Figure 3 shows the change in hysteresis loop shape as stress is increased for a Rotelloy
8 sample that was annealed at 880°C. On the application of an initial tensile stress,
the coercivity and d.c. hysteresis loss decrease. As the stress is further increased, the
coercivity increases, going through an irreversible change and signifi cant increase as the
mechanical yield point is reached. The optimum stress for the best magnetic properties
for Rotelloy 8 occurs at around 50 MPa due to the creation of a more favourable
direction of magnetisation resulting from changes in the energy contribution from
magnetostriction.