The first-principles discrete variational method was used to study the effect of impurities such as B, C, N and O upon edge dislocation motion in the body-centered cubic phase at 0K. The results of simulations of the dislocation motion showed that a dislocation line, upon passing an atom on the slip plane, had to surmount an energy barrier. Impurity atoms which were trapped in the dislocation core could increase the energy barrier. With regard to the extent to which the energy barrier was increased, C had the greatest, O the least, and B and N had an intermediate effect. This explained the solid-state hardening behaviours of B, C and N in Fe. The B, C and N also exhibited a marked site-competition behavior for dislocation cores, as compared with O. Interactions between the impurities and their first-nearest neighbours played an important role in the above effect. Most of the bonding was due to 2p-3d hybridization.

Electronic Effects of Light Impurities on Edge Dislocation Motion in Iron at T = 0K. Y.Q.Feng, C.Y.Wang: Journal of Alloys and Compounds, 2000, 312[1-2], 219-27