Comprehensive dissolution current noise analysis during stress corrosion cracking of Cu3Au alloys

Potentiostatic electrochemical noise measurements are performed on Cu3Au po lycrystals over the whole duration of slow strain-rate tensile tests up to brittle cracking in acidic sulfate medium. According to previous works, thr ee different potential testing conditions are chosen, which lead to a more or less enhanced embrittlement. At first glance, one observes successively "silent" and "active" electrochemical zones over the whole duration of the mechanical test. Qualitative signal analysis using deterministic chaos theo ries reveals that (i) the electrochemical behavior of the strained specimen is purely deterministic, (ii) the local maximum Lyapunov exponent, lambda( 1), is sensitive to corrosion-deformation interactions, and (iii) there is a clear tendency of lambda(1) to decrease well before entering in the crack propagation regime, regardless of the electrochemical conditions used. (C) 1999 The Electrochemical Society. S0013-4651(98)01-051-X. All rights reser ved.