Superplastic behavior of a Ni-Co-base superalloy with high γ′-phase content

The Ni-Co-base superalloy with a 750 °C service temperature contains a substantial number of refractory and γ′-phase forming elements that cause high deformation resistance, low thermoplasticity, and a limited hot-working window. The traditional deformation processing is carried out at low strain rates and high temperatures > 1100 °C, which is extremely strict on equipment working conditions. We coarsened the γ′-phase to facilitate the dynamic recrystallization (DRX) and inhibit grain growth, obtaining small grains of less than 10 µm. Ultimately, the superplasticity of the alloy can reach 1650% elongation at temperatures below 1000 °C and a high strain rate of 0.01/s.