Stress-modified electrochemical reactivity of metallic surfaces: atomic force microscopy imaging studies of nickel and alloyed aluminum

In this paper, we demonstrate that externally applied tensile and compressive stresses can systematically modify the electrochemical surface reactivity of pure and alloyed metals. Atomic force microscopy AFM.is used to statistically characterize the extent and nature of interface change for nickel and aluminum alloy 2024-T3 subjected to electrochemical conditions under various levels of stress. Statistical analysis of AFM images reveals that the extent of electrochemical reactivity is significantly enhanced when subjecting the sample to tensile as opposed to compressive stress; this enhancement increases monotonically as the level of applied stress is systematically increased. Surface morphologies differ on the pure nickel and alloyed aluminum samples, with the nickel interfaces exhibiting facetted features which are aligned 1208 from one another while the surface features on aluminum alloy 2024-T3 are circular pores. These results unambiguously indicate that the kinetics for electrochemical metallic processes, which nucleate at surface defects and grain boundaries, can be significantly modified by the presence of external stress fields. q2000 Elsevier Science B.V. All rights reserved.