Sliding of copper [001]-twist grain boundaries detected by shear deformation of liquid B2O3 particles on the grain boundaries

From a Cu–0.065mass%B solid solution alloy, bicrystals having [001]-twist grain boundaries with various misorientation angles were prepared by the Bridgman method. Cu bicrystals containing B₂O₃ particles were made from the bicrystals by internal oxidation treatment. The Cu–B₂O₃ bicrystals were tensile tested at high temperatures, where B₂O₃ particles become liquid. The amount of grain-boundary sliding was measured from the amount of shear deformation of the liquid B₂O₃ particles on a sliding grain boundary. Shear deformation of voids where the B₂O₃ particles was embedded was also utilized to measure the amount of grain-boundary sliding. The temperature and misorientation-angle dependence of the grain-boundary sliding is discussed for the Cu–B₂O₃ bicrystals. Since the liquid B₂O₃ particles easily deform at high temperatures, the measured amount of grain-boundary sliding is considered to reflect the inherent nature of the Cu [001]-twist grain boundaries. Using the present method of measurements, up to 2 μm grain-boundary sliding can be measured with an accuracy of about 0.1 μm.