Prediction of the interfacial relationship between Y₂O₃ and TiN using first-principles calculations

The hypereutectic Fe-Cr-C-N-Ti composite alloy has excellent wear resistance, in which TiN is an important strengthening phase. This paper aims to add the rare earth oxide Y₂O₃ to this alloy to refine TiN, and further enhance the service life of the alloy. The first-principles method was employed to investigate the interfacial relationship between Y₂O₃ and TiN. The mismatch degrees between the different low-index crystal planes of Y₂O₃ and TiN were calculated. Then, the plane with the minimum mismatch degree between Y₂O₃ and TiN was selected, and the surface convergence test was conducted. Based on this, an interfacial model of Y₂O₃//TiN was established, and its interfacial properties were calculated. The effectiveness of Y₂O₃ as the hetero-nucleation core of TiN was analyzed. The results show that the mismatch degree between the Y₂O₃ (111) plane and the TiN (110) plane is 8.19%, which indicates that the hetero-nucleation effect of Y₂O₃ on TiN is moderately effective. The surface model was constructed using the Y₂O₃(111) plane and the TiN(110) plane. It was found that when the layer number of the TiN(110) surface model reached 9, the surface energy converged to 2.75 J m^-2. The interface adhesion work and interface energy of four Y₂O₃(111)//TiN(110) interfacial models were calculated. Among them, the interfacial adhesion energy of the O-N interface is the largest, which is 0.45 J m^-2. Meanwhile, the interfacial energy of the O-N interface is the smallest, which is 3 J m^-2. It indicates that the O-N interface model is the most stable. The chemical bonds in this model are mainly the combination of Ti-O ionic bonds and N-O covalent bonds. Therefore, Y₂O₃ meets the conditions to serve as the hetero-nucleation core of TiN and tends to form an O-N terminated hetero-nucleation interface, which can provide a theoretical basis for the development of a new hypereutectic Fe-Cr-C-N-Ti-Y₂O₃ alloy.