Corrosion behavior and microstructure of titanium implanted with α and β stabilizing elements

Abstract

The polished surface of pure Ti were implanted with Al (200 keV), or V (200 keV), or Nb (100 and 150 keV) to doses ranging from 1 × 10 17 to 8 × 10 17 ions cm −2. The implanted surface simulates a range of alloying in composition and microstructure. X-ray diffraction (XRD) measurement reveals α Ti on Al-implanted samples and ( α + β) Ti on V- or Nb-implanted samples. The tendency is observed in increasing corrosion resistance from α- toward ( α + β)-phase. In deaerated 5 M HCl, the ion-implanted Ti surface containing V-stabilized or Nb-stabilized β-phase is spontaneously passive, while Al-implanted surface displaying an active/passive behavior. In aerated Hank's solution (HS), all the implanted surfaces are passive. The passive current density decreases in the order of the implanted additives Al, V, and Nb for HS and V, Al, and Nb for 5 M HCl, suggesting different protective surface films formed in the two media examined. Enhanced reoxidation was confirmed on implantation alloyed surfaces by Auger electron spectroscopy (AES) and X-ray photoelectron spectroscopy (XPS) analysis. The corrosion in HS is governed by a predominantly TiO 2 surface film. The cathodic kinetics is seen to affect the corrosion behavior in 5 M HCl.