锶、钕对Mg-9Al-1Si-0.3Zn合金微观组织和力学性能的影响

Effects of Sr and Nd Addition on Microstructure and Mechanical Properties of Mg-9Al-1Si-0.3Zn Alloy

摘要:

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。

Abstract:

A large amount of coarse Chinese-script-like Mg2Si particles in the magnesium alloys containing much silicon is harmful to the mechanical properties of the alloys. Sr and Nd were added in Mg-9Al-1Si-0.3Zn alloy to refine the coarse Mg2Si, and the effect of the added elements on microstructures and mechanical properties of the alloy were studied. The refining mechanism of Sr and Nd to Mg2Si was analyzed. The results show that the Chinese-script-like morphology of the Mg2Si particles is improved and uniform polygonal block are formed with the addition of Sr element. When the Sr addition is 0.16 wt%, the particles appear in a completely polygonal morphology. When both Sr and Nd elements are added to the alloy, an intermetallic compound of Mg, Al, Nd and Si elements precipitate; the more added Nd, the more new phases, which act as the heterogeneous nuclei for the growth of the Mg2Si particles. The Mg2Si particles are refined as an irregular shape under the combination effects of Sr and Nd elements. The grain-refinement on Mg2Si particles improves the mechanical properties of the alloy.