The interplay between magnetism and dislocation core properties in NiAl alloys was examined the using quantum mechanics/molecular mechanics simulations. A magnetism-driven site preference of Fe and Co impurities at the dislocation core was observed. When occupying the Ni sub-lattice, Fe and Co impurities were found to induce spontaneous dislocation cross slip. When occupying the Al sub-lattice, the impurities render the originally undissociated dislocation to split into two partials. Finally, a magnetism-driven dislocation mobility which occurred when Fe impurity occupied the Al sub-lattice was observed, which had also been discovered experimentally. The magnetic interaction between the impurities and the host atoms was responsible for the significant changes in the dislocation core structure and mobility.

Magnetism-Driven Dislocation Dissociation, Cross Slip, and Mobility in NiAl. Y.Zhao, C.Wang, G.Lu: Physical Review B, 2010, 82[6], 060404