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Abstract—The review presents the original experimental data on the structure formation and properties of titanium, aluminum, copper, and their alloys upon intense deformation and shock-wave conditions. The main volume of the article is devoted to the production of the submicrocrystalline and nanocrystalline non-ferrous metals and alloys by dynamic channel-angular pressing. The optimal regimes of DCAP which make it possible to obtain high-quality bulk samples without surface defects were determined for the each material. The changes in the morphological and dimensional characteristics of the structure of different materials depending on the deformation regime were studied in detail using complex analytical methods. The mechanisms of the deformation and deformation strengthening of metals and alloys in a wide range of strain-rate deformation have been considered. New data on the thermal stability of SMC and NC materials obtained by the dynamic pressing are presented. The analysis of change in the dynamic characteristics upon shock-wave compression depending on the nature of alloys has been carried out. The relationship between the composition and structure of the SMC aluminum, copper, and their alloys obtained by DCAP with mechanical properties in a wide range of strain rates of 3 × 10–3–6 × 105 s–1 has been established. In conclusion, the principles of the creation of SMC and NC of fcc materials with different energy of stacking fault defects of aluminum, copper and their alloys and titanium by methods of severe plastic deformation (SPD) are described. [ABSTRACT FROM AUTHOR]

Welding a high quality aluminum matrix discontinuously reinforced composite is a difficult task and can be expensive. Joining the composite to a commercial aluminum alloy can reduce costs by only using the expensive material where it is needed. The solid state process Friction Stir Welding, FSW, is a promising alternative to fusion welding techniques since it can avoid the problems related to the molten metal and its solidification. We study the effect of the lateral off-set on the strength and fracture location in welds of 8 mm thick 2024Al alloy and 17%SiC/2124Al composite. We used a novelty diagonal set up to adjust the rotational and welding speed, and to select the three lateral off-sets for straight welds. The lateral off-set determines the amount of plastic deformation that the plates' contact surface undergoes. Therefore, it affects the shape and bonding quality of the alloy-composite boundary, which determines the strength of these welds. The highest joint efficiency (90% of 2024Al-T351) was obtained for the centered off-set, which had the most resistant boundary. However, the results suggest that a joint with an off-set of around 1.5 mm into the retreating side could exceed the efficiency obtained. [ABSTRACT FROM AUTHOR]

Hybrid microwave sintering is a promising method to enhance better properties of sintered metallic alloys. Mixtures of Zn-Al-Cu-Mg elements with 8, 12 and 27 wt-% fractions of Al were sintered by hybrid microwave method and compared with conventionally sintered products. Compositional, structural and thermo-mechanical characteristics of the sintered products were investigated. Analysis of the results confirmed the significant technical and economic advantages of hybrid microwave sintering to conventional sintering. The coefficient of thermal expansion was reduced from 28·25 to 21·23 µm (m °C)−1 by increasing the Al content from 8 to 27 wt-%. [ABSTRACT FROM AUTHOR]

Highlights: [•] Formation of Ti2Ni and thermal stresses leads to formation of cracks in weld metal. [•] Sound defect-free joint could be obtained with change of fusion metal composition. [•] Inserting a copper interlayer restricts formation of the Ti2Ni in weld metal. [•] Hardness of Ti–Cu IMCs is less than hardness of Ti–Ni IMCs. [Copyright &y& Elsevier]

Abstract: Friction stir welding (FSW) technique is considered to offer advantages over fusion welding in terms of dissimilar jointing. However, some challenges still exist in the butt FSW of dissimilar Ti and Al metals. The present research employed a modified butt joint configuration into the FSW of Ti–6Al–4V alloy to Al–6Mg alloy with a special pin plunge setup, aiming to obtain a high-quality Ti-to-Al joint, avoid butt flaw or Al melting, and reduce the tool shoulder attrition. Under different FSW process conditions, the examinations and analyses of macro/micro-structures, mechanical tensile properties and fractographies of the dissimilar joints were conducted. The joint mechanical tensile strength can reach more than 92% of the parent Al alloy strength, with a tensile fracture path within the Al alloy butt side. The characteristics and formation mechanisms of the diffusion typed and reaction typed Ti–Al butt-welded interface structures were detailed. The bulky intermetallic compounds (IMC) interlayer at the butt-welded interface had a negative effect on the joint tensile strength, comparing with the Ti–Al diffusion bonding interlayer of ∼2 μm in thickness, which was produced via lower tool rotating speed and lower pin-offset value towards Ti alloy butt side. [Copyright &y& Elsevier]

