氢致材料失效是未来氢能源开发、利用中面临的重要难题。氢会削弱金属键并促进空位演化，导致金属粘聚强度降低；同时，会促进位错形核、运动和增殖，导致塑性增强。在两者共同作用下，氢致金属失效宏观上表现为脆性但微细观上为韧性。它是典型的多场/多维缺陷/多尺度耦合动力学（3MCD）问题，涉及氢扩散、捕捉和输运，以及氢致多维缺陷之间复杂的相互作用，人们对其物理机制和过程不甚明了。本项目拟围绕氢致多维缺陷相互作用机理这一关键科学问题，通过微细宏观实验，直观揭示氢致失效的3MCD机理；发展氢扩散-多维度缺陷耦合动力学和氢扩散-晶体塑性耦合动力学理论、算法和程序，实现对氢致失效的3MCD模拟；结合系列实验和复杂过程多尺度模拟对比分析，从3MCD的新角度，定量表征氢致宏观脆性和微细观韧性间的跨尺度关联；提出氢增强塑性协调的损伤失效机制和氢致失效准则。为氢环境下材料和结构的安全防护、设计和评定提供理论和技术支持。

Hydrogen-induced metal failure is a key challenge in the future development and utilization of hydrogen energy. Hydrogen can weaken metallic bond and aggravate vacancy nucleation and conglomeration, causing a reduction of the cohesion strength of metal. Hydrogen can also accelerate dislocation nucleation, movement and multiplication, leading to an increase in plastic deformation. As a result of the combined effects of these two factors, hydrogen-induced metal failure appears brittle at macro-scale but ductile at micro/meso-scale, which is typically characterized as a "multi-physical field/multi-defect/multi-scale coupled dynamics (3MCD)" problem. It involves not only hydrogen diffusion, entrapment and transport, but also interactions of multiple material defects induced by the hydrogen, such as the vacancy-point defect, dislocation-line defect, grain/phase boundary-face defect, and void/crack-volume defect. In this project, the quantitative relation between the hydrogen-induced brittleness at macro-scale and ductility at micro/meso-scale will be investigated in details, with a special emphasis on the hydrogen-induced interaction between multi-defects. First, a series of micro-/meso-/macro-scopic tests will be performed, aiming to uncover the 3MCD mechanisms of hydrogen-induced metal failure by using the high-resolution TEM/SEM. Next, a meso-scopic hydrogen diffusion and multi-defect coupled dynamics program, together with a continuum hydrogen diffusion and crystal plasticity coupled dynamics program, will be developed, based on the proposed theories and computational schemes. Then, multiple coupled simulations will be carried out to compare with the corresponding experimental results, so as to quantitatively relate the brittle failure behaviors at macro-scale to the plastic deformation and damage mechanisms at micro-/meso-scale. Finally, a new hydrogen-induced enhanced plasticity-mediated vacancy damage and decohesion mechanism will be developed and a hydrogen-induced failure criterion will be presented. These studies can provide strong theoretical and technological supports to safety defence、design and assessment of materials and structures operating in hydrogen environment.