First principles analysis on the nucleation interface of La2O3(110)/ NbC(110)

Niobium carbide (NbC), as a reinforcement phase, has been applied in the alloy to enhance its service life. It is important to refine the NbC in the alloy. In this paper, the nucleation interface of La2O3(110)/NbC(110) was analyzed and the mechanism of NbC refined by La2O3 was investigated by first principles. Firstly, the mismatch degree of La2O3/NbC interface was calculated. According to the surface convergence, the interface models of La2O3/NbC were established. Then, the combined work and energy of the La2O3/NbC interfaces were calculated. Finally, the interface bonding properties were analyzed by the charge density, differential charge density and projected density of states. The results show that the mismatch degree of La2O3(110)/NbC(110) interface is smallest, which is 7.1%. La2O3(110) and NbC(110) lattice planes were selected to establish four kinds of interface models, which are named as O-Hollow, O-Interface, OLa-Hollow and OLa-Interface in turn. The adhesive work of O-Hollow interface is the largest, which is 0.995J/m2. And its interface energy is the smallest, which is 3.055J/ m2. Meanwhile, the bonding types of O-Hollow interface are mainly a combination of La-C and Nb-O bonds. In summary, La2O3 can be as a moderate effective heterogeneous nucleus of NbC, then NbC be refined by La2O3.

Automated summary

In this paper, the nucleation interface of La2O3(110)/NbC(110) was analyzed and the mechanism of NbC refined by La2O3 was investigated by first principles. The results show that La2O3 can be used as an effective heterogeneous nucleus to refine NbC.