On the role of atomic ordering in the formation of a high-coercivity state in iron-cobalt-vanadium alloys

Processes that occur in the iron-cobalt-vanadium alloy with 52% Co and 7% V (vicalloy) upon heating to 1000°C and cooling have been studied by the dilatometric and magnetometric methods. It has been found that upon heating two phase transitions occur in the alloy, namely, B2-type atomic ordering in the α phase and a polymorphic α → γ transformation, whose temperature intervals differ considerably. An analysis of the dependences of the coercive force and the hardness of the alloy on the annealing temperature has shown that the maximum magnitudes of these parameters correspond to the ordering temperatures in the α phase. There was made an assumption that the magnetization reversal process in the alloy tested is related to the displacement of ferromagnetic domain walls and their pinning at the boundaries of antiphase domains ordered by the B2 type.