Discrepancies between microscopic (TEM) and macroscopic (texture) observations in high temperature deformation of FeAl and Fe3Al-based alloys

Macroscopic texture measurements of Fe3Al-based alloys deformed at 925≤T≤1325 K in the B2 structure regime by rolling, forging and extrusion, at deformation rates of 10−4–101 s−1, agree well with the numerically predicted textures for the 〈111〉{110}+〈110〉{112} slip system activation [1, 2], for each of these deformation histories. These results appear to be in disagreement with prior transmission electron microscopy (TEM) observations, that overwhelmingly support the activation of 〈100〉{011} and 〈100〉{001} slip systems at high temperature [3–7]. To reconcile this discrepancy, we revisit the issue of TEM observations within the framework of a deformation experiment in the Gleeble™ apparatus, where the high temperature deformation substructure is `quenched-inʹ by imposing cooling rates of about 103 K.sec−1. Thus the incidence of thermally induced dislocation reorganization is minimized. TEM examinations reveal that the `quenched-inʹ dislocation substructure is indeed dominated by 〈111〉 dislocations and not 〈100〉 dislocations.