The 15th International Conference on Aluminium Alloys

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Authors: Na Xue, Hui Song, Chang Bing Zhou, Xiao Jiao Wang, Wen Qing Liu
Abstract: As-cast Al-Sc alloys and Zr-containing Al-Sc-Zr alloys were aged at 300°C for different times, the Al-Sc-Zr alloy showed more excellent precipitation strengthening. The atom probe tomography (APT) was applied to characterize the precipitates in the two alloys, the results show that the precipitates in Al-Sc-Zr alloy is smaller in size and is higher in number density than that in the Al-Sc alloy at same aging time, it is because that the Zr addition reduces the diffusion rate of Sc, and which retains the growth of precipitates and results in the excellent precipitation strengthening of Al-Sc-Zr alloy.
Authors: Wei Jun He, Chun Hong Li, Zhi Qiang Li, Bai Feng Luan, Qing Liu
Abstract: Carbon nanotubes reinforced aluminum alloy (CNTs/Al alloy) composite was fabricated by the method of flake powder metallurgy. With Gleeble-3500 system, hot compression tests at different temperatures and strain rates were conducted to investigate the effect of temperature and strain rate on the deformation behaviors of the CNTs/Al alloy composite. Experimental results show that the composite’s ductility is worse at higher deformation temperature within range of 300 oC-450 oC. Additionally, the composite’s ductility is better at higher strain rate, which is against general knowledge. The microstructure before and after deformation were characterized by SEM and TEM. It demonstrates that the grain size of the composite is always in the nanoscale. The abnormal effects of temperature and strain rate on the ductility may be explained by the evolution of work hardening capability at different deformation conditions.
Authors: Sergey Betsofen, Vladislav Antipov, Maxim Knyazev, Margarita Dolgova
Abstract: A quantitative approach to the determination of the phase composition in the Al-Mg (Cu)-Li alloys has been developed on the basis of the balance equations of chemical and phase compositions as well as the lattice parameter measurement of the α solid solution. It is shown that, for the Al-Mg (Cu)-Li alloys, the ratio between the fractions of the δ' (Al3Li) and S1 (T1) phases is determined by the ratio between the molar fractions of Li and Mg (Cu). By means of this technique it is shown that in Al-Cu-Li alloys the proportion of δ'-phase is much higher than ternary T1-phase, and the proportion of δ'-phase and a ternary phase (S1) are approximately equal in alloys of Al-Mg-Li system. The equations for the calculation of the contents of the S1 (Al2MgLi), T1 (Al2CuLi) and δ' (Al3Li) phases in the 1420, 1424, 5090 alloys (Al-Mg-Li alloys) and in the 1440, 1441, 1450, 1460, 1461, 1464, 1469, 2050, 2090, 2091, 2094, 2098, 2099, 2195, 2198, 2199, 2297, 8090 (alloys (Al-Cu-Li alloys) are given.
Authors: Qian Ning Guo, Xiu Chuan Lei, Robert E. Sanders Jr, Xiao Fang Yang, Yan Xiang Liang, Lu Wang, Zhen Zhen Fan
Abstract: Alloy 5182 has been extensively used in the O temper for automotive sheet parts requiring high formability and moderate strength. The grain size of the sheet has been shown to impact strength, formability, and Lüdering behavior during forming. The present study examined the effect of heating rate on the recrystallization behavior of the alloy. Various heating rates, recovery treatments and annealing temperatures were used to manipulate the final grain size. Metallographic observations, EBSD and hardness tests were used during the research. The results are discussed in terms of operative recrystallization mechanisms for this alloy.
Authors: Jie Ke Ren, Zhi Guo Chen, Ji Qiang Chen, Shuai Feng, Jing Peng
Abstract: A novel thermomechanical treatment (TMT) was proposed for increasing the strength of 6156 aluminum alloy while maintaining a high elongation, which is based on artificial aging at low temperature, cold rolling and natural aging. The corresponding tensile properties and microstructure of 6156 aluminium alloy under different treatments were investigated. The yield strength and the ultimate tensile strength are increased by over 50 MPa over those of T3, while a high elongation rate is maintained. The fracture mechanism of T4 and TMT state alloy are typical ductile fracture, while that of T6 and T8 state alloy is a mixture of ductile fracture and shear fracture. For the TMT processed 6156 alloy, though no obvious precipitates can be observed in the matrix, tangled dislocations around primary phase in the matrix, as well as a high density of dislocations piled up at the grain boundary were observed. The mechanism of the novel TMT, by which the mechanical properties of the alloy is greatly improved, is the synergistic effect of composite structures, including dislocation substructures, the complex of Mg-Si clusters/vacancies, as well as GP zones.
