Xu, J.Liu, W.Xu, S.Munroe, P.Xie, Z.2018-08-242018-08-242018Journal of Alloys and Compounds, 2018; 749:406-4230925-83881873-4669http://hdl.handle.net/2440/113894Available online 15 March 2018In this work, the structural stability, mechanical properties and electronic structure of β-Ta<inf>5</inf>Si<inf>3</inf> with different Al additions were first predicted by first-principles density functional calculations. The binary and ternary β-Ta<inf>5</inf>Si<inf>3</inf> are thermodynamically and mechanically stable, but their thermodynamic stability slightly decreases with Al additions. The elastic constants, bulk modulus (B), shear modulus (G) and Young's modulus (E) of Al-alloyed β-Ta<inf>5</inf>Si<inf>3</inf> were calculated. According to the criteria involving the bulk/shear modulus (B/G ratio) and Poisson's ratio, the D8<inf>m</inf>-structured ternary Ta<inf>5</inf>Si<inf>3</inf>, where two Si^4a atoms are replaced by two Al atoms, shows improved ductility. Based on the theoretical analysis, the β-Ta<inf>5</inf>(Si<inf>0.83</inf>Al<inf>0.17</inf>)<inf>3</inf> nanocrystalline coating was deposited onto polished Ti-6Al-4V alloy substrates by double cathode glow discharge plasma method. The phase constitution, microstructure and composition of the coating were analyzed using X-ray diffraction (XRD), scanning electron microscopy (SEM) including energy dispersive X-ray spectroscopy (EDS) and transmission electron microscopy (TEM). The as-deposited coating was composed of nearly rounded D8<inf>m</inf>-β-Ta<inf>5</inf>Si<inf>3</inf> grains with an average size of ∼4 nm and exhibited strong (002) and (400) preferred orientation. After Al alloying, the hardness and the compressive residual stress of the β-Ta<inf>5</inf>Si<inf>3</inf> decreased, and the contact damage resistance and adhesion strength increased. The electrochemical corrosion properties of the β-Ta<inf>5</inf>(Si<inf>0.83</inf>Al<inf>0.17</inf>)<inf>3</inf> nanocrystalline coating were compared to the binary β-Ta<inf>5</inf>Si<inf>3</inf> coating and Ti-6Al-4V in 3.5 wt% NaCl solution by potentiodynamic polarization and electrochemical impedance spectroscopy (EIS) techniques. It was shown that the corrosion resistance of the β-Ta<inf>5</inf>Si<inf>3</inf> was improved through the substitution of Al for Si.en© 2018 Elsevier B.V. All rights reserved.First-principles theoretical calculations; refractory metal silicides; electrochemical corrosion; mechanical propertiesJournal article003008560010.1016/j.jallcom.2018.03.1560004326662000482-s2.0-85044503556404433