Characterization of Fe/Pt bulk multilayers and FePt formation
Résumé
Experimental investigations of the microstructure and physical properties of Fe/Pt multilayers and the hard magnetic FePt (L10) phase are reported. Accumulated cold rolling of a stack of pure Fe and Pt foils was used to produce a series of bulk multilayers of various internal scales (10 mm–10 nm). Annealing treatments were carried out to transform the multilayer via interfacial reactions into the ordered FePt (L10) phase. By combining different experimental techniques, it was shown that scale reduction operates by plastic co-deformation of both phases without any interfacial product. Crystallographic texture refinement, a strong increase in mechanical strength and a lowering of the transformation temperature occur with scale reduction. Kinetics and phase transformations were studied. Magnetic domain structure images were correlated to the grain and defect structure of the FePt phase.