Al和Ni偏析对铁素体钢中富Cu析出相界面结合的贡献
Contributions of Al and Ni segregation to the interfacial cohesion of Cu-rich precipitates in ferritic steels
摘要：
本文研究了两种典型合金元素铝和镍的偏析行为对铁素体钢中富铜析出相界面结合性能的影响，以期了解钢的脆化。采用第一性原理方法计算了铝和镍在析出物界面和相应断裂面处的能量和键合性质。结果表明，铝和镍在析出相界面的偏聚都是能量上有利的。我们发现，铜沉淀物的界面结合力的增强铝偏析，但降低了镍偏析。相反的作用可以归因于铝和镍的价态的不同对称特征。富铜析出相的镍致界面脆化增加了铁素体钢的韧脆转变温度（DBTT），并解释了许多实验现象，如反应堆压力容器钢的DBTT的变化取决于铜和镍的含量。
英文摘要：
We characterise the influence of the segregation behaviours of two typical alloying elements, aluminium and nickel, on the interfacial cohesive properties of copper-rich precipitates in ferritic steels, with a view towards understanding steel embrittlement. The first-principles method is used to compute the energetic and bonding properties of aluminium and nickel at the interfaces of the precipitates and corresponding fracture surfaces. Our results show the segregation of aluminium and nickel at interfaces of precipitates are both energetically favourable. We find that the interfacial cohesion of copper precipitates is enhanced by aluminium segregation but reduced by nickel segregation. Opposite roles can be attributed to the different symmetrical features of the valence states for aluminium and nickel. The nickel-induced interfacial embrittlement of copper-rich precipitates increase the ductile-brittle transition temperature (DBTT) of ferritic steels and provides an explanation of many experimental phenomena, such as the fact that the shifts of DBTT of reactor pressure vessel steels depend the copper and nickel content.
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