Sadatoshi Inada1 and Koichi Uesaki2
1Department of Mechanical Engineering, Faculty of Engineering, Tokushima University, Tokushima
The behaviors of precipitates along grain boundaries of vacuum melted copper compressed at elevated temperatures between 650° and 830°C were studied, using furnace-cooled specimens.
The results were as follows:
(1) The precipitates particles observed by electron microscope on the surface of the specimens without compression at elevated temperatures were dispersed over the surfaces independently of grain boundaries. The precipitates were so small that they were hardly observed by a hot stage microscope.
(2) When specimens were kept under low compressive stresses at elevated temperatures, precipitates were observed along grain boundaries not only on surfaces but also in the inner parts of specimens.
(3) It may be considered that the causes for the results mentioned in (1) and (2) are as follows: Solute atoms transferred in the opposite direction to the vacancy flow segregate on the surface or along grain boundaries which play a role as sources or sinks for vacancies.
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