Importance of solute-solute interactions on glass formability

Microalloying experiments on amorphous Al₈₄La₄Er ₂Ni₈TM₂ alloys were performed with the substitution of all 3d TM (transition metal) elements and one 4d TM element. The critical thickness of the amorphous alloys was used as a criterion for glass formability in this system. The results show that, other than atomic size differences and the negative heats of mixing among the solvent and solute atoms, the atomic interactions among the solute atoms play an important role on glass formation. When the solute-solute interaction becomes repulsive (positive heat of mixing), glass formability suffers. Similarly, when the solute-solute interaction becomes highly attractive, exceeding that between the solvent and solute atoms, glass formability is also degraded. Evaluation of a large number of known multicomponent bulk metallic glasses provides additional support to these conjectures. This study shows that the solute-solute interaction plays an important role in glass formation, which has not been recognized previously.