Study of ball milled nanocrystalline Fe-50%Al alloy: structural and magnetic properties

Abstract

Structural, morphological and magnetic changes induced by ball milling in Fe–50%Al alloy have been investigated using X-ray diffraction, scanning electron microscopy and vibrating sample magnetometer techniques. The MA process induces a progressive dissolution of Al into Fe, resulted in the formation of an extended nanostructured Fe(Al) solid solution with BCC structure only after 5 h of milling. The grain size of constituents was decreased to the nanometre range (between 6 and 8 nm) and the constituents dissolved at the nanograin boundaries. Expansion in lattice parameter accompanied by reduction in crystallite size occurs during transition to nanostructured alloy. The corresponding magnetic measurements show continuous decrease in saturation magnetisation and increase in coercivity, retentivity and squareness ratio with increase in milling time. The systematic variation of the magnetic properties has been correlated with the evolution of microstructure, reduction in grain size and enhanced intergranular exchange coupling.