Implantation of silicon ions into a surface layer of the Ti6A14V titanium alloy and its effect upon the corrosion resistance and structure of this layer

The effect of silicon ion implantation upon the corrosion resistance and structure of the surface layers formed during the implantation in the Ti6A14V titanium alloy was examined. The silicon doses were 0.5, 1.5, 3.0 and 4.5 x 10(17)Si(+)/cm(2), and the ion beam energy was 100 keV. The corrosion resistance of the samples exposed to a 0.9% NaCl solution at a temperature of 37 degrees C was measured using electrochemical methods. The structure of the surface layers formed during the implantation was examined by a transmission electron microscope (TEM). The results of the corrosion resistance examinations have shown that the unimplanted and 0.5 x 10(17)Si(+)/cm(2) implanted samples undergo uniform corrosion. At higher silicon doses, the samples show pitting corrosion. The highest corrosion resistance was shown by the alloy implanted with 0.5 x 10(17)Si(+)/cm(2). It has been found that, after a long-term (1200 h) exposure to a 0.9% NaCl solution, the corrosion resistance of the samples is greater than that observed after a short-term exposure. TEM examinations have shown that, beginning from a dose of 1.5 x 10(17)Si(+)/cm(2), the surface of the Ti6A14V alloy samples becomes amorphous. Heating of the 1.5 x 10(17)Si(+)/cm(2) implanted samples at 200 and 500 degrees C does not change their structure, whereas after heating at 650 degrees C, the amorphous phase vanishes. (C) 2000 Kluwer Academic Publishers.