Sr对AZ91D镁合金半固态等温热处理后的组织的影响

Effect of Strontium on Microstructure of AZ91D Magnecium Alloy after Semi-solid Isothermal Heat Treating

通过对等温热处理温度和时间等工艺参数的控制，研究了变质剂Sr对AZ91D镁合金半固态等温热处理后组织的影响。结果表明，随着等温时间的延长，未变质处理的合金组织将由树枝晶变成近球状组织，而经Sr变质处理的合金组织将由树枝晶变成细小的球状组织，都将逐渐合并长大。等温热处理过程中，树枝晶经历了熔断、粒状化、球化和粗化。

The effect of strontium （Sr） on the microstructure of AZ91D magnecium alloy subjected to semi-solid isothermal heat treating was investigated through control of the isothemal heat treatment temperature and the holding time at temperature. The results show that with the extension of holding time, a change from dendrite to approximately spherical structure will occur in the AZ91D alloy without being modified, a change from dendrite to fine globular structure will occur in the AZ91D alloy modified by strontium, and the two microstructures will all gradually grow up. Melting,granulation, spheroidization and coarsening of the dendrite will successively occur in the AZ91D alloy during the isothermal heat treating.