Effect of gas composition on corrosion behavior and growth of apatite on plasma nitrided titanium alloy Beta-21S

► Titanium alloy β21S was nitrided in 100% N2 and H2 diluted N2 plasmas. ► Nitriding in H2 diluted plasma results in higher hardness. ► Corrosion resistance of H2 diluted sample is higher than 100% N2 nitrided samples. ► Nitriding lowers the corrosion resistance of base alloy in SBF. ► H2 dilution leads to more growth of hydroxide and apatite in Hank's solution.