晶粒细化、Al元素、Zr（Hf， Sc）微量元素协同效应对核结构材料ODS钢的耐腐蚀性和力学性能的优化及机理研究

Oxide dispersion strengthened (ODS) ferritic steels are promising candiated structural materilas for advanced nuclear energy facilities such as fission GEN IV and ADS because they exhibit good mechanical properties and good irradiation resistance to hardening, swelling and embrittlement.However, the corrosion resistance and mechanical properties are not good enough to be used in the extreme conditions such as strong corrosion and high temperature,need to be further improved.The present proposal plans to improve the present preparation technology to increase the grainboundary number density and the effective difussion cofficient of alloy Cr elements by refining grain, to form dense Al2O3 protected layer on ODS steel surface by adding Al element, by adding minor Zr (Hf, Sc) elements to prevent the coarsing of the oxide particles caused by the Al doping and hence raise number density of oxides and number density of grain boundary precipitates as well as suppressing the formation of tungsten carbide to improve the corrosion resistance and high temperature mechanical properties of ODS steel.To explore the three synergistic effects of grain refinement, Al, Zr (Hf,Sc) minor element effect on optimizaiton of the mechanical properties and corrosion resistance of ODS alloy , and study the mechanism of liquid metal stress corrosion induced embrittlement of ODS steel, and provide scientific data for maximum optimizaiton of corrosion resistance and mechanical properties as well as final application in advanced nuclear energy systems.

ODS合金以其优异的力学性能和抗辐照硬化、脆化性能而成为第四代裂变堆及ADS等未来先进核能系统结构材料的强有力的候选材料。但目前，ODS合金在先进核能系统工作环境（高温、强腐蚀）下的耐腐蚀性能及力学性能还不能满足实际应用的需要，需要进一步改善。本项目拟通过晶粒细化增加晶界密度、提高Cr元素的等效扩散系数、Al添加在合金表面形成致密氧化铝保护层、Zr(Hf,Sc)的添加抑制Al添加导致的氧化物晶粒粗化而提高氧化物数密度和晶界沉淀相数密度、抑制碳化钨的形成等原理及优化ODS制备工艺制备出高抗腐蚀性及力学性能优秀的ODS合金。系统地研究晶粒细化、Al、Zr(Hf,Sc)微量元素三者协同效应对ODS合金耐腐蚀及力学性能优化的物理机制，初步探索液态金属LBE对ODS合金的应力腐蚀脆化机制，为ODS合金抗腐蚀性和力学性能最大优化并最终应用于先进核能系统提供科学数据。

ODS 合金以其优异的力学性能和抗辐照硬化、脆化性能而成为第四代裂变堆及ADS 等未来先进核能系统结构材料的强有力的候选材料。但目前，ODS 合金在先进核能系统工作环境（高温、强腐蚀）下的耐腐蚀性能及力学性能还不能满足实际应用的需要，需要进一步改善。本项目通过晶粒细化增加晶界密度、提高Cr 元素的等效扩散系数、Al 添加在合金表面形成致密氧化铝保护层、Zr(Hf,Sc)的添加抑制Al 添加导致的氧化物晶粒粗化而提高氧化物数密度和晶界沉淀相数密度等原理及优化ODS 制备工艺制备出了高抗腐蚀性及力学性能优秀的Fe–16Cr–2W–0.5Ti–0.4Y2O3–4Al–1Zr (16Cr–4Al–Zr–ODS)合金。微结构研究表明微量Zr元素，确实能够形成更小的Y-Zr-O纳米颗粒来抑制添加Al导致的氧化物颗粒粗化。尺寸主要分布于25nm左右，其数密度达到了2.5 * 1021m-3，比仅含Al元素样品的数密度提高了两个数量级。而且这种均匀细小的氧化物颗粒将会大大增加晶粒形核的机会，从而形成了更加细小的晶粒（8微米左右），大大提高了ODS钢的力学性能：抗拉强度接近1200MPa，延伸率约为27%，同时保持了很好的抗腐蚀氧化性能。同时系统地研究了晶粒细化、Al、Zr(Hf,Sc)微量元素三者协同效应对ODS 合金耐腐蚀及力学性能优化的物理机制，初步探索了Al/Zr元素对ODS钢抗辐照性能的影响。为ODS 合金抗腐蚀性和力学性能最大优化并最终应用于先进核能系统提供了科学数据。