Molecular dynamics study of melting, diffusion, and sintering of cementite chromia core–shell particles

For the additive manufacturing of chromium-oxide coated stainless steel powders, melting, diffusion, sintering behaviors cementite phase in during heat treatment can affect products’ physical and chemical properties, thus, are worth studying. In this work, we use ReaxFF reactive force-field-based molecular dynamics simulations to investigate at level through an atomistic-scale representation for with a Cr2O3 coating passivation layer. Additionally, also compare Lindemann indices core–shell particle those pure same size, order understand influence layer on melting. Results indicate that shell does not change melting temperature particle. However, layer’s oxygen atoms diffuse into core increase impurity Fe3C crystal, destabilizing structure core. We observe starts from while, contrast, pure-cementite begins surface. addition, comparison mean squared displacements hydrogen (H), (O), carbon (C), chrome (Cr), iron (Fe) solid (900 K) liquid (2000 phases indicates atom mobility is significantly higher than phase. H O exhibit Fe, Cr C atoms. When elevated 900 K 2000 K, content rises, while declines. Furthermore, simulation shows there four stages phase: two particles move randomly (Stage 1) until they make first contact 2), layers subsequently intermingle 3), finally cores fuse 4). The involves former three stages. sufficiently high bring Stage 4 time scale our simulations.