Magnetic properties of Mn-Al alloy after HPT deformation

Abstract In this study, we reported on the possibility to produce a bulk permanent magnet based on Mn55Al43C2 alloy by high-pressure torsion (HPT) deformation. The results show that using room temperature HPT deformation it is possible to obtain a small volume disk-shaped magnetic sample of 0.5 mm thickness and 8 mm diameter deformed for 1, 3 and 5 turns. The maximum coercive force of Hc = 0.37 T (3.7 kOe) at Ms = 0.49 T (75 emu/g) was obtained for the sample deformed for 5 turns (e = 5.16). The reason for enhance of coercive force is accumulation of crystalline defects acting as pinning centers for domain walls. Subsequent heat-treatment of deformed samples at temperature ranging 500–650 °C reduces the coercive force down to 0.24 T (2.4 kOe) with the simultaneous recovery of saturation Ms almost up to initial value 0.75 T (115 emu/g).