Immersion test with crevice formation

Figure 11.85. Specimens after end of immersion test with crevice formation, (a)-(c) show specimens 1-3 [120].

Immersion test with crevice formation, no short-circuit/ visual, stereomicroscopy 2 3 3 5 3 3 5 2 1... 

One recent development in the static immersion testing from Newman et al. [116] originated with Bengough and May [JJ5]. Recent experimentation [116] involved exposing samples of alpha-brass in NaCl solutions with additions to simulate the local environment in crevices or otherwise inhibited transport. Under these severe conditions, dealloying can be shown to occur without an applied potential and may be reduced or eliminated by addition of arsenic to the alloy. The authors suggest that these results support the percolation mechanism with surface diffusion for dealloying rather than mechanisms that rely on formation of metastable phases or disproportionation of the less noble element. 

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