0.3Be alloy directly in the atmosphere. XRD and AES analysis indicated that the oxide film on the surface of the molten Mg–9Al–0.5Zn–0.3Be alloy exhibited a duplex structure, which was in agreement with the result of thermodynamic analysis. The outer layer of the oxide film mainly consists of MgO, which grows according to the parabolic law. The inner layer is a mixture of MgO and BeO, and its growth follows a linear law approximately. This inner layer acts as a barrier to reduce the outward diffusion of Mg2+, which leads to the excellent ignition proof performance. An oxide model was established to describe the oxidation procedure on the surface of the molten Mg–9Al–0.5Zn–0.3Be alloy.


Journal ArticleDOI
TL;DR: In this paper, the effect of heat treatment on the filiform corrosion susceptibility of rolled aluminium alloy AA3005 at temperatures in the range 150-500°C was investigated and it was shown that a drastic loss of corrosion resistance takes place as a result of annealing at temperatures exceeding 350°C.

Journal ArticleDOI
TL;DR: In this article, the effect of inhomogeneous distribution of second phase particles on strength and damage has been studied using a model system based on rapidly solidified Al-Cu alloys which result in Al-cuAl2 composites, Materials with both a homogeneous and bimodal distribution of the CuAl2 particles have been produced.
Abstract: The effect of an inhomogeneous distribution of second phase particles on strength and damage has been studied here using a model system based on rapidly solidified Al–Cu alloys which result in Al–CuAl2 composites, Materials with both a homogeneous and bimodal distribution of the CuAl2 particles have been produced. When tested in compression (i.e. little or no damage) the clustered materials are significantly stronger than homogeneous alloys containing the same overall CuAl2 volume fraction. These results are consistent with a previously published self-consistent model.

Journal ArticleDOI
TL;DR: In this article, a three-dimensional transient finite element model (FEM) featuring heat transfer, consolidation and thermal degradation was used for simulating the resistance welding between carbon fiber (CF) rein-forced polyetherimide (PEI) and aluminium substrates (7075-T6 grade alloy) was presented.
Abstract: An investigation of the resistance welding between carbon fiber (CF) rein-forced polyetherimide (PEI) and aluminium substrates (7075-T6 grade alloy) is presented. A three-dimensional transient finite element model (FEM) featuring heat transfer, consolidation and thermal degradation was used for simulating the process. Two mechanisms are distinguished in the consolidation model: (1) removal of the initial surface profile of the laminate modelled by the establishment of intimate contact between the two substrate surfaces and (2) penetration of the thermoplastic (TP) polymer in the micro-pores of the aluminium oxide surface modelled using a capillary flow model. The “optimal” welding time based on the maximum lap shear strength (LSS) was determined for various power levels and correlated to the bonding time predicted by the FEM. Consolidation quality and failure mechanisms were discussed in relation to processing parameters. The effect of the welding operation on overaging (annealing) of the aluminium alloy ...

Journal ArticleDOI
TL;DR: In this paper, the formation of non-planar interfaces as a consequence of morphological instability at the solid/liquid interface during solidification of the liquid layer at the bonding temperature is predicted.

Journal ArticleDOI
TL;DR: In this paper, the effects of grain size, composition and superlattice type on the low-temperature and high temperature superplastic properties of titanium aluminides are compared.
Abstract: Data on superplastic behavior of intermetallic alloys with high ordering energy, such as stoichiometric TiAl and Ti3Al and a number of alloys based on TiAl, with submicron grain size are summarized. The small grain size resulted in a temperature range for superplasticity of 600–900°C that is 200–400°C lower than that for material with micron-sized grains. This paper reports on the effects of grain size, composition and superlattice type on the low-temperature and high temperature superplastic properties of titanium aluminides. Low temperature and high-temperature superplastic properties of the titanium aluminides are compared.

Patent
09 Feb 2001
TL;DR: In this paper, a brazing sheet product having a core sheet made of an aluminium alloy, having one or both of the surfaces of said core sheet clad with an aluminium clad layer, and a layer comprising nickel on the outersurface of either the core sheet or layers, characterised in that there is a layer (4) comprising zinc or tin as a bonding layer between the aluminium layer or layers and the layer (3) comprising nickel.
Abstract: The invention relates to a brazing sheet product having a core sheet (1) made of an aluminium alloy, having one or both of the surfaces of said core sheet clad with an aluminium clad layer (2), and a layer (3) comprising nickel on the outersurface of one or both said aluminium clad layer or layers (2), characterised in that there is a layer (4) comprising zinc or tin as a bonding layer between said outersurface of said aluminium clad layer or layers (2) and said layer (3) comprising nickel and wherein the aluminium clad alloy layer comprising, in weight percent: Si 2 to 18; Mg up to 8.0; Zn up to 5.0; Cu up to 5.0; Mn up to 0.30; In up to 0.30; Fe up to 0.80; Sr up to 0.20; at least one element selected from the group consisting of: Bi 0.01 to 1.0; Pb 0.01 to 1.0; Li 0.01 to 1.0; Sb 0.01 to 1.0; Mg 0.2 to 2.0 impurities each up to 0.05, total up to 0.20 balance aluminium.

