抄録
The annealing characteristics of the pure coppers and the dispersion strengthend copper alloy were compared. The dispersion alloys were prepared by ballmill-mixing electrolytic copper powder (-325 mesh) with thoria, alumina or tungsten powder up to 3.0 volume percent, followed by compacting, sintering, hot extruding and cold drawing. The three kinds of pure coppers were used for comparison to the dispersion strengthened alloys-1st produced from vacuum melted cathode copper, 2nd from sintered copper powder and 3rd from vacuum melted copper powder. The specimens cold to drawn 1.6mm in diameter were annealed at temperature up to 1050°C for 2hr in vacuum.
The properties of annealed pure coppers were affected by the impurity concentration. The purity of electrolytic copper powder was worse than that of cathode copper. On annealing at temperature above the recrystallization temperature, the grain size of pure copper produced from cathode copper became larger with an increase in annealing temperature and the mechanical properties were lower. In the case of copper specimens produced from copper powder, the marked change of the grain size and of the mechanical properties did not occur until the annealing temperature reached at the 2nd recrystallization temperature, which was about 800°C. When these specimens were annealed at temperature above 800°C, the very coarse grains appeared and the mechanical properties were much poorer and the electric resistance was higher than as drawn.
However, in the case of the dispersion strengthened alloys containing a dispersed phase of 3.0 volume percent, it was shown that even though annealed at 1050°C the marked grain growth of matrix did not occur, and the mechanical properties and the electric resistance also showed the same value as that annealed at 600°C. Among the three dispersion strengthened alloys, the alloy containing thoria had the most excellent mechanical properties and high temperature stability.
