超音速电弧喷射雾化银合金粉体的亚稳固溶扩展

Metastable solution expansion of Ag alloy powders by ultrasonic arc spray

采用超音速电弧喷射雾化（UAS）制备Ag-10Cu、Ag-28Cu、Cu-10Ag、Ag-10Ni和Ag-5Fe快速凝固合金粉末，用XRD对银合金粉末的亚稳固溶扩展进行研究。结果表明：Ag-10Cu、Ag-28Cu和Cu-10Ag合金粉末的平均亚稳固溶度分别为7．09％、20．11％和3．06％（摩尔分数）：当粉末粒度不大于50μm时，Ag-28Cu共晶合金粉末形成完全亚稳固溶体，而Ag-10Cu和Cu-10Ag未形成完全固溶体；Ag-10Ni和Ag-5Fe粉末（65～15μm）的亚稳固溶度分别为0．72％～1．30％Ni和0．29％～0．57％Fe，亚稳固溶度随粉末粒度减小而增加。合金生成热和冷却速率分别是判断亚稳固溶扩展能力的热力学参数和动力学参数，合金生成热越小、冷却速率越高，亚稳固溶度就越大。超音速电弧喷射雾化有利于降低合金生成热和获得很高的冷却速率，因此，银合金粉末获得大的亚稳固溶扩展。

Ag-10Cu, Ag-28Cu, Cu-10Ag, Ag-10Ni and Ag-5Fe alloy powders were prepared by ultrasonic arc spray. The metastable solution expansion of Ag alloy powders was studied by XRD. The results show that the average metastable solution of Ag-10Cu, Ag-28Cu and Cu-10Ag powders are 7.09%, 20.11% and 3.06%, respectively. The Ag-28Cu eutectic powders are single phase metastable fcc solid solution, while the powder size is not larger than 50 μm, but single phase metastable fcc solid solution cannot form in Ag-10Cu or Cu-10Ag powders. The metastable solution of Ag-10Ni and Ag-5Fe powders （65-15 μm） are 0.72%-1.30% Ni and 0.29%-0.57% Fe, respectively, and the metastable solution increases with decreasing powder size. The forming heat and the cooling rate are thermodynamics parameter and dynamics parameter for estimating the metastable solution expansion extent of alloy powders. The larger the extent of metastable solution expansion, the smaller the forming heat of alloy and the larger the cooling rate.