COPRECIPITATION OF VACANCIES AND CARBON-ATOMS IN QUENCHED PLATINUM

The geometry of secondary defect structures observed in quenched platinum containing various amounts of carbon is shown to be consistent with a simple model based on the premise of a strong impurity (carbon) atom/vacancy binding energy. When the ratio of carbon atoms to vacancies (Cc/Cv) is large, co-precipitation as platelets on {100} planes occurs; whereas when Cc/Cv is small, the effects of carbon are still manifest; the defect geometry is dominated by the vacancy behavior, and loops on {111} planes form. Consideration of the mechanism of defect formation on {100} planes leads to conclusions about the structure of the carbon atom/vacancy complex, its migration and stability. An electron microscopy analysis of the {100} defects is in excellent accord with the proposed model. Implications concerning the likely behavior of carbon atoms in a radiation environment are considered, and an interstitial impurity solute segregation effect to vacancy sinks is predicted. © 1979.