On three-dimensional defects in the Ni 3Al( γ′) phase identified by the computed imaging technique

Abstract

Despite the large number of studies on the plastic properties of L1 2 crystals, the crystalline defects produced by high temperature deformation of phases based on Ni 3Al( γ′) are not yet thoroughly understood. Some examples of unusual three-dimensional defects have been observed in deformed γ′ precipitates of the industrial nickel-based two-phase superalloy CMSX2 and in deformed specimens of the L1 2 alloy 9Al14Ti3.5Cr73.5Ni (atomic percent). These defects, which involve superlattice stacking faults, stair-rod-dislocation-like defects and superpartial dislocations, are analysed by both conventional and high resolution electron microscopy, and the computed imaging technique coupled with two-beam diffraction theory.