Relation of various GFA indicators to the critical diameter of Zr-based BMGs

In the face of a large number of glass forming ability (GFA) thermal indicators that can be found in the literature, the authors have made an attempt to order a variety of them by their correlation with the critical diameters (D-c) of four various Zr-based alloys. D-c(s) were determined by the wedge test and varied from 4.5 to 10.4 mm. Characteristic temperatures, determined by the DTA, were used to calculate some GFA thermal indicators: Delta T-xg, T-rg, K-gl, alpha, beta(1), beta(2), gamma, gamma(m), delta and xi. The data were used to built plots: GFA indicator versus D-c. Using the logarithmic fitting, the R-2 correlation coefficient was determined for each indicator. Ordering the GFA indicators by the R-2 ascending values allowed both qualitative as well as quantitative comparisons. It was revealed that the Delta T-xg indicator exhibited weak correlation (R-2 = 0.019) with the D-c in contrast to beta(1), gamma, gamma(m), delta and xi. It was also proven that the solidus temperature should not be used in a formula of a GFA indicator in order to achieve high correlation with the D-c. The authors also made an attempt to modify the formula of the gamma(m) indicator in order to improve the R-2 value. It was possible to raise it to the level of 0.882 -a new GFA indicator x was proposed. (C) 2014 Elsevier B.V. All rights reserved.