Effect of recrystallization and degree of order on the magnetic and mechanical properties of soft magnetic FeCo-2V alloy

The magnetic and mechanical properties of Fe-49%Co-2V sheet, used in the rotors of electric generators in aircrafts, have been investigated as a function of heat treatments. Experimental results show that magnetic and mechanical properties depend on the boundary spacing both in partially and completely recrystallized samples. Coercivity linearly depends on the inverse of the boundary spacing and yield strength follows an experimental Hall-Petch relationship with boundary spacing. Nevertheless, it appeared that for similar boundary spacing and similar texture, the yield strength can be increased when the alloy is more rapidly cooled after annealing. This process tends to limit the ordering of the alloy, keeping the magnetic losses intact. The link between the degree of order, measured by neutron diffraction, and yield strength has been established in the FeCo-2V alloy. Moreover, a significant effect of the degree of order on the frictional stress has been evidenced. Therefore, optimal compromise between magnetic and mechanical properties could be obtained when the alloy is partially recrystallized with the lowest degree of order.