A significant contribution to the overall mechanical behaviour of microstructural materials is provided by the interaction of dislocation movement and grain boundaries. As a consequence, polycrystals are observed to respond with a higher strength for smaller grain sizes, a phenomenon which can not be modeled with classical single crystal plasticity theories. Gradient plasticity theories have be...

The resistance of high-angle grain boundaries to cleavage cracking in Fe–3wt.%Si bicrystals is discussed in context of linear elastic fracture mechanics based on an energy method. The grain boundary toughness is determined by the fracture work associated with the plastic shear along the grain boundary and the crack-trapping effect. The influence of the crystallographic misorientation and the si...

The study of microstructural evolution in polycrystalline materials has been active for many decades so it is interesting to illustrate the progress that has been made and to point out some remaining challenges. Grain boundaries are important because their long-range motion controls evolution in many cases. We have some understanding of the essential features of grain boundary properties over t...

Structural transformations at interfaces are of profound fundamental interest as complex examples of phase transitions in low-dimensional systems. Despite decades of extensive research, no compelling evidence exists for structural transformations in high-angle grain boundaries in elemental systems. Here we show that the critical impediment to observations of such phase transformations in atomis...

The effects of grain boundary character on the intergranular corrosion susceptibility of 2124 aluminum alloy were examined. In the study, the alloy was heat treated at 540oC and corrosion tested according to ASTM G110 standards. After obtaining grain orientations from the automated Electron Back-Scatter Diffraction (EBSD), both grain boundary character and grain boundary plane distributions wer...

Grain boundary segregation provides a method for stabilization of nanocrystalline metals – the selection of an alloying element that will segregate to the boundaries can lower the grain boundary energy, attenuating the driving force for grain growth. The segregation strength, relative to mixing enthalpy, of a binary system determines the propensity for segregation stabilization. This relationsh...

The optical properties of polycrystalline ZnO have been studied to elucidate the occurrence of random laser action. The spatially-resolved refractive index has been mapped out by using the scanning electron energy loss spectroscopy across the grain boundary. It is observed that the refractive index decreases gradually when the probe beam is approaching to the grain boundary. A thin reflective l...

THE following comments are directed to the sections (2) ‘‘revisit to the grain growth problems in alumina’’ and (3) grain growth without a liquid phase in the article of concern. The purpose of this comment is to challenge the authors’ assertions and refute the following arguments, namely, first that ‘‘MgO can be considered a very effective grain growth promoter in the sintering of alumina,’’ s...

Impurity doping often alters or improves the properties of materials. In alumina, grain boundaries play a key role in deformation mechanisms, particularly in the phenomenon of grain boundary sliding during creep at high temperatures. We elucidated the atomic-scale structure in alumina grain boundaries and its relationship to the suppression of creep upon doping with yttrium by using atomic reso...

The five parameter grain boundary character distribution quantifies the relative areas of different types of grain boundaries, distinguished by their lattice misorientation and grain boundary plane orientation. The viewpoint presented in this paper is that this distribution is a sensitive metric of polycrystalline structure that can be related to macroscopic properties. To demonstrate the influ...