Nanocrystalline materials show a higher strain-rate sensitivity in contrast to the conventional coarse-grained materials and a different grain size dependency. To explain these phenomenon, a finite element model is constructed that considers both grain interior and grain boundary deformation of nanocrystalline materials. The model consist of several crystalline cores with different orientations...

Initial powder mixtures of Cu, Fe and Co are exposed to severe plastic deformation by high-pressure torsion prepare solid solutions. A broad range compositions is investigated, whereas this study aims at the synthesis soft magnetic materials therefore formation a homogeneous nanocrystalline microstructure. For intermediate ferromagnetic contents, room temperature yields single-phase supersatura...

– The mesoscopic elastic response of cluster-assembled carbon films was measured by Brillouin light scattering. The values of bulk modulus and shear modulus were estimated from the shifts of both surface and bulk phonon peaks. The most basic mechanical properties of these new materials were so investigated down to the scale of a few hundreds of nanometers. The shear modulus is found in the rang...

A lower limit for the grain size of nanocrystalline solids obtained by crystallization of the glass and its dependency on the crystallization temperature are thermodynamically considered. It is found that the nanocrystalline materials have the smallest grain size when the crystallization temperature is roughly half of the melting temperature. At this temperature, the Gibbs free energy differenc...

nanocrystalline ceria has been considered as support for carbon monoxide preferentially oxidation. in this study ceria was prepared by precipitation method and the effects of preparation conditions, such as ph of solution (8-10), aging time (1-12 hr), drying temperature (80-120 °c), calcination time (2-6 hr) and temperature (400-600 °c) were investigated on ceria synthesized powders properties....

Calcium silicate hydrate (CSH) is the major volume phase in the matrix of Portland cement concrete. Total x-ray scattering measurements with synchrotron x rays on synthetic CSH(I) shows nanocrystalline ordering with a particle diameter of 3.5(5) nm, similar to a size-broadened 1.1 nm tobermorite crystal structure. The CSH component in hydrated tricalcium silicate is found to be similar to CSH(I...

A new physical mechanism or mode of plastic deformation in nanocrystalline metals and ceramics is suggested and theoretically described. The mode represents the cooperative grain boundary (GB) sliding and stress-driven GB migration process. It is theoretically revealed that the new deformation mode is more energetically favorable than "pure" GB sliding and enhances the ductility of nanocrystall...

This paper describes a new strategy to generate nanocrystalline drugs through the precipitation of drug molecules in attoliter nanowells. We controlled the size of arsenic trioxide (ATO) nanocrystals by simply changing the concentration of ATO solution in the nanowells; particles with sizes ranging from 55 to 175 nm were formed. This approach only requires the drugs to be soluble in a solvent a...

AB -type intermetallic compounds were prepared by the melt spinning method. Structure analysis was carried out by X-ray 5 diffractometry, SEM and high resolution electron microscopy. The hydrogen storage capacity was determined by isothermic mass controlled absorption of hydrogen and by electrochemical charge /discharge cycles. A variation of the preparation parameters showed that a nanocrystal...