Ni晶界上金属和非金属元素的相互作用

摘要

采用基于密度泛函理论的第一性原理计算方法,研究了常用合金化元素与非金属元素在晶界(GB)的偏析及其相互作用.选取2种类型的晶界结构进行研究:密排的晶界和较疏松的晶界.溶解能计算表明,金属和非金属元素在Σ5晶界上均有明显的偏析行为,而在Σ3晶界上的偏析现象不明显.通过计算常用过渡族合金化元素与非金属杂质C、H、O、N、B在各自最稳定位置的相互作用能,发现Ru、Re、W和Ta对O有强烈的排斥作用,因此对晶界抗氧化有益处;Ta排斥H,有抗晶界氢脆的效果.通过对金属元素与非金属元素在晶界上相互作用的系统研究,为Ni合金的晶界工程提供有价值的参考.%First-principles calculations based on density functional theory are used to study the segrega-tion of metallic and nonmetallic elements as well as their interactions on the grain boundary(GB)of nickel. Two typical GBs are constructed:close-packed GB and quite open GB.According to the solution energy cal-culation,both the metallic and nonmetallic elements show strong segregation behavior on the ∑5 GB, while for the∑3 GB,the segregation is not so significant.The interaction energies between the common transition alloying elements and nonmetallic elements C,H,O,N and B are calculated when they occupy the most ener-gy-favorable positions.It is found that Ru,Re,W and Ta exhibit strong repulsion to O,indicating beneficial effects for the oxidation resistance behavior;Ta shows strong repulsive interaction to H,which should be help-ful for the inhibition of the hydrogen-embrittlement.The present work is useful for the grain boundary engi-neering of Ni-based superalloy by systematically studying the interaction between metallic and nonmetallic ele-ments at grain boundaries.