Strain-induced disorder stimulation of Antiphase boundaries’ (APBs) formation in B2 Fe-Al based alloys

Current study was undertaken with the purpose of imposing the formation of shear Antiphase Boundaries (APBs) in Fe-Al based B2 alloys by applied external stress. To shed light on shear APBs formation mechanisms, it was decided to apply stress on materials which do not contain thermal APBs, i.e., APBs-free material. Appropriate compositions were chosen complying with compositional requirements summarized in our previous research on Al-Fe based materials. Following application of ∼5 % compressive stress, APBs formed in Fe₆₆Al₃₄ and (Al₄₀Cr₁₀)Fe₅₀ alloys, but not in Fe₆₄Al₃₆ and (Al₄₅Cr₅)Fe₅₀ alloys. Dislocation analysis revealed a significant increase in the <111> type dislocations after deformation, indicating strain-induced disorder. A consistent ratio of about 80 % <111> dislocations (out of total number of dislocations) was observed at the onset of shear APBs formation across studied compositions, suggesting a critical disorder threshold required for the shear APBs formation. This study demonstrates that strain can be used to decrease the order and promote APBs formation in Fe-Al based B2 alloys. Since Al-Fe B2 was proved to be a model system of AlCoCrFeNi B2 matrices, we believe that suggested disorder evaluation tool, based on dislocation analysis, as well as understandings attained here can have a broader impact on rapidly growing field of multicomponent metallic alloys.