Intermixing of a system with positive heat of mixing at high strain rates

This paper investigates a mode of mechanically driven alloying of elements that are otherwise immiscible at temperatures well below the equilibrium melting point. Using molecular dynamics simulations, we have studied the alloying between Ag and Cu, a positive-heat-of-mixing (formula presented) binary system with little solid solubility near ambient temperature, during high strain rate deformation at temperatures ⩽600 K. Above a critical strain rate, both elements undergo mechanical melting into undercooled liquids, which are miscible at 600 K due to the reduced magnitude of the (formula presented) in the liquid state compared with that in the crystalline state. The nonequilibrium deformation maintains the melt state and assists the intermixing reaction between elemental Ag and Cu through stress-directed atomic flow. Upon unloading, the intermixed amorphous Ag-Cu crystallizes towards a supersaturated fcc solid solution. The scheme described is a process of low-temperature amorphization and intermixing of elements, and as such differs from the well-known liquid quench route that starts from an already-mixed liquid alloy at high temperatures.