中文摘要：

提高了Cu含量的核反应堆压力容器（RPV）模拟钢经过880℃水淬和660℃调质处理,在370℃时效不同时间后,利用原子探针层析技术（APT）进行分析.结果表明：样品经过1150 h时效后,富Cu团簇正处于析出过程的形核阶段;经过3000和13200 h时效后析出了富Cu团簇,团簇的平均等效直径分别为1.5和2.4 nm,团簇中Cu的平均浓度分别为45%和55%（原子分数）,团簇的数量密度约为4.2×10~（22）m~（-3）;样品经过13200 h时效后,α-Re基体中的Cu含量为（0.15±0.02）%,仍然高于Cu在α-Fe中平衡固溶度的理论计算值,说明这时富Cu团簇的析出过程还没有达到平衡.对渗碳体的分析结果表明,Ni,Si和P偏聚在渗碳体和α-Fe基体的相界面附近,Mn,Mo和S富集在渗碳体中;并没有观察到Cu在相界面上偏聚的现象.

英文摘要：

Reactor pressure vessel（RPV） is nonreplaceable component for the pressurized water reactor（PWR） in the nuclear power plants.RPVs are usually made of low alloy ferritic steels and A508-III steel is one type of these materials.After long-term service under the neutron irradiation,the ductile-to-brittle transition temperature（DBTT） of the RPV steel,which is the main parameter used to measure the degree of the embrittlement,will shift towards higher temperature.This phenomenon is termed irradiation-induced embrittlement,and it is a main factor to affect the operation safety and the lifetime of nuclear power plants.It is realized that the irradiation-induced embrittlement is mainly attributed to the precipitation of Cu-rich nanophases with a high number density.The precipitation process of Cu-rich nanophases can be well characterized by an atom probe tomography（APT） analysis for their size,composition and number density,and the Cu-rich nanophases obtained by the APT analysis are usually termed Cu-rich clusters.It is worthwhile to investigate the precipitation process of Cu-rich clusters by thermal aging for better understanding the mechanism of embrittlement.In order to accelerate the precipitation of Cu-rich clusters,experiment was performed by a RPV model steel containing higher Cu content than commercially available A508-III steel.RPV model steel was prepared by vacuum induction melting with higher content of Cu（0.6%,mass fraction）.The specimens of the RPV model steel were tempered at 660℃for 10 h followed by air cooling after water quenching from 880℃,and then they were isothermally aged at 370℃for different time.The precipitation process of Cu-rich clusters is investigated by APT analysis.The results show that the Curich clusters are on the stage of the nucleation when the specimens were aged at 370℃for 1150 h.After specimens were aged for 3000 and 13200 h,the average equivalent diameter of the Cu-rich clusters increases from 1.5 nm to 2.4 nm,and the average Cu content in the Cu-rich c