Abstract
An annealing process of cold rolled α Cu-3% Si alloys was directly observed by hardness tests, dilatation measurements, optical microscopy and transmission electron microscopy. The main results may be summarized as follows:
(1) By annealing a cold rolled specimen, the “anneal hardening” occurred at 200∼300°C, and softening due to recrystallization at 380°C. At the latter temperature an abnormal expansion was discovered.
(2) By transmission electron microscopy,
(i) a number of dislocation networks and parallel striations which were believed to take place due to stacking faults or twins were observed in a 60% rolled specimen.
(ii) In a specimen annealed at 200°∼300°C after cold rolling, complicated imperfections were observed, but the dislocations and the striations in the cold rolled specimen were not found, It is believed that the appearance of the complicated imperfections might be associated with the “anneal hardening” observed in hardness tests.
(iii) In a specimen annealed at 350°C, recrystallization grains with twins were observed.
