The plastic deformation behaviour of long-range ordered iron-aluminium alloys

Abstract

The compressive deformation behaviour of iron-aluminium alloy single crystals containing 23·8, 28·0 and 30·0 at. % Al has been investigated in the temperature range from 77° to 683°K. The results of these experiments verify the unusual deformation behaviour first observed in polycrystals. Specifically, long-range ordered alloys may exhibit, depending upon temperature and composition, deformation stages which are produced by superlattice dislocations of various degrees of perfection. Single crystals may deform via the formation of as many as four linear work-hardening stages followed by a parabolic stage. The existence of the linear stages requires that superlattice dislocations be nucleated during deformation. An analysis of the super-lattice dislocation nucleation process is therefore included. This analysis is adequate to describe the conditions required for formation of the linear stages in agreement with experiment.