Oxidation Behavior of Pt–Ir Modified Aluminized Coatings on Ni-base Single Crystal Superalloy TMS-82+

Abstract

The oxidation resistance of Pt-Ir modified aluminized coatings, prepared by magnetron sputtering, was investigated. Cyclic oxidation tests revealed that Pt-30 at%Ir and Pt-50 at%Ir modified aluminide coatings demonstrated a smaller mass change compared with Pt, Pt-80 at%Ir and Ir modified aluminide coatings. Cross-sectional analyses following cyclic oxidation tests showed that the TGO layer formed on the Pt modified aluminide coating surface is almost twice as thick as those on the Pt-30 at%Ir and Pt-50 at%Ir coatings. In addition, the Pt-30 at%Ir and Pt-50 at%Ir samples had a much smoother surface than the Pt modified coatings after cyclic oxidation, and the latter suffered from severe surface rumpling. However, when the Ir content exceeded 80 at% in Pt-Ir modified coatings, internal voids formed during cyclic oxidation. These results show that the addition of 30-50 at%Ir to Pt-modified aluminized coatings is most effective in enhancing oxidation resistance.

Effect of Hf Addition on Oxidation Properties of Pt-Ir Modified Aluminide Coating

“…1, there were no significant microstructual differences observed in the two specimens, similar to the microstructure previously reported. 13) Both the coatings consisted of a 70-80 mm thick Pt, Ir, Ni, Al enriched layer consisting of PtAl 2 and -(Pt, Ir, Ni) Al phases beneath the surface, followed by a 10 mm thick intermediate Ni, Al enriched layer, a 10 mm thick interdiffusion zone (IDZ) and the substrate. Both the specimens near (5 mm beneath) the surface showed no significant compositional differences either, which were 57Al-22Ni-9Pt-2Ir-and other trace elements (at%).…”

“…5) Application of Ir based alloys for bond-coats has been proposed by the authors' group. [6][7][8][9][10][11][12][13] As one of these approaches, oxidation and hot corrosion resistances of PtIr-Al alloy systems were evaluated, and Ir addition to PtAl bond-coat was revealed to enhance oxidation and hot corrosion resistances. [11][12][13] On the other hand, proper addition of reactive elements such as Zr, Y, Hf to bond-coat is reported to minimize the detrimental effect of S and to enhance the scale adhesion.…”

“…[6][7][8][9][10][11][12][13] As one of these approaches, oxidation and hot corrosion resistances of PtIr-Al alloy systems were evaluated, and Ir addition to PtAl bond-coat was revealed to enhance oxidation and hot corrosion resistances. [11][12][13] On the other hand, proper addition of reactive elements such as Zr, Y, Hf to bond-coat is reported to minimize the detrimental effect of S and to enhance the scale adhesion. [14][15][16][17][18] Among them, Hf addition is of particular interest because it is known to reduce the scale growth rate and thus effective in enhancing oxidation resistance.…”

Interdiffusion in the Ir-Rich Solid Solutions of Ir-Pt, Ir-Rh, and Ir-Re Binary Alloys

“…It has been demonstrated that Ir addition is effective in enhancing the oxidation and hot corrosion resistance of PtAl. [9][10][11][12] For further improvement in protection performances, application of Ir based alloys to the bond-coats has been proposed. [13][14][15][16][17][18][19] At the same time, a Re modified aluminide coating has been shown to exhibit notable performance as a diffusion barrier.…”

Interdiffusion in L12-Ni3Al Alloyed with Re

“…Multicomponent diffusion mobility database [2] for c phase, together with the alloying studies [3][4][5][6][7][8][9][10] to modify coherent precipitate (c¢) have yielded excellent design criteria to develop advanced superalloys. Recent development of refractory-based superalloys with L1 2 precipitates, and refractory-modified aluminide coatings [11][12][13][14][15][16] warrant a better understanding of interdiffusion in Ni 3 Al with alloying additions.…”