Abstract
The structure and formation of sequence faults in certain topologically close-packed structures with primary layers containing pentagons and triangles are discussed. We use the Pearson-Shoemaker notation to describe such faults. An analysis of recent high-resolution electron microscopy observations of domain boundaries in a Laves phase and a μ-phase alloy is carried out, which suggests that it is more appropriate to interpret these boundaries as sequence faults rather than as thin slabs of other topologically close-packed phases.