Er和Gd复合变质对Mg-3.2Si合金组织及性能的影响  

Effect of Er and Gd Compound Modification on Primary Mg_2Si Phase in Hypereutectic Mg-3.2Si Alloys

作　　者：柏世梅 尧军平[1] 廖露亮 

机构地区：[1]南昌航空大学航空制造工程学院

出　　处：《特种铸造及有色合金》2016年第12期1337-1341,共5页Special Casting & Nonferrous Alloys

基　　金：国家自然科学基金资助项目(51164027);江西省教育厅重点科技项目(GJJ14502);江西省科技厅国合项目(20151BDH80054)

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20-30μm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%。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_2Si 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_2Si phase with size in 20~30μm can be observed,exhibiting the desirable modification effects.However,when addition of rare earth is excessive,the primary Mg_2Si phase becomes coarse.Er and Gd can enrich on the primary Mg_2Si 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.

关 键 词：MG-SI合金 MG2SI 稀土Er和Gd 

分 类 号：TG146.22[一般工业技术—材料科学与工程] TG243.1[金属学及工艺—金属材料]