The variations of thermal conductivities of solid phases versus temperature for pure Sn, pure Zn and Sn-9 wt.% Zn, Sn-14 wt.% Zn, Sn-50 wt.% Zn, Sn-80 wt.% Zn binary alloys were measured with a radial heat flow apparatus. The thermal conductivity ratios of liquid phase to solid phase for the pure Sn, pure Zn and eutectic Sn-9 wt.% Zn alloy at their melting temperature are found with a Bridgman-type directional solidification apparatus. Thus, the thermal conductivities of liquid phases for pure Sn, pure Zn and eutectic Sn-9 wt.% Zn binary alloy at their melting temperature were evaluated by using the values of solid phase thermal conductivities and the thermal conductivity ratios of liquid phase to solid phase. [ABSTRACT FROM AUTHOR]

Highlights: [•] Successful dissimilar joining of 5A02 Al and pure Cu by friction stir welding. [•] A composite-like structure strengthened the weld nugget zone. [•] Nano-scaled reaction layers at the Al/Cu interface were observed and identified. [•] Formation mechanism of microstructure in the weld nugget zone was clarified. [•] Both composite structure and ultra-thin layers enhanced joint strength. [ABSTRACT FROM AUTHOR]

The present work has been conducted to study the effect of rolling parameters (strain rate and temperature) on the microstructural evolutions and mechanical properties of 6061 aluminum alloy. The results indicate that the predominant restoration process during rolling at 250°C is dynamic recovery, and the driving force is not high enough to trigger dynamic recrystallization. However, primary recrystallized grains were clearly evident in the microstructure of the specimen rolled at 350°C. Moreover, at 450°C not only the volume fraction of dynamically recrystallized grains is increased but the formation of some new precipitates is recognized. The tensile test results show that the room temperature strength and ductility are increased by increasing the rolling temperature in the range of 250–450°C. Moreover, at a given rolling temperature the yield strength is decreased with increasing strain rate. The observed trends are explained through microstructural evolutions upon hot rolling as well as dynamic precipitation of Mg2Si and the Fe or Cu rich particles. [ABSTRACT FROM AUTHOR]

Abstract: In current research, the effect of Ti (Al–5Ti–1B) master alloy on the macrostructure of A6070 Al alloy has been investigated. The results revealed that the optimum Ti content to achieve a fine-grained structure was found to be 0.02wt.%. Then, in order to investigate the effect of strain-induced melt activation (SIMA) process on the microstructures of unrefined and 0.02% Ti-refined A6070 alloy optical and scanning electron microscopy (SEM) were used. The results showed that as the applied pre-deformation increases, the globular size decreases and the sphericity of globules increases. The results revealed that for the desired microstructure of the alloy during SIMA process, the optimum temperature, holding time and strain are 630°C, 20min and 30%, respectively. The results showed that the average globule size achieved to a minimum value of 68μm and 55μm in the unrefined and 0.02% Ti-refined alloy, respectively. The results obtained from tensile testing showed that SIMA process increases the tensile properties of the alloy significantly, although due to occurrence of recrystallization during SIMA process, tensile ductility increases more than tensile strength. [Copyright &y& Elsevier]

Abstract: The aim of this study is to investigate the possibility of manufacturing an aluminum automotive component (a small sized car door panel) using a highly reconfigurable and cheap forming process. Specifically, the sheet hydroforming process and rapid tooling technique were combined, with the objective of making the resulting process more flexible and less expensive. Sheet hydroforming experiments were carried out using a layered die created assembling 2D laser cut layers and testing three Al alloys (AA2024, AA5754, AA7475); process parameters (Closing Force and Pressure) were evaluated by means of finite element simulations, mainly focused on the curve defining the Closing Force as a function of the forming Pressure and on friction conditions, which have a significant effect on the distribution of sheet thickness in formed parts. Both numerical simulations and experimental tests highlighted that sound parts could be obtained if a hard enough sheet material together with the appropriate Closing Force and forming Pressure are used. The proposed approach, combining the hydroforming process with a rapid tooling technique, proved to be effective in rapidly manufacturing prototypes and thus in shortening the product design process. [Copyright &y& Elsevier]

