National Aeronautics and Space Administration


Date of this Version



Surf. Interface Anal. 2015, 47, 844–853


U.S. Government Work


Oxidation resistant, strain tolerant MAX phase coatings are of general interest for high temperature applications. Accordingly, Cr2AlC MAX phase coupons were vacuum diffusion bonded to an advanced turbine disk alloy at 1100 °C for compatibility studies. The interface revealed an inner diffusion zone consisting of ~10 μmof β-Ni(Co)Al, decorated with various γ′ (Ni,Co)3Al, Ta(Ti,Nb)C, and W(Cr,Mo)3B2 precipitates. On the Cr2AlC side, an additional ~40-μm Al-depletion zone of Cr7C3 formed an interconnected network with the β-Ni(Co)Al. On the superalloy side, enhanced carbide precipitation developed over a depth of ~80 μm. Subsequent annealing for 100 h and 1000 h at 800 °C coarsened some features, enhanced TCP precipitation in the superalloy, but only enlarged the diffusion layers by ~5 μm at most. Because of Al depletion from the MAX phase and corresponding Al enrichment of the alloy, the reaction zone displayed similarities to an oxidized Cr2AlC surface and an aluminized superalloy, respectively.