Dauphiné twinning and texture memory in polycrystalline quartz

Abstract Mechanical twinning in polycrystalline quartz was investigated in situ with time-of-flight neutron diffraction and a strain diffractometer. Dauphiné twinning is highly temperature sensitive. It initiates at a macroscopic differential stress of 50–100 MPa and, at 500°C, saturates at 400 MPa....
Ausführliche Beschreibung

Abstract Mechanical twinning in polycrystalline quartz was investigated in situ with time-of-flight neutron diffraction and a strain diffractometer. Dauphiné twinning is highly temperature sensitive. It initiates at a macroscopic differential stress of 50–100 MPa and, at 500°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. Ausführliche Beschreibung