Energies of impurities and doping effect at 5.3 degrees low angle grain boundaries in steel

A model of 5.3 degrees low angle grain boundaries in steel is set up by usi ng elastic theory of dislocations. The first-principle calculations of ener gies and the electronic structures of impurities for a 5.3 degrees low angl e grain boundary(GB) in steel have revealed important features of the impur ity effect, In Fe,impurities such as S,P weaken the intergranular cohesion, resulting in 'loosening' of the GB, The presence of B,C,N on the contrary e nhances the GB. Boron plays a dual role in steel, not only does it presence at GBs enhance the intergranular cohesion,but also accomplishes 'site comp etition cleaning' by displacing the other impurity atoms off the GB.