Defect Characterisation in MnAl-C Using EBSD and ECCIWednesday (26.09.2018) 11:00 - 11:15 S1/01 - A04 Part of:
In the Mn-Al system, a metastable phase, known as tau, can be produced in near-equiatomic alloys doped with C (i.e. MnAl-C). The tau phase has a high magnetisation, magnetocrystalline anisotropy and Curie temperature; contains no critical elements and therefore has great potential as a rare earth free permanent magnet. In spite of this, the highest remanence and coercivity which have been achieved in practice in such materials are significantly below the estimated upper limits. This is currently the barrier to the application of MnAl-C as a permanent magnet. The explanation for the poor measured magnetic properties lies in the microstructure of the material, which is characterised by a range of defects including antiphase boundaries, twin and grain boundaries, stacking faults and dislocations. Previous studies have indicated that all of these can interact with magnetic domain walls. The combination of EBSD and ECCI enables detailed characterisation of the type, density and distribution of these defects over large areas and thus is a powerful tool to study the effect of different processing routes on the microstructure and magnetic properties of tau-MnAl-C.