Rejuvenation induced suppression of crystallization in one La-based metallic glass by ultraslow cold rolling

Rejuvenation has been verified to be one effective strategy to improve mechanical properties of metallic glasses. However, the influence of rejuvenation on glass stability and crystallization kinetics is unknown. In this work, based on deformation map, one approach by ultraslow cold-rolling induced rejuvenation without producing shear bands was proposed to suppress crystallization and enhance thermal stability in one La-based metallic glass. Evolution of recovery enthalpy, hardness and elastic modulus with different cold-rolling rates and normal strains were investigated. Moreover, TTT diagrams and the corresponding dynamic relaxation behaviors for as-cast, cold-rolled and annealed samples were obtained. It was found that annealing treatment decreases activation energy and the amount of β relaxations, thus accelerating crystallization. In contrast, ultraslow cold rolling obviously increases activation energy and the amount of β relaxations, which largely suppresses crystallization. These results provide enlightenment for enhancing the stability of metallic glasses by mechanically regulating the energy states.