Research on the Hot Deformation Behavior and Mechanism of a New Nickel-Based P/M Superalloy

Based on hot-compression simulations combined with SEM and TEM analyses, the high-temperature deformation behavior and mechanisms of a new nickel-based powder superalloy FGH101 were investigated over 1020–1110 °C and strain rates of 0.001–0.05 s−1. From the experimental data, the variations in the strain-rate sensitivity index m, the apparent activation energy for hot deformation Q, and the grain-size exponent p were determined as functions of strain rate and temperature. Hot deformation processing maps and mechanism maps incorporating dislocation density were established. The processing maps clearly revealed the evolution of formable regions at different temperatures and strains, while the mechanism maps successfully predicted the dislocation evolution and its operative hot deformation mechanisms by introducing the grain size evolution corrected by Burgers-vector compensation and the rheological flow stress behavior compensated by the modulus. The results indicated an optimal processing window of 1060–1100 °C at 0.001–0.003 s−1. Within the tested regime, as the strain rate decreased, the operative mechanism for grain-boundary sliding transitioned from pipe-diffusion control to lattice-diffusion control. These findings provide a solid theoretical basis for the design and optimization of the isothermal forging process of the new FGH101 alloy.