Magnetic and X-Ray DiffractionInvestigations of the Reordering of a Ball Milled Fe-40Al at%Alloy

The reordering of a ball milled, disordered, Fe-40Al at.% B2 alloy has been studied structurally by means of X-ray diffraction and magnetically by vibrating sample magnetometer measurements. The reordering process of the alloy consists of several steps: short range reordering, ordered domain growth, recrystallisation, etc. At low annealing temperatures, the anneal out of point defects induces short-range reordering with a concomitant reduction in magnetic moment and stress induced anisotropy. Long-range order nucleates independently inside each coherently scattering domain and then, when recrystallisation occurs at higher annealing temperatures, it can propagate from one grain to the other. The susceptibility results support the presence of these independent crystallites. At the highest annealing temperature, 700°C, the parameters for the original unmilled powder are recovered.