Effect of Er and Gd Compound Modification on Primary Mg<sub>2</sub>Si Phase in Hypereutectic Mg-3.2Si Alloys

Bai Shimei; Yao Junping; Liao Luliang

doi:10.15980/j.tzzz.2016.12.027

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Effect of Er and Gd Compound Modification on Primary Mg₂Si Phase in Hypereutectic Mg-3.2Si Alloys
Vol. 36, Issue 12, Pages: 1337-1341(2016)
Published： 2016 ，
DOI： 10.15980/j.tzzz.2016.12.027

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[1]柏世梅,尧军平,廖露亮.Er和Gd复合变质对Mg-3.2Si合金组织及性能的影响[J].特种铸造及有色合金,2016,36(12):1337-1341.

Bai Shimei, Yao Junping, Liao Luliang. Effect of Er and Gd Compound Modification on Primary Mg₂Si Phase in Hypereutectic Mg-3.2Si Alloys. [J]. Special Casting & Nonferrous Alloys 36(12):1337-1341(2016)
[1]柏世梅,尧军平,廖露亮.Er和Gd复合变质对Mg-3.2Si合金组织及性能的影响[J].特种铸造及有色合金,2016,36(12):1337-1341. DOI： 10.15980/j.tzzz.2016.12.027.

Bai Shimei, Yao Junping, Liao Luliang. Effect of Er and Gd Compound Modification on Primary Mg₂Si Phase in Hypereutectic Mg-3.2Si Alloys. [J]. Special Casting & Nonferrous Alloys 36(12):1337-1341(2016) DOI： 10.15980/j.tzzz.2016.12.027.

摘要

通过金相、扫描电镜和电子探针等方法研究了稀土Er和Gd复合变质对过共晶Mg-3.2Si合金组织和力学性能的影响

并探讨了其变质机理。结果表明

在过共晶Mg-3.2Si合金中

添加约0.6%的Er时

初生Mg2Si相的尺寸由150μm减小到40μm

其形态由粗大树枝状变为不规则多面体形状;在此基础上

继续添加0.6%的Gd

可获得20

0μm的多面体初生Mg2Si相

变质效果最佳;但稀土添加过量

会出现过变质现象。其变质机理是稀土在初生Mg2Si相表面富集

影响其生长过程并改变其生长方式;合金凝固时

稀土Er、Gd的晶体结构相同

形成了连续固溶体。当加入0.6%的Er和0.6%的Gd时

合金的抗拉强度与伸长率分别达到112 MPa和3.2%。

Abstract

Effects of Er and Gd compound addition on microstructure and mechanical properties of hypereutectic Mg-3.2Si ally were investigated by optical microscopy

scanning electron microscopy and EMPA.And modification mechanism of the Er and Gd was also described.With 0.6%（mass fraction

the same below）Er addition

size of the primary Mg

Si phase in Mg-3.2Si alloy is refined from 150μm to 40μm with structure transformed from bulky dendritic into irregular polyhedron shape.And then adding0.6% Gd

polyhedron primary Mg

Si phase with size in 20

0μm can be observed

exhibiting the desirable modification effects.However

when addition of rare earth is excessive

the primary Mg

Si phase becomes coarse.Er and Gd can enrich on the primary Mg

Si phase to control its growth process and change growth mode.Moreover

Er and Gd can generate the continuous solid solution during solidification because of the same lattice structure.With compound adding 0.6% Er and 0.6% Gd

tensile strength and elongation of the alloy reach 112 MPa and 3.2%

respectively.