面向高温、高压、高应变速率极端条件钨/钢梯度界面设计及界面孪晶变形机理研究

钨/钢梯度材料是高温、高压、高应变速率等极端服役环境下极有潜力的结构材料，然而现有梯度界面设计仅考虑了准静态下的材料性能，而没有针对到极端条件这一特定环境。因此，本项目针对高温、高压、高应变速率下材料出现的孪晶变形行为，综合极端条件下动态响应规律和准静态下材料性能进行钨/钢梯度界面设计。我们将通过分子动力学模拟研究界面对孪晶变形的作用机理，找出能够阻碍极端条件下孪晶变形的关键因素，结合准静态下第一性原理梯度层关键性能参数，利用计算机模拟退火算法组合优化梯度界面性能，设计出具有稳定界面结合、能够抵抗孪晶变形的钨/钢梯度界面结构，提升我们对材料在极端条件下响应行为基本科学问题的认识，为新型钨/钢梯度复合材料的研制和推广提供理论指导。

Tungsten/steel composite material is one of the most promising structural materials for applications in extreme conditions such as high temperature, high pressure, and high strain rate. Unfortunately, the design of tungsten/steel composite structure, at current stage, is mainly based on quasi-static physical properties, without consideration of the special requirement of extreme conditions. In view of this issue, we target on the rational design of tungsten/steel graded interface by combining the quasi-static physical properties and dynamic properties at extreme conditions, specifically, the newly observed twinning deformation at high temperature, high pressure, and high strain rate. In this project, we will first calculate the quasi-static physical properties of tungsten/steel alloys in the whole concentration range using first principles calculation. Then, we will study the twinning behavior on the tungsten/steel interface by means of molecular dynamics simulation and, more importantly, find out the optimum interface structure which can block the movement of twinning under extreme conditions. By integrating the quasi-static physical properties from first principles calculation and the dynamic properties from molecular dynamics simulation, we will perform a combinatorial optimization on the tungsten/steel graded interface properties through a simulated annealing algorithm. The rational design of tungsten/steel graded interface will yield an optimum tungsten/steel graded material with strong interface bond and the resistance of twinning deformation. In addition, our findings not only help us design and utilize tungsten/steel composite material, but also shed lights on the understanding of mechanical behavior of materials under extreme conditions.