A simple criterion to predict the glass forming ability of metallic alloys

Abstract

A new and simple criterion with which to quantitatively predict the glass forming ability (GFA) of metallic alloys is proposed. It was found that the critical cooling rate for glass formation (RC) correlates well with a proper combination of two factors, the minimum topological instability (λmin) and the Δh parameter, which depends on the average work function difference (Δφ) and the average electron density difference (Δnws1/3) among the constituent elements of the alloy. A correlation coefficient (R2) of 0.76 was found between Rc and the new criterion for 68 alloys in 30 different metallic systems. The new criterion and the Uhlmann’s approach were used to estimate the critical amorphous thickness (ZC) of alloys in the Cu-Zr system. The new criterion underestimated RC in the Cu-Zr system, producing predicted ZC values larger than those observed experimentally. However, when considering a scale factor, a remarkable similarity was observed between the predicted and the experimental behavior of the GFA in the binary Cu-Zr. When using the same scale factor and performing the calculation for the ternary Zr-Cu-Al, good agreement was found between the predicted and the actual best GFA region, as well as between the expected and the observed critical amorphous thickness.