Journal ArticleDOI
TL;DR: In this paper, the authors investigated the ultimate strength of stiffened aluminium panels with predominantly torsional failure modes by experimental and theoretical analysis and compared the numerical predictions with strength of material formulations used in DNV Rules for Classification of High Speed and Light Craft (Rules for classification of high speed and light craft, Hull structural design (1996)), NORSOK (Design of steel structures (1998)) all for steel, using the relevant values of the modulus elasticity and yield strength of aluminium, as well as EUROCODE 9 (Eurocode 9, Part 1-1: General rules
Abstract: The aim of this paper is to investigate the ultimate strength of aluminium plates with flatbar stiffeners with a torsional buckling or tripping failure mode. The formulations for torsional buckling of stiffeners in steel plating are still debated. Compared with steel structures, the ultimate strength of aluminium structures is sensitive not only to residual stresses and initial deformations, but also to the deterioration of mechanical strength in heat-affected zones (HAZ). In the present paper, the ultimate strength of stiffened aluminium panels with predominantly torsional failure modes is investigated by experimental and theoretical analysis. Stiffened panels made of the aluminium alloy AA5083-H116 and AA6082-T6 are considered. Various height of flatbar and various thickness of plate and stiffener were studied. The test results are compared with numerical predictions by using the finite element code ABAQUS (ABAQUS Version 5.7 (1997)), considering the influence of initial deflections, welding residual stresses and HAZ. The influence of HAZ and residual stresses on the ultimate strength of stiffened aluminium panels with the actual failure mode is discussed in detail. The numerical predictions are also compared with strength of material formulations used in DNV Rules for Classification of High Speed and Light Craft (Rules for classification of high speed and light craft, Hull structural design (1996)), NORSOK (Design of steel structures (1998)) all for steel, using the relevant values of the modulus elasticity and yield strength of aluminium, as well as EUROCODE 9 (Eurocode 9, Part 1-1: General rules (1998)).

Journal ArticleDOI
TL;DR: In this article, several physical vapour deposited (PVD) coatings, namely, TiN, CrN and TiCN, were evaluated for their ability to eliminate soldering during high pressure die casting of aluminium alloys.
Abstract: During high-pressure die-casting (HPDC) of aluminium alloys, there is a tendency for the molten alloy to react with the tool steel die, core pins and inserts. This occurrence within the high pressure die casting (HPDC) industry is referred to as ‘soldering’. It is of concern to high-pressure die casters because of down-time due to the regular removal of the soldered layer and its detrimental affect on die life and casting quality. In this investigation, several physical vapour deposited (PVD) coatings, namely, TiN, CrN and TiCN, were evaluated for their ability to eliminate soldering during HPDC of aluminium alloys. Accelerated semi-industrial trials were carried out in a 250-t Toshiba HPDC machine using a specially designed die made of P20 tool steel with removable core pins. The results from these trials showed that PVD coatings can act as a physical barrier coating preventing any reaction between the molten aluminium alloy and the tool steel. Thus the problem of soldering on such tools as core pins can be eliminated in high HPDC of aluminium alloys. In the accelerated trials, it was found that soldering was replaced by a built-up layer of cast aluminium alloy, which was less detrimental to tool life and reduced machine down-time due to the reduced need for tool polishing. The experimental results were confirmed by conducting in-plant HPDC trials.

Journal ArticleDOI
TL;DR: In this paper, the fatigue properties of a thermomechanically treated 7475 aluminium alloy have been investigated and it was shown that the alloy exhibited superior fatigue life compared to conventional structural aluminium alloys and comparable stage II crack growth rate.
Abstract: Fatigue properties of a thermomechanically treated 7475 aluminium alloy have been studied in the present investigation. The alloy exhibited superior fatigue life compared to conventional structural aluminium alloys and comparable stage II crack growth rate. It was also noticed that the fatigue crack initiated from a surface grain and the crack extension was dominated by ductile striations. Analysis also revealed that this alloy possessed fracture toughness and tensile properties superior to that noticed with other structural aluminium alloys. Therefore the use of this alloy can safely reduce the overall weight of the aircraft.

