Mechanism of NbC heterogeneous nucleation on TiN in microalloyed steel: A first-principles study

Abstract

In this work, the interfacial properties and bonding feature of NbC(1 0 0)/TiN(1 0 0), NbC(1 1 0)/TiN(1 1 0) and NbC(1 1 1)/TiN(1 1 1) interfaces were investigated by using the first-principles method. And the mechanism of NbC heterogeneous nucleation on TiN in microalloyed steel was revealed. The results showed that the (1 0 0) surface is more stable than (1 1 0) for both NbC and TiN. Besides, NbC(1 1 1)/TiN(1 1 1) interface-III (with C3Ti1 termination) possesses the largest work of adhesion, followed by the NbC(1 1 0)/TiN(1 1 0) interface and NbC(1 0 0)/TiN(1 0 0) interface. Additionally, NbC(1 1 1)/TiN(1 1 1) interfaces with CTi bonding are more stable than NbC(1 1 1)/TiN(1 1 1) interfaces with NbN, NbTi and CN bondings. The bonding of NbC(1 0 0)/TiN(1 0 0) interface-A (with NbN termination) and NbC(1 1 0)/TiN(1 1 0) interface-A (with CTi termination) are mainly consist of covalent bonds. While NbC (1 1 1)/TiN(1 1 1) interface-III has strong covalent bonding and weak metallic bonding. Furthermore, in the entire range of Ti and C chemical potentials, the interfacial energy of NbC(1 1 1)/TiN(1 1 1) interface-III is smaller than those of NbC(1 0 0)/TiN(1 0 0) interface-A and NbC(1 1 0)/TiN(1 1 0) interface-A. Thus, the priority about NbC/TiN heterogeneous nucleation interface is in the order of (1 1 1), (1 0 0), and (1 1 0).