Abstract
We propose an explanation of anomalies observed in the behaviour of deformation hardening of Invars. An extremely strong volume magnetostriction, typical of Invars, results in an enhancement of the exchange contribution to the energy of the dislocation system by about three orders of magnitude with respect to its value in conventional ferromagnets. Both the self-energy of individual dislocations and the interaction between them, determined usually only by the elastic deformation, in Invars is strongly diminished by the contribution of the exchange energy. This fact explains the strong suppression of the deformation hardening rate in the second stage as well as its strong temperature and content dependence in Invars.