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Authors: Jian Guo Li, Min Huang, Zimu Shi, Dong Yu Liu
Abstract: The AlTiC master alloy has been prepared in different components to refine 99.8%Al and 99.98%Al, then compared to two typical Al5Ti1B in refining efficiency and the grain nuclear. The result showed that the refining efficiency seemed better if the nucleation of high pure aluminum revealed complexity and variety. It may due to that the latency heterogeneous nucleation was efficient on the whole, consequently accelerated refining efficiency.
313
Authors: Jing Pei Xie, Ji Wen Li, Zhong Xia Liu, Ai Qin Wang, Yong Gang Weng, Tian Fu Song, Zhi Yong Liu, Jie Fang Wang
Abstract: The in-situ Ti alloying of aluminium alloys was fulfilled by electrolysis, and the material was made into A356 alloy and used in automobile wheels. The results show that the grains of the A356 alloy was refined and the second dendrites arm was shortened due to the in-situ Ti alloying. Trough 3-hour solution treatment and 2-hour aging treatment for the A356 alloy, the microstructures were homogeneous, and Si particles were spheroid and distribute in the matrix fully. The outstanding mechanical properties with tensile strength (σb≥300Mpa) and elongation values (δ≥10%) have been obtained because the heat treatment was optimized. Compared with the traditional materials, tensile strength and elongation were increased by 7.6~14.1% and 7.4~44.3% respectively. The qualities of the automobile wheels were improved remarkably.
317
Authors: Zhong Xia Liu, Ming Xing Wang, Tian Fu Song, Yong Gang Weng, Jing Pei Xie, Zhi Yong Liu
Abstract: The in-situ Ti alloying of low-Ti Al alloys and their application in A356 alloys were studied. The results show that the currency efficiency is comparable to that of pure Al, which is about 92%. The absorptivity of Ti is over 95%. Such obtained A356 alloys with different Ti content have excellent grain refinement effect and fading resistance comparing with the tradition A356 alloys. The refinement of grain always companies the refinement of Si particles. The strength is comparable to that of the tradition A356 alloys whether the alloys are unmodified or modified with Sr, but the ductility and quality index are superior to that of the tradition A356 alloys. The alloys with 0.1%Ti have the optimal mechanical properties.
321
Authors: Yan-li Ji, Tie Tao Zhou, Pei Ying Liu
Abstract: The influence of Zn content and Zn/Mg ratio on the equilibrium phase amounts of major ageing strengthening phase η’ (MgZn2) in lithium containing 7000 series aluminum alloys has been investigated by means of thermodynamic calculations. The results show that, comparing with Li-free 7000 series aluminum alloys, Zn/Mg ratio is no longer the determinant for the amount of η’ and only increasing Zn content that can increase the amount of η’. And the results were discussed with existing experiments.
325
Authors: Wei Chen, Chang Qing Sun, Yun Liang Li
Abstract: : According to the theory of liquid metal forging and liquid metal extrusion, a new kind of fabricating method for particles reinforced metallic matrix composite was put forward by author. In this paper, the extrusion process to semisolid thick liquid after the mixture was studied by means of the theoretical analysis and experimental methods. Mechanical characteristics of solidification during flowing and plastic deformation during solidification of the composite were found. So the base was built up for selecting technology parameters and for building a stabile process
329
Authors: Yasuo Yamada, Cui E Wen, Tadashi Asahina, Kiyotaka Katou, Tsutomu Sonoda, Mamoru Mabuchi
Abstract: Manufactured cellular aluminums have been developed for a wide range of automotive applications where weight savings, improved safety, crashworthiness and comfort are required. The plateau deformation behavior of cellular aluminums under compressive loading makes this new class of lightweight materials suitable for energy absorption and comes close to ideal impact absorbers. In the present study, aluminum hollow hemispheres were firstly processed by pressing. Hollow sphere aluminum samples with a body-centered cubic (BCC) packing were then fabricated by bonding together single hollow spheres, which were prepared by adhering together hollow hemispheres. Hollow sphere aluminum samples with various kinds of sphere wall thicknesses of 0.1 mm, 0.3 mm and 0.5 mm but the same outside diameter of 4 mm were investigated by compressive tests. The effects of the sphere wall thickness on the mechanical properties and energy absorption characteristics were investigated.
333
Authors: Tatsuo Sato, Shoichi Hirosawa
Abstract: The nano-scale precipitate microstructures and properties of age-hardenable aluminum alloys such as Al-Cu, Al-Mg-Si and Al-Zn-Mg alloys were investigated using conventional electrical resistivity and hardness measurements, TEM and 3D-AP techniques. To increase mechanical strength and ductility of the alloys nano-scale precipitates were effectively controlled by applying new type heat treatments and microalloying elements. In the initial stage of phase decomposition of the alloys containing microalloying elements several types of nanoclusters were formed and distinctly detected by the 3D-AP technique. These nanoclusters greatly affect the nucleation of the subsequent precipitates and resultantly mechanical properties. In Al-Mg-Si and Al-Zn-Mg alloys complicated two-step aging behaviors were found to be originated in the positive or negative effect of the nanoclusters with different structures.
337
Authors: Ryoji Nakamura, Hisaki Watari, Shinji Kumai
Abstract: Two kinds of roll casters, which were suitable for high speed roll casting, were devised. One was a vertical type twin roll caster, and the other was an unequal diameter twin roll caster. The semisolid roll casting using a cooling slope was adopted to these roll casters. The solid fraction was smaller than 5%. 3 mm thickness of 6111 strip was cast at 60 m/min by the vertical type twin roll caster, and 5 mm thickness of 6111 strip was cast at 30 m/min by the unequal diameter twin roll caster. The microstructure of the as-cast strip was equiaxed and spherical, not columnar. The mechanical properties of the strip rolled from roll-cast strip were almost as same as that of the strip made from cast ingot.
343
Authors: Akio Hirose, Fumiaki Matsui, Hirotaka Imaeda, Kojiro F. Kobayashi
Abstract: In the present study, we fundamentaly analyzed the interfacial reaction and evaluated the joint strength in dissimilar diffusion bonding of Al alloys to steels. The growth of the reaction layer consisting of FeAl3 and Fe2Al5 intermetallic compounds followed the parabolic growth low. The joints with 5000 series Al alloys had a higher growth rate of the reaction layer than the joints with A6061 Al alloy. The joints of A6061 Al alloy to HT980steel had the lowest growth rate of the reaction layer. The joint strength depended on the thickness of the reaction layer. The A6061 Al alloy/steel joints had the maximum joint strength at around 1µm of average reaction layer thickness.
349
Authors: Sung Kyu Son, Mahoto Takeda, Takao Endo
Abstract: The precipitation behavior in an Al-Cu alloy isothermally annealed at 373K~493K was studied, using the Vickers microhardness tests, Differential scanning calorimetry(DSC) and Transmission electron microscope(TEM) observations. An additional endothermic peak was found in DSC measurements which may be attributed to the θ″-phase independent from the formations of the G.P.(Ⅱ) and the θ′-phase at the aging temperatures. High resolution transmission electron microscopy (HRTEM) revealed that the G.P.(Ⅰ) is formed at a very early stage of isothermal aging at 463K. Comparing the Vickers microhardness and TEM images, it was concluded that G.P.(Ⅱ) is mainly responsible for the peak hardness.
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