Mg-Y-Mn-Sc合金的铸态组织及其热处理行为

Microstructure and Heat Treatment Behavior of Mg-Y-Mn-Sc Alloy as-Casting

采用水淬工艺制备了Mg-Y-Mn-Sc合金铸锭,通过OM、SEM、XRD等分析手段,研究了合金铸态组织结构特征以及经不同时间520℃固溶处理后组织结构的演变行为。结果表明,合金铸态组织的晶粒粗大,枝晶不发达,有大量的“辫”状孪晶,存在第二相呈颗粒状按线形排列分布。随着固溶时间的延长,晶粒由大变小,然后变粗;孪晶由少增多,最后随着晶粒的变大而逐渐减少,其组织和结构变化明显地表现出固溶体分解、分散相的溶解和聚集行为。通过控制固溶温度和时间。

The ingot of Mg-Y-Mn-Sc alloy casting was prepared by water quenching. The microstructure of the alloy casting and the evolvement behavior after solution under 520℃ for different time were studied. The results show that the grains of casting microstructure are much coarse, the dendrites are underdeveloped with large numbers of plait-like twin grains and second phase particles are linear distribution. Along with solution time, the grains are changing from large to small and then becoming thick. The number of twins is increasing. Finally, the number of twins decreases gradually with grains growing. The microstructure evolvement of the alloy exhibits evidently decomposing of solid solution, dissolving and congregating of dispersive phases. Through controlling the time and the temperature of solution, the effect of refining grains of the alloy casting can be obtained.