Achieving controllable strength-plasticity balance in metallic glass: Potential energy gradient

Metallic glasses (MGs) have long been plagued by a dilemma concerning their strength and plasticity. This has restricted the potential applications of these materials. Inspired by the concept of gradient materials, we have devised a novel strategy to address this challenge by leveraging potential energy gradients. In this study, we have designed three distinct types of MGs, each exhibiting controllable step potential energy gradients. Extensive molecular dynamics simulations have demonstrated that potential energy gradient MGs, characterized by a spatial gradient distribution of free volume, possess a "shear band deflection" ability. This free-volume gradient structure promotes the branching and deflection of shear bands, disperses deformation, and delays damage, thereby conferring additional plasticity to the gradient MGs. Concurrently, the high icosahedral content in potential energy gradient MGs contributes to their strength. The simultaneous enhancement of strength and plasticity can be modulated by altering the direction and step amplitude of the potential energy gradient, indicating that the long-standing trade-off between strength and plasticity in MGs can be addressed by controllable potential energy gradients.