Transitions in the Chromium–Manganese and Nickel–Vanadium Sigma Phases

Abstract

TRANSITIONS occur in the chromium–manganese sigma phase at 1,005° C. and in the nickel–vanadium sigma phase [see Nature, January 12, 1952, p. 70] at a temperature below 800° C. In both these systems the structure present above the transition temperature has been investigated by high-temperature camera photographs. The films show that the same main X-ray reflexions are given by the high-temperature phase as are observed at room temperature. Alloys quenched from the high-temperature phase regions do not show decomposed micro-structures. The transitions may be of the order–disorder type.