微量Si、Ba、Sn对AZ91铸态组织的影响

Effects of Trace Si,Ba and Sn on the As-cast Microstructure of AZ91 Magnesium Alloy

研究了Si、Ba、Sn元素对AZ91镁合金铸态组织的影响。结果表明,添加少量的Si能够细化AZ91合金晶粒,但当Si含量(质量分数,下同)达0.50%时,会产生粗大的汉字状Mg2Si相。向AZ91-0.5Si合金中加入微量的Ba后,粗大的Mg2Si相消失,这与合金中形成了Al4Ba相有关。添加一定量的Sn能够形成高熔点的Mg2Sn相,对合金有细化晶粒的作用,添加量为0.50%时β(Mg17Al12)相由网状变为弥散的颗粒状。分析认为,0.50%的Sn可以提高Al原子在α(Mg)中的固溶度。

Effects of Si, Ba and Sn element on the as-cast microstructure of AZ91 magnesium alloy have been observed. The results show that although trace Si addition can refine the grain size of AZ91 magnesium alloy, 0.5%Si addition can result in the creation of coarse Chinese script Mg_2Si phase in the alloy. Coarse Mg_2Si particles can not be observed with adding minor Ba into AZ91 magnesium alloy containing 0.5% Si, which is attributed to the formation of Al_4Ba phase in the alloy. Trace Sn addition can refine the grain size of the alloy due to the creation of Mg_2Sn phase with a high melt point, where β-Mg_ 17 Al_ 12 phase is converted from net-like structure into disperoids with 0.50% Sn addition. And 0.50% Sn addition can increase solid solution degree in Al atom.