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当镁合金中添加含量较高的Si时,会形成大量粗大汉字状的Mg2Si,严重影响合金的力学性能。通过Sr和Nd及其复合添加细化Mg-9Al-1Si-0.3Zn合金中粗大的Mg2Si,研究添加元素对合金微观组织和室温力学性能的影响,分析了Sr和Nd对Mg2Si的细化机制。结果表明,随着Sr的加入,汉字状Mg2Si的形貌得到改善,形成了均匀的多边形块状;当Sr添加到0.16%(质量分数,下同)时,Mg2Si得到了完全的细化。当同时添加Nd和Sr元素时,合金中出现新的以Mg,Al,Nd和Si形成的物相;随着Nd的增加,这种新的物相增多,这种化合物提供了Mg2Si相细化的异质核心。在Sr和Nd的复合作用下,汉字状Mg2Si被细化,合金的力学性能得到改善。
When a high content of Si is added to the magnesium alloy, a large amount of coarse Chinese character Mg2Si is formed, which seriously affects the mechanical properties of the alloy. The effect of added elements on the microstructure and mechanical properties at room temperature of the alloy was studied by adding coarse Mg2Si in the refined Mg-9Al-1Si-0.3Zn alloy with Sr and Nd and their composite, and the refinement mechanism of Sr and Nd to Mg2Si was analyzed. The results show that with the addition of Sr, the morphology of the Chinese character Mg2Si is improved and a uniform polygonal block is formed. When Sr is added to 0.16% (mass fraction), Mg2Si is completely refined. When both Nd and Sr were added, a new phase of Mg, Al, Nd and Si appeared in the alloy. With the increase of Nd, the new phase increased, and this compound provided the Mg2Si phase refinement Heterogeneous core. Under the combined effect of Sr and Nd, the Chinese character Mg2Si is refined and the mechanical properties of the alloy are improved.