21 research outputs found
High temperature compressive deformation behavior of an extruded Mg-8Gd-3Y-0.5Zr (wt.%) alloy
No full textInternational audienceThe deformation behavior of an extruded Mg-8Gd-3Y-0.5Zr alloy has been characterized by compression tests in the temperature range of 400-490 degrees C and strain rate range of 10(-4) s(-1) to 10(-2) s(-1) with the objective to evaluate the superplastic deformation conditions as well as the rate-control ling mechanisms. The strain rate sensitivity index m decreases with increasing temperature in the strain rate range of 10(-4) s(-1) to 5 x 10(-4) s(-1), which was attributed to grain growth. Optimum superplasticity characterized by grain boundary sliding accommodated by dislocation creep was obtained at 400 degrees C and at 10(-4) s(-1). Dynamic precipitation leading to precipitates distributed mainly in the grain boundaries was responsible for the stable microstructure and the increase of the stress during deformation under this condition. Moreover, at strain rate higher than 5 x 10(-4) s(-1), it remained relatively constant of about m approximate to 0.3 and the activation energy Q was found to be equal to 131 kJ/mol which was close to the activation energy for lattice diffusion of Mg
Atomic force microscopy of photochemistry and the Baeyer–Villiger reaction of 4,4′-dimethylbenzophenone in the solid state
No full textOrdered thin films of alkyloxy-substituted benzaldehydes on a graphite surface studied by scanning tunneling microscopy
No full textMineralizing types, geological characteristics and geodynamic background of Triassic molybdenum deposits in the northern and southern margins of North China Craton
No full textTriassic magmatism and Mo mineralization in Northeast China: geochronological and isotopic constraints from the Laojiagou porphyry Mo deposit
No full textNature and significance of the late Mesozoic granitoids in the southern Great Xing’an range, eastern Central Asian Orogenic Belt
No full textEffects of dietary protein levels and protease supplementation on growth performance, carcass traits, meat quality, and standardized ileal digestibility of amino acid in Pekin ducks fed a complex diet
No full textTectonic Uplift of the Yili Basin during the Last Stage of the Late Pleistocene: Evidence from ESR and OSL Dating of Sediments in the Huocheng Area, Xinjiang
No full textEffect of qi-tonifying and stasis-eliminating therapy (益气活血法) on expression of vascular endothelial growth factor and its receptors Flt-1, Flk-1 in the brain of intracerebral hemorrhagic rats
No full textMicroscale elastic strain evolution following damage in Ti-SiC composites
No full textFiber fractures are crucial in initiating damage zones that ultimately determine the strength and lifetime of fiber-reinforced metal matrix composites. The evolution of damage in a metal matrix composite (MMC) comprised of a row of unidirectional SiC fibers (32 vol pct) surrounded by a Ti matrix was examined, for the first time, using X-ray microdiffraction. Multiple strain maps including both phases were collected in situ under applied tensile stress. The elastic axial strains were then compared to predictions from a modified shear-lag model, which, unlike other shear-lag models, considers the elastic response of both constituents. The strains showed good correlation with the model. The results confirmed, for the first time, both the need and validity of this new model specifically developed for large scale multifracture simulations of MMCs. The results also provided unprecedented insight for the model, revealing the necessity of incorporating such factors as plasticity of the matrix, residual stress in the composite, and selection of the load sharing parameter
