锌对稀土镁合金组织与力学性能的影响

Effect of Zinc on Microstructure and Mechanical Properties of Mg-RE Alloys

采用OM,XRD,SEM和EDS等试验手段研究了Zn对稀土镁合金Mg-4Y-1Ca(%,质量分数)微观组织和力学性能的影响。结果表明:随着Zn(x=1%,3%,5%)的加入,Mg-4Y-1Ca合金中生成的Mg24Y5二元相逐步转变为Mg3Y2Zn3(W相)+Mg12YZn(X相)三元相,铸态组织细化,第二相沿晶界成网状分布;经热挤压变形后,合金再结晶后晶粒细化明显,第二相弥散分布于基体和晶界上,强度提高的同时伸长率也获得较大提升,其中Mg-4Y-1Ca-5Zn合金表现最为显著。得益于Zn添加对再结晶晶粒细化和W相、X相弥散强化的共同作用,Mg-4Y-1Ca-5Zn合金经热挤压处理后具有较佳的综合力学性能,屈服强度、抗拉强度和伸长率分别达到198 MPa,271 MPa和24.6%。

The effects of Zn on the microstructure and mechanical properties of Mg-4 Y-1 Ca(%,mass fraction)magnesium alloys were investigated by optical microscope(OM),X-ray diffractometer(XRD),scanning electron microscope(SEM)and energy dispersive spectrometer(EDS)and so on.The results showed that with the addition of xZn element(x=1%,3%,5%),the Mg24Y5 binary phase in Mg-4 Y-1 Ca alloy was gradually transformed to Mg3Y2Zn3(W phase)+Mg12YZn(X phase)ternary phases;the grains size of as-cast alloys were refined and network second phase distributed along the grain boundary.After hot extrusion deformation,grains were obviously refined after alloys recrystallization and the second phase was uniformly distributed on the matrix and the grain boundary and the elongation was also significantly improved,meanwhile,the strength was increased,especially in Mg-4 Y-1 Ca-5 Zn alloy.The yield strength,ultimate tensile strength and elongation of extruded Mg-4 Y-1 Ca-5 Zn alloy reached to 198,271 MPa and 24.6%,respectively,which were primarily attributed to grain refinement and strengthening effect of the dispersed second phases(W phase and the X phase).