Electrochemical behaviour of chromium-implanted magnesium in hydroxide, chloride and sulphate solutions

Despite the development and subsequent improvement of new Mg-based alloys, their vulnerability to oxidation and corrosion continues to pose a major obstacle to their more generalized use. The possibility of blocking high diffusivity paths, such as grain boundaries, by ion implantation may help to improve their oxidation and corrosion resistance, because mass transport through these short circuiting paths is reduced. Electrochemical techniques were used to investigate the effect of Cr ion implantation in the electrochemical behaviour of Mg in aqueous solutions. In particular ion implanted fluences of 5 x 10(16) and 5 x 10(17) at./cm(2) have been evaluated in solutions of NaCl, NaOH and Na2SO4. The corroded surfaces and products were analysed by ion beam analysis, scanning electron microscopy and X-ray diffraction. A model of the corrosion mechanism is proposed to explain the obtained results. (C) 2008 Elsevier B.V. All rights reserved.