Oxidation Assisted Crack Growth of Ni-based Superalloys

摘要

Ni-based superalloys are used in some of the most demanding applications, such as gas turbines for military and commercial aircraft, and industrial power plants. At elevated temperature, these materials can suffer damage from surface oxidation, creep deformation, oxidation induced grain boundary embrittlement, and microstructural evolution. These four damage processes can operate in a synergistic fashion and cause catastrophic failure of Ni-based alloys. The interaction of oxidation and creep deformation is not fully understood. This paper reviews the oxidation-assisted damage mechanisms that operate in the presence of creep deformation in the crack tip region. The emphasis will be on quantitative descriptions of the kinetics of these various time-dependent mechanisms. The paper will attempt to link the various mechanisms and their kinetics with time-dependent crack tip stress fields and model time-dependent crack growth due to dwell time in these materials. Directions for future research in this area will also be explored.