Authors: Hiroki Tanaka, Yasunori Nagai
Abstract: Thermal stability of substructures in 6000 series aluminum alloys containing Mn and Zr elements was investigated using plane-strain compression test. In order to form thermally stabilized substructures, the deformation parameters should be selected so as to correlate with kinetic precipitation during the deformation. For substructures of the alloys containing Mn and Zr elements, the substructures were stable during the heat treatment at 540 ̊C when the alloys were deformed at a temperature above 350 ̊C. The sheets rolled above 350 ̊C at a strain rate of under 3 s-1 per pass showed the fibrous structure and well developed β-fiber textures after the heat treatment at 540 ̊C. The sheets with the fibrous structure had an average Lankford value larger than one.
Authors: Sergey Betsofen, Vladislav Antipov, Maxim Knyazev, Margarita Dolgova
Abstract: Phase composition, texture and mechanical properties of plates 80 mm thick from Al-2.8Cu-1.7Li-0.5Mg-0.5Zn-0.1Zr-0.06Sc alloy were investigated. It has been found that strength characteristics are maximum in median section (ultimate strength and the yield stress of 570 MPa and 540 MPa, respectively). In 0,25T section (where T is the plate thickness) these quantities make 530 MPa and 490 MPa, and in the short transverse direction of only 490 MPa and 440 MPa. Textural studies showed that on medium layer of a plate 0,3-0,35T thick is observed identical to a matrix and δ'-phase intensive single-component texture with an arrangement of the plane {011} parallel to the plate plane with domination of a "brass" texture component {110} <112>.
Authors: Wei Chen, Pi Zhi Zhao, Yu Li Zhou, Yan Feng Pan
Abstract: AA8021 aluminum alloy twin-roll cast strips with 7mm gauge were rolled to 3.8mm gauge sheets and given homogenization, further rolled into 0.55mm gauge foil stocks with intermediate annealing. This paper investigated the influence of homogenization conditions on microstructures of foil stocks in detail. The results show that, for the foil stock made from the sheet without homogenization, the grain structure is partially recrystallized. While the grain structure of foil stock made from the sheet with medium temperature homogenization is fully recrystallized, but it is coarse near sheet surface. However, foil stock made from the sheet with high temperature homogenization has fine and uniform recrystallized grain structures. The differences of grain structures among these three kinds of foil stocks can be understood by the variation in solid solution content of Fe, Si, Mn and distribution of intermetallic compounds. The optimized homogenization condition was adopted by our plant to produce foil stock, and its grain structure was fine and uniform. The surface quality of final aluminum foil rolled from the foil stock could meet high grade requirements of customers.
Authors: Jun Tai Lu, Hui Huang, Hao Wu, Sheng Ping Wen, Kun Yuan Gao, Zuo Ren Nie
Abstract: Effect of solution treatment on the properties and microstructural evolution of Al-Zn-Mg-Cu-Er-Zr alloy was investigated by hardness test, conductivity test, exfoliation corrosion test, scanning electron microscope (SEM), transmission electron microscopy (TEM). The results show that the hardness of single-stage solution treated samples first increase and then decrease, the conductivity and volume fraction of the residual phase particles decrease with increasing solution temperature. Compared to conventional multi-stage solution, slow heating process solution treatment can dissolve plenty of residual phases and further improve the hardness and decrease conductivity. Besides, the effect of solution treatment on EXCO is discussed, the result of exfoliation corrosion of SHT8 sample test is judged as EA. Moreover, the effect of the presence of nanometer-sized Al3(Er,Zr) particles on the microstructural evolution during solution treatment has also been discussed in detailed.
Authors: Tong Hui Liu, Sheng Ping Wen, Xiao Lan Wu, Kun Yuan Gao, Hui Huang, W. Wang, Zuo Ren Nie
Abstract: To investigate the effect of cold-rolling and aging on precipitation and recrystallization behavior of Al-0.04Er-0.08Zr (at. %) alloy, two thermo-mechanical processes containing peak aging + cold-rolling (A + CR) and cold-rolling + isochronal aging (CR + A) were studied. In A + CR process, the hardness of alloy under cold-rolled state was much higher than the maximum obtained during isochronal aging, due to the strong interaction between precipitates and dislocations or sub-grain boundaries. Furthermore, the recrystallization temperature was 475 °C as indicated by the hardness curve. The microstructure analysis revealed that the sample annealed at 525 °C for 1 h still don’t recrystallize fully. For CR + A, it turned out that the deformation play a small role in improving the maximum of hardness. But comparing with those without deformation, the existence of deformation accelerated the rate of precipitation process and obtained higher electrical conductivity.

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