Influence of substitution of La by Gd on crystallization behavior of Al-Ni-La metallic glasses

A series of Al100-a-bNia(La1-xGdx)b metallic glass ribbons, where a = 9–10, b = 4.5–5.5 and x = 0–1, were prepared by melt-spinning under identical conditions for investigating the dependence of crystallization behavior on the mutual substitution between La and Gd. In general, as the rare earth gradually changes from full La to full Gd, the thermal stability decreases and the formation of α-Al as primary phase is favored. A parameter taking the number and strength of various solvent-solute bonds into account was proposed to evaluate the thermal stability of present and other Al-TM-RE (TM-transition metal and RE-rare earth) metallic glasses, and good agreement was achieved between the theory and experimental results. Substitution of La by Gd releases additional “free Al atoms” and enhances the segregation of solvent Al atoms, therefore promoting the formation of α-Al at the first crystallization stage. •The optimal glass former and its neighbors in Al-Ni-La systems were base alloys.•La was substituted by Gd in each base metallic glass to study crystallization behavior.•A parameter was proposed for predicting thermal stability of Al-Ni-(La-Gd) metallic glasses.•The inhomogeneity with free-Al volume dominates the type of primary phase.