Prediction of glass-forming composition ranges in Zr-Ni-Al alloys

Abstract

Glass-forming composition ranges in the alloy system Zr-Ni-Al are predicted by applying Miedema's semi-empirical method. The compositional dependence of the formation enthalpies of amorphous ΔH(Amo), solid solution ΔH(SS), and intermetallic compound phases ΔH(Comp) is calculated. We propose that the enthalpy difference parameters of ΔH(SS) - ΔH(Amo), ΔH (Amo) - ΔH(Comp) and simple criteria, including electronegativities, can be used to predict the glass-forming composition ranges (GFR) and the dominant factors determining the glass-forming ability (GFA). The wide GFR in the system, apart from the Al-rich region, and the tendency of the intermetallic compounds to form and constrain any extension of the GFR, are clearly predicted by a combining evaluation of these parameters and the simple criteria. The large negative heat of mixing, the atomic size difference among the constituent elements, and the short-range order stabilize the glassy phase leading to a high GFA of the alloy system. Furthermore, the composition dependence of crystallization temperatures Tx and the glass transition temperatures Tg can be estimated on the basis of the enthalpy values. Results compare well with the experimental data.