Abstract: A magnesium alloy AZ21 was multi-directionally forged at room temperature to cumulative strains of ΣΔɛ =1.5 and then subjected to various annealing treatments. The results showed that the initial grains were gradually subdivided into ultrafine ones by mechanical twins. The annealing temperature had a pronounced effect on the microstructural evolution. At 523K, a homogeneous structure with a mean grain size of 3.8μm was obtained, which exhibited remarkable texture weakening compared with the as-annealed specimen, resulting in significantly increase of ductility and stretch formability. Increased and decreased annealing temperature can both lead to a coarsening of grain size. Moreover, the analysis on the recrystallization kinetics during annealing indicated that it could be well described by Johnson–Mehl–Avrami–Kolmogorov model and the activation energy for recrystallization was calculated to be about 63.4kJ/mol. [Copyright &y& Elsevier]

Abstract: Effects of Si addition (1.0wt.%) on microstructure and mechanical properties of Mg–8Gd–4Y–Nd–Zr alloy have been investigated using scanning electron microscopy (SEM) equipped with energy dispersive spectrum (EDS), X-ray diffraction (XRD), hardness measurements and tensile testing. The results indicated that the addition of Si led to the formation of Mg2Si and (RE+Si)-rich particles, which enhanced the Young’s modulus of the alloy by 7GPa while decreased the yield strength and ultimate strength by 10MPa and 31MPa, respectively. The tensile properties of the Mg–8Gd–4Y–Nd–Zr–Si alloy are as follows: Young’s modulus E =51GPa, yield strength σ 0.2 =347MPa, ultimate strength σb =392MPa and elongation δ =2.7%. The increase in Young’s modulus was attributed to the formation of particles with high Young’s modulus, while the decrease in strength was ascribed to the decrease in volume fraction of metastable β′ precipitates caused by the consumption of rare earth atoms due to the formation of the rare earth containing particles. [Copyright &y& Elsevier]

The purpose of this study is to investigate the effects of Ti addition (1 and 2% Ti) and aging heat treatment on the mechanical and wear characteristics of Al-12Si-20Mg cast alloys. In preliminary studies conducted to determine the aging parameters, cast alloys were kept at 550 °C for 2 h before being quenched into water and aged at 200 °C for five different periods (3, 6, 9, 12, and 15 h). As the specimen aged for 12 h had the highest hardness value, all the specimens were aged at 200 °C for 12 h. The microstructures of the as-cast and aged specimens were analyzed using an optical microscope and a scanning electron microscope. The hardness of the investigated alloys was measured by micro-hardness test. The wear tests were carried out using the pin-on-disk model wear test apparatus, and the results were evaluated according to weight loss. According to the wear test results, the wear behavior of the investigated alloys changed depending on the aging heat treatment applied and the load. While Ti addition and the aging heat treatment applied reduce the weight loss at low loads (5 N), they increase the weight loss at higher loads (10 and 20 N). [ABSTRACT FROM AUTHOR]

Abstract: The objective of this work was to fabricate a suitable porous Ti–10Mo alloy as the human bone replacement implants. The porous Ti–10Mo alloy was fabricated by mechanical alloying and then consolidated by powder metallurgy technique. NH4HCO3 powder was used as space-holder. It was indicated that the mean pore size, porosity, compressive strength, and elastic modulus of porous Ti–10Mo alloy could be tailored by the amount of NH4HCO3, and then could be matched with those of human bones. Furthermore, porous Ti–10Mo alloy was treated by alkali heat treatment and soaked in the 1.5 times simulated body fluid (1.5SBF). It was observed that the surface and the inside pore wall of porous Ti–10Mo alloy with 25wt.% NH4HCO3 covered with the apatite layer after soaked in 1.5SBF for 28days. These phenomena indicated that the surface modified porous Ti–10Mo alloy exhibited a high potential for bone-bonding, which was expected to be used as bone tissue implant. [Copyright &y& Elsevier]

In this research, the constitutive relationships of BT25 titanium alloy based on regression and artificial neural network (ANN) methods were established and studied by analyzing the results of hot compression tests. The isothermal compression tests were conducted on a Gleeble 1500 thermo-mechanical simulator in the deformation temperatures ranging from 940 to 1000 °C with an interval of 20 °C and the strain rates of 0.01, 0.1, 1.0, and 10.0 s with a height reduction of 60%. The average deformation activation energy of the alloy was derived as 623.26 kJ/mol at strain of 0.7 by using the non-linear regression method and assuming a hyperbolic sine equation between the stress, strain rate, and deformation temperature. On the basis of the experimental data samples, an ANN model was proposed and trained. The hot processing parameters of temperature, strain rate, and strain were used as the input variables and the flow stress as the output variable. The comparison of experimental flow stresses with predicted values by ANN model and calculated value by regression method was carried out. It was found that the predicted results by ANN are in a good agreement with the experimental values, which indicates that the predicted accuracy of the constitutive relationship established by ANN model is higher than that using the multivariable regression method. [ABSTRACT FROM AUTHOR]

