Synergistic effect of reactive element co-doping in two-phase (γ' + β) Ni-Al alloys

To propose reactive element (RE) co-doping strategy, the oxidation behaviour of Dy, Hf, Y, Zr single- and co-doped Ni-30Al alloys was comparatively studied. All the alloys containing Dy or Y exhibited improved scale adhesion due to the pinning effect of the pegs at the scale/alloy interfaces and the reduced residual stress by the flaky oxides formed on the alloy surfaces. Compared to the corresponding RE single-doping, Dy/Hf, Dy/Zr, Hf/Y and Y/Zr co-doping further reduced the scale growth rate, revealing a synergistic effect. The role of reactive element co-segregation in the formation of synergistic effect was analyzed.