Powder metallurgy on its way to nanocrystalline structures

Abstract

Metallic and ceramic dense nanocrystalline (nc–)materials with average grain sizes of about 5 to 100 nm may be produced by means of powder technology at relatively low temperatures. This is achieved by using nano–dispersed, i.e. highly sinter–active starting powders. It is the extremely high grain–/phase–boundary area that determines the unusual properties of the resultant PM–components. The various suitable PM–methods for the production of pure as well as composite nc–materials are shortly reviewed including the sol–gel–process, mechanical alloying and the inert gas evaporation method. Some of the fascinating potentials of PM–fabricated nc–materials due to their peculiar magnetic, electronic and mechanical behaviour are elucidated.