Mechanical and electrochemical properties of nanocrystalline (Mo1−xCrx)3Si coatings: Experimental and modeling studies

Abstract

a b s t r a c tFour (Mo 1Àx Cr x ) 3 Si 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 (Mo 1Àx Cr x ) 3 Si 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 (Mo 1Àx Cr x ) 3 Si coatings increased with increasing Cr addition. To gain a deeper understanding of the effect of Cr alloying on the electrochemical behavior of these (Mo 1Àx Cr x ) 3 Si 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 Mo 3 Si coatings. The findings provide a promising foundation for the development of mechanically robust, corrosionresistant Mo 3 Si-based coatings for surface protection.