Systematic experiments have been performed to investigate the rate sensitivity of deformation in fully dense nanocrystalline Ni using two different experimental techniques: depth-sensing indentation and tensile testing. Results from both types of tests reveal that the strain-rate sensitivity is a strong function of grain size. Specifically microcrystalline and ultra-fine crystalline pure Ni, wi...

Microcompression testing is used to probe the uniaxial stress–strain response of a nanocrystalline alloy, with an emphasis on exploring how grain size and grain boundary relaxation state impact the complete flow curve and failure behavior. The yield strength, strain hardening, strain-to-failure and failure mode of nanocrystalline Ni–W films with mean grain sizes of 5, 15 and 90 nm are studied u...

Biochar may improve soil hydrology by altering soil porosity, density, hydraulic conductivity, and water-holding capacity. These properties are associated with the grain size distributions of both soil and biochar, and therefore may change as biochar weathers. Here we report how freeze-thaw (F-T) cycling impacts the grain size of pine, mesquite, miscanthus, and sewage waste biochars under two d...

Size effects on Volume thermal expansion of nanomaterials. The experimental measurements show that volume thermal expansion of nanosolids is larger than those of their bulk counterparts. On considering the surface effect, a simple model is derived to study the size dependence of volume thermal expansion of nanomaterials for spherical nanoparticles, nanowire and nanofilms. The size dependence of...

Recent observations with dust detectors on board the interplanetary spacecraft Ulysses and Galileo have recorded a substantial flux of large interstellar grains with radii between 0.25 and 2.0 μm entering the solar system from the local interstellar cloud. The most commonly used interstellar grain size distribution is characterized by a a power law in grain radii a, and extends to a maximum gra...

In the short crack regime of the fatigue process, grain boundaries in steels are barriers against crack growth. In this paper, we use: (1) a method involving crack density; and (2) a method of dimensional analysis, to evaluate the effects of grain size and grain-boundary resistance on short crack behaviour and fatigue life. The results show that the fatigue life increases with a decrease in gra...