Effect of Zr on creep deformation behaviors of PM Ni-based superalloys

In this study, the creep tests of three PM Ni-based superalloys with different Zr contents were carried out at 700 °C/780 MPa, 750 °C/550 MPa and 800 °C/400 MPa, respectively. The effect of Zr on creep deformation behaviors was studied by OM, SEM, EBSD and AC-STEM. The results show that the addition of appropriate Zr (0.1 wt.%) inhibits crack initiation and premature cracking, prolongates the creep rupture time, reduces the minimum creep rate, and increases the proportion of steady-state creep duration. However, excessive Zr content (0.5 wt.%) can promote the continuous precipitation of μ, σ, and Ni₇Zr₂ phases at the grain boundaries, which is easy to become a crack source and reduce the creep performance. In general, the alloy with 0.1Zr addition has high creep strength, low tendency of intergranular cracking at high temperature, and the best overall creep performance. This study provides a theoretical basis for the appropriate addition of Zr in PM Ni-based superalloys and provides some ideas for the optimization of alloy composition and design of novel PM Ni-based superalloys.