辐照弥散氧化物增强钢塑性变形和断裂的细观机理及多尺度模拟

纳米弥散氧化物增强钢（ODS钢）是新一代先进堆和未来聚变反应堆候选材料；该材料优良的抗辐照力学性能源于内嵌Y、Ti、O纳米氧化物独特的NaCl式稳定原子结构以及“纳米氧化物”-“位错”-“辐照缺陷”复杂的交互作用。本项目拟以辐照和中高温条件下纳米ODS钢塑性响应、变形局部化、裂尖损伤演化及其内在机理为核心问题；以“点缺陷（空位和间隙原子）”-“棱柱位错环”-“滑动位错”-“纳米氧化物颗粒与界面”-“塑性局部化与裂尖变形损伤”相互关联为切入点；以分子动力学、离散位错动力学和晶体塑性有限元多尺度模拟结合细观实验（如纳米压痕和微柱压缩）验证为手段，建立描述“辐照缺陷-位错-纳米氧化物及其界面”多维缺陷作用和演化的晶体塑性本构关系；分析不同辐照剂量、温度和加载条件下该材料的塑性响应和裂尖变形损伤。从多尺度深入了解纳米ODS钢辐照力学行为及内在机理，为其结构分析、安全评定和优化提供理论和技术支持。

Since the introduction of the dispersed nano Y/Ti oxide with speical NaCl-type atom structure and the induced complex interactions beween nano oxides,dislocations and irradiated defects, the nano-oxide dispersion strengthened steels (i.e. ODS steel) have a much better irradiation resistance than traditional steels. For this, ODS steels are considered as candidate materials for the future nuclear fission reactors, as well as potential fusion reactors. In this project, we focus on the problems of plastic responses,deformation localization and crack-tip damamge evolution for the nano ODS steels under different-dose irradiation and high/morderate temperatures, trying to clear the relations between irradiated point defects (i.e. vacancy and self-interstitial atom), irridated prismatic dislocation loops, gliding dislocations, nano-oxide paticles/their interfaces, and the plastic response/crack-tip damage evolution of Nano ODS steels. A new crystal plasticity constitutive relation including the multi-dimensional models of point defects, prismatic loops, dislocation density and void damage will be builtd for the nano-ODS steel. By the molecular dynamics simulation, discrete dislocation simulation and the finite element analysis basing on the above crystal plasticity theory, the irradiated plastic reponse, deformation localization, crack-tip damage evolution and their intrinsic dislocation and defect mechanisms are simulated and analyzed carefully in a multiscale way under different irradiation doses, various termperatures and different loading conditions for the nano-ODS steels. All these works tend to provide the scientific and technical supports for the mechanical analysis and further material design of nano-ODS steels.