Interplay of Surface Diffusion and Surface Tension in the Evolution of Solid/Liquid Interfaces : Dealloying of β-Brass in Aqueous Sodium Chloride

• Autores: Martín, H.; Carro, P.; Hernández Creus, A.; Morales, J.; Fernández, G.; Esparza, P.; González, S.; Salvarezza, Roberto Carlos; Arvia, Alejandro Jorge
• Año de publicación: 2000
• Idioma: inglés
• Tipo de recurso: artículo
• Materia: Ciencias Exactas; Química; β-Brass; Scanning tunneling microscopy; Electrodissolution
• Institución: Universidad Nacional de La Plata

The dealloying of β-brass in 0.5 M aqueous NaCl was studied by electrochemical techniques at different temperatures in the range 278 K ≤ T ≤ 318 K, complemented with in situ scanning tunneling microscopy (STM) imaging. In the potential region where the electrodissolution of zinc and the formation of vacancies and copper islands take place, two different roughness regimes were distinguished. When dealloying involves only a few monolayers (ML) the process approaches a quasiuniform alloy electrodissolution, whereas after electrodissolution of more than 20 ML, void formation takes place. In both regimes the interface evolution was analyzed by applying the dynamic scaling method to in situ STM imaging data. The first roughness regime exhibits a stable interface consisting of copper-rich islands that coarsen with time according to a surface diffusion controlled process. The second roughness regime exhibits an unstable interface due to a curvature dependent corrosion rate enhancing zinc electrodissolution at cavities. The overall interface evolution is well-described by a differential stochastic equation containing an electrodissolution term and surface rearrangement terms related to surface diffusion and negative surface tension effect.
Instituto de Investigaciones Fisicoquímicas Teóricas y Aplicadas