合金元素对bcc-Cu/NiAl共析出影响的第一性原理研究

First-principles Study on Effect of Alloying Elements on Co-precipitation of bcc-Cu/NiAl

bcc-Cu和NiAl共析出是高强度钢常用且有效的强化方式。为了探究不同合金元素对bcc-Cu/NiAl共析出影响,本工作利用第一性原理计算了合金元素X(X=Cr,Co,Mo,W,V,Mn)对bcc-Cu(001)/NiAl(001)界面性质的影响,并分析上述合金元素掺杂前后界面黏附功、界面能和电子性质。研究结果表明,当Cr、Mo、W、V、Mn掺杂Al终端bcc-Cu/NiAl界面时,界面的黏附功升高,界面能下降,有利于bcc-Cu/NiAl共析出,其中Mo、W、V合金化效果更佳。掺杂Ni终端界面时,界面稳定性低于掺杂Al终端时。电子结构分析表明,掺杂Al终端时,掺杂原子与界面处Cu原子之间的电子轨道产生明显杂化,显著加强原子间的相互作用。而替换Ni原子时,轨道杂化程度较弱。Mo、W、V掺杂后,界面处电荷密度增加,Cu原子与合金原子之间形成更强的非极性共价键。

Co-precipitation of bcc-Cu and NiAl is an effective strengthening method commonly used for high strength steel.To investigate thoroughly the effects of different alloying elements on the co-precipitation of bcc-Cu/NiAl,the interfacial properties of element X(X=Cr,Co,Mo,W,V,Mn)-doped bcc-Cu(001)/NiAl(001)interfaces were studied based on first principles.The analysis of interfacial adhesion work,interfacial energy and electronic properties could clarify the significance of interfacial alloying.The calculated results show that when the Al-terminal bcc-Cu/NiAl interface dopes with Cr,Mo,W,V,Mn,the adhesion work increases,the interfacial energy decreases,promoting co-precipitation of bcc-Cu/NiAl,but the effects are more stronger when Al replaced by Mo,W or V.The interfacial stability of Ni-terminal interface is lower than that of Al-terminal interface.The electron structure analysis shows that Cr,Co,Mo,W,V,Mn have obvious hybridization of electron orbitals with Cu atoms at the interface and significantly strengthen the interatomic interaction when Al-terminal bcc-Cu/NiAl interface is doped.When Ni-terminal interface is doping,the hybridization degree is weak.After Mo,W and V doping the interface,the charge density at the interface increases,and stronger non-polar covalent bonds are formed between Cu atoms and alloying atoms.