The Effects of a New Grain Boundary Phase in Ni-AI Alloy

摘要

In a γ/γ' nickel-aluminum alloy, a new phase has been identified along grain boundaries by conventional transmission electron microscopy. This phase is identified to be of the C_6Cr_(23) type structure with lattice parameter 10.48A, which is approximately three times that of NisAl or nickel. This grain boundary precipitate is found to be coherent with the γ phase in one grain. The chemical composition of this grain boundary precipitate is determined by energy dispersive x-ray spectroscopy and parallel electron energy loss spectroscopy. The deformation mechanism of this grain boundary precipitate is investigated on post-mortem specimens which have been carefully deformed by nanoindentation after jet-polishing.