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AA6101 Al alloy is widely used as a high-strength conductive aluminum alloy, and the contents and existence of Mg and Si can influence its electrical conductivity and mechanical properties obviously. In this paper, experiments were conducted to find the optimal Mg, Si additions and Mg/Si ratio and then combined with heat treatment to improve the EC and mechanical properties at the same time. Firstly, considering the proper Mg/Si ratio, two optimal Mg and Si additions were determined: Al–0.7Mg–0.5Si and Al–0.4Mg–0.7Si with EC of 51.5%IACS and 51.4%IACS, and through homogenization treatment, their EC improved to 57.0%IACS and 55.7%IACS, respectively. Then, appropriate Fe was added to further control Si to achieve the balance of EC and mechanical properties. Results showed that for AA6101 Al alloy the ideal Mg/Si mass ratio was 1.4 and high Mg and low Si can obtain good EC and mechanical properties. Besides, it can be found that at low Mg/Si ratio, the alloy conductivity takes longer to reach its peak hardness. So the best performance Al–0.7Mg–0.5Si–0.2Fe alloy was obtained within the range of AA6101 national standard. The EC of Al–0.7Mg–0.5Si–0.2Fe can reach 56.3%IACS, and hardness is 91.3 Hv. Based on the study, a schematic diagram was drawn to analyze the influence mechanisms of Mg, Si and Fe on EC and hardness of AA6101 Al alloy. [ABSTRACT FROM AUTHOR]

In this paper, the effect of deep cryogenic treatment (DCT) on the microstructure and properties of automotive 6063 aluminum alloy at different times was investigated with automotive 6063 aluminum alloy as the research object. The results show that under the conditions of deep cryogenic treatment, the lattice distortion occurs in the alloy matrix microstructure, and the resulting internal stress promotes the large proliferation of dislocations within the alloy and the increase of dislocation density; meanwhile, after the deep cryogenic treatment, the deformed grains are transformed into recrystallized and sub-crystals structural grains, the grains are refined, and the size of the grains is refined from the original 25.2 μm to 20.3 μm, with fine equiaxed crystals. Among them, the mechanical properties of the DCT36h specimen were the best, and its hardness, tensile strength, yield strength and elongation reached 142.44 HV, 328.32 MPa, 177.42 MPa, and 29.29%, which were 34.17%, 5.62%, 11.10%, and 32.77% higher than the original sample, respectively. We believe that the main mechanism for the increase in toughness is multiple reinforcement such as dislocation strengthening, grain refinement strengthening, precipitated phase strengthening and texture strengthening. [ABSTRACT FROM AUTHOR]

Aluminum (Al) alloys are of great importance and interest because of their extensive applications in various engineering fields. Lightweighting of our infrastructure has been a driver for more than the last two decades as our need to reduce carbon footprint on a global scale has become an inevitable reality. As a result, we have witnessed much progress in alloy development in Al alloys, especially with the advent of Integrated Computational Materials Engineering (ICME) and other computational tools. However, the limitations of the properties one may attain through alloy development to date have relied on the traditional solvent/solute model, where the matrix is Al with additions of elements (solute) to the matrix. Despite making much progress, we are still locked-in to the strength-ductility curve without any appreciable increase in modulus (stiffness) of the alloy. High Entropy Alloys (HEAs) provide a new paradigm as they differ from conventional alloys in entropy-based mixing logic of various elements, which is different from the solvent/solute model. HEAs offer the opportunity to move out of the strength-ductility curve as well as the opportunity to increase the alloy's modulus. In this paper, we present a retrospective view of Al alloys, followed with an understanding of the principles of HEAs, and lastly, with the idea of applying high entropy concept to conventional Al alloys to develop a novel Al alloy category, which we have coined HEAl. Preliminary results with a commentary on potential future opportunities are also given. [ABSTRACT FROM AUTHOR]

Cold rolling the CC AA 5754 aluminum alloy to different reductions was followed by an hour of annealing at 537 °C under varied pressures. The changes in microstructure and texture were studied. According to the findings, high-pressure heat treatment restricts recrystallization, and the restriction effect is stronger as pressure rises. The refining impact of high-pressure heat treatment can refine recrystallized grains, and it becomes stronger as the rolling reduction gets higher. The variation of recrystallization texture is significantly affected by high-pressure heat treatment. The sheet with a 19.6% reduction is found to have a weak cube texture at atmospheric pressure and 2 GPa, but the sheet that has been annealed at 4 GPa and 6 GPa has a strong cube texture and a weak β fiber rolling texture. High-pressure heat treatment improves the intensities of the cube and R textures in the fully recrystallized sheets with the same reduction. The strengthening impact of R texture from high-pressure heat treatment improves with increasing rolling reduction. [ABSTRACT FROM AUTHOR]

Aluminum alloy is the optimum material for weight reduction and widely used in a lot of industries including automobile, rail transportation, aerospace, and so on. Ternary Ti3AlC2 powder was adopted in this study to improve the laser welding quality of 6061 Al alloy. Addition of the Ti3AlC2 powder could increase the width and stability of the molten pool, which was beneficial to inhibit the formation of defects such as pore, spatter, rugged surface, sagging, and undercut. Reaction products of Ti3AlC2 powders including Ti3AlxC2, TiAl3, and TiC impeded the growth of dendrites and could serve as nucleating agent, resulting in the formation of massive isometric crystals and dispersed precipitates. The refinement strengthening and dispersion strengthening could impede the extension of deformation and made up the influences of uneven melting loss of alloying elements, leading to the increase and uniformity of weld hardness from 53.1 HV0.2 to 74.9 HV0.2. Both of the welded joints with and without assistant powder fractured at the welds. Elimination of pores increased the loading area of weld while generation of precipitates impeded the extension and connection of dimples, leading to the improvement of tensile strengths from 191.0 to 232.5 MPa and displacements from 0.95 to 1.59 mm. [ABSTRACT FROM AUTHOR]

Al-Mg alloys are normally prone to lose part of their yield and tensile strength at high temperatures due to insufficient thermal stability of the microstructure. Here, we present a Ca-modified Al–Mg–Sc alloy demonstrating high strength at elevated temperatures. The microstructure contains Al4Ca phases distributed as a network along the grain boundary and Al3(Sc,Zr) nano-particles dispersed within the grains. The microstructure evolution and age-hardening analysis indicate that the combination of an Al4Ca network and Sc-rich nano-particles leads to excellent thermal stability even upon aging at 300 °C. The tensile strength of the alloy for temperatures up to 250 °C is significantly improved by an aging treatment and is comparable with the commercial heat-resistant aluminum alloys, i.e., A356 and A319. At a high temperature of 300 °C, the tensile strength is superior to the above-mentioned commercial alloys, even more so when expressed as the specific strength due to the low density of Ca-modified Al–Mg–Sc alloy. The excellent high-temperature strength results from a synergistic effect of solid solution strengthening, grain boundary strengthening and nanoparticle order strengthening. [ABSTRACT FROM AUTHOR]