Rejuvenation by compressive elasto-static loading: The role of static stress on a Zr-based metallic glass

Abstract

Calorimetric, mechanical, and microstructural characterizations are used to investigate the rejuvenation of Zr55Cu30Al10Ni5 (at%) bulk metallic glass (BMG) by elasto-static loading (ESL). The as-cast BMG samples are compressed at room temperature for 24 h while being subjected to static stresses that ranged from 40 %, 70 %, 80 %, and 90 % of the yield stress. The BMG undergoes structural rejuvenation as a result of the compressive ESL treatment, increasing the free volume content at all applied static stresses. The amount of energy that has been stored, as determined by the relaxation exotherms that precede glass transition, appears to be a function of static stress and reaches a maximum of 13.2 J g−1 at the highest applied stress, which is twice the stored energy of the as-cast sample. A steady increase in plastic strain, a decline in hardness, and a fall in Young's modulus are linked to enthalpy rejuvenation of the BMG. According to microstructural investigations, ESL introduces structural heterogeneities into the BMG that are linked to structural dilatation at the short- and medium-range atomic scales. This study emphasizes rejuvenation as the main effect of ESL treatment on the BMG under study.