Abstract: Laser deposited titanium alloy Ti–6Al–4V was sub-critically annealed in the α+β phase region and the microstructure evolution process and microstructure characteristics were systematically investigated as functions of annealing temperature and time during the sub-critical annealing process. A unique bi-modal microstructure consisting of coarse crab-like primary α and fine lamellar transformed β is obtained by sub-critical annealing in the upper part of α+β phase region. The crab-like morphology of the primary α becomes more manifest with the increasing anneal temperature up to its β-transus temperature. The annealing treatment has significant effect on the volume fraction, size and aspect ratio of primary α, while the aging treatment mainly affects the volume fraction and aspect ratio of primary α and the width and volume fraction of secondary α. Formation of the crab-like primary α is due to the preferential epitaxial growth of secondary α on the edge of primary α along with the 〈1210〉 preferred crystallographic direction during the diffusive β-decomposition process. The sub-critically annealed alloy exhibited the maximum microhardness by further aging at approximately 600°C, which is 9% higher than that of the as-annealed one and 4% higher than the as-deposited one. [Copyright &y& Elsevier]

Abstract: The isothermal annealing behaviors of a magnesium alloy AZ31, deformed by multi-directional forging (MDF) at ambient temperature to cumulative strains ranging from 0.2 to 1.5, was investigated at 473K. The deformed microstructure is characterized by several types of twins formed in various directions during MDF and their intersections with one another. The Johnson–Mehl–Avrami–Kolmogorov (JMAK) plots of Xrex-t curves are approximated by a linear relationship with an exponent of 2.6 at early stages of annealing irrespective of prior strains, but always break at long times, leading to lower values of the exponent. The non-linear JMAK plots may result from the inhomogeneity of deformed microstructures. The annealing process is composed of new grain formation at the intersections and subsequent large-distance migration of their boundaries, that is discontinuous static recrystallization (dSRX). The annealing characteristics of the cold-deformed Mg alloy are discussed comparing with the contrastive ones of the hot-deformed alloy. [Copyright &y& Elsevier]

Abstract: The present research work, describes the development of particulate filled alloy composites consisting of ZA-27 alloy as a base material and titania particulate as reinforcing materials. The objective of the present work is to study the erosion wear behavior of particulate filled alloy composites by Taguchi experimental design technique at four different impact velocities (25–79m/s), erodent temperature (40–100°C), impingement angles (30–90°) and erodent size (250–550μm) respectively. A finite element simulation model (ANSYS/AUTODYN) for damage assessment in erosion is developed and validated by a well designed set of experiments. It is observed that the experimental results are in good agreement with the computational results and the proposed simulation model is very useful for damage assessment. However, a series of steady state erosion analysis is also conducted by varying the impingement angle and impact velocity one at a time while keeping other factors remains constant before studying the Taguchi experimental results. From this analysis it is observed that the peak erosion rate occur at about 60° impingement angle at constant impact velocity (66m/s), erodent size (450μm), stand-off-distance (75mm) and erodent temperature (60°C) for all the composites. However, the steady state erosion rate as a function of impact velocity for unfilled composite shows maximum erosion rate as compared to filled composites at constant impingement angle (45°), erodent size (450μm), stand-off-distance (75mm) and erodent temperature (60°C) respectively. Finally, the damage mechanisms of eroded surfaces are investigated using scanning electron microscope (SEM). [Copyright &y& Elsevier]

