Ni–W diffusion barrier: Its influence on the oxidation behaviour of a β-(Ni,Pt)Al coated fourth generation nickel-base superalloy

Cyclic oxidation and diffusion barrier behaviors of oxides dispersed NiCoCrAlY coatings

“…Especially, for the advanced Ni-base single crystal superalloys containing high levels of refractory elements such as W, Mo, Re and Ru, inward diffusion of Al from the coating and outward diffusion of Ni from the superalloy could lead to the formation of secondary reaction zones (SRZ) and topologically close packed phase (TCP) in the superalloy. It has been shown that SRZ and TCP lead to a significant reduction in the hightemperature stress-rupture creep resistance of the single crystals [14][15][16].…”

“…Other proposed approaches involve diffusion barrier layers, such as TiN layer [20], Al-O-N thin-film layer [21,22], Cr-O-N thin-film layer [22], Re (W)-Cr-Ni layer [23,24] and Ni-W diffusion barrier [15]. Among various diffusion barrier candidates, ␣-Al 2 O 3 is a very effective diffusion barrier material to suppress the inter-diffusion between MCrAlY and superalloy [25,26].…”

Spontaneous reaction formation of Cr23C6 diffusion barrier layer between nanocrystalline MCrAlY coating and Ni-base superalloy at high temperature

“…Both metallic and ceramic diffusion barriers have been studied [16][17][18][19][20][21][22][23][24][25]. The Re-Cr(Mo)-Ni layer was stable and effectively retarded the interdiffusion between the Al reservoir layer and the alloy, and improved oxidation resistance of a Ni3Al-based superalloy IC6 and a single-crystal (SC) Ni-based superalloy TMS-82+ [16,17].…”

“…The Re-Cr(Mo)-Ni layer was stable and effectively retarded the interdiffusion between the Al reservoir layer and the alloy, and improved oxidation resistance of a Ni3Al-based superalloy IC6 and a single-crystal (SC) Ni-based superalloy TMS-82+ [16,17]. A Ni-W base diffusion barrier (DB) on a fourth generation Ni-base superalloy was found to be able to reduce the Al depletion in the β-(Ni,Pt)Al coating and to delay the phase transformations in the coating and the SRZ formation [18]. Cr-based interlayers have also been demonstrated to be capable of improving high temperature oxidation properties of MCrAlY coatings on Ni-base superalloy, which are primarily ascribed to the inhibition effect on the inward diffusion of Al [4,19].…”

Oxidation and diffusion barrier behaviors of double-layer NiCoCrAlY coatings produced by plasma activated EB-PVD

“…Several material systems, including high-melting metals (W, Ir, and Ru) [19][20][21], intermetallic phases [22] and ceramics (TiN, AlN, CrON, AlON, Cr 2 O 3 , and Al 2 O 3 ) [23][24][25][26], were proposed to inhibit inter-diffusion of elements between the substrate and coating. Although most of the barrier candidates mentioned above are characterized by low effective diffusion coefficient of metal ions through them, the application of an intermediate layer results in the following problems: no adequate metallurgical bonding between the substrate and coating; poor thermo-mechanical compatibility with the superalloy; regression due to diffusion and phase transformation; and complicated manufacturing process.…”