Exchange coupled rare-earth free Mn-Al/Fe nanocomposite magnets by spark plasma sintering

The structural and magnetic properties of Mn-Al/Fe nanocomposites fabricated by spark plasma sintering (SPS) followed by short annealing (SA) were investigated by varying the soft phase, Fe-content from 0 to 10 wt.%. The SPSed samples mainly revealed equilibrium β-phase with some traces of γ2, ε and τ-phases and the intensity of τ-phase peaks tends to improve with the SA process. Upon increasing the Fe-content, the saturation magnetization (Ms) values of Mn-Al/Fe nanocomposites tend to increase; while their coercivity (Hc) values are found to be decreased. A good combination of Hc (2.3 kOe) and Ms (40.3 emu/g) values was obtained for the Mn-Al+5 wt.% Fe nanocomposite magnet.