Extraordinary Deformation Modes in Ni-Base Superalloy CM247LC at Room Temperature

After tensile deformation at room temperature and a strain rate of 3.0 × 10−4 s−1, microstructures of [001]-oriented single crystal Ni-base superalloy CM247LC are characterized by transmission electron microscopy. We found that besides pairs of a/2〈110〉 dislocations, shearing of γ′ precipitates by single a/6〈112〉 partial dislocations accompanied by the formation of Shockley dislocation loops, isolated stacking faults and extended stacking faults as well as microtwinning also occur in the alloy at the very beginning of plastic deformation.