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

对Ag-Cu-X （X=Ni, Co, Fe）三元体系液相混相间隙进行了预测，并通过热力学计算优化了三元合金的组成。采用感应熔炼法制备钢锭，采用气雾化法制备粉末。因此，粉末的每个球形颗粒都呈现出卵状微观结构，其外围和核心分别由高导电性富银相和Cu-X相组成。将所得粉体在700~900℃下烧结成块状试样，测定其电阻率，评价其作为高导电材料的潜力。一些烧结Ag- cu - x合金的电阻率与烧结的纯Ag样品相叠加。结果表明，从Cu-X颗粒核心分解出的富银相以及外围的富银相形成了致密连续的富银基体网络，从而降低了烧结材料的电阻率。

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.