不同冷速Ag-5Sc合金的凝固组织

采用感应熔炼钢模凝固、慢速平衡凝固、液态快速凝固制备Ag-5Sc二元合金。借助差示扫描量热仪(DSC)、金相显微镜、电子探针(EMPA)和X射线衍射仪(XRD)研究合金在不同冷速条件下的组织结构、钪的分布和形成的化合物相。结果表明,钢模凝固形成环状Ag4Sc相与共晶组织交替的环形层状组织结构,其它组织为致密细小的共晶组织。慢冷凝固是粗大的胞状共晶组织,胞状间存在块状Ag4Sc相。液态快冷凝固为呈细小蜂窝状结构,组织为等轴晶粒。钢模凝固环形和慢冷凝固块状Ag4Sc相中钪元素分布密度比共晶中的Ag4Sc相高,液态快冷合金中钪元素分布均匀。

Solidification structure of Ag-5Sc alloy with different cooling rates

Ag-5Sc binary alloy was prepared by induction melting, slow equilibrium and liquid rapid solidification. Its microstructure, scandium distribution and chemical phases were studied by DSC, metallographic microscope, EPMA and XRD. The results showed that the ring-shaped layered structure with alternating Ag4Sc phase and eutectic structure was formed during solidification of steel mold. The other structure was fine eutectic. Slow cooling solidification formed a coarse cellular eutectic structure with massive Ag4Sc phase between cells. The rapid solidification of liquid generated a honeycomb structure with equiaxed grains. The distribution density of scandium element in the solidification ring and slow solidification agglomerate was higher than that in the eutectic, and the distribution of scandium element in the liquid quick cooling alloy was uniform.