Correlations between viscosity and glass-forming ability in bulk amorphous alloys

According to the classical crystallization theory, the influences of kinetics and thermodynamics on glass-forming ability (GFA) for bulk metallic glasses has been investigated. The theoretical analysis shows that crystallization resistance is in proportion to the viscosity of " nose " temperature (T_n) while crystallization driving force is inversely proportional to the viscosity of crystallization onset temperature (T_x) on reheating in time-temperature-transformation (TTT) curve, and therefore a GFA parameter ω₀, defined as (T_g-T₀)/ (T_x-T₀)- (T_g-T₀)/ (T_n-T₀), was proposed (wherein T_g and T₀ are glass transition temperature and Vogel temperature respectively). The parameter ω₀ shows an excellent correlation with the critical cooling rate for glass formation of bulk metallic glasses, with the statistical correlation factor of R²=0.9626. Furthermore, the relationships between the GFA and T_rg, ΔT_x, γ, γ_m, ΔT_rg, α, β, δ and φ, as well as the fragility of liquid could be explained reasonably based on our proposed ω₀ parameter.