Arc ion plated-Cr2O3 intermediate film as a diffusion barrier between NiCrAlY and γ-TiAl

Microstructure evolution and formation mechanism of laser-ignited SHS joining between Cf/Al composites and TiAl alloys with Ni–Al–Ti interlayer

“…The content of each element does not show much difference. The similar layer was reported by Cheng et al [15] and confirmed to be cNi 0.35 Al 0.30 Ti 0.35 in Refs. [15][16][17].…”

“…3a) was taken on this reaction layer, which is consistent with the results in Refs. [15][16][17]. The light phase (Point B) is determined to be the Ni-rich NiAl owing to the high content of Ni.…”

Formation kinetics of multi-layered interfacial zone between γ-TiAl and glass–ceramic coatings via interfacial reactions at 1000°C

“…The occurrence of severe interdiffusion between the metallic coating and c-TiAl at elevated temperatures results in the formation of thick brittle intermetallic compound (AlCo 2 Ti or AlNi 2 Ti) layers and Kirkendall voids at the interface, which could greatly worsen the overall performance of the coating [23]. Therefore, a diffusion barrier is necessary while applying these types of coatings on c-TiAl [24]. As variations of MCrAlY, TiCrAl coatings were more chemically compatible with c-TiAl, which also showed good oxidation resistance at high temperatures up to 1100°C [5,25,26].…”

A magnetron sputtered microcrystalline β-NiAl coating for SC superalloys. Part I. Characterization and comparison of isothermal oxidation behavior at 1100°C with a NiCrAlY coating

“…The crack formation might be caused by CTE mismatch and initiate at the defects, which are difficult to be avoid in the film deposition. In our previous work, the effectiveness of an arc ion platedCr 2 O 3 intermediate film as a diffusion barrier between NiCrAlY and ␥-TiAl was evaluated by annealing at 1000 • C. The results showed that Cr 2 O 3 acted as an active diffusion barrier by formation of two continuous ␣-Al 2 O 3 layers at both the TiAl/Cr 2 O 3 and Cr 2 O 3 /NiCrAlY interfaces, suppressing the inward diffusion of Ni from NiCrAlY overlay coating to ␥-TiAl substrate effectively [49]. The active diffusion barrier may take advantage of low temperature arc ion plating at about 200 • C. In addition, the thermally grown alumina layers from the Cr 2 O 3 layer were separated by a metallic Cr layer, which may enhance the spallation resistance.…”