The effect of impurity content on thermally activated deformation in NiAl single crystals

Abstract

NiAl-base materials are attractive candidates for high temperature structural applications due to their low density, excellent oxidation resistance and high thermal conductivity. However, in single crystal and polycrystalline form, NiAl suffers from low tensile ductility and toughness. The mechanisms responsible for the limited ductility of NiAl single crystals are still in question. For this reason, thermally activated deformation in NiAl single crystals has been studied with the use of strain-rate change experiments. The preliminary results suggest that the intrinsic mobility of a , and to a lesser extent a dislocations, is limited below the DBTT in NiAl. To examine the influence of interstitial impurities and the possibility that strain-aging embrittlement is the mechanism responsible for the limited ductility of NiAl, further experiments on high purity NiAl crystals have been conducted for comparison to the results on commercial purity crystals.