1000 to 1300 K slow plastic compression properties of Al-deficient NiAl

Nickel aluminides containing 37, 38.5 and 40 at. pct Al have been fabricated by XD synthesis and hot pressing. Such materials were compression tested in air under constant velocity conditions between 1000 and 1300 K. Examination of the microstructures of hot pressed and compression tested aluminides indicated that the structure consisted of two phases, gamma-prime and NiAl, for essentially all conditions, where gamma-prime was usually found on the NiAl grain boundaries. The stress-strain behavior of all three intermetallics was similar where flow at a nominally constant stress occurred after about two-percent plastic deformation. Furthermore, the 1000 to 1300 K flow stress-strain rate properties are nearly identical for these materials, and they are much lower than those for XD processed Ni-50Al. The overall deformation of the two phase nickel aluminides appears to be controlled by dislocation climb in NiAl rather than processes in gamma-prime.