Microstructure-Resistivity Correlations in Controlled Waspaloy Microstructures

Abstract

AbstractNickel-base superalloys are an important class of metallic ‘nanocomposite’ structural materials known for their good strength retention abilities at high homologous temperatures for long service times. Literature on electrical resistivity studies of age-hardening superalloys is limited. The current work is focused on developing microstructure-electrical resistivity correlations in controlled Waspaloy microstructures. The microstructures are ‘controlled’ as the size distribution of g¢ precipitates is varied systematically. The microstructures are produced upon aging the initial homogenized alloy at nominal temperatures of 700°C, 800°C and 875°C for times up to 100 hrs. Resistivity measurements did not reveal a g¢ nucleation regime for the sampled aging intervals. The primary microstructural evolution mechanism contributing to the observed changes in resistivity was g¢ coarsening. Interestingly, the microstructures resulting from progressive aging at 700°C showed a slow transformation of etch-pits from perfect polygonal shapes to more irregular shapes.