Multilayer stacking faults in b.c.c. metals

The symmetry of the unrelaxed energy of multilayer stacking faults on the {112} plane in the b.c.c. lattice is studied. The property that the single-layer fault energy does not depend on the sense of displacement in the ⟨111⟩ direction is generalized for multilayer faults. It is pointed out that the triple-layer fault deduced from the structure of the metastable ω phase may be stable, and furthermore that this fault is related to another fault which may be regarded as a distorted close-packed structure.