New Sigma-Phases in Binary Alloys of the Transition Elements of the First Long Period

TLDR: The structure of the brittle intermediate Σ-phase in the system iron-chromium has not yet been determined; but isomorphous phases have been found in the systems iron-vanadium, cobalt and iron-molybdenum as discussed by the authors.

Abstract: THE structure of the brittle intermediate Σ-phase in the system iron–chromium has not yet been determined; but isomorphous phases have been found in the systems iron–vanadium1, cobalt–chromium2 and iron–molybdenum3. All these phases occur at or near to the equiatomic composition, and this has led K. W. Andrews4 to suggest that they are connected with superlattice formation. Recent work in this Laboratory has led to the discovery of four new Σ-phases the compositions of which are of interest. The existence of two of these phases was predicted by Beck and Manly5.