Electrical Characterization of Aged Waspaloy Microstructures
Non-destructive evaluation (NDE) techniques offer the potential advantage of achieving fast throughput microstructural characterization as well as monitoring that could be extremely valuable in assessing the mechanical integrity of turbine engine components. It is well known that the γ′ precipitate size and distribution can often determine the mechanical strength of nickel base alloys. In this investigation, Waspaloy, an age-hardening superalloy, was chosen as the candidate to produce varied microstructures, which were subsequently characterized via the DC four-probe resistivity method. Specimens with average grain sizes of 13, 52 and 89 μm were obtained upon solutionizing at 1045°C, 1090°C and 1145°C respectively. The specimens were annealed at 1045°C to stabilize the vacancy concentration prior to aging at 800°C for times ranging from 0.1 to 100 hours. Sub-grain microstructures examined in the SEM showed progressive growth of γ′ precipitates with increased aging duration in all cases. The measurements of DC four-probe resistivity showed a consistent drop in the resistivity with increased aging time, which was concurrent with the growth of the precipitates.
T. Chandra, K. Tsuzaki, M. Militzer and C. Ravindran
V.S. Kumar et al., "Electrical Characterization of Aged Waspaloy Microstructures", Advanced Materials Research, Vols. 15-17, pp. 876-881, 2007