Abstract: Electron beam welding (EBW) was applied to 50mm thick damage-tolerant Ti–6Al–4V (TC4-DT) alloy, and microstructure, microhardness and tensile properties of the defect-free welded joints were examined. The results indicated that the microstructure of the base metal is composed of primary α phases and the lamellar (α+β) bimodal structure. For the EBW joint, martensite basketweave microstructure is formed in fusion zone (FZ). Moreover, the heat affected zone (HAZ) near FZ consists of acicular martensite and a small portion of primary α phase. The HAZ near base metal consists of primary α phase and transformed β containing aciculate α. It is found that the boundary of the two portions of the HAZ was dependent on the β phase transus temperature during weld cooling. Microhardness values for FZ and HAZ are higher than that of base metal, and there are the peak values for the HAZ near the weld metal. The fracture locations of all the EBW tensile specimens are in base metal, and the ultimate tensile strength of the joints may reach about 95% of the base metal. In addition, with the depth increasing along the weld thick direction, the grain size of the FZ decreases and microhardness increases. [Copyright &y& Elsevier]

Abstract: An eutectic lead – tin alloy was casted in the form of cylindrical billets that were machined down, and then processed in a 90° equal channel angular pressing (ECAP) die, via route C to four passes. Evaluation of the microstructure was done via optical and scanning electron microscopy. This process resulted in dynamically recrystallized α + β structure of interphase boundary size of ∼6μm. Tensile testing was performed at different initial strain rates at three temperatures of 25 (room temperature), 50 and 75°C. The steady state true stresses were depicted and plotted against the respective strain rates. A constant strain rate sensitivity parameter m of 0.44 was observed at the three testing temperatures. The high value of m, the activation energy along with large elongation percent suggest the operation of grain boundary sliding as rate controlling process. The value of elongation percent (ductility) was also depicted and plotted as a function of strain rate at various temperatures. It was noticed that, the ductility values at each temperature attain a maximum value and this maximum value increases and shifts to high strain rates with increasing temperature. [Copyright &y& Elsevier]

Abstract: Sintered bronze with the addition of graphite as self lubricant is widely used in sliding bearings and bushes applications, especially where grease and oil lubricant cannot be considered. Aim of this work is to study the dry sliding wear behavior of a porous sintered bronze–graphite composite, which is characterized by a transition from solid lubrication to adhesive wear. In this last condition graphite loses its efficiency as solid lubricant due to the frictional heat. The efficiency of the solid lubrication was examined at different loads and sliding velocities; it decreases on increasing both load and velocity. The behavior in the different dry sliding conditions was investigated and the corresponding flash temperature was calculated. Results indicate that transition occurs when the flash temperature reaches at least 360K. Some design guidelines were then proposed, based on a P 0 vs. v map, which defines the parameters ensuring both that no plastic deformation occurs and that solid lubrication is efficient during dry sliding. The relative design scheme gives a tool to verify if the dimensional and geometrical characteristics of the part are guaranteed during its expected life. [Copyright &y& Elsevier]

Abstract: A numerical finite element analysis is undertaken to directly simulate failure of solder joint caused by cyclic shear deformation. In the model the tin (Sn)-silver (Ag)-copper (Cu) solder and two copper substrates constitute a lap-shear testing configuration. A progressive damage model is incorporated into the rate-dependent elastic-viscoplastic response of the solder alloy, resulting in the capability of simulating damage evolution and eventual failure through crack formation. The study concerns three different applied shear strain rates, 1, 10 and 100s−1, under both the monotonic and cyclic loading conditions. It is found that, in the reference case of monotonic loading, the strain at failure can be influenced significantly by the fracture path in the solder. There is a tendency for cracking to occur closer to the interface during cyclic loading. The initiation of fatigue cracks is generally insensitive to the applied strain rate. However, the total fatigue life, in terms of the number of cycles to final failure, is seen to decrease significantly in the case of highest strain rate. [Copyright &y& Elsevier]

Abstract: In the present study the microstructural and high-temperature mechanical properties of 7010 Aluminum Alloy (AA) resulting from friction stir processing (FSP) were analyzed and compared to unprocessed material. The sheets were processed perpendicularly to the rolling direction that resulted into fine-grained microstructure having the size of about 7μm. The high-temperature deformation characteristics and mechanical properties of the processed material were studied using hot tensile tests at temperatures of 703, 723 and 753K and at different strain rates in the range of 1×10−2–1×10−4 s−1. Correlation between the flow stress σ and strain rate and temperature, T gave an apparent stress exponent na of 5 and apparent activation energy Qa of 260kJ/mol. The high value of Qa was attributed to the presence of threshold stress under the present experimental conditions. [Copyright &y& Elsevier]

