Microstructure evolution of the interfacial phase in a melt-spun nanocrystalline Hf-Ni alloy

Abstract

Abstract By using the melt-spinning technique, a nanocrystalline (NC) Hf11Ni89 alloy was prepared which is composed of a major nanophase of HfNi5 compound (with an average grain size of about 10 nm) and an interfacial phase of a Ni(Hf) solid solution. The thermal stability and the microstructure evolution kinetics of the interfacial Ni(Hf) phase were characterized by means of magnetothermal analysis (MTA). Evident magnetic property changes were observed for the interfacial phase in the NC sample at temperatures far below the detectable grain growth temperature, corresponding to diffusion of Hf (depletion) in the interfacial phase and the Ni solid-solution precipitation process from the supersaturated HfNi5 nanophase. Kinetic parameters such as characteristic temperatures and activation energies were obtained for these microstructural evolution processes by using the quantitative MTA measurements during isochronal and isothermal annealing treatments. The kinetics of the Hf depletion in the interfacial Ni(Hf) phase and the dimensionality of the Ni precipitate are found to be sensitive to the annealing temperature.