PEER REVIEWED Enhanced Electrochemical and Tribological Properties of AZ91D Magnesium Alloy via Cold Spraying of Aluminum Alloy Sumera Siddique 1,2 • Cheng-Xin Li 3 • Ayrton A. Bernussi 2,4 • Syed Wilayat Hussain 5 • Muhammad Yasir 5 Submitted: 27 December 2018 / in revised form: 12 July 2019 Ó ASM International 2019 Abstract Magnesium (Mg) alloys have remarkable phys- ical and mechanical properties for various aerospace applications. However, the high corrosion susceptibility and low wear resistance of Mg alloys restrict their wider use. To overcome these problems, 6061 Al alloy coatings were fabricated via the cold spraying process on the AZ91D Mg alloy substrate and a detailed comparative study on the wear and corrosion properties was carried out. The microstructure analysis of the compact coatings revealed low porosity with no phase change during the deposition process. The coatings showed improved corro- sion resistance up to seven times as confirmed by poten- tiodynamic polarization and electrochemical impedance spectroscopy measurements in 3.5 wt.% NaCl aqueous solution. The as-deposited coatings were also compared with commercial bulk alloys of similar composition for their suitability to industrial applications. The tribological behavior of the coatings and substrate was investigated using tribometer. The wear resistance of the coatings improved more than two orders of magnitude as compared to the substrate. Abrasive and oxidative wear mechanisms were dominant in the coatings and substrate. The results showed that cold spraying of 6061 Al alloy on AZ91D Mg alloy could be an auspicious process to overcome the poor corrosion and wear resistance of this Mg alloy for practical industrial applications. Keywords cold-sprayed coatings Á corrosion protection Á magnesium alloy Á wear resistance Introduction Magnesium (Mg) alloys are excellent materials for a large range of applications. Their high damping capacity, low density, good specific strength and recyclability make them an appropriate candidate for the automotive/aerospace applications where these properties have great potential to reduce fuel consumption, thereby contributing to energy savings and reducing environmental impact (Ref 1-4). Although the surface properties of Mg alloys are accept- able for certain applications, their poor corrosion and wear resistance prevent the wider applications of these materials (Ref 5, 6). Therefore, the corrosion protection of Mg alloys has been receiving a great deal of interest in recent years. So far, there are mainly two methodologies to improve the corrosion performance of Mg alloys: composition variation and surface engineering. Pan et al. (Ref 7) reported that the development of new Mg alloys improved their corrosion resistance when compared to commercial Mg alloys. However, their anti-corrosion performance is still poor when compared to Al-based alloys. On the other hand, the surface modification of prevailing Mg alloys is an eco- nomical and effective approach to prevent them from & Muhammad Yasir muhammadyasir85@gmail.com 1 Department of Physics and Astronomy, Texas Tech University, Lubbock, TX 79409, USA 2 NanoTech Center, Texas Tech University, Lubbock, TX 79409, USA 3 State Key Laboratory for Mechanical Behavior of Materials, School of Materials Science and Engineering, Xi’an Jiaotong University, Xi’an 710049, Shaanxi, People’s Republic of China 4 Department of Electrical and Computer Engineering, Texas Tech University, Lubbock, TX 79409, USA 5 Department of Materials Science and Engineering, Institute of Space Technology (IST), 1-Islamabad Highway, Islamabad 44000, Pakistan 123 J Therm Spray Tech https://doi.org/10.1007/s11666-019-00915-8