Microstructures and properties of aluminum film and its effect on corrosion resistance of AZ31B substrate
(1. School of Materials Science and Engineering, University of Science and Technology Beijing, Beijing 100083, China;2. College of Materials Science and Engineering, Chongqing Institute of Technology, Chongqing 400050, China)
Abstract: Aluminum films with thickness of 8.78-20.82 μm were deposited on the AZ31B magnesium alloys by DC magnetron sputtering. The influences of aluminum film on the micro-mechanical properties and corrosion behavior of the magnesium alloys were investigated. The morphology of aluminum film was examined by scanning electron microscopy and the microstructure of aluminum film was analyzed by X-ray diffractometry. Nanoindentation and nanoscratch tests were conducted to investigate their micro- mechanical properties. Moreover, potentiodynamical polarization test performed in 3.5%NaCl solution was carried out to study their anticorrosion performances. The results show that the surface hardness of AZ31B magnesium alloy with aluminum film is 1.38-2.01 GPa, higher than that of the magnesium alloy substrate. The critical load of Al film/AZ31B substrate is in the range of 0.68-2.77 N. The corrosion current density of AZ31B with aluminum film is 2-3 orders of magnitude less than that of bare AZ31B. And the corrosion potential with aluminum film positively shifts. Thus aluminum film can increase the corrosion resistance of Mg alloys obviously.
Key words: AZ31B magnesium alloy; aluminum films; micro-mechanical properties; corrosion resistance; magnetron sputtering