The Structure of Extruded NiAl

The deformation structure of Ni-rich NiAl extruded at 550°C has been characterized by transmission electron microscopy and by optical microscopy. Dislocations having a«100» Burgers vectors were found as complex networks, tangles, and prismatic loops. a«110» dislocations which were rare, were concluded to arise from reactions of a«100» dislocations. Evidence of recovery and recrystallization was obtained. Extrusion was deemed to have been possible by the operation ofhk0 «001» slip systems (often in plane strain flow) plus diffusion-assisted processes.