Superdislocations and antiphase boundary energies in deformed Fe3Al single crystals with chromium

Abstract

The influence of Cr additions on the positive temperature dependence of the flow stress and on the antiphase boundary (APB) energies of Fe3Al was investigated. Single crystals of binary Fe28 at.% Al and ternary Fe28 at.% Al6 at.% Cr were deformed in uniaxial compression between room temperature and 1273 K. The dislocation arrangement and the dissociation of superdislocations were studied by transmission electron microscopy using the weak-beam technique. The operative slip systems are discussed on the basis of direct measurements of the APB energies. Three types of fault energies of superdislocations were analyzed as a function of temperature (up to 1003 K) and chromium concentration: the nearest-neighbor APB energy in the slip plane, the next-nearest-neighbor APB energy in the slip plane and the nearest-neighbor APB energy in the cross-slip plane. A procedure for calculating APB energies from effective pair potentials is given. The calculated results are in good agreement with the experimental data.