The semisolid microstructural evolution of a severely deformed A356 aluminum alloy
The semisolid microstructural evolution of a severely deformed A356 aluminum alloy
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DOI：
10.1016/j.matdes.2013.02.051
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发表时间：
2013-08-01
影响因子：
8.4
通讯作者：
Hassas-Irani, S. B.
中科院分区：
文献类型：
--
作者：
Haghdadi, N.;Zarei-Hanzaki, A.;Hassas-Irani, S. B.
通过应用一种新的剧烈塑性变形方法——累积反向挤压（ABE），在300℃的温度下成功地加工了铸造A356铝合金，获得了由圆形细小Si颗粒组成的剧烈变形显微组织。研究了 ABE 加工材料在不同等温温度下以半固态浸泡不同时间后的微观结构演变。研究表明，所提出的半固态热机械路线将产生精细的半固态微观结构，其中球状 α-Al 球体被连续液膜包围。结果表明，ABE 处理后在 580 摄氏度下保持 10 分钟和/或在 590 摄氏度下保持 6 分钟，可获得最佳的触变特性，即高形状系数和低球体尺寸。触变结构特征也从球化和粗化机制以及微观结构演化动力学方面得到了适当的讨论。加工材料的几乎线性半固态粗化行为表明奥斯特瓦尔德熟化机制在球体生长中的突出作用。 (C) 2013 Elsevier Ltd. 保留所有权利。
A cast A356 aluminum alloy was successfully processed through applying anew severe plastic deformation method, accumulative back extrusion(ABE), at the temperature of 300 degrees C. In consequence, a severely deformed microstructure consisting of round and fine Si particles has been obtained. Microstructural evolution of the ABE-processed material soaked for various times at different isothermal temperatures in semisolid state was investigated. It has been shown that the proposed semisolid thermomechanical route would lead to a fine semisolid microstructure, where the spheroidal alpha-Al globules are surrounded by continuous liquid film. The results indicate that the ABE processing followed by 10 min holding at 580 degrees C and/or 6 min at 590 degrees C has led to the best thixotropic characteristics, i.e., the high shape factors and low globule sizes. The thixotropic structure characteristics have been also properly discussed in terms of globularization and coarsening mechanisms as well as the kinetics of microstructural evolutions. The almost linear semisolid coarsening behavior of the processed material indicates the outstanding role of Ostwald ripening mechanism in the growth of globules. (C) 2013 Elsevier Ltd. All rights reserved.