The structure of a〈100〉 and a〈110〉 dislocation cores in NiAl

Abstract

High resolution TEM has been used to observe the core structures of a〈100〉 and a〈110〉 edge dislocations in stoichiometric NiAl. The images indicate that the a〈100〉 edge dislocations have large elastic strain fields but the cores are non-dissociated. Two core structure for the a〈100〉 edge dislocations have been observed. One configuration is climb dissociated into two a 2 〈111〉 partial dislocations which are about 1.0 nm apart. These partial dislocations are linked by an anti-phase boundary (APB) which lies normal to the glide plane. In the second configuration, the a〈110〉 core is decomposed into two a〈100〉 dislocations. The implications of these observed core configurations are discussed with respect to dislocation mobility and the macroscopic flow behavior of NiAl.