Search

Changes in the physicochemical behavior of starch affect texture formation during the processing of Ginkgo seeds. Novel Ginkgo seed crisps come from explosion puffing drying combined with freeze drying (EPD-FD) or from freeze drying combined with explosion-puffing drying (FD-EPD). During EPD-FD, puffing power decreased due to higher tissue resistance, and tighter intercellular connections of starch due to the generation of a new diffraction peak during explosion puffing pre-drying (EPPD). The crystal structure of starch was destroyed during further FD, resulting in low porosity and quality. In the FD-EPD process, freeze pre-drying (FPD) prompted the generation of loose starch particles, crystal structure changes, and large pores and water migration channels. Further, EPD produces a more significant puffing force, which causes greater damage to starch granules and breaks the hydrogen bonds. It forms large pores and high porosity and brittleness, concomitant with a better texture structure. [ABSTRACT FROM AUTHOR]

Batch annealing technique is mainly used in industry for improving productivity as a few steel coils were stacked and heated in a bell‐type furnace. The microstructure evolution, texture formation and mechanical properties of 16 % chromium ferritic stainless steel under different simulated batch annealing and subsequent cold‐rolled annealing conditions were investigated in this work. Results showed that batch annealing process applied in mass production could not produce fully recrystallized and homogenously equiaxed grains even at very high temperatures up to 900 °C for 30 hours. With increased batch annealing temperature, a large number of chromium carbides precipitated in ferrite, while some unstable Fe‐carbide precipitates were gradually dissolved. Relatively lower cold‐rolled annealing temperature (830 °C) led to finer grains and superior mechanical properties of 16 % chromium ferritic stainless steel. Increased batch annealing temperature improved the intensity of {111}//normal direction γ‐fiber textures at the expense of other orientations including {hkl}<110> α‐fiber, {334}<48‾ 3>, thus improving the formability of ferritic stainless steel. [ABSTRACT FROM AUTHOR]

Abstract The existing macroscale models of the calcium (alumino)silicate hydrate (C-(A-)S-H), the main binder of concrete, assume that the nanocrystallites maintain random orientation under any loading conditions. However, using synchrotron-radiation-based XRD, we report the development of preferred orientation of nanocrystalline C-A-S-H, from random at ambient pressure to strongly oriented under uniaxial compression with lateral confinement. The c -axes of the nanocrystals tend to align with the primary load. This preferred orientation is preserved after removing of external loading. The texture, quantified using a standard Gaussian fiber orientation distribution function (ODF), was used to calculate the averaged bulk elastic tensor of oriented C-(A-)S-H. It changes from isotropic (without texture) to transversely isotropic (with texture). Our results provide direct evidence of the reorientation of nanocrystalline C-(A-)S-H as a mesoscale mechanism to the irreversible deformation of cement-based material. The implications of these results for modeling the mechanical property of C-(A-)S-H at the macroscale are discussed. [ABSTRACT FROM AUTHOR]

In this work, we determined the grain growth mode and texture formation process experimentally and theoretically in crystallization process of Ge2Sb2Te5 thin films, which were prepared by ion beam sputtering using Ge2Sb2Te5 alloy target. Experiment results demonstrated that crystalline grains had a trend of island growth during annealing, the texture components of cube {100}<001> and rotation cube {100}<011> are present in 250 °C annealed thin films, and {0001} basal texture component was produced in 400 °C annealed thin films. Theoretical analysis proved the mechanism and driving forces of grain growth and cubic texture formation: grains gathered in the basal surface as island because of large lattice mismatch, meanwhile, the preferred orientation of thin films was triggered by the minimization of lattice mismatch strain energy. The calculation results were in conformance with the experimental results. Researches about grain growth mode and texture formation of Ge2Sb2Te5 thin films may provide an advice to increase the crystallization rate of phase change material. [ABSTRACT FROM AUTHOR]

Calcium silicate hydrate (C–S–H) is the primary binding phase of cement-based and alkali-activated materials. The preferred orientation of C–S–H under non-hydrostatic pressure (e.g., uniaxial/biaxial load) is overlooked yet crucial in understanding concrete's multiscale mechanical performance. Here, we unveil the texture formation of C–S–H under compressive deviatoric stress, S, from 0 to ∼200 MPa, using high-pressure X-ray diffraction. Texture initiated at S < 12 MPa: the c -axis (normal to the basal plane) of C–S–H nanocrystallites preferentially re-oriented towards the direction of the principal compressive stress. Below S ∼100 MPa, the preferred orientation intensified through translation and rotation of C–S–H nanocrystallites; above ∼100 MPa, the texture stopped growing then weakened, suggesting internal transformations of C–S–H nanocrystallites. The time-dependence of the preferred orientation development is unveiled by the texture weakening after full unloading. The findings implicate that concrete creep under service loads is contributed by the intergranular preferential re-orientation of C–S–H nanocrystallites, not interlayer sliding or silicate chain breakage. [ABSTRACT FROM AUTHOR]