The Observation of TGSCC Nucleation in α-Brass/NH3 System

Transgranular stress corrosion cracking (TGSCC) of α-brass in cuprous ammoniacal solution was investigated to illustrate the nucleation (initiation) mechanism of TGSCC. The cuprous ammoniacal solution used tin this study is at equilibrium with Cu, which means no formation of oxide film on the specimen surface and no general corrosion occurring. TGSCC nucleation was observed to occur by localized preferential anodic corrosion along slip traces formed on the specimen surface during straining in solution. The orientation of crack surfaces formed by the nucleation and the propagation of TGSCC were different from each other: the former is {111} and the latter {110}. This represents that both events do not occur by the same mechanism. The observation of TGSCC nucleation in this investigation also shows that the thin film technique using TEM is not appropriate for a study on the propagation mechanism of TGSCC