Current permanent magnets such as NdFeB contain a significant fraction of rare earths (Dy, Nd), resulting in an increasing cost and higher supply risk. Potential low cost substitutes include the L10 tetragonal structure of equiatomic Mn-Al and the L10 equiatomic Fe-Ni. While the former exhibits a relatively low energy product (~ 110 kJ/m3), the latter material may approach the energy product of Nd-Fe-B.

We have grown equiatomic Fe-Ni films by electrodeposition at both very low and very high growth rate, in order to understand the influence of the driving force for growth on the morphology and the defectivity of the films. A citrate/glycinate electrolyte with low metal ion concentration exhibited after annealing at 300 C a coercivity of 1000 Oe, which cannot be ascribed only to internal stresses. A sulfate based electrolyte with high metal ion concentration, suitable to achieve high growth rates, presents a large defect density. The talk will cover the synthesis and characterization of the materials, with emphasis on the crystal structure and the correlation between microstructure, phase and magnetic properties.