热处理对Mg-8Gd-2.5Nd-0.5Zr合金组织和力学性能的影响

Effects of heat treatment on microstructure and mechanical properties of Mg-8Gd-2.5Nd-0.5Zr alloy

通过OM、XRD、TEM、SEM和电子拉力试验机等,研究了固溶和时效处理对Mg-8Gd-2.5Nd-0.5Zr(质量分数,%)合金显微组织和力学性能的影响。结果表明:合金铸态组织由α-Mg基体和含Mg5Gd相、Mg12Nd相的粗大枝晶组成,经过热处理后,合金中方块状颗粒相明显增多,且分布在晶界处;固溶时效态合金析出的纳米尺寸方块相可有效强化合金。时效态合金中β'析出相形态类似多个纺锤形相连接而成,相互之间的夹角呈120°,且具有周期结构。铸态、固溶态和时效态合金在不同状态下的室温拉伸强度分别为:189.3、201.4和251.1MPa。

Microstructure and mechanical properties of Mg-8Gd-2.5Nd-0.5Zr （mass fraction,%） alloy after solid solution and aging treatment were studied by OM,XRD,TEM,SEM and tensile experiment.The results show that the microstructure of as-cast alloy is composed of α-Mg matrix and crystal containing Mg5Gd and Mg12Nd phases.After heat treatment,more cuboid-shaped particles are founded.The nanoscale stripe phase is precipitated out,and the alloy is strengthened effectively.The β＇phase of aged alloy is multiple spindle with periodic structure,and the mutual angle is 120°.The tensile strength of the alloy are 189.3MPa （as-cast）,201.4 MPa （solid solution state） and 251.1 MPa （aging state）,respectively.