Abstract: The fracture behaviour of the aluminium alloy AA7075-T651 is investigated for quasi-static and dynamic loading conditions and different stress states. The fracture surfaces obtained in tensile tests on smooth and notched axisymmetric specimens and compression tests on cylindrical specimens are compared to the fracture surfaces that occur when a projectile, having either a blunt or an ogival nose shape, strikes a 20mm thick plate of the aluminium alloy. The stress state in the impact tests is much more complex and the strain rate significantly higher than in the tensile and compression tests. Optical and scanning electron microscopes are used in the investigation. The fracture surface obtained in tests with smooth axisymmetric specimens indicates that the crack growth is partly intergranular along the grain boundaries or precipitation free zones and partly transgranular by void formation around fine and coarse intermetallic particles. When the stress triaxiality is increased through the introduction of a notch in the tensile specimen, delamination along the grain boundaries in the rolling plane is observed perpendicular to the primary crack. In through-thickness compression tests, the crack propagates within an intense shear band that has orientation about 45° with respect to the load axis. The primary failure modes of the target plate during impact were adiabatic shear banding when struck by a blunt projectile and ductile hole-enlargement when struck by an ogival projectile. Delamination and fragmentation of the plates occurred for both loading cases, but was stronger for the ogival projectile. The delamination in the rolling plane was attributed to intergranular fracture caused by tensile stresses occurring during the penetration event. [Copyright &y& Elsevier]

Abstract: A combined experimental–numerical study of tailor-made blanks (TMBs) with dissimilar alloys is presented in this paper. The selected adhesive is AF163-2K (from 3M). Metal sheets are made from two dissimilar aluminum alloys, namely 2024-T3 and 7075-T6. The 7075-T6 sheet acts as a base sheet on top of which a 2024-T3 sheet is bonded. While the thickness of the base sheet (7075-T6) is the same (=2.0mm) for all specimens, the thickness of the upper sheet (2024-T3) varies between 0.5mm and 2.5mm. The bonded sheets are machined to the standard dog bone shape. In addition, a thickness difference either perpendicular to the loading direction (transverse specimens) or parallel with it (longitudinal specimens) is created by milling. The tensile tests are conducted, while measuring the three-dimensional deformations of the sheets using digital image correlation technique. It is shown that, in contrast with the TMBs with similar-alloys (both sheets made from 2024-T3), the upper sheet does not delaminate during the test. The failure mode is therefore metal fracture. This is an important conclusion, because it improves the in-plane straining limits of adhesively-bonded TMBs. A Finite Element Method (FEM) model of the tensile tests is created. The adhesive damage and metal failure are, respectively, modeled using cohesive interface and distributed continuum damage theories. It is shown that the FEM model can explain the behavior observed in the experiments. The lower ductility of the base sheet together with competition between two failure mechanisms, namely metal failure and delamination, are found responsible for the observed behavior. [Copyright &y& Elsevier]

Abstract: This paper describes the design and examination of W/Ni double interlayer to produce a joint between SiC and ferritic stainless steel. Diffusion bonding was performed by a two steps solid state diffusion bonding process. Microstructural examination and mechanical properties evaluation of the joints show that bonding of SiC to steel was successful. EDS and XRD analysis revealed that W5Si3 and WC were formed at SiC/W interface. The diffusion products at W/Ni interface, Ni-rich solid solution Ni(W) or intermetallic compound Ni4W, was found to be dependent on the second step joining temperature. Neither intermediate phases nor reaction products was observed at Ni/steel interface for the joints bonded at the temperature studied. The average tensile strength of 55MPa which is insensitive to the second step process was measured for as-bonded SiC/steel joint and the failure occurred at SiC/W interface. The hardness near the various bonded interfaces was also evaluated. [Copyright &y& Elsevier]

Abstract: The effects of Sn addition on the as-cast microstructure, mechanical properties and casting fluidity of the ZA84 magnesium alloy are investigated. The results indicate that adding 0.5–2.0wt.%Sn to the ZA84 alloy not only can result in the formation of Mg2Sn phase but also can refine the Mg32(Al,Zn)49 phase and suppress the formation of Mg32(Al,Zn)49 phase, and with the increase of Sn amount from 0.5wt.% to 2.0wt.%, the morphology of Mg32(Al,Zn)49 phase gradually changes from coarse continuous and/or quasi-continuous net to relatively fine quasi-continuous and/or disconnected shapes. In addition, adding 0.5–2.0wt.%Sn to the ZA84 alloy can improve the tensile and creep properties, and casting fluidity of the alloy. Among the Sn-containing ZA84 alloys, the ZA84 alloy added 1.0wt.%Sn exhibits the best ultimate tensile strength, elongation and casting fluidity while the ZA84 alloy added 2.0wt.%Sn has the best yield strength and creep properties. [Copyright &y& Elsevier]

