title: Direct observation of individual dislocation interaction processes with grain boundaries.
abstract: In deformation processes, the presence of grain boundaries has a crucial influence on dislocation behavior; these boundaries drastically change the mechanical properties of polycrystalline materials. It has been considered that grain boundaries act as effective barriers for dislocation glide, but the origin of this barrier-like behavior has been a matter of conjecture for many years. We directly observe how the motion of individual dislocations is impeded at well-defined high-angle and low-angle grain boundaries in SrTiO3, via in situ nanoindentation experiments inside a transmission electron microscope. Our in situ observations show that both the high-angle and low-angle grain boundaries impede dislocation glide across them and that the impediment of dislocation glide does not simply originate from the geometric effects; it arises as a result of the local structural stabilization effects at grain boundary cores as well, especially for low-angle grain boundaries. The present findings indicate that simultaneous consideration of both the geometric effects and the stabilization effects is necessary to quantitatively understand the dislocation impediment processes at grain boundaries.
authors.affiliation: Institute of Engineering Innovation, School of Engineering, The University of Tokyo, Bunkyo, Tokyo 113-8656, Japan.; Center for Elements Strategy Initiative for Structural Materials, Kyoto University, Kyoto 606-8501, Japan.
authors.forename: Shun
authors.initials: S
authors.lastname: Kondo
authors.affiliation: Institute of Engineering Innovation, School of Engineering, The University of Tokyo, Bunkyo, Tokyo 113-8656, Japan.
authors.forename: Tasuku
authors.initials: T
authors.lastname: Mitsuma
authors.affiliation: Institute of Engineering Innovation, School of Engineering, The University of Tokyo, Bunkyo, Tokyo 113-8656, Japan.; PRESTO (Precursory Research for Embryonic Science and Technology), Japan Science and Technology Agency, Kawaguchi, Saitama 332-0012, Japan.
authors.forename: Naoya
authors.initials: N
authors.lastname: Shibata
authors.affiliation: Institute of Engineering Innovation, School of Engineering, The University of Tokyo, Bunkyo, Tokyo 113-8656, Japan.; Center for Elements Strategy Initiative for Structural Materials, Kyoto University, Kyoto 606-8501, Japan.; Nanostructures Research Laboratory, Japan Fine Ceramics Center, Nagoya, Aichi 456-8587, Japan.; WPI Advanced Institute for Materials Research, Tohoku University, Sendai, Miyagi 980-8577, Japan.
authors.forename: Yuichi
authors.initials: Y
authors.lastname: Ikuhara
keywords: Materials science; dislocation; grain boundary; in situ transmission electron microscopy; mechanical property; plastic deformation