It was noted that the -phase was isostructural with -Mn and frequently precipitated in steels during annealing. The structural defects which were identified by means of transmission electron microscopy of -phase particles were considered. These defects were translational boundaries that were characterized by very simple fault vectors of the form, 1/3<110> or 1/4<111>. Interpretation of the latter fault vector led to a new description of -Mn crystals. It was recalled that -Mn was considered to be a complex phase because it did not obey the Frank-Kasper rules for topologically close-packed phases. It was therefore concluded that the present defect-based view constituted a new method for describing these phases.

A.Proult, P.Donnadieu: Philosophical Magazine Letters, 1995, 72[5], 337-44