Thermodynamic characteristics of Ti-based glass-forming alloys

Based on thermodynamic characteristics of the stable metallic liquid at melting temperature and the supercooled liquid, the present work calculated the mixing enthalpy Delta H-mix, the mixing entropy Delta S-mix and the Gibbs free energy difference between the supercooled liquid and the resulting crystalline phases Delta G of typical Ti-based amorphous alloys. The results show that for the case of larger Delta S-mix, moderate Delta H-mix for the stable liquid and smaller Delta G for the supercooled liquid, Ti-based alloys tend to achieve high glass-forming ability (GFA). A new parameter, beta, defined as (T-g - T-k)/(T-t - T-g), has been introduced to evaluate the GFA of Ti-based bulk amorphous alloys (wherein T-g, T-t, and T-k represent the glass transition temperature, the liquidus temperature, and the Kauzmann temperature. respectively). Experimental data imply that the larger the beta, the better the GFA for Ti-based amorphous alloys. (C) 2009 Elsevier B.V. All rights reserved.