Applying High-Pressure Torsion to Deformation of a Recrystallized -MnAl Alloy: Results and Problems

In this study, the effect of high-pressure torsion (HPT) on the structure, phase composition and magnetic properties of ferromagnetic MnAl-C alloy were investigated. tau-phase MnAl disks were treated in two different initial conditions: first, a disk was deformed for 20 revolutions in "as-transformed" state, and second, the deformed disk was recrystallized and then deformed for 20 revolutions again. Repeated deformation produced a coercive force of 2.0 kOe which is significantly lower than the one obtained earlier after first HPT deformation (3.7 kOe). It was demonstrated that the low level of the coercive force was associated with the failure to achieve the specified strain during HPT and with deformation inhomogeneity both in depth and along the radius of the sample. This behavior of the material during HPT was due to the high hardness of the tau-MnAl-C ferromagnetic alloy. The article suggests variants for improving the machinability of the alloy to achieve the required strain.