Statistical analysis of twin/grain boundary interactions in pure rhenium

Using electron backscatter diffraction, over 1,000 grain boundary/twin interactions were investigated in pure Re after uniaxial compression. Crystallographic factors such as grain boundary disorientation angle and twin plane and shear vector alignment were taken into account as well as the Schmid factor. It was found that the crystallographic relationship between coincident twin pairs at grain boundaries fall into two categories. In the first category, the twin pairs satisfied two criteria: the twin plane alignment was maximized across the boundary and the twin variant was kept constant across the boundary. In the second category, twin variant selection appeared to be driven by the macroscopically applied stress state, as resolved locally by the Schmid factor. In comparison to published results on twin/grain boundary interactions in Mg and Zr, it was found that twins transmit across grain boundaries in Re far more readily,regardless of the grain boundary disorientation angle. This is likely to be a function of the anomalously low twin boundary energy in Re as well as the difference in magnitude of the twinning shear vector and the associated local stress field in the different materials systems, with the {112‾1} system being dominant in Re and the {101‾2} being dominant in Mg and Zr.