Witthaya Eidhed
材料科学技术（英文）
The purpose of this paper was to investigate the effects of solution treatment time and Sr-modification on the microstructure and property of the Al-Si piston alloy. It was found that as-cast microstructures of unmodified and Sr-modified Al-Si alloys consisted of a coarse acicular plate of eutectic Si, Cu3NiAl6 and Mg2Si phases in the α-Al matrix but different in size and morphology. Both size and inter-particle spacing of Si particles were significantly changed by increasing the solution treatment time. After a short solution treatment, the coarse acicular plate of the eutectic Si appears to be fragmented. Fully modified microstructure of Sr-modified alloy can reduce the solution treatment time compared to unmodified alloy. The maximum of a peak hardness value is found in the very short solution treatment of both Al-Si piston alloys. Compared to 10 h solution treatment, the solution treatment of 2–4 h is sufficient to achieve appropriate microstructures and hardness. The short solution treatment is very useful to increase the productivity and to reduce the manufacturing cost of the Al-Si piston alloys.
关键词:
Al-Si based alloy
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Witthaya Eidhed
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Hiroyasu Tezuka
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Tatsuo Sato
材料科学技术（英文）
The effects of Cr and Cr/Mn combined additions on the semi-solid microstructure of wrought Al-Mg-Si alloys are investigated. In the Cr-added alloy, the Al7Cr compound is formed with homogeneously distributed in the α-Al matrix after homogenization. Both of the Al7Cr and α-Al12Mn3Si2 dispersiod particles are found in the homogenized microstructure of the Cr/Mn-added alloy. In the semi-solid microstructures, the smallest α-Al grains are obtained in the 60% cold-rolled alloys. After prolonged holding time, the α-Al grain size of the Cr/Mn-added alloy is smaller than that of the Cr-added alloy. Heavy deformation by cold-rolling accelerates spheroidization of the α-Al grains. The D-SSF process is found to be useful to modify the microstructures of both the Cr-added and Cr/Mn-added Al-Mg-Si alloys.
关键词:
D-SSF process
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