中文摘要：

采用光学显微镜、扫描电镜（SEM）、X射线衍射（XRD）及拉伸实验等方法研究了热处理对挤压态AZ61-x%La镁合金显微组织和力学性能的影响。结果表明,经过T6处理后,原来弥散分布于晶界周围的β-Mg17Al12相经历了从完全溶解到重新析出的过程,并重新分布于晶界周围;β-Mg17Al12相由铸态的网状结构变成块状结构。在晶内一部分区域也出现了小块状的β相。合金中的稀土相能细化晶粒,显著提高合金的硬度。经过T6处理之后合金的抗拉强度,屈服强度和伸长率都有提高,但硬度略有下降。T5处理对合金的力学性能影响不大。

英文摘要：

The effects of heat treatment on microstructure and mechanical properties of extruded AZ61-x% La magnesium alloy were investigated by optical microscope（OM）,scanning electron microscope（SEM）,X-ray diffraction（XRD） as well as tensile testing. The results showed that,after the T6 treatment,the β-Mg17Al12 phases dispersed around the grain boundary suffered completely dissolved re-precipitated and re-distributed around the grain boundaries; the morphology ofβ-Mg17Al12 phase changed from network to blocky. In addition,some fine block β phases were also observed in the region of grain. Rare earth phase could refine grains and significantly improve the hardness of the alloy. However,after T6 treatment,hardness was decreased even though the tensile strength,yield strength and elongation of alloy has increased. Meanwhile,T5 treatment has less effect on the mechanical properties of the alloy.