Yield stress and stress anomaly in an Fe3Al alloy

Abstract

The mechanical properties of an Fe-28 at.% A1 alloy have been examined in detail from room temperature up to 700°C. The solute additions contained in this alloy lead to higher strength at all temperatures than is shown by the binary alloy. These high strengths are associated with dissociated imperfect superdislocations from room temperature up to a stress peak. The anomalous stress peak is found at 500°C, somewhat below the temperature range where disordering of D0₃, order to the B2 ordered state occurs and the Burgers vector of the dislocations present changes from ⟨111⟩ to ⟨100⟩. The reason for the anomalous peak, the locking of the ⟨111⟩ superdislocations and the eventual change to ⟨100⟩ dislocations is a local climb-locking process operating on the ⟨111⟩ superdislocations.