Experimental and computational studies of the Cu–Hf binary system

The thermodynamic properties and phase equilibria of the Cu–Hf binary system with five intermetallic compounds were studied by experiments, first-principles calculations and CALPHAD modeling. The experimental investigations included differential thermal analysis, scanning electron microscopy, energy dispersive X-ray microanalysis and micro-X-ray diffraction focusing on the 30–60 at.% Hf composition range to determine the invariant reaction temperatures. Cu10Hf7 was confirmed to melt incongruently. The enthalpies of formation of all five binary Cu–Hf compounds were predicted through first-principles calculations. The atomic configuration of one of the compounds, Cu51Hf14, was postulated through systematic first-principles calculations with 65 atoms instead of 68 atoms, denoted by hp68 in the literature. The thermodynamic description of the Cu–Hf binary system was then obtained from the new experimental data and first-principles calculations.