Synthesis and Processing of Metallic Nano-powders For the Study of their Mechanical and Magnetic Properties

摘要

An original technique called cryogenic evaporation-condensation, has been developed to produce metallic nano-powders. The process is based on the evaporation and the cryo-condensation of a vapour produced by overheating a levitated metal droplet placed within the stream of a cryogenic liquid. The vapour condenses leading to a continuous formation of nanoparticles. Metals with moderate vapour tension (0.1 torr at about 2000 K), give nanopowders with average grain size of 50 nm at production rates from 0.1 g.mn~(-1) to 2 g.mn~(-1). Details on the process are reported with special emphasis on the synthesis and the characterisation using transmission electron microscopy (TEM, including energy filtering) of copper and Fe_(x)-N_(1-x)) nanopowders. Properties of nanopowders are illustrated by the mechanical behaviour of nanostructured copper and the magnetic behaviour of Fe_(x)-Ni_(1-x) with 0.1