A new type of 〈0 0 1〉 junction observed in a (B2) Fe–Al–Ni–B alloy by TEM in situ straining

Single crystal foils of an FeAl alloy containing Ni and B are strained at elevated temperatures in an in situ dedicated transmission electron microscope (TEM). The observed characteristic “fork-shaped” dislocation configurations are shown to be a kind of “〈0 0 1〉 junction”. This junction comes from a reaction between two 〈1 1 1〉 superdislocations gliding on different {1 1 2} planes; it results in the presence of a long and sessile edge 〈0 0 1〉 dislocation along the intersection of the glide planes. Several hypothetical core structures of such a junction are proposed and their possible effects on macroscopic mechanical properties of the alloy are discussed.