Abstract
In general high-pressure experiments, solid pressure medium causes complicated stress condition. Examining cylindrical samples by the deformation-DIA (D-DIA) module, which simplifies stress condition, we have tried to address such non-hydrostaticity issue. Our results reveal that lattice strain, from which physical quantities such as “pressure” or “volume” are calculated, may vary depending on the amount of deformation, referred to as total axial strain, even at a steady pressure and temperature condition. Understanding the relation between lattice strain and total axial strain is therefore of fundamental importance for precise in situ strain measurements. High-pressure studies have not monitored total axial strain so far, but the total strain could be the reason why strain measurements have varied from one study to another. In addition to precise strain measurement, total axial strain also controls plastic deformation. Plastic deformation develops texture, which is observed as an intensity variation in the diffraction Debye ring; thus we can now observe texture development as a function of total strain. Flow mechanism during plastic deformation can be inferred from the texture development. Controlling and monitoring total axial strain is not only essential for precise strain measurement of conventional high-pressure study, but crucial for discussion in plastic property in the next decade of in situ observation.
