Dauphin茅 twinning and texture memory in polycrystalline quartz
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- 作者：H.-R. Wenk ; M. Bortolotti ; N. Barton ; E. Oliver and D. Brown
- 关键词：Quartz ; Mechanical twinning ; In situ neutron diffraction ; FEM
- 刊名：Physics and Chemistry of Minerals
- 出版时间：November, 2007
- 出版年：2007
- 期刊代码：117_0342-1791
- 类别：ear
- 卷：34
- 期：9
- 页码：599-607
- 数据来源：sp
摘要
Mechanical twinning in polycrystalline quartz was investigated in situ with time-of-flight neutron diffraction and a strain diffractometer. Dauphin茅 twinning is highly temperature sensitive. It initiates at a macroscopic differential stress of 50–100 MPa and, at 500掳C, saturates at 400 MPa. From normalized diffraction intensities the patterns of preferred orientation (or texture) can be inferred. They indicate a partial reversal of twinning during unloading. The remaining twins impose residual stresses corresponding to elastic strains of 300–400 microstrain. Progressive twinning on loading and reversal during unloading, as well as the temperature dependence, can be reproduced with finite element model simulations.