Keynote: Oxygen Diffusion and Its Coupling with Crystal Plasticity in a Nickel-Based Superalloy

摘要: Nickel-based superalloys, consisting of g-matrix phase and superior g¢-precipitate phase, are strategically important class high temperature corrosion-resistant materials, which widely used in power generation, nuclear aerospace industries. The usage nickel superalloys is irreplaceable critical gas turbine systems (e.g. aero-engines). As a structural material that usually exposed to static or cyclic loads aggressive environments (up 1000°C), it understand the resistance crack initiation propagation improve service-lifing accuracy components provide guidance future alloy development. At temperature, fatigue growth such alloys air can be drastically accelerated by two three orders (10 2 ~10 3 ) magnitude due oxidation damage, one major concerns for integrity turbines. Oxidation-accelerated failure process closely linked with diffusion oxygen along rapid paths, as slip planes grain boundaries, into local area increasing tensile stress, tips. oxygen, through chemical reactions elements, embrittles surrounding metal prompts propagation. In literature, tip was generally modelled using simplified approach, considered only influence hydrostatic stress (i.e., trace Cauchy stress) neglected full interaction between mechanical deformation diffusion. this paper, efforts were made model coupling single crystal base superalloy. approach has been numerically incorporated plasticity model, not previously reported yet. Using method, finite element analyses diffusion, coupled plastic deformation, have carried out predict penetration at associated change near-tip field. This also includes prediction under fatigue-oxidation conditions, comparison experimental data. Keywords: Crystal plasticity; Oxygen diffusion; Full coupling; Finite element; Crack tip; Acknowledgements: work funded EPSRC (Grants EP/K026844/1) UK collaboration NASA, Alstom, E.On dstl. research leading these results received funding from European Union Seventh Framework Programme (FP7/2007-2013) grant agreement No. PIRSES-GA-2013-610547 TAMER.