Microstructure control of monotectic hybrid powders for developing multi-functional properties

通过热力学计算，预测了Ag-Cu-X(X=Ni，Co，Fe)三元系的相容间隙，优化了三元合金的组成。采用感应熔炼法制备了钢锭，并用气体雾化法制备了粉末。因此，每个球形颗粒都具有卵形结构，其外围和核心分别由高导电性的富银相和铜-X相组成。将制得的粉末在70 0~90 0℃范围内烧结成块状样品，并测量其电阻率，以评价其作为高导电材料的潜力。一些烧结的Ag-Cu-X合金的电阻率与纯Ag样品的电阻率相吻合。结果表明，颗粒的Cu-X核和外围的富银相分解形成致密的、连续的富银网络，导致烧结材料的电阻率下降。

Miscibility gap in liquid phase in the Ag-Cu-X (X=Ni, Co, Fe) ternary systems was predicted and composition of the ternary alloys was optimized by thermodynamic calculation. Ingots were prepared by induction melting and powdered by gas-atomizing method. Consequently, each spherical particle of the powders exhibits egg-type microstructure, whose periphery and core consist of high-conductive Ag-rich phase and Cu-X phase, respectively. Obtained powders were sintered at 700～900℃ to form massive samples and their resistivity was measured to evaluate their potential for the high-conductive material. Resistivity of some sintered Ag-Cu-X alloys stacks up with a sintered pure Ag sample. It was found that Ag-rich phase decomposed from Cu-X core of particles as well as Ag-rich periphery forms dense and continuous network of the Ag-rich matrix, which results in the decrease of resistivity of sintered materials.