Accurate quantification of glass-forming ability by measuring effective volume relaxation of supercooled melt

Herein, we elucidate how to accurately quantify glass-forming ability (GFA) by measuring effective volume relaxation of supercooled melt. We propose a new parameter, denoted as kappa, for representing the relaxation, which is calculated by combining temperature-dependent changes of normalized specific volume reflecting relative volume relaxation with the normalized temperature range reflecting the relative position of the C curve in a Time-Temperature-Transformation (TTT) diagram. The interrelationship between the kappa parameter and critical cooling rate is elaborated by measuring V-T diagrams and TTT diagrams of Zr55Co26Al19 and Zr46Cu30.14Al8Ag8.36Be7.5 glass-forming alloys and discussed in comparison with representative GFA parameters reported up to date. These results would give us a guideline on how to precisely evaluate GFA by linking volumetric aspect to thermodynamic and kinetic aspects for glass formation and help develop customized glass-forming alloys as well as a highly precise control of glass formation process. (C) 2017 Author(s).