B. Malki et al., Stress corrosion cracking behavior of alpha-brass as a function of the oxide transport properties in NaNO2 solutions, J ELCHEM SO, 148(9), 2001, pp. B357-B367
In this paper, we relate the transport properties of the anodic oxide films
formed on alpha -brass in NaNO2 solutions to the mechanical response of th
e alloy during slow strain rate tensile tests. A range of electrolyte conce
ntrations were investigated, from 5 x 10(-4) M (pH 7.1) to 8.4 M (pH 8.8).
Surface analysis [X-ray photoelectron spectroscopy, Auger electron spectros
copy (AES), and AES depth profiling] techniques were used to investigate th
e films composition. We begin by defining an electrochemical and mechanical
criterion of crack initiation. Then three concentration regimes are reveal
ed, for which a net correlation can be established between the oxide film p
ermeability to metal cations and the susceptibility to stress corrosion cra
cking (SCC): (i) in the dilute regime, the passive film on alpha -brass is
highly permeable while crack initiation requires high mechanical loading; (
ii) in the intermediate regime, both the protective character of the oxide
film and the susceptibility to SCC are maximum; and (ii!) in the concentrat
ed regime, on the contrary, both the film permeability and the extension of
the plastic domain are increasing with NaNO2 concentration. (C) 2001 The E
lectrochemical Society.