Investigation of ordering phenomenon in Me-Pt (Me=Fe,Ni) liquid alloys

Abstract

The phase diagrams of Fe-Pt and Ni-Pt liquid alloy systems show the existence of FePt and NiPt intermetallic compounds, respectively, in their solid intermediate states, and the associative tendency between unlike atoms in these liquid alloys has been analysed using the self-association model. The concentration dependences of mixing properties such as the free energy of mixing, GM; the concentration fluctuations, Scc(0), in the long-wavelength limits; the chemical short-range order (CSRO) parameter, α1; as well as the chemical diffusion, enthalpy and entropy of the mixing of Fe-Pt and Ni-Pt liquid alloys have been investigated to determine the nature of ordering in the liquid alloys. The results show that heterocoordination occurs in the alloys at all concentrations. The effect of CSRO on Scc(0), chemical diffusion, D, and the order parameter, α1, has been considered. The ordering phenomenon in the liquid alloys is also related to the effect of the atomic size mismatch volume on Scc(0). © 2008 National Institute for Materials Science.