Improving fatigue property of Zr-Ni-Al metallic glass by tailoring chemical composition with high structure stability

Improving the tolerance to fatigue damage for bulk metallic glass (BMG) is of vital importance for its industrial applications during long-term mechanical service. In this work, the composition dependence of structure stability against thermal and mechanical stimuli are studied with Zr-Ni-Al BMGs from the perspective of atomic topo-logical packing and chemical affinity. Large atomic size disparity and strong interactions between component elements facilitate the stability of glass structure, which impart BMGs with relatively higher glass transition temperature and yield strength. Fatigue failure of BMG initiates from the accumulation of inelastic shear transformation events on the sample surface under cyclic loading. The fatigue endurance limit of Zr-Ni-Al BMG is effectively improved by tailoring the chemical composition with increased structure stability, which is char-acterized by high mismatch entropy and mixing enthalpy. Aluminum plays a role in enhancing the fatigue tolerance of Zr-Ni-Al BMGs, which presumably arises from the covalent-like bond character of aluminum that promotes the formation of rigid atomic packing motifs with great resistance to shear rearrangement, and consequently mitigates the fatigue crack initiation process.