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The present study demonstrate the effect of stacking fault energy (SFE) on the evolution of crystallite size, dislocation density, twin density, stacking faults, and their mutual interactions during cryorolling in pure copper (SFE 78 mJ/m 2 ) and copper–zinc alloys with varying Zn content of 10 wt% (SFE 35 mJ/m 2 ), 20 wt% (SFE 19 mJ/m 2 ), and 30 wt% (SFE 14 mJ/m 2 ). The dislocation density, twin density and extrinsic fault probability increase whereas crystallite size decreases upon cryorolling and with the decrease of SFE. Accumulation of dislocations at the twin boundaries causes dynamic recrystallization, promotes grain refinement by forming subgrains inside the twin lamellae. Detail investigation on the activity of structural defects during cryorolling of Cu/Cu-Zn alloys has been done through resistivity measurements. Nanoindentation studies have performed to understand the deformation kinetics of the cryorolled Cu/Cu-Zn alloys with high concentration of structural defects in term of strain rate sensitivity and activation volume. A micromechanical model has been used to demonstrate the effect of SFE and the role of structural defects during nanostructuring at cryogenic temperature. [ABSTRACT FROM AUTHOR]

Nanotwinned α-brass (Cu–30 wt.% Zn) with varying lamellae thickness in the range of 28–170 nm, has been produced by cryorolling (CR). The effect of CR strain ( ɛ CR = 0.2–0.95) on the evolution of homogeneity and refinement in terms of twin lamellae thickness, twin spacing, and their distribution, have been studied using high-resolution transmission electron microscopy (HRTEM) and microhardness measurements. Analysis of X-ray peak broadening has shown that the crystallite size reduces down to 20 nm at ɛ CR = 0.95, which scales with the subgrain size in preexisting twin lamellae, as revealed under HRTEM. The effect of dislocation density and crystallite size on the strength of nanotwinned brass has been correlated using an analytical model. [ABSTRACT FROM AUTHOR]

Abstract: Nano-sized porous γ-aluminas have been successfully synthesized by control precipitation method using aluminium nitrate as precursor and different precipitating agents. The synthesized materials have been characterized by SEM, FTIR, XRD and N2 adsorption–desorption. Sample prepared by ammonium bicarbonate route possess spherical nano-sized particle with crystallite size in the range 4.7–5.7nm, surface area 190m2/g and pore volume ∼0.467cm3/g. It also exhibits excellent fluoride adsorption capacity. [Copyright &y& Elsevier]