| Popis: |
In this study, we aimed to (i) answer the question if water affects the strength of marble deforming at high temperature and (ii) establish criteria that allow assessment of the role of water in microstructure development in marble. Samples of Carrara marble were axially compressed at temperatures ranging 600–1000 8C and strain rate w10 K5 s K1 , with or without addition of 0.4–2.1 wt% water. Water-added samples were found to be slightly weaker than dry samples. Microstructurally, all samples showed grain flattening and twinning at 600 8C and dynamic recrystallization dominated by grain boundary migration at higher temperature. Grain boundaries in wet samples showed isolated or semi-continuous remnants of fluid pockets. The average grain roundness R and fractal dimension D relating grain diameter d and grain perimeter P (Pfd D ) for wet recrystallized samples were systematically lower than for dry samples. At 600 8C, high pore fluid pressure probably enhanced dilatation of wet samples and helped grain boundary sliding (GBS), thereby lowering the strength. At higher temperature, fluid-enhanced grain boundary migration served as a recovery process, reducing the contribution of GBS to creep. Overall, water has little effect on strength and microstructure of marble experimentally deformed at high temperature. q 2005 Elsevier Ltd. All rights reserved. |
Full Text from ScienceDirect