Influence of ordering phenomena on carbon segregation in tungsten screw dislocation

Concentration profiles on the different sites of tungsten screw dislocation are calculated as a function of the nominal carbon atom concentration, temperature and dislocation density. Rigid lattice Monte Carlo simulations and associated mean-field modelling are performed based on interaction energies from ab initio calculations. We show that the repulsive interactions induce ordering phenomena that drastically change the concentration in the core of the dislocation and leads to ordered structures among the octahedral sites. We detail the domains of short-range ordering (SRO) and long-range ordering (LRO). Evolution of the distribution of carbon atoms in tungsten screw dislocation with increasing temperature. The carbon atoms are in red on the prismatic line and in orange on the octahedral lines. Empty sites are in white. [Display omitted]