Influence of carbon and oxygen impurities on diffusion along tilt boundaries in nickel and silver
The effect of carbon and oxygen impurity atoms on the diffusion along tilt grain boundaries with misorientation axes <111>, <100> and <110> in fcc metals Ni and Ag was studied by mean of molecular dynamics method. It is shown that impurities in most cases lead to an increase in the self-diffusion coefficient along grain boundaries, because of the deformation of the crystal lattice near impurity atoms, which leads to additional distortions and free volume along the boundaries. Moreover, the smaller the grain boundary initially contains the free volume, the stronger the impurities affect the self-diffusion along it. In this regard, the greatest influence of impurities was observed for the <110> tilt boundaries and the smallest - for the <100> boundaries. Carbon impurity exerted an influence on self-diffusion along the considered boundaries, as a rule, stronger than oxygen.