Dislocation Morphologies in TiB2/NiAl

Abstract

AbstractThe addition of 20 volume percent titanium diboride in particulate form (1-3 μm) to nickel aluminide (TiB2/NiAl) results in a twofold increase in the high temperature strength of NiAl. Theories that have been proposed to account for the high temperature strength of discontinuous reinforced metal matrix composites can not be adequately used as a basis to explain the observed strengthening.An investigation was undertaken of NiAl, 10 V% TiB2/NiAl and 20 V% TiB2/NiAl in the annealed condition and after deformation, allowed to cool slowly. There is a low dislocation density in the annealed samples and the dislocation density did increase slightly as a result of deformation. However, deformation did produce some intriguing dislocation arrangements; for example, it was found that there was a high dislocation density within the TiB2 in the deformed higher volume fraction composites and the dislocation density within NiAl matrix was not uniform.