Abstract
The deformation and annealing behaviors of copper composites containing various volume fractions of molybdenum were studied by means of internal friction measurements.
The results obtained are as follows:
(1) Strain amplitude-independent internal friction of copper composites containing molybdenum more than the critical volume fraction decreased sharply by a low reduction by cold rolling. This may be attributed to the locking of free vibratile dislocations, which were produced by the difference in thermal expansion coefficient between copper and molybdenum, by cold rolling.
(2) Strain amplitude-independent internal friction of pure copper and copper composites containing molybdenum less than the critical volume fraction increased with increasing reduction by cold rolling; after attaining a peak around 5% reduction by cold rolling, the value decreased and then increased rapidly.
(3) Strain amplitude-independent internal friction of the cold rolled pure copper decreased by annealing up to about 100°C (recovery), and at 100° to 150°C (recrystallization) in two steps. Strain amplitude-independent internal friction of the composites decreased by annealing corresponding to the recovery and recrystallization of the copper matrix, but the value increased by annealing above about 200°C.
