نتایج جستجو برای: nanoultrafine grain structure
تعداد نتایج: 1622609 فیلتر نتایج به سال:
Nanocrystalline metals with average grain sizes of only a few nanometers have recently been observed to fail through the formation of shear bands. Here, we investigate this phenomenon in nanocrystalline Ni which has had its grain structure stabilized by doping with W, with a specific focus on understanding how strain localization drives evolution of the nanoscale grain structure. Shear banding ...
In this study, nano-hydroxyapatite scaffolds with high mechanical strength and an interconnected porous structure were prepared using NTSS for the first time. The first step was performed using a laser characterized by the rapid heating to skip the surface diffusion and to obtain the driving force for grain boundary diffusion. Additionally, the interconnected porous structure was achieved by SL...
The prevalence of colloid deposition at grain-to-grain contacts in two porous media (spherical glass beads and angular quartz sand, 710-850 microm) was examined using X-ray microtomography (XMT) under conditions where the colloid-grain surface interaction was solely attractive (lacking an energy barrier to deposition), and under fluid velocity conditions representative of engineered filtration ...
The mechanisms of texture development were examined for BaTiO₃ and a (K,Na,Li)(Nb,Ta)O₃ solid solution made by the templated grain growth method, and compared with the mechanism in Bi0.5(Na,K)0.5TiO₃. The dominant mechanism was different in each material; grain boundary migration in BaTiO₃, solid state spreading in Bi0.5(Na,K)0.5TiO₃, and abnormal grain growth in the (K,Na,Li)(Nb,Ta)O₃ solid so...
An experimental program is described in which the bending and longitudinal dynamics of structures simulating solid-propellant rocket motors are being studied. The structure is considered to be a cylindrical grain of solid propellant to which is bonded a thin steel case. Vibrations of the empty steel cylinder suspended in a free-free condition are studied first. Secondly, a similar steel cylinde...
In this research, samples of AlMg0.7Si aluminum alloy are deformed up to three passes using equal channel angular pressing (ECAP). Formation of a sub-micron structure after three passes of ECAP is demonstrated. Microstructural stability of the samples is investigated at temperatures of 300-500 °C. At 300 °C, fine recrystallized structure forms after 10 min which remains stable when the ...
We present the results of in-situ studies of evolution of grain boundary misorientations in ultrafine grained (UFG) aluminum alloy Al-4 Cu-0.5 Zr (wt%) during annealing. The structure of the UFG alloy was obtained by severe plastic deformation method. Misorientations between the grains were measured using single reflection technique. It was found that relaxation processes during annealing are a...
Phonological sensitivity at different grain sizes is a good predictor of reading acquisition in all languages. However, prior to any explicit tuition in alphabetic knowledge, phonological sensitivity develops at the larger grain sizes—syllables, onsets, and rimes—in all languages so far studied. There are also developmental differences in the grain size of lexical representations and reading st...
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