Abstract
Planar faults occur abundantly on (001), (110) and (11 1) planes in the C14 Laves phase precipitated in a Fe-based superalloy, and these faults will divide the latter into many parallel domains. The structure of the domain boundaries has been studied by HREM and no disorder has been found. Pentagonal antiprisms are reorganized at these boundaries, forming other tetrahedrally close-packed phases, such as differently oriented μ or C phases on (110) and (11 1) boundaries. The domain boundary structure has been discussed from the point of view of the intergrowth of various tetrahedrally close-packed structures with juxtaposed pentagonal antiprisms.