材料期刊网

Bulk nanocrystalline copper samples weighted 5 gram with average grain size d=25nm were synthesized by inert gas condensation and in situ compacting method. The microhardness study is carried out in this paper considering two influence factors of density and grain size. The specimens with different densities and grain sizes were obtained through compacting the as-evaporated particles under pressures from P=0.5 to 2.5 GPa at room temperature and annealing the specimen as-compacted under 1 GPa at temperature fi om T=373K to 773K respectively. The results show that the nanocrystalline copper specimens exhibit higher microhardness than conventional coarse-grained copper, and the microhardness rises with the increase of compacting pressure and reaches a maximum value under P=2.5 GPa, which is six times as high as that of conventional copper. The specimen density also plays an important role on the microhardness of bulk nanocrystalline copper except for the grain size. (C) 1997 Acta Metallurgica Inc.