Nanoscale characterization of FeNi alloys processed by high-pressure torsion using photoelectron emission microscope

Photoelectron emission microscopy observation is performed on an FeNi alloy processed by high-pressure torsion (HPT) in order to microscopically analyze magnetic domain structure, elemental distribution, and surface morphology. While belt-like magnetic domain structures with widths of 3 to 5 μm are observed at about 2 mm away from the sample disc center, only narrower magnetic domain structure is observed at 1 mm away from the disc center. While these magnetic domain structures are related to a product during the HPT process, they are related neither to inhomogeneity of elemental distribution nor to surface morphology. Therefore, it is suggested that the observed magnetic domains should be originated from an L 1 0 phase. The present analysis indicates that atomic diffusion is significantly enhanced by processing the samples with HPT and post-annealing.