The effects of alloy composition and heat treatment on the intrinsic coercivity ${}_i{H}_c$ of ${\mathrm{SmCo}}_{\mathrm{5}}$ magnets were studied. Alloys having six chemical compositions near that of stoichiometric ${\mathrm{SmCo}}_{\mathrm{5}}$ were used to produce magnets via the usual powder metallurgy techniques. Magnets were either as sintered (1150 $°\mathrm{C})$ or sintered (1150 $°\mathrm{C})$ and treated at 850 $°\mathrm{C}.$ The substantial increase in ${}_i{H}_c$ due to the 850 $°\mathrm{C}$ heat treatment occurs reversibly and with a negligible change in lattice parameters, Curie temperature $T_c$ and anisotropy field $H_A.$ Quantitative metallography and thermomagnetic measurements showed that the microstructural constituent present in addition to the ${\mathrm{SmCo}}_{\mathrm{5}}$ phase in hyperstoichiometric alloys is composed of both the ${\mathrm{Sm}}_{\mathrm{2}}{\mathrm{Co}}_{\mathrm{7}}$ phase and the ${\mathrm{Sm}}_{\mathrm{5}}{\mathrm{Co}}_{\mathrm{19}}$ phase. Measurements of magnetization in dc magnetic fields up to 33 T suggest that $H_A$ is around 53 T, considerably higher than previously reported values. The coercivity of the magnets is discussed in terms of thermal equilibrium populations of lattice defects.

In 2.2% Si electrical steel, the magnetic hysteresis behavior is sharply sheared by a rather small plastic deformation (0.5%). A modification to the Jiles–Atherton hysteresis model makes it possible to model magnetic effects of plastic deformation. In this paper, with this model, it is shown how a narrow hysteresis with an almost steplike hysteresis curve for an undeformed specimen is sharply sheared by plastic deformation. Computed coercivity and hysteresis loss show a sharp step to higher values at small strain due to an $n=1∕2$ power law dependence on residual strain. The step is seen experimentally.