Adhesion of the γ-Ni(Al)/α-Al2O3 interface: a first-principles assessment

Abstract We assess density functional theory studies of the effects of interfacial stoichiometry, Al activity, S segregation and Hf doping on the adhesion of the γ-Ni(Al)/α-Al2O3 interface. Computations of the Al activity in γ-Ni(Al) and of the interfacial phase diagram between 1300 and 1600 K suggest that the interface phase is Al-rich, but close to the boundary with the stoichiometric phase. We reveal that the Al-rich phase has significantly stronger adhesion than the stoichiometric phase and that S substantially decreases the adhesion of both. We demonstrate that doping with Hf yields a substantial improvement in adhesion, manifest in three ways: (i) It can pin S in bulk γ-Ni(Al), even up to 1600 K. (ii) It segregates and, once there, can strengthen the relatively weak stoichiometric interface (attaining a work of separation comparable to that for the strong Al-rich interface). (iii) It has the potential to displace S from interstitial interface sites.

[1]  E. Carter,et al.  Effects of segregating elements on the adhesive strength and structure of the α-Al2O3/β-NiAl interface , 2007 .

[2]  B. Gleeson,et al.  Surface segregation of Pt in γ′-Ni3Al: A first-principles study , 2007 .

[3]  C. Elsasser,et al.  Ab initio study of electronic densities of states at copper-alumina interfaces , 2007 .

[4]  M. Li,et al.  Improved Cr2O3 adhesion by Ce ion implantation in the presence of interfacial sulfur segregation , 2007 .

[5]  Temperature dependence of the activity of Al in dilute Ni(Al) solid solutions , 2006 .

[6]  Brian Gleeson,et al.  Thermal Barrier Coatings for Aeroengine Applications , 2006 .

[7]  C. Elsässer,et al.  Structure at abrupt copper–alumina interfaces: An ab initio study , 2005 .

[8]  D. Morse,et al.  HEAVY METAL–INDUCED OXIDATIVE STRESS IN ALGAE 1 , 2003 .

[9]  I. Wright,et al.  Influence of Sulfur, Platinum, and Hafnium on the Oxidation Behavior of CVD NiAl Bond Coatings , 2002 .

[10]  Joshua R. Smith,et al.  The connection between ab initio calculations and interface adhesion measurements on metal/oxide systems: Ni/Al2O3 and Cu/Al2O3 , 2002 .

[11]  E. Carter,et al.  Weak bonding of alumina coatings on Ni(1 1 1) , 2001 .

[12]  Anthony G. Evans,et al.  Mechanisms controlling the durability of thermal barrier coatings , 2001 .

[13]  Joshua R. Smith,et al.  Stoichiometric interfaces of Al and Ag with Al2O3 , 2000 .

[14]  J R Smith,et al.  Nonstoichiometric interfaces and Al2O3 adhesion with Al and Ag. , 2000, Physical review letters.

[15]  A. Evans,et al.  On the Role of Imperfections in The Failure of a Thermal Barrier Coating Made by Electron Beam Deposition , 2000 .

[16]  J. Smialek.  Maintaining adhesion of protective Al2O3 scales , 2000 .

[17]  R. Raj,et al.  Growth and structure of copper thin films deposited on (0001) sapphire by molecular beam epitaxy , 1995 .

[18]  J. Smialek,et al.  The effects of reactive element additions and sulfur removal on the adherence of alumina to Ni‐ and Fe‐base alloys , 1995 .

[19]  Wetting and adhesion of Ni-Al alloys on α-Al2O3 single crystals , 1995, Journal of Materials Science.

[20]  Joachim Mayer,et al.  The niobium/sapphire interface: Structural studies by HREM , 1994 .

[21]  P. Hou,et al.  The role of reactive elements in oxide scale adhesion , 1994 .

[22]  Smith,et al.  Impurity effects on adhesion: Nb, C, O, B, and S at a Mo/MoSi2 interface. , 1993, Physical review. B, Condensed matter.

[23]  Wang,et al.  Accurate and simple analytic representation of the electron-gas correlation energy. , 1992, Physical review. B, Condensed matter.

[24]  D. Vanderbilt,et al.  Soft self-consistent pseudopotentials in a generalized eigenvalue formalism. , 1990, Physical review. B, Condensed matter.

[25]  H. Nickel,et al.  Thermodynamic Study of the Liquid and Solid Alloys of the Nickel-Rich Part of the Al — Ni Phase Diagram Including the AlNi3 Phase , 1990 .

[26]  W. Quadakkers,et al.  Addition of yttrium, cerium and hafnium to combat the deleterious effect of sulphur impurity during oxidation of an NiCrAl alloy , 1989 .

[27]  J. Smialek.  Adherent Al2O3 scales formed on undoped nicrai alloys , 1987 .

[28]  J. Smeggil,et al.  A relationship between indigenous impurity elements and protective oxide scale adherence characteristics , 1986 .

[29]  N. S. Bornstein,et al.  Reactive element-sulfur interaction and oxide scale adherence , 1985 .

[30]  H. Monkhorst,et al.  SPECIAL POINTS FOR BRILLOUIN-ZONE INTEGRATIONS , 1976 .