Predicting the glass-forming ability of rare earth-contained Fe-based alloys by features of dynamic transition in their melts

Abstract

In this work, we firstly focus on the features of dynamic behaviors of two rare earth-contained alloy systems Fe-B-(Nb)-Y and Fe-(Co)-Cr-Mo-C-B-Y well above their liquidus temperatures. Compared with a relatively distinct viscosity discontinuity observed in the Fe-based melts without rare earth elements, such discontinuity becomes indistinct. However, analysis on the detected viscosity data indicates a dynamic crossover still exists in both of the two alloy systems. Using the parameter F representing the degree of the dynamic transition during cooling, the feature of the dynamic transition in these two alloy systems has been quantified and the negative correlation of F and the glass-forming ability (GFA) has been observed. A scenario of microstructural evolution has been built to explain this correlation. This work sheds light on controlling the GFA of rare earth-contained Fe-based alloys from the viewpoint of the melt dynamics, which belongs to the long-term standing issue of the liquid-solid inheritance.