In this work, the correlation between magnetic-domain structure and microstructure in combined reaction-processed equiatomic L10 FePd has been investigated using magnetic force microscopy. The microstructure consisted of approximately equiaxed grains with an average grain size of ∼1 μm and a grain size distribution ranging from below the theoretical critical domain size (Dcrit∼0.2–0.3 μm) up to approximately 5 μm in diameter. The domain structure was characterized as “mixed” in nature, consisting of smaller single-domain grains, larger multidomain grains, and a larger scale interaction domain structure encompassing many grains. The domain boundaries separating interaction domains tended to lie along grain boundaries, and it is proposed that the observed interaction domains should be considered in descriptions of the magnetization and magnetization reversal behavior of this material. In particular, pinning of interaction domain walls by intragranular features of the microstructure such as grain boundaries and single-domain grains could play a role in the measured coercivities.

The L1 0 ordering equiatomic intermetallic FePd has been used as a model system for the investigation of the evolution of microstructure and properties during annealing at temperatures below the ordering temperature after cold deformation. The two different routes for the preparation of equiaxed L1 0 FePd polycrystals, annealing after cold deformation in the disordered FCC state or after cold deformation in the ordered state, produce similar grain size distributions, differ in the transformation kinetics and in the sequence of texture evolution during the post-cold-deformation annealing. Cold deformed L1 0 FePd progresses through the classic stages of annealing known from studies of disordered elemental metals and alloys based on them. The reduced long range order parameter of the 'mechanically disordered' FePd is recovered in the early stages of annealing and both the recrystallization and the grain growth stages are quite sluggish, presumably because of the slow diffusion processes in the L1 0 lattice. Mater. Res. Soc. Symp. Proc. Vol. 980