Mechanical behaviour and corrosion performance of thin film magnesium WE alloys

Abstract

Mg based thin films are of increasing interest due to the potential in varying the corrosion properties in comparison to bulk alloys of the same nominal composition. In this work the mechanical behaviour and the corrosion performance of sputtered thin films consisting of magnesium alloys with the compositions Mg4Y3Gd and Mg4Y3Nd were investigated by tensile tests and electrochemical corrosion tests, respectively. The tensile tests showed that the sputtering parameters have an enormous influence on the mechanical properties of the thin films. By variation of the Ar sputtering pressure and the DC sputtering power it was possible to fabricate films with widely varying mechanical behaviour reaching from brittle to very ductile films which could be strained to more than 30%. The determined dependency between mechanical properties and deposition conditions was found to be present in both investigated alloys. The corrosion tests revealed that the corrosion behaviour of the investigated samples is not correlated to the mechanical properties of the thin films, as the rate of corrosion and the tendency to localized corrosion do not change significantly upon the deposition conditions, which dramatically influence the mechanical properties.