Effect of Hf addition on evolution of microstructure and strengthening behavior in Ni-based ODS superalloy

In this study, two kinds of Zr-containing Ni-based ODS superalloys, ODS-Zr (Ni-20Cr-0.5Ti-0.3Al-0.6Zr-0.6Y2O3, wt%) and ODS-Zr+Hf (Ni-20Cr-0.5Ti-0.3Al-0.6Zr-0.8Hf-0.6Y2O3, wt%), were prepared by high-en-ergy milling and hot isostatic pressing (HIP) process. Evolution of microstructure and tensile property caused by Hf addition was analyzed and discussed. The result showed that the addition of Hf changes significantly oxide type and refines oxide size. Y4Zr3O12, Y2TiO5 and three-type Y-Al oxides including monoclinic-structure Y4Al5O12 (YAM), orthogonal and hexagonal YAlO3(YAM and YAH) are found in ODS-Zr. In contrast, only Y2Hf2O7, Y4Zr3O12 and Y2TiO5 but no Y-Al oxides are viewed in ODS-Zr+Hf. The average diameter of oxides in ODS-Zr and ODS-Zr+Hf is 16.6 nm and 13.0 nm, respectively. The size difference between two alloys is ascribed to different oxide constitution in two alloys. Moreover, Hf addition enhances tensile strength of alloys at 25 degrees C and 700 degrees C meanwhile improves tensile ductility at 700 degrees C.(c) 2023 Elsevier B.V. All rights reserved.

Automated summary

Two kinds of Zr-containing Ni-based ODS superalloys, ODS-Zr and ODS-Zr+Hf, were prepared by high-energy milling and HIP process. The addition of Hf significantly changed the oxide type and refined the oxide size. The size difference between the two alloys is attributed to different oxide constitution. Moreover, Hf addition enhanced the tensile strength at 25°C and 700°C and improved the tensile ductility at 700°C.