Journal ArticleDOI
TL;DR: In this paper, the effect of Mg on the sintering phenomenon of aluminium alloy powder particles has been examined using XPS analysis of the chemical reaction at the top most surface of the particle during heating.
Abstract: The effect of Mg on the sintering phenomenon of aluminium alloy powder particles has been examined using XPS analysis of the chemical reaction at the top most surface of the particle during heating. The relative density of the sintered material increases by 9% according to the increase of Mg content. The mechanical properties of the sintered material also increase remarkably as the Mg content in the particle increases. The ratio of the dimple patterns observed at the fractured surface after the tensile test also increases. It is considered that Mg acts to deoxidise the Al2O3 film that covers the particle surface as a barrier and helps sintering between the particles.

Journal ArticleDOI
TL;DR: In this paper, a microstructure-property relationship was established for AZ91D, which is one of the highest strength magnesium alloys, by measuring the fracture behavior of the material.
Abstract: Recently magnesium alloys, owing to their low density and excellent specific strength have been attractive to designers as an advanced material for coping with energy conservation and environmental pollution regulations. Much of the recent developments of magnesium alloys and processes have been driven by the requirements of the aerospace industry, although some successful ones have found application in other high performance applications particularly those in the automotive area [1, 2]. However, low fatigue strength under service conditions has been an important factor in limiting the use of magnesium alloys in highly stressed designs. As there have been few publications on the fatigue behaviors of magnesium alloys and magnesium composite materials, it is the aim of this study to establish some microstructure-property relationship for AZ91D, which is one of the highest strength magnesium alloys. AZ91D alloy was subjected to solution heattreatment at 380 ◦C for 8 h and then at 420 ◦C for 24 h in argon atmosphere followed by water quench at 25◦C. The solution treated alloy was aged at 200 ◦C for 24 h in a vacuum oven. Uniaxial tensile test was carried out at an initial strain rate of 1 × 10−4/s using cylindrical specimens with 6 mm gauge diameter and 30 mm gauge length on an Instron machine equipped with a computer data acquisition system [3]. The microhardness was measured for each heat treatment condition using a Vickers microhardness tester under a 200-g load and 15 s duration. Fatigue life of each of the microstructures was then characterized using cylindrical tension-compression type specimens at a fixed frequency of 25 Hz and load ratio ( R) of 0.1 using a servo hydraulic universal testing machine of 25 kN capacity in the laboratory environment. The fatigue crack growth rates were studied using 1/2 compact tension (CT) specimens as described in ASTM standard E64793 [4]. All specimens were optically polished using 0.5-micron diamond particles before testing. Fatigue crack growth rates as a function of the alternating stress intensity factor range ( 1K = Kmax− Kmin) were determined on the fabricated specimens under load control mode in a servo-hydraulic machine. These tests were conducted in the laboratory air at room temperature (25◦C) using a sine-wave cyclic frequency of 10 Hz and a load ratio ofR= 0.1. The crack extensions in the test specimens were monitored using a stereo microscope on optically polished specimen surfaces. The major emphasis in these studies was laid on crack path morphology and determining the 1Kth values. In order to achieve these values, all tests were started with an initial 1K ≈ 5 MPa√m, and load-shedding was done in steps keeping the load-ratio of R= 0.1. The tests were terminated at the 1K value where no physical crack growth could be monitored for 1 million cycles of loading. Fracture surfaces of all tested specimens were gold coated immediately after the tests. The coated fracture surfaces were examined using SEM. The optical micrographs of as cast, solution treated and aged microstructures are shown in Fig. 1. In the as-cast state, the β phase (Mg17Al12) can be seen at the grain boundary and eutectic α phase exists at the adjacent toβ phase as shown in Fig. 1a. In the solution treated condition, Fig. 1b showed that some β phase still remains at the grain boundaries without dissolving. In the solution and aged condition, β phase precipitates again at the grain boundaries as shown in Fig. 1c. Tensile properties and hardness of AZ91D alloy in three different heat treatment conditions are shown in Table I. It can be seen from the table that the hardness, tensile, and yield strength of the material are significantly improved after heat treatment. However, the elongation to failure is lowest in the case of solution and aged condition material. The differences in the fracture behaviors between the as-cast and the heat treated AZ91D alloy can be seen from the SEM fractographs in Fig. 2a through c. The absence of radial zone in the fracture surface of aged specimen as shown in Fig. 2c indicates that crack initiation takes place in several locations and such cracks grow and join to form the fibrous zone and also intergranular propagation of the cracks mainly from the defects. This is in agreement with the low elongation of the aged specimens. The fractographs, Fig. 2a and b, of as-cast and solution treated specimens show predominantly cleavage fracture. The S-N data obtained from the fatigue life test (Fig. 3) show that the solution treated material has improved fatigue strength at any given stress level as compared to as-cast or aged materials.