Powder metallurgy on its way to nanocrystalline structures

A survey is given on some methods for the preparation of metallic and ceramic dense nanocrystalline materials with average grain sizes between 5 and 10O nm The use of nano-dispersed, i.e. highly sinter-active starting powders allows the realization of extremely high grain-/phase-boundary area that determine the unusual properties of the resultant P/M parts and materials. The various suitable P/M methods for the production of pure as well as composite nc- materials include the sol-gel process, mechanical alloying and the inert gas condensation method. Some of the fascinating potentials of P/M fabricated nc-materials due to their magnetic electronic and mechanical behaviour are elucidated