A first-principles study of titanium oxide clusters formation and evolution in a steel matrix

Abstract

The structures and evolution law of Ti_mO_n clusters in a bcc Fe matrix are studied by using first-principles calculations. In a bcc lattice, the Ti and O atoms attract each other strongly when the second nearest neighbor site to interstitial O has been replaced by Ti. The Ti–O and Ti–Ti bonds are two dominating factors affecting the stability of clusters. Ti–O bonds have more contributions to the stability of clusters than Ti–Ti bonds. The stoichiometric ratio of Ti to O tends to stay 1 : 1 in titanium oxide clusters by absorbing Ti/O atoms and then the cluster tends to absorb O atoms. The stable rhombus-shaped structure Ti₂O₂ is suggested to be the smallest unit of titanium oxide inclusions in steel. This work provides practical information for further study of oxide inclusion nucleation.