Corrosion Properties of Supersaturated Magnesium Alloy Systems


The range of applications for magnesium alloys is still limited due to their relatively poor corrosion behavior. In recent years, various new magnesium alloys were developed, some of them with improved corrosion properties, thus opening new fields of application. However, the number of alloying elements for the use in conventional cast processes is limited due to their interaction with liquid magnesium or large differences in the melting temperatures. The possibilities for grain refinement by post-processing are also restricted. However, PVD techniques are able to produce supersaturated precipitation free and microcrystalline magnesium layers. Using ion beam and magnetron sputtering, binary or ternary Mg-Al, Mg-Ti and Mg-Si alloy systems as well as standard alloys (AM50, AZ91 and AE42) were deposited on silicon as well as on magnesium substrates. Effects of the microstructure on the corrosion properties will be studied by comparing as cast material and PVD coatings using potentiodynamic polarization, polarization resistance and electrochemical impedance techniques.
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