メカニカルアロイングを応用したNbCおよびTaC分散強化銅の作製

抄録

To prepare a dispersion-strengthened copper, mechanical alloying was carried out using pure Cu, Nb, Ta and graphite powders. After the mechanical alloying for 144.0 ks, the Cu-Nb-C solid solution+NbC mixture powder and the Cu-Ta-C solid solution+Ta+TaC mixture powder were obtained in the Cu-Nb-C and Cu-Ta-C systems, respectively. These powders were heat-treated in a vacuum at various temperatures from 873 to 1323 K. In the Cu-Nb-C and Cu-Ta-C systems, Nb and C or Ta and C reacted, resulting in precipitation of very fine NbC and TaC particles in copper. In the Cu-Nb-Ta-C system, very fine (Nb, Ta) C particles were precipitated. The mean particle sizes of the NbC and TaC particles were about 3.0 nm by the heat-treatment at 873 K for 3.6 ks and 15.0-20.0 nm at 1273 K for 3.6 ks. The mean particle sizes of these carbide particles have a tendency to decrease with decreasing heat-treatment temperature. The hardnesses of NbC- and TaC-dispersion-strengthened coppers were very high; for example, the room temperature hardnesses of Cu-2.50 vol%NbC and Cu-10.0 vol%NbC alloys were Hv 280 and 350, respectively, after the mechanical alloying for 72.0 ks followed by the heat-treatment at 873-973 K for 3.6 ks.