Structural evolution under elastic cyclic loading in a Ti-based metallic glass

Multiple characterization techniques including DSC, TEM, XRD, HV and SEM were utilized to investigate the structural evolution of metallic glass (MG) under elastic cyclic loading. It is found that the relaxation enthalpy (served as the reflection of free volume contents) in the fatigued specimen was raised by similar to 5 times as compared with as-cast specimen. The cyclic loading induces the larger interatomic distance and smaller coordination number. Besides, the micmhardness reduction from similar to 545.6 +/- 15.3 to similar to 518.7 +/- 4.8 was observed in the as-cast and fatigued specimens, indicating the cyclic loading induced softening behavior. Such results reveal that the elastic cyclic loading can cause the irreversible structural change with the increase of free volume. Then the key problem of shear band formation under cyclic stress level lower than yield strength was clarified by the free volume theory.

Automated summary

Multiple characterization techniques were used to investigate the structural evolution of metallic glass under elastic cyclic loading. The results showed that cyclic loading led to increased relaxation enthalpy, larger interatomic distance, and smaller coordination number. The micmhardness of the specimens also decreased. The free volume theory clarified the key problem of shear band formation under cyclic stress level lower than yield strength.