Hard Magnetic MnAl and MnBi Ribbons Made from Molten State by Rapid Cooling

MnAl and MnBi ribbons were made from the molten alloys by the single-roller rapid-quenching technique, and their crystallographical, mechanical and magnetic properties were studied. Long, flexible MnAl ribbons were produced, and the ferromagnetic τ-phase was obtained by a simple annealing treatment. The best magnetic properties were B r=3.75 kG, I H c=1.83 kOe and (B H)max=2.1 MGOe for 56 at%MnAl ribbon. The MnBi ribbons were short and brittle, but they appear to be more stable chemically than the cast alloy. The best characteristics of the MnBi ribbons were B r=3 kG, I H c=1.5 kOe and (B H)max=1.6 MGOe.