Effect of Al alloying on cavitation erosion behavior of TaSi nanocrystalline coatings.

To broaden the scope of non-aerospace applications for titanium-based alloys, both hexagonal C40 binary TaSi and ternary Al alloyed TaSi nanocrystalline coatings were exploited to enhance the cavitation erosion resistance of Ti-6Al-4V alloy in acidic environments. To begin with, the roles of Al addition in influencing the structural stability and mechanical properties of hexagonal C40 Ta(SiAl) compounds were modelled using first-principles calculations. The calculated key parameters, such as Pugh's index (B/G ratio), Poisson's ratio, and Cauchy pressures, indicated that there was a threshold value for Al addition, below which the increase of Al content would render the Ta(SiAl) compounds more ductile, but above which no obvious change would occur.