Competition between grain growth and grain size reduction in polar ice

Autor: Rößiger, J., Bons, P. D., Griera, A., Jessell, M. W., Evans, L., Montagnat, M., Kipfstuhl, Sepp, Faria, S. H., Weikusat, Ilka
Rok vydání: 2011
Zdroj: EPIC3Journal of Glaciology, INT GLACIOL SOC, 57(205), pp. 942-948, ISSN: 0022-1430
Popis: Static (or ‘normal’) grain growth, i.e. grain boundary migration driven solely by grain boundary energy, is considered to be an important process in polar ice. Many ice-core studies report a continual increase in average grain size with depth in the upper hundreds of metres of ice sheets, while at deeper levels grain size appears to reach a steady state as a consequence of a balance between grain growth and grain-size reduction by dynamic recrystallization. The growth factor k in the normal grain growth law is important for any process where grain growth plays a role, and it is normally assumed to be a temperature-dependent material property. Here we show, using numerical simulations with the program Elle, that the factor k also incorporates the effect of the microstructure on grain growth. For example, a change in grain-size distribution from normal to log-normal in a thin section is found to correspond to an increase in k by a factor of 3.5.
Databáze: OpenAIRE