Magnetic properties of partially crystallised Fe–Co–Hf–Zr–B–Cu alloys

Abstract HITPERM-type alloys were investigated to determine the influence of boron, zirconium and hafnium content on magnetic softness, and to find the crystallisation temperature allowing one to obtain the lowest coercive field, Hc. The second crystallisation stage temperature decreases with the increase of B content, suggesting that boron impairs the stability of the two-phase structure at high temperatures. The addition of Hf improves thermal stability, better than Zr. After annealing for 1 h, Hc of the alloys after the optimum heat treatment is between 17 and 26 A/m. The lowest values of Hc are obtained for the alloys with Hf only.