Structural and magnetic evolution of ball milled nanocrystalline Fe-50 at.% Al alloy

Abstract

Abstract Investigations regarding structural, morphological, and magnetic changes induced by ball milling of Fe-50 at.% Al alloy have been carried out. The mechanical alloying process induces a progressive dissolution of Al into Fe, resulting in the nucleation and establishment of an elongated nanostructured Fe(Al) solid solution with the bcc structure only after 5 hr of milling. The average crystallite size of components decreased to ~5 nm and the components diffused to the nanograin boundaries during transition to nanostructured composite. Scanning electron microscopy and transmission electron microscopy confirmed the crystallite size determination and Fe(Al) solid solution formation obtained from X-ray diffraction analysis. The corresponding magnetic (Mössbauer and vibration sample magnetometer) studies confirm that there is magnetic behaviour retained in the FeAl alloys samples even after 5 hr of milling but magnetization decreases as the milling time increases. The ball milling process involves the loss of long range order and reduced grain size, which induces a transition from a paramagnetic to ferromagnetic state. The continuous refinement of grains and the antiphase interface grain bounderies play a major part in the observed variation in the magnetic properties.