The Ductility of Stoichiometric and Ni-Rich Polycrystals of Ni3Al: The Effect of Strain Rate

Abstract

ABSTRACTPolycrystals of stoichiometric Ni3Ai are brittle in air at room temperature, at least at strain rates from 10-4 s-1 to 7 s-1. This is indicative of intrinsic brittle behavior. Nickel-rich (Ni24A1) polycrystals, on the other hand, undergo a brittle-to-ductile transition upon raising the strain rate to above about 10-2 s-1. It is argued that the transition reflects the suppression of environmental embrittlement, not of the intermetallic per se but of a Ni-rich solid solution that decorates the grain boundaries of the off-stoichiometric alloy.