Ferromagnetism in Compression Stressed Transitional Bulk Nanostructured FE₅₀AL₅₀ Alloy

Mechanically alloyed powders were consolidated to produce bulk polycrystalline Fe-50 at.%Al alloy. Consolidation was achieved by cold compaction and sintering. Annealing was applied to the consolidated samples to obtain an ordered structure. Annealed samples were further deformed plastically by a range of compression stresses. Combination of characterization techniques including X-ray diffraction, transmission electron microscope, vibrating sample magnetometer and Vicker’s micro hardness were used to examine different properties. Results indicated that annealed sample exhibits ordered and non-magnetic phase while deformation induces simultaneously a transition to both disorder and ferromagnetism. The transitional alloy at intermediate state possesses partial disorder and low magnetization. Ferromagnetism is governed by anti site in the ordered matrix, in fact, the long range order and lattice expansion contribute to the increase in magnetism at low compression stresses while it is only due to the lattice expansion at higher stresses. The nano grain refinement inhibits plastic flow of metals, causing an increase in micro hardness while the order to disorder transition can be assessed by micro hardness measurements. Furthermore, several other factors like vacancy and dislocation also influence micro hardness behaviour.