富Cr析出物、He泡及位错环对F/M钢辐照硬化影响的位错动力学研究

Since irradiation experiments of Ferritic/Martensitic (F/M) FeCr alloys show that F/M steels develop much less swelling than austenitic steels during neutron or charged particle irradiation，in addition, it is well-known that high Chromium contents of F/M alloys provide good resistance against corrosion, so they are considered as one of the most attractive candidate materials for future nuclear facilities, such as Fusion Reactor, ADS and Generation IV reactors.The mechanisms of irradiaiton hardening and embrittlement of F/M steels are not understood right now.This proposal will focus on the hardening effects of dislocation loops (enriched or not Cr), Helium bubble and Cr precipitates studied by dislocation dynamics, Molecular dynamics and Metropolis Monte Carlo methodes. The segregation mechanism of Cr to dislocation loop, the hardening mechanism of enriched dislocation loops, Helium bubbles and Cr precipitates will be studied indetail.Then, we will investigate the synergy in the hardening due to Cr precipitates, He bubbles and dislocation loops. At last, a physical model describes the hardening of F/M steels will be developed.

铁素体/马氏体（F/M）钢是第四代堆和聚变堆重要的候选结构材料之一。F/M钢的辐照硬化及脆化所呈现出来的特性是国际上的研究热点和难点。本研究拟采用位错动力学结合分子动力学、迈氏Monte Carlo方法，在课题组前期工作的基础上研究位错环、He泡及富Cr析出物的硬化机理，探明辐照是否会导致位错环富Cr、富Cr位错环对位错运动影响机理、He泡尺寸及温度对硬化的影响、富Cr析出物的硬化机理，分析位错环、He泡及富Cr析出物对F/M钢辐照硬化影响的协同作用机理，建立F/M钢辐照硬化物理模型，为F/M钢的抗辐照性能优化提供理论依据。

在国家自然科学基金的资助下，本课题组针对引起FeCr合金硬化的机理开展了深入研究。采用迈氏蒙特卡洛方法研究了FeCr合金中Cr含量、温度等对Cr团簇析出及位错环上Cr偏析行为的影响，并与实验结果符合较好。利用分子动力学方法研究了位错环与位错相互作用机理，分析了Cr元素偏析、温度、作用位置、位错环类型的影响；利用分子动力学方法研究了He泡与位错相互作用，分析了He泡尺寸、He泡中He/V比例、温度等的影响；利用分子动力学方法研究了Cr析出物与位错相互作用，分析了Cr析出物尺寸、析出物中Cr含量、温度、不同作用位置的影响。研究结果表明，位错环、He泡、Cr析出物是引起F/M钢辐照硬化的主要因素，同时硬化与温度、微观结构具体信息有关，如位错环上Cr偏析量、He泡中He/V比例、析出物中Cr含量等均会影响微观结构与位错相互作用。本研究结果从原子尺度上为认识FeCr合金辐照硬化机理提供帮助。