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

Abstract

In the present study, the effect of Hf addition on oxidation kinetics of Pt-Ir modified aluminide coatings was investigated. Pt-15 at%Ir and Pt-15 at%Ir with trace amount of Hf films with 7$8 mm thick were deposited on a Ni-based single crystal superalloy TMS-82+ using magnetron sputtering, followed by a diffusion treatment and conventional Al pack cementation. While there were no significant microstructual differences observed in as aluminized specimens, cyclic oxidation test at 1423 K revealed clear advantages of Hf addition. Hf containing coatings showed smaller mass change with retarded surface rumpling during cyclic oxidation test. These results confirmed the beneficial effects of Hf addition reported for other alloy systems such as Pt modified -0 coatings and Pt modified aluminide coatings.

An investigation of phase separation in the Ir–Pt binary system

“…In the Ir-Pt alloys, where Ir is added as a solution-hardening element, improved mechanical properties have been obtained at high temperatures [1][2][3]. In recent years, these alloys have been intensively investigated as coating materials for Ni-based superalloys, and found to exhibit promising oxidation resistance at high temperatures [4][5][6][7][8][9]. In contrast, at lower temperatures good mechanical properties due to the miscibility gap [1] is expected.…”

Observation and modeling of α-NiPtAl and Kirkendall void formations during interdiffusion of a Pt coating with a γ-(Ni-13Al) alloy at high temperature

“…Voids have also been observed at the bond-coating/substrate interface [18][19][20][21]. Vialas and Monceau [19] and Haynes et al [22] attributed their formation to a Kirkendall effect, but without clear proof.…”

“…Vialas and Monceau [19] and Haynes et al [22] attributed their formation to a Kirkendall effect, but without clear proof. Yamaguchi et al [20] suggested that cyclic oxidation is an additional source for vacancy supersaturation. Stacy et al [23] considered that hydrogen dissolution in the material during the Pt electroplating process could be a cause of void formation.…”

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

“…[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. [20] Despite such promising performances of Ir in structural and coating application fields, only limited information is available for atomic diffusivity in Ir based alloys.…”