高注量辐照RPV钢的热处理微观结构及其对再辐照损伤行为的影响研究

应用三维原子探针和纳米压痕技术研究了高温高注量质子初始辐照、辐照后退火及再辐照条件下核反应堆压力容器(RPV)钢中的微结构演变,及其与力学性能之间的关系。三维原子探针结果表明:初始辐照(1.6 dpa)条件下,RPV钢中产生了大量的富Mn-Ni-Si团簇;辐照后经500℃1 h退火处理,富Mn-Ni-Si团簇基本回复,但仍然存在少量包含Mn和Ni的稳态团簇;再辐照(0.1 dpa和1.6 dpa)时,RPV钢中又产生了新的富Mn-Ni-Si团簇,其数密度和平均尺寸随再辐照注量的增加而增加;初始辐照和再辐照的RPV钢中均未有富Cu原子团簇析出。纳米压痕结果表明初始辐照、辐照后退火和再辐照的RPV钢中均产生了明显的硬化现象。稳态团簇是退火后的RPV钢的硬度高于未辐照样品的硬度的主要原因。富Mn-Ni-Si团簇是高温高注量质子辐照国产低Cu含量RPV钢的一个硬化源。

Effect of Thermo-Mechanical Processing on Precipitate Formation in Next Generation HSLA Steel

Development of advanced high strength steels (AHSS) using a conventional rolling setup is one of the biggest challenges to steel industry.It has been found that fine precipitation in a soft matrix,formed after hot rolling,can markedly improve the mechanical properties.In this work,three dimensional atom probe tomography (3D-APT) has been used to study the formation of precipitates in thermomechanically simulated steel.3D-APT data reveals co-existence of numerous nano clusters with precipitates.Also,quantitative analysis of the nano clusters and precipitates shows clusters are as small as 1nm in size.Precipitates are found to be disc shaped with the composition of equilibrium precipitates (TiMo)C.Thus,3D-APT is seen as an ideal technique to complement TEM to understand the nanoscale features in thermomechanically processed steel for further improvements in the mechanical properties of AHSS.

钼材料杂质元素晶界偏聚的研究进展

钼属于体心立方结构的过渡族金属,在室温附近易发生脆性破坏,其室温脆性包括由过渡族金属元素核外电子排布决定的本征低温脆性和晶界脆性,晶界脆性与杂质元素在晶界处的偏聚紧密相关。本文开篇简述了钼材料发生脆性行为的内在机制,在此基础上,结合第一性原理计算和三维原子探针层析技术论述了C,O,H,N,B等间隙杂质及Re,Zr,Hf等典型金属杂质元素在钼材料晶界处偏聚的状态及其对材料宏观性能的影响:总结了间隙元素与钼晶界原子的键合特性以及对晶界强度的影响规律,重点关注了O,N元素对钼晶界结合力的弱化,和微量C,B元素对晶界结合力的强化以及对O的消耗;探讨了金属掺杂化学在钼材料晶界偏聚中的作用以及塑性特性与掺杂金属的键合电子数的密切联系,整理了Re元素的显著作用以及σ相的析出机制,和微量Zr,Hf元素的弱本征脆化以及对O和N的消耗。归纳了典型间隙元素在钼材料变形态和再结晶后的晶界偏聚规律,最后对以杂质元素晶界偏聚的角度来改善钼材料脆性断裂进行了展望。