Prediction of Critical Compositions for Bulk Glass Formation in La-Based, Cu-Based and Zr-Based Ternary Alloys

Abstract

Using a quasi-chemical method coupled with Miedema’s semi-empirical method, we have estimated critical glass-forming compositions for bulk metallic glasses of metal-metal type alloys such as La–Ni–Al, Cu–Zr–Ti and Zr–Ni–Al that exhibit maximum temperature spans of their supercooled liquid region, ΔT_x (=T_x−T_g), reaching 37–77 K. We applied Cowley’s chemical short-range order (CSRO) parameters η_ij for specific constituent i-j atomic pairs calculated by the quasi-chemical method to obtain the short-range order parameter γ of the amorphous phase, which is used as a constant in the calculation of formation enthalpies by Miedema’s method. In this study, the constant γ is treated as a function of the composition of atomic pairs such as γ_ij(η_ij). From the calculated results, it appears that the most negative value of η_ij corresponds to a highly stable liquid state because of the occurrence of chemical short-range order, implying that bulk metallic glasses can be produced. Stability and instability of the liquid phase have been discussed in terms of the compositional dependence of Cowley’s CSRO parameters and enthalpy difference parameters. The calculated results predict fairly well the critical glass-forming compositions for the various bulk metallic glasses, even predicting the asymmetrical composition dependence of the glass-forming composition ranges. Furthermore, the relation of η_ij (=η₁₂) with interaction parameters ε₁² yields the characteristics of interaction between dissimilar solutes in 0-1-2 ternary metallic solutions.