稀土Gd对Mg-Nd-Zn-Zr镁合金组织和性能的影响  

Effect of Gadolinium on the Microstructure and Mechanical Properties of Mg-Nd-Zn-Zr Cast Magnesium Alloys

作　　者：李杰华[1] 介万奇[1] 杨光昱[1] 

机构地区：[1]西北工业大学,陕西西安710072

出　　处：《稀有金属材料与工程》2008年第10期1751-1755,共5页Rare Metal Materials and Engineering

基　　金：国家基础研究发展规划资助项目(G2000067202);西北工业大学博士论文创新基金(CX200705)资助

摘　　要：以Mg-Nd-Zn-Zr合金为基础,通过调整Nd和Zn的含量进行合金成分优化设计,并在新选择的较优成分点通过加入合金化稀土元素Gd,研究了Gd对Mg-Nd-Zn-Zr镁合金铸造组织和力学性能,尤其对高温力学性能的影响。研究发现,Mg-Nd-Zn-Zr镁合金铸态组织由α-Mg基体和Mg12Nd化合物组成。加入合金化稀土元素Gd后,NG31试验镁合金中没有形成三元相,但铸态组织中枝晶间分布的Mg12Nd化合物变得更加细小均匀。经过固溶处理后,Mg-Nd-Zn-Zr试验镁合金铸态组织中枝晶间以及晶界上的化合物完全溶入基体,而NG31试验镁合金在晶界上还有一些颗粒状的化合物。在时效处理时该化合物会以细小弥散的化合物从α-Mg基体中析出。无论Mg-Nd-Zn-Zr镁合金还是NG31试验镁合金,T6态热处理后都具有优良的室温力学性能,抗拉强度分别达到275MPa和280MPa,屈服强度也分别保持在158MPa和165MPa。随着Nd含量的增加和Zn含量的降低,Mg-Nd-Zn-Zr镁合金的抗拉强度和屈服强度升高,延伸率也随之增加。随着Gd的加入,抗拉强度和屈服强度升高,而延伸率却有所下降。同时,在所有的测试温区内NG31的高温瞬时抗拉强度和屈服强度都高于Mg-Nd-Zn-Zr试验镁合金。NG31试验合金在250℃的抗拉强度仍然保持在215MPa,屈服强度仍能够达到155MPa,甚至还高于200℃时的屈服强度(141MPa)。The new element points was selected by adjusting Nd and Zn content based on Mg-Nd-Zn-Zr magnesium alloys, and the effects of Gadolinium on the microstructures and mechanical properties of Mg-Nd-Zn-Zr magnesium alloy were studied. The main research results are as follows： （1） The as-cast microstructure of Mg-Nd-Zn-Zr alloy and NG31 alloy consist of a-Mg grains with Mg12Nd phase on the grain boundary. （2） After solution heat-treatment, Mg12Nd phase of Mg-Nd-Zn-Zr alloy were dissolved in the matrix, however, there was still discontinued Mg12Nd phase at grain boundary of NG31 alloy. （3） The mechanical properties of Mg-Nd-Zn-Zr alloy and NG31 alloy at room temperature are satisfactory, with σb =275 MPa, σ02 =158 MPa for Alloy-A2 and σb = 280 MPa, σ0.2 =165 MPa for NG31 alloy respectively. （4） With the increase of Nd and the decrease of Zn, the ultimate strength, yield strength and the elongation of Mg-Nd-Zn-Zr alloy at room temperature were increased slightly. The ultimate strength and yield strength of NG31 alloy are higher than those of Mg-Nd-Zn-Zr alloy at room temperature, but the elongation is lower. （5） With the temperature increasing, the ultimate strength and yield strength of Alloy-A2 at elevated temperature were decreased sharply. The ultimate strength of NG31 alloy kept at 215 MPa at 250 ℃, and the yield strength also kept at 155 MPa higher than 141 MPa at 200 ℃.

关 键 词：稀土Gd 组织 性能 Mg—Nd-Zn-Zr镁合金 固溶处理 

分 类 号：TG146.22[一般工业技术—材料科学与工程]