First-principles study on effect of alloying elements on heterogeneous nucleation of reverse austenite on Cu precipitation

Abstract

The mechanical properties of ultra-high strength martensite steel strongly depend on the shape, size and content of the reversed austenite. In general, the plasticity and toughness of the materials can be improved effectively by increasing the content of the reversed austenite. After aging treatment of Cu-bearing as-quenched steel with martensitic microstructure, Cu particles precipitate at the boundary of martensitic structure and act as heterogeneous nucleation sites to promote the nucleation of reversed austenite. In order to explore the effects of different alloying elements on heterogeneous nucleation of reversed austenite on Cu particles, the effects of <i>X</i> (<i>X</i> = Cr, Al, Mo, W, Ni, Co, Mn) on the interfacial properties of Cu/<i>γ</i>-Fe are studied via first-principles method. The adhesion work, interfacial energy and electronic structure of the interfaces before and after the replacement of Cu and Fe atoms at Cu/<i>γ</i>-Fe boundaries are calculated. The results show that when the alloying elements replace Cu atoms at the Cu/<i>γ</i>-Fe interface, strong <i>X</i>—Fe covalent bond forms at the Cu/<i>γ</i>-Fe interface, the adhesion work increases and the interfacial energy decreases, and thus improve the heterogeneous nucleation capability of reverted <i>γ</i>-Fe on Cu particles. When Fe atoms at the interface are replaced, the stability of the interface changes little, and the bonding between the doped atoms and the neighboring atoms is weak.