TY - CONF A1 - Vöse, Markus A1 - Fedelich, Bernard ED - Maruyama, K. ED - Abe, F. ED - Igarashi, M. ED - Kishida, K. ED - Suzuki, M. ED - Yoshimi, K. T1 - Grain boundary cavitation under time-varying normal stresses N2 - In a polycrystal, the development of creep damage, especially for low extemal loads, is related to nucleation and difiüsive growth of cavities on the grain boundaries. For low stresses, the contribution to cavity growth by dislocation creep of the suirounding material can be neglected. However, grain boundaiy diffitsion is mainly driven by the local normal stiess acting on the grain boundaiy. Under creep conditions, even under a constant extemal load, an individual grain boundaiy generally experiences a time-varying normal stress, due to stress redistributions within the polycrystalline stiuctuie. Indeed, a constrained cavitating grain boundaiy is relieved, since matter is transported to and deposited in the grain boundaiy plane, which causes the adjoining giains to drill apart. A Simulation proceduie based on the use of complex holomoiphic fiinctions for solving the diffiision problem has been used to investigate multiple cavity growth on a grain boundaiy subjected to a constant normal stress. A simplified model has been developed to describe the cavitation behaviour observed in the simulations. Finally, the analysis of cavitation simulations with time-vaiying nomial stresses, including the cases with veiy low or negative stresses, has been used to extend the simplified cavitation model to more general normal stiess time profiles. T2 - 12th International Conference on Creep and Fracture of Engineering Materials and Structures CY - Kyoto, Japan DA - 27.05.2012 KW - Creep damage KW - Grain boundary diffusion KW - Cavitation KW - Simulation KW - Evolution equations PY - 2012 SP - 1 EP - 4 AN - OPUS4-27544 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Vöse, Markus A1 - Fedelich, Bernard A1 - Owen, J. T1 - A simplified model for creep induced grain boundary cavitation validated by multiple cavity growth simulations N2 - Simulations of cavitation processes on a grain boundary under creep conditions have been carried out, taking into account nucleation, growth, coalescence and sintering of multiple cavities. Cavity growth rates have been calculated through a resolution procedure based on the use of holomorphic complex functions. Three dimensionless parameters have been identified that are responsible for the cavitation development. Parameter studies have been carried out in order to characterise the mechanisms that are responsible for the cavitation development. These studies have been used to develop a physically motivated, simplified model in order to describe the cavitation development of the simulations in terms of global state variables. The simplified model is able to reproduce the cavitation development for all considered combinations of the dimensionless parameters and allows the description of the thickening behaviour of a cavitating grain boundary. KW - Creep damage KW - Grain boundary diffusion KW - Cavitation KW - Simulation PY - 2012 DO - https://doi.org/10.1016/j.commatsci.2012.01.033 SN - 0927-0256 VL - 58 SP - 201 EP - 213 PB - Elsevier CY - Amsterdam AN - OPUS4-25630 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER -