The effect of the tensile stress and the work-hardening on the coercivity of polycrystalline wires of Fe-Ni

Abstract

The changes of the coercive force as a function of plastic strain for two different domain distributions (corresponding to the cases respectively at which an external tensile stress was applied or released) are studied for a Fe-Ni 72% alloy with low anisotropy energy and positive magnetostriction. It is found that this material shows a large anomaly not previously observed in the dependence of the coercive force on the strain in the initial stage of the stretching (0.4÷2.5)% in correspondence to the stage of linear hardening of face-centred cubic polycrystals. On the contrary at high strains the experimental results contribute to confirm further the theory of Trauble both for the random domain distribution and for 180° domains lined up parallel to the field axis. The previous theory of Vicena gives a somewhat less good agreement with the experimental results.