Environmentally induced time-dependent failure mechanisms in CFCCs at elevated temperatures.

The results of several studies suggest that a variety of mechanisms exist for time-dependent failure in CFCCs at elevated temperatures. The failure mechanisms of CFCCs at elevated temperatures when oxidation processes occur during deformation are presented and discussed in the framework of a "Failure Mechanism Map". In particular, the transition between the oxidation embrittlement mechanism (OEM) and the interfacial removal mechanism (IRM) is discussed with respect to oxygen concentration, exposure temperature, and carbon interphase thickness. Experimental data and modeling from studies, using flexural loading, at PNNL is combined with observations reported by others to produce the map.