Comparative analysis of glass-formation in binary, ternary, and multicomponent alloys

In the present work we analyze the composition ranges over which bulk metallic glasses (BMGs) are produced in ternary, quaternary, and quinary amorphous alloys. The maximum diameter of the sample over which an amorphous structure can be retained, referred to as the critical diameter, _Dc, is consistently large over specific composition ranges. For ternary BMGs, these most stable glasses are centered around the compositions, in decreasing order of accompanying D_c: A₄₄B₃₈C₁₈, A ₄₄B₄₃C₁₃, A₆₅B₂₅C ₁₀, A₅₆B₃₂C₁₂, A₅₅B ₂₈C₁₇, A₇₀B₂₀C₁₀, and A₆₅B₂₀C₁₅. As a general trend, the most stable glasses have the lowest concentrations of solvent atoms. Structural analysis using the efficient cluster packing model suggests that the best ternary glasses are near the isostructural composition, which represents the maximum degree of atomic confusion. Both M_Dc and Δ T_x = T_x - T_g, the difference between the crystallization and glass transition temperatures, are larger in quaternary and quinary systems relative to typical values for ternary BMGs. Glass-forming ability increases with complexity of the alloy, i.e., increasing number of alloying elements. The above results shed some light not only on compositional dependence of the formation of glassy phase but also its relation to the structure of the glasses.