Effects of Deviation from Stoichiometry on Deformation Behavior of Hard-Oriented NiAl Single Crystals

Abstract

ABSTRACTNi-44A1, Ni-50Al and NiAl-0.3 at.% Hf single crystals have been studied in compression to understand the effects that alloying additions and deviation from stoichiometry can have on the mechanical response of NiAl-based single crystals. While all three single crystals deform through a<111> slip at lower temperatures, the active slip systems differ at higher temperatures. Climb of a<010> dislocations contributes to deformation in Ni-50AI single crystals beyond the slip transition temperature, while Ni-44Al and NiAl-0.3Hf crystals deform through a<101> glide. But several microstructural differences have been observed in the mode of deformation between Ni-44Al and NiAl-0.3Hf crystals. In addition, significant strengthening is exhibited in the Hf-doped crystals at higher temperatures. The post-deformation microstructure is also observed to be sensitive to both strain and strain rate. A possible explanation is offered for some of the observed differences in deformation behavior between the three alloys.