Hot deformation behavior and microstructure evolution of a novel nickel-based powder metallurgy superalloy

Abstract

With the increase in service temperature of aero-engine hot components, the requirements for the high-temperature performance and processability of the powder metallurgy (PM) superalloys used for preparing turbine disks also increase. To overcome the bottlenecks that constrain the preparation and microstructure control of PM superalloys, this work investigates the impacts of hot compression parameters on the hot deformation behavior and microstructure evolution of a novel PM superalloy, FGH4113A. Hot compression tests were conducted on the FGH4113A alloy, which underwent hot isostatic pressing, within a temperature range of 1050 °C–1150 °C and at a consistent true strain rate ranging from 0.001s−1 to 1s−1. The results reveal that the flow stress decreases progressively with the reduction of strain rate and the rise in temperature. Optimal hot deformation conditions are identified at a temperature of 1110 °C with strain rates ranging from 0.1s−1 to 1s−1, and a temperature of 1130 °C with strain rates between 0.01s−1 and 0.1s−1. Within these optimal regimes, grains are uniform, and the average grain size is maintained within10μm. Grain evolution during hot compression involves original grain deformation, followed by recrystallization, subsequent grain coarsening, and then deformation again. Additionally, the γ′ area fraction diminishes with an increase in deformation temperature. Specifically, as the deformation temperature raises from 1050 °C to 1110 °C, and subsequently to 1150 °C, at a rate of 0.001s−1, the primary γ′ area fraction diminishes progressively from 6.2 % to 3.0 % and ultimately to zero. Above 1130 °C, the γ′ area fraction remained largely unaffected by variations in strain rate. These insights are pivotal, offering both experimental data and theoretical perspectives for optimal microstructure control in PM superalloys.