Magnetic Properties of an Equi-Atomic PtCo Single Crystal Having a [111] Orientation

The equi‐atomic alloy of PtCo (77 wt% Pt, 23 wt% Co) is a high energy product, high coercive force permanent magnet material. Polycrystalline magnets of PtCo are isotropic. Measurements of the intrinsic coercive force as a function of crystallographic orientation made on a small PtCo single crystal showed it to be anisotropic. The maximum H_ci value was found to occur in the 〈111〉 direction. Subsequently, a larger single crystal was produced in the form of a right circular cylinder for the purpose of making B‐H measurements in the [111] direction. Values were obtained for B_r, H_c, H_ci, and (BH)_max from hysteresis graphs of both the single‐crystal PtCo magnet with a [111] orientation and the conventional isotropic polycrystalline PtCo magnet. Values measured were:

$$\begin{array}{ccccc}& B_r& H_c& H_{\mathrm{ci}}& \mathrm{\hspace{0.17em}(}\mathrm{BH}{)}_{\max }\\ \mathrm{Single\; crystal}\text{\hspace{0.17em}〈111〉}& 6500& 5900& 8200& {\text{9.8×10}}^6\\ \mathrm{Polycrystalline}& 6400& 5500& 7500& {\text{9.2×10}}^6.\end{array}$$