Direct observation of the shear APB interface in Fe₃Al by HREM

Atomic arrangements at a nearest neighbour anti-phase boundary (APB), on the (1(formula presented)0) plane, connected by 1/2[111] superpartials in Fe₃Al were directly observed in an edge-on view using high resolution electron microscopy (HREM). In HREM images, Al atom positions projected along the [110] direction were revealed as white dots. A single step on the APB interface, which is related to a jog on the partial dislocation line, was identified directly from the geometrical patterns of the white dots. Detailed comparisons of the experimental data with simulated images indicated that the apparent relaxation of atomic rows at the APB is very localized to its interface even at the step.