The deformation and crack initiation mechanisms were analyzed in a textured AZ31B-O Mg alloy subjected to fully-reversed, strain-controlled cyclic along the rolling direction after 50 cycles (approximately 33% of fatigue life). Distinct bands corresponding pyramidal slip or tensile twins found 538 grains out 2100 grains. Slip trace analysis showed that 72.3% 18.4% twin boundaries. Both twinning...

The purpose of this paper is to describe the five-parameter grain boundary character distribution (GBCD) of polycrystalline silicon and compare it to distributions measured in metals and ceramics. The GBCD was determined from the stereological analysis of electron backscatter diffraction maps. The distribution of grain boundary disorientations is non-random and has peaks at 36", 39", 45", 51", ...

The plastic deformation behavior was investigated by using nanoindentation in a magneto-sputtered nanocrystalline (nc) Cu film with an average grain size of 14 nm. The determined critical shear stress to initiate plasticity in the nc-Cu sample (about 8.3 GPa) is identical to that for nucleation of lattice dislocations in an annealed coarse-grained Cu (8.5 GPa), and both values are close to the ...

Mesoscale models are used to study dynamic deformation and failure in silicon carbide (SiC) and aluminum oxynitride (AlON) polycrystals. Elastic and anisotropic elastic-plastic crystal models represent mechanical behavior of SiC and AlON and grains, respectively. Cohesive zone models represent intergranular fracture. Failure data that can be used to inform macroscopic continuum models of cerami...

ABSTRACT In this paper I summarize our recent investigations (Park and Kim, Phys Chem C 111:14903, 2007; Solid State Ionics 179:1329, 2008) on the origin of the grain-boundary resistance in a doped LaGaO3, a perovskite-structured solid electrolyte. The partial electronic and ionic resistances of the bulk and the grain boundaries, as well as the total resistance, in 1 mol% Sr-doped LaGaO3 were m...

Abstract As high-entropy alloys receive an increasing amount of attention, interesting scientific question arises: can grain boundaries be “high entropy”? In 2016, we proposed “high-entropy boundaries” as the boundary counterparts to materials. Here, discuss underlying interfacial thermodynamics elaborate relevant concepts. We emphasize that are neither equivalent in materials nor simply “compo...

We derive general relations between grain boundaries, rotational deformations, and stress-free states for the mesoscale continuum Nye dislocation density tensor. Dislocations generally are associated with long-range stress fields. We provide the general form for dislocation density fields whose stress fields vanish. We explain that a grain boundary a dislocation wall satisfying Frank’s formula ...

9 = 0.6 I / s ' 7 = 6.0 0 7 = 2 4 i ti 3 = 6 0 Through close control over green-state powder processing, pure alumina ceramics of 0.5-pm grain size were obtained by sintering at 1250°C. The static grain growth of this material was modest at temperatures below 1300°C. However, dynamic grain growth occurred rapidly during superplastic deformation. Therefore, although the ultrafine-grained alumina...

Olivine is the most important phase in the Earth’s upper mantle, where the bulk rock composition varies on average from lherzolitic to harzburgitic, where the olivine fractions are normally >60 %. Olivine is of major importance for Earth’s mantle dynamics and the presence of grain boundaries in olivine and their type might partially be responsible for attenuation phenomena as well as thermal an...