An extremely strong volume magnetostriction, which was typical of Invars, resulted in an enhancement of the exchange contribution (to the energy of the dislocation system) by some 3 orders of magnitude with respect to the value in conventional ferromagnets. The self-energy of individual dislocations, and the interaction between them, which was usually determined only by the elastic deformation, was strongly diminished in Invars by the contribution made by the exchange energy. This explained the strong suppression of the deformation hardening rate in the second stage, as well as its strong temperature and composition dependences in Invars.

Exchange-Mediated Interaction of Dislocations and Deformation Hardening of Invar Alloys. M.Molotskii, V.Fleurov: Philosophical Magazine A, 2002, 82[6], 1173-81