Abstract: The potentiodynamic polarization behavior of copper alloys in chloride solutions (1M NaCl) of different pH’s (6.5 and 10) was investigated. Three commercial alloys of nominal composition Cu–30Ni (Cu–Ni), Cu–30Zn (Cu–Zn) and 90Cu–8Al–2Fe (Cu–Al) were considered. Results at pH of 6.5 showed no evidence of passivity with polarization behavior being dominated by the Cu component. At pH of 10, however, some evidence of limited passivity was seen. Passivity was more evident in buffered chloride (pH 10), in particular for Cu–Zn which showed remarkable passive behavior over a wide potential range. A sudden increase in the current density occurred when the anodic potential exceeded a certain critical potential, i.e., film breakdown potential. The results of these experiments are discussed in reference to potential–pH (Pourbaix) diagrams of the alloying elements. [Copyright &y& Elsevier]

Abstract: Diamagnetic Cu was added into hard magnetic Nd–Fe–Al bulk metallic glass in the present study. The effects on the magnetic properties and glass-forming ability (GFA) were assessed using vibrating sample magnetometer and thermal expansion method. The results show that Nd60Fe20Cu10Al10 have highest GFA and the coercivity is high up to 313kA/m as well. The former was attributed to the more negative mixing heat between Cu and Nd and the latter was caused by the emergence of ferromagnetic Fe-rich phase or cluster. Given a further increasing on copper, a sharp reduction happens to magnetic properties. This reduction can be attributed to the emergency of soft magnetic and non-magnetic crystalline phases (NdCu5, Nd-rich phase, δ phase and Nd phase). [Copyright &y& Elsevier]

Abstract: In this paper, the effects of processing parameters on microstructures of thixoformed ZA27 alloy cylindrical rods were investigated. The results indicated that the microstructure of the formed rod was basically uniform except that of the section near the inner gate. But the detailed microstructure observation or quantitative examination showed that the primary particle fraction slightly decreased along the axial direction but it relatively more obviously decreased along the radial direction. The primary particle size increased and the primary particle fraction decreased with the increase of reheating duration. Both the size and fraction of primary particles decreased with elevating the reheating temperature and increased with increasing the die temperature. The secondary solidification began with the direct growth of the secondary primary phase on the surface of the primary α′ particles and completed by forming lamellar eutectics. The secondarily solidified structure was significantly affected by die temperature while the other two parameters, reheating temperature and reheating time had no obvious effect. [Copyright &y& Elsevier]

Direct laser fabrication (or LENS) has been used to build up solid samples from powders of the alloy Ti–6Al–4V. The effects of processing conditions, such as laser power, scan speed, powder feed rate, etc. on the microstructure of the build have been assessed. It has been found that Ti–6Al–4V is very susceptible to the formation of columnar grains during laser deposition. Long columnar grains dominate the microstructure of the laser-deposited Ti–6Al–4V alloy for a large range of laser powers and are formed for all but very high laser powers. The scale of columnar grains also increases with decrease of the laser scan speed and when other parameters are maintained constant. For the lowest powers used a change from a near fully dense product to a very porous structure is found. The laser-fabricated Ti–6Al–4V has a basket weave microstructure and the size of the α and β laths increases with increase of laser power and decrease of scan speed. During the addition of the new layers, there is a tendency for coarsening of the α and β laths in the re-heated region near the top of the previous layer. This effect is most obvious in the area where heat extraction is rapid, such as the region near the substrate and is not obvious when the whole region remains hot, as occurs towards the top of the sample. In this region, the α/β laths coarsen throughout the whole of each layer. It is shown that the influence of the substrate in acting as a variable heat sink makes prediction of the effects of altering process variables on the microstructure very difficult. [Copyright &y& Elsevier]

The response of a recently developed burn-resistant Ti alloy (Ti–25V–15Cr–2Al–0.2C, wt%) to direct laser fabrication has been assessed. The influence of laser processing conditions on the microstructure and on the tensile properties at room and at elevated temperatures and on the creep properties has been investigated. In contrast to Ti–6Al–4V the burn-resistant alloy has been found to form equiaxed, rather than columnar grains during laser fabrication for a very wide range of processing conditions. The factors which influence whether equiaxed grains or columnar grains are formed during laser fabrication are discussed and the influence of the laser process route on properties is discussed in terms of the microstructural differences found in laser fabricated and conventionally processed samples. [Copyright &y& Elsevier]

