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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 effects of Ce / La (x = 0,0.1,0.5,1.0) on the microstructure and creep properties of AZ91D magnesium alloy were studied. The results of X-ray diffraction (XRD), optical microscope (OM), scanning electron microscopy (SEM) and energy dispersive X-ray spectroscopy (EDX) showed that the addition of Ce / La to the AZ91D magnesium die- In addition to the Mg17Al12 phase, a new rare earth compound Al11RE3 (RE = Ce / La) compound was also formed, and the microstructure of the alloy was refined to improve the mechanical properties at room and elevated temperatures. The high temperature thermal stable Al11RE3 (RE = Ce / La) phase produced AZ91D + xCe / La (x = 0,0.1,0.5,1.0) alloy has better creep resistance at 150 ℃ and 50MPa than AZ91D magnesium alloy, Compared with AZ91D, the Ce / La alloy has a 0.2% creep elongation and a minimum creep rate of 2.02 × 10-8 s-1 from 2.30 × 10-8s-1. The creep microstructure analysis shows that the creep mechanism of AZ91D alloy is dominated by the grain boundary slip mode, and the Al11 RE3 (RE = Ce / La) phase stabilizes and retards the grain boundary fracture process.