AZ61+xCe(x=0～1.5)合金的微观组织研究

Study on microstructures of AZ61+xCe(x=0～1.5) alloys

研究了不同铈含量对AZ61镁合金铸态及热处理态显微组织的影响。结果表明:与AZ61合金铸态组织相比,加入铈后,合金中的β相数量减少,形态变细,铸态晶粒得以细化;含铈合金中大部分铈与铝结合生成高熔点、高热稳定性的Al3Ce稀土相;在固溶处理中,β相完全溶解而Al3Ce相仍以针状或棒状存在于晶界附近,起到了阻碍晶粒长大的作用。基于XRD、SEM、EDS测试结果,并应用Miedema混合焓模型对稀土相的形成进行了分析,由于Ce与Al的亲和力远大于Ce与Mg的亲和力,合金中Ce与Al结合形成Al3Ce稀土相。

The influences of different Ce contents on the microstructures of as-cast and heat treated AZ61 magnesium alloys were investigated.The results showed that,with the Ce addition, the content of β phase was reduced,and the grain size of as-cast AZ61 alloy was refined remarkably.The Ce element mainly distributed by high thermal stable Al_3Ce compound.After solid-solution treatment,the β phase was completely dissolved into the matrix,whereas the Al_3Ce phase was still distributed at the grain boundaries as needle-like or rodlet grains.Based on the XRD,SEM and EDS results,and the Miedema model of mixed enthalpy,is because of the greater affinity between Ce and Al than that between Ce and Mg,is the formation of Al_3Ce phase in AZ61-Ce alloys.