The co-precipitation of vacancies and carbon atoms in quenched platinum

Abstract

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 ( C c / C v ) is large, co-precipitation as platelets on {100} planes occurs; whereas when C c / C v 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.