Liquid phase separation in immiscible Ag–Ni–Nb alloy and formation of crystalline/amorphous composite

Phase decomposition in liquid miscibility gap presents a unique opportunity for designing amorphous/crystalline composites with a multilayer structure. One of typical monotectic systems, Ag–Ni alloy, is selected, and element Nb is added in the Ag–Ni alloy. The new ternary Ag–Ni–Nb monotectic alloys are rapidly quenched by using melt spinning technique. It is revealed that the ternary alloy undergoes a liquid–liquid phase decomposition and forms two immiscible Ag-rich and NiNb-rich liquids. Subsequently, the immiscible liquids solidify into Ag-rich crystalline and NiNb-based amorphous phases, respectively. Self-assembled amorphous/crystalline composites with double layer and sandwich type structures have been developed. The structure of the alloy ribbons with a dependence on the composition changes from a particle-dispersed structure to double layer structure and to sandwich type structure. The phase formation and thermal property of the quenched alloys are investigated. The formation mechanism of the crystalline/amorphous composite structures has been discussed.