第一性原理研究Nb、Sn、Cu、Fe和Cr对Zr(0001)晶面抗疖状腐蚀性能的影响

Effect of Nb,Sn,Cu,Fe and Cr on Zr(0001)Surface Nodular Corrosion Resistance:First Principles Study

采用密度泛函理论研究Nb、Sn、Cu、Fe和Cr 5种合金元素对氧在Zr(0001)晶面吸附能的影响,发现Nb、Sn和Cu会促进氧在Zr(0001)晶面吸附,Fe和Cr对氧吸附的影响因吸附的位置不同而存在差异。研究5种合金元素对氧化后Zr(0001)晶面化学键的破坏情况,发现Nb对Zr(0001)晶面破坏程度最小而且可以迅速复原,Sn可以使(0001)晶面相邻的两个化学键都变长,对晶面的破坏性大。最后讨论5种合金元素在Zr(0001)晶面的偏聚能,发现Sn、Fe和Cr偏聚能为负值,容易偏聚到Zr(0001)晶面,而Nb和Cu偏聚能为正值,不易在Zr(0001)晶面偏聚。综合以上分析,Nb可以促进氧在Zr(0001)晶面的吸附行为,氧化后(0001)晶面可以快速复原,从而阻碍其他氧原子进入,抑制疖状腐蚀的发生。Sn容易偏聚到Zr(0001)晶面,可以促进氧在Zr(0001)晶面吸附,氧化后会造成Zr(0001)晶面较大的破坏,促进氧进入Zr(0001)晶面,促进疖状腐蚀的发生。

Density functional theory is used to study the influence of Nb,Sn,Cu,Fe and Cr on the adsorption energy of oxygen on crystal face of Zr(0001).It was found that Nb,Sn and Cu promote adsorption of oxygen on the surface,and the influence of Fe and Cr on oxygen adsorption is different due to the location of the oxygen adsorption.Secondly,we studied destruction of microtexture on the oxidized surface by the alloying elements.It was found that the damage of Nb to the crystal face of Zr(0001)is the least and it can be recovered quickly,while Sn makes two chemical bonds longer,so the damage to the crystal face is great.Finally,the segregation of Sn,Fe and Cr to surface is exothermic,while the segregation of Nb and Cu to surface is endothermic.We conclude that Nb promotes the adsorption of oxygen on Zr(0001)crystal face,and the surface recovers quickly after oxidation,which preventing the entry of oxygen atoms and inhibiting the occurrence of nodular corrosion.Sn segregateds on Zr(0001)crystal face easily,which promotes the adsorption of oxygen on Zr(0001)crystal face,and causes the microstructure distortion of Zr(0001)crystal face.After oxidation,the crystal surface of Zr(0001)is damaged greatly,which promotes the rapid entry of oxygen and the occurrence of nodular corrosion.