使用往复挤压细化Mg-4Al-2Si (AS42)合金组织,利用OM,SEM和TEM研究Mg2 Si颗粒形貌和分布特征.结果表明,铸态AS42合金中Mg2Si颗粒呈共晶汉字状和初生块状.共晶Mg2 Si经2道次往复挤压后全部破碎,且分布均匀.经6道次挤压后初生Mg2 Si颗粒全部破碎,细小的Mg2 Si颗粒已基本球化.往复挤压合金中Mg2Si颗粒尺寸遵循Weibull分布,颗粒平均尺寸、标准差和相对密度随挤压道次增加而提高,经过8道次挤压后分别为1.3μm、0.7μm和540％.%Microstructure of as-cast Mg-4Al-2Si (AS42) alloy was refined by reciprocating extrusion (REX), the morphologic and distribution characteristics of Mg2Si particles were investigated by employing optical microscopy, scanning electron microscopy, and transmission electron microscopy. The results show that the Mg2 Si particles in as-cast AS42 alloy are in the forms of eutectic Chinese scripts and primary polyhedral particles. After 2-pass REX, all eutectic Mg2Si particles are broken and distributed uniformly. After 6-pass REX, all primary Mg2Si particles are broken and the fine Mg2Si particles are spheroidized basically. The distribution of the Mg2Si particles in the extruded alloy follows Weibull function. After 8-pass REX, the average size, uniformity and the relative density of Mg2Si particles are 1. 3μm, 0. 7μm and 540%, respectively.
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