Mechanical and electrochemical properties of nanocrystalline (Mo ₁₋ₓCrₓ)₃Si coatings: Experimental and modeling studies

Abstract

Four (Mo1-xCrx)3Si nanocrystalline coatings with a cubic A15 structure were fabricated onto Ti-6Al-4V substrates using a double-cathode glow discharge technique. The elastic modulus and hardness of the nanocrystalline (Mo1-xCrx)3Si coatings were measured by nanoindentation and their electrochemical behavior was investigated by potentiodynamic polarization and electrochemical impedance spectroscopy (EIS) in a 3.5 wt% NaCl solution. The results showed that the corrosion and abrasion damage resistance of the nanocrystalline (Mo1-xCr x)3Si coatings increased with increasing Cr addition. To gain a deeper understanding of the effect of Cr alloying on the electrochemical behavior of these (Mo1-xCrx)3Si coatings, the electronic structure and Mulliken populations were modeled by first-principles calculations. It revealed that the Cr alloying can enhance the protective nature of passive layers developed on the Mo3Si coatings. The findings provide a promising foundation for the development of mechanically robust, corrosion-resistant Mo3Si-based coatings for surface protection. © 2014 Elsevier B.V. All rights reserved.