三维拉应力下块体非晶合金变形行为及断裂机理研究

剪切软化一直被视为非晶合金的本征变形特征，这直接导致非晶合金的室温脆性，极大地影响了其应用前景。因此，如何抑制剪切软化，改善合金的室温变形能力成为非晶领域重要的研究方向。本项目将通过引入三维拉应力抑制剪切带的产生和扩展，系统研究不同应力状态对非晶合金变形和断裂行为的影响，揭示非晶合金全新的变形行为及断裂机理。并结合自由体积模型和分子动力学模拟，深入探索非晶合金在三维拉应力状态下的变形机制、自由体积变化规律和断裂机理，揭示其室温韧性产生的本质。通过本项目的研究，将为高性能块体非晶合金的结构设计提供理论依据，这对于拓展其应用前景具有重要意义。

Shear induced softening is considered as the nature phenomenon in bulk metallic glasses (BMGs), which leads to little plasticity at room temperature, and highly restricts the application of BMGs as structure materials. How to suppress shear banding and to improve the deformation ability of BMGs at room temperature has become one of the most important topics. In this project, the formation and propagation of shear band will be suppressed by introducing the triaxial tensile stress and the deformation behavior and fracture mechanism of BMGs will be investigated, revealing a new deformation behavior and fracture mechanism. Combining with free volume analysis and molecular dynamics simulations, the deformation mechanism, change in free volume and fracture mode of BMGs under triaxial stress state will be further discussed which will help us to understand the nature of ductility in metallic glasses. This study will represent a quantum leap in our understanding on the fundamentals of the deformation and fracture mechanism of metallic glasses, and designing high-performance alloys for engineering application of metallic glasses.