铈镧混合稀土对AZ91D压铸镁合金显微组织和蠕变性能的影响

Effect of Ce/La on Microstructure and Creep Property of Die-Cast AZ91D Alloys

研究了不同含量Ce/La(x=0,0.1,0.5,1.0)对AZ91D镁合金显微组织及蠕变性能的影响。通过X射线衍射(XRD)、金相显微镜(OM)、扫描电镜(SEM)及能谱分析(EDX)观察与分析表明,压铸AZ91D镁合金中添加Ce/La后,除了α-Mg,β-Mg17Al12相之外,还生成了新的稀土化合物Al11RE3(RE=Ce/La)化合物,并且细化了合金显微组织、提高了合金室温和高温力学性能。生成的Al11RE3(RE=Ce/La)高温热稳定相使AZ91D+xCe/La(x=0,0.1,0.5,1.0)合金在150℃,50MPa下的蠕变抗力优于AZ91D镁合金,1%Ce/La的合金与AZ91D相比,蠕变延伸率低了0.2%,最小蠕变速率从2.30×10-8s-1降低到2.02×10-8s-1。蠕变试样的微观组织结构分析表明:AZ91D合金的蠕变机制主要以晶界滑移方式为主,Al11RE3(RE=Ce/La)热稳定相在晶界处延缓和阻碍了晶界断裂的过程。

The effect of Ce/La on the microstructures and creep property of die-cast AZ91D alloys containing varied contents of Ce/La(0%,0.1%,0.5%,1.0%)was studied.X-ray diffraction,optical microscopy,scanning electron microscopy and energy disperse spectroscopy were used to analyze microstructures and creep properties of the alloys at room temperature and high temperature.Results showed that the new phase compositions of die-cast AZ91D alloys adding in a small amount of Ce/La mainly consisted of β-Mg17Al12 and Al11RE...