稀土La对Mg-4.5%Zn合金铸态组织细化的影响

Effect of rare-earth La on microstructure of Mg-4.5%Zn as-cast magnesium alloy

在Mg-4.5%Zn合金中,加入少量稀土元素La(质量分数为0.3%,0.6%,0.9%),发现该元素可以有效地细化镁合金铸态的晶粒,晶粒尺寸由原始的150μm^230μm细化到20μm^35μm,细化后的Mg-4.5%Zn合金拉伸强度由112 N/mm2提高到154 N/mm2。进一步分析认为,其细化机制是La在镁合金熔体中形成Mg12La化合物,该化合物对晶界有抑制长大的作用。

Adding rare-earth La in Mg-4.5%Zn as-cast magnesium alloy was prepared by vacuum sinter to refine the grains of Mg- Zn alloys. The grain size of Mg-4.5% Zn as-cast magnesium alloy changed from about 150μm - 230 μm to 20 μm - 35μm and the tensile strength increased from 112 N/mm^2 to 154 N/mm^2 after adding rare-earth La. The refinement mechanism attributes to be the formation of large amount of nucleus of Mg12 La compounds in the solution of magnesium alloy.