Potentiostatic electrochemical noise measurements are performed on Cu3Au polycrystals over the whole duration of slow strain-rate tensile tests up to brittle cracking in acidic sulfate medium. According to previous works, three 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 theories 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.