2006 Volume 47 Issue 8 Pages 1918-1921
Platinum-iridium films (Ir=0,32,46,83,100 at%) were deposited on the nickel-base single crystal superalloy TMS-82+ through magnetron sputtering. After annealing and aluminizing, the Pt-Ir modified aluminide coatings mainly consisted of PtAl2 and β-(Ni,Pt,Ir)Al phases. Hot corrosion resistance of the different Pt-Ir modified aluminide coatings was evaluated through exposure at 1173 K with the Na2SO4+10 mass%NaCl salt coatings. The lowest mass gain (2.99×10−3 kg/m2, after 100 h) was observed for the Pt-46Ir aluminide coating, which formed the dense and continuous protective Al2O3 scale on the surface. The effect of Ir on the corrosion resistance of Pt-Ir modified aluminide coatings was discussed from three aspects—phase transformation, protective scale formation and the role of a Pt-Ir enriched layer.