Two models of strain–time creep curve description were applied to a set of experimental data obtained recently by testing a newly developed Mg–Al–Si–RE alloy (AS21X) produced by die-casting. Due to the absence of extensive tertiary creep, the simplified equations for constant-stress creep tests of the Li–Akulov and Bagley–Jones–Freed models were used to identify material parameters in the 70–180 °C range. In both models, secondary creep rate data fit well in the whole stress–temperature range considered. The description of primary creep was generally good, except for the high-stress range at 70 °C. In all cases, the predicted strain vs. time creep curves became more accurate as the contribution of secondary creep to strain increased. Above 0.002% strain, the models can reliably be applied in the stress–temperature range investigated. The extrapolation of predicted times at fixed strains were one or more orders of magnitude above the highest experimental times (6×106 s for 0.02 strain) and will require additional testing at lower stress. [Copyright &y& Elsevier]

Direct laser fabrication (or LENS) has been used to manufacture near net shape components. Good geometry control and surface finish have been achieved. Parts with various geometries, including a certain degree of overhang, have been built successfully using DLF for Ti alloys and SiAl alloys. It has been found that some alloys can be laser processed easily, i.e., have a large processing window whilst others have very small processing windows, in which case the microstructure of the build is very sensitive to the laser process parameters. [Copyright &y& Elsevier]

A recently developed burn-resistant Ti alloy has been used as a model Ti alloy to assess the response of Ti alloys to direct laser fabrication. The microstructure and homogeneity of laser deposited burn-resistant alloy have been assessed with respect to those obtained by conventional processing routes. Oxygen is one of the most important factors which controls the mechanical properties of Ti alloys and the effect of the oxygen content on the microstructure of the burn-resistant alloy has been examined after laser processing in air, using the argon carrier gas as protection and in a glove box with an argon atmosphere with O2<5 ppm. The microstructures observed for these different atmospheres are very different and are discussed in terms of the extent of oxygen pick-up. [Copyright &y& Elsevier]

The effect of oily film corrosion-prevention compounds on the fatigue behaviour of aluminium alloy 7075-T6 mechanically fastened joints was investigated. Unpainted double-lap joints with a single bolt fastener were tested under constant-amplitude fatigue loading with and without treatment with lubricative corrosion-prevention compound (CPC). Fatigue tests were conducted with different levels of fastener clamping force to determine the variation in fatigue life as a function of the clamping force with and without the CPC. Fractography of the failed specimens indicated that there are two distinct modes of fatigue initiation, one dominated by fretting and the other dominated by bearing at the fastener hole. It was found that in joints with high fastener-clamping force, the application of lubricative corrosion-prevention compounds increases the fatigue life, whereas the use of CPC is detrimental to the life of joints with low fastener-clamping force. [Copyright &y& Elsevier]

Aluminium alloy 5083 is used in the fabrication of lightweight, high-speed marine vessels. The high cyclic service stresses on such structures render welded joints in them fatigue-critical. This paper presents experimental investigations on fatigue crack behaviour of welded 5083-H321 aluminium alloy plates. Crack propagation in the heat-affected zone of welded specimens was determined from tests conducted on single edge-notched tension specimens. Three-dimensional finite-element analysis was employed to determine stress intensity factors for cracks in the weld line. The crack closure effects of weld residual stresses were evaluated. The residual stresses significantly influence the crack growth rates. Fatigue behaviour of weld repairs in cracked plates was also investigated. The weld-repair process significantly increases the grain size and the size of defects in the heat-affected zone. The results indicate that weld repair of cracks in welded joints provides little improvement in residual life. [Copyright &y& Elsevier]

Bending is one of the processes frequently applied during manufacture of aluminium components. The bending operation involves springback, which is defined as elastic recovery of the part during unloading. In manufacturing industry, it is still a practical problem to predict the final geometry of the part after springback and to design appropriate tooling in order to compensate for springback. In this paper, commercially available finite-element analysis (FEA) software is used to analyse bending and springback of different aluminium materials of different thickness. The amount of springback, the total equivalent plastic strains and the equivalent von Mises stresses are presented. The FEA results are compared with empirical data. [Copyright &y& Elsevier]