Origin of high glass forming ability of Y-containing FeB-based alloys

Using extended X-ray absorption fine structure, the origin of high glass forming ability (GFA) for the ternary Fe–Y–B system has been successfully correlated with local atomic structure. It is confirmed that the incorporation of minor large-sized Y atoms promotes the formation of complex B6(Fe,Y)23 phase, compared with Fe3B phase in the Fe–B binary alloy. With further addition of Y (up to 6 at.%), excessive internal strain leads to the distortion of B6(Fe,Y)23-like phase and eventually favors the formation of amorphous state during solidification. Consequently, GFA increases from 0.025 mm Fe78B22 thin ribbon to 2 mm Fe72Y6B22 rod.