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The influence of nanostructuring by high pressure torsion (HPT) on strength and electrical conductivity in the Cu-Cr alloy has been investigated. Microstructure of HPT samples was studied by transmission electron microscopy with special attention on precipitation of small chromium particles after various treatments. Effect of dynamic precipitation leading to enhancement of strength and electrical conductivity was observed. It is shown that nanostructuring leads to combination of high ultimate tensile strength of 790-840MPa, enhanced electrical conductivity of 81%-85% IACS and thermal stability up to 500 °C. The contributions of grain refinement and precipitation to enhanced properties of nanostructured alloy are discussed. [ABSTRACT FROM AUTHOR]

Abstract: The synthesis of Cu100−x Ag x (0.05at.%< x <0.30at.%) nanoparticles using an evaporation–condensation process has been studied. Particular attention has been paid to the composition of the as-prepared powders. Compared to the master alloy, systematic enrichment in Ag of the particles is observed at the beginning of the synthesis but a continuous decrease in the Ag content of the powders is observed during the process. Even though, after de-agglomeration, the chemical composition of the powders is, in average, homogeneous. We have shown that optimized synthesis conditions give spherical particles with a mean diameter of 50nm and a reasonable yield rate. [Copyright &y& Elsevier]

Abstract: The present work investigates experimentally curling magnetic configurations locally observed in almost dispersed Permalloy nanoparticles in the remanent state. Magnetic analysis is performed in a field emission TEM using off-axis electron holography. Particularly, electron holography is used to characterize the magnetic microstructure of Fe30Ni70 nanoparticles, whose average diameter (50nm) is expected to be close to the critical size for a curling magnetic structure (vortex) formation. The vortex core diameter D core and the bulk magnetic profile of the vortex are measured and compared with a “rigid vortex” micromagnetic model. The connection between vortex structure and the characteristic micromagnetic length of the system deduced from magnetization curve measurements is discussed. [Copyright &y& Elsevier]