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对Ca含量为2wt%的挤压态X20镁合金在410 ℃固溶处理20 h,采用光学显微镜 (OM)、扫描电镜 (SEM) 结合能谱分析 (EDS)以及透射电镜 (TEM) 对固溶处理前后的组织进行了表征,利用XRD衍射仪考察了固溶处理前后合金的相组成。结果表明,经固溶处理后,合金初始组织中β-Mg17Al12相的数量明显减少,同时析出新相Al2Ca。Al2Ca的形成可归结于残余β-Mg17Al12中高的Ca原子所造成的Mg原子被Ca原子取代,同时Al2Ca相自身高的结构稳定性也是其在Mg-Ca和Al-Ca系竞争析出中胜出的原因。
The microstructure of X20 magnesium alloy in extruded state with 2wt% Ca content was investigated by OM, SEM, EDS and TEM at 410 ℃ for 20 h. The microstructure of the alloy before and after the treatment was characterized by XRD. The phase composition of the alloy before and after solution treatment was investigated. The results show that after the solution treatment, the amount of β-Mg17Al12 phase in the initial microstructure of the alloy decreases obviously, while the new phase Al2Ca is precipitated. The formation of Al2Ca is attributed to the replacement of Mg atoms by Ca atoms by the high Ca atoms in the residual β-Mg17Al12, and the high structural stability of Al2Ca phases is also the reason for its superiority in the competitive precipitation of Mg-Ca and Al-Ca systems .