Microhardness of nanocrystalline palladium and copper produced by inert-gas condensation

Abstract

This report describes the major results of a Vickers microhardness study of nanocrystalline palladium and copper produced by the inert-gas condensation method. Small grain size is known to have a strong influence on mechanical properties at low and intermediate temperatures, as observed in the Hall--Petch effect, Coble creep, and superplasticity. Until recently, the mechanical properties of nanocrystalline materials with mean grain diameters of 5 to 50 nm have not been explored. A microhardness study on conventional compacted tungsten powder indicated that the Hall--Petch effect extends to the 150 nm range; and effects of nanocrystalline grain size on mechanical properties of TiO{sub 2} have been investigated.