Abstract
Ti-6Al-4V was plasma nitrided using several N2/H2 ratios and substrate temperatures. In order to investigate the combined influence of these parameters on phase composition and thickness of the coatings, the phases in the as received, annealed, and nitrided Ti-6Al-4V samples were identified with Rietveld refinement. In the as-received and annealed samples the structure parameters of -Ti and -Ti were slightly changed, due to the substitution of titanium atoms by Al or V in the - and -Ti unit cells. A combination of multiple angle grazing incidence X-ray diffraction, nuclear reaction analysis and cross sectional micrographs showed compound layers consisting of an outer layer of stoichiometric -TiN over a phase mixture of -TiN and -Ti2N, formed on top of a nitrogen diffusion region in the alloy. Higher nitriding temperatures induced thicker compound layers, and higher nitrogen content of the plasma induced thicker fine-grained -TiN top layers. Keywords: plasma nitriding, Ti-6Al-4V, titanium nitride, Rietveld analysis.
Highlights
The most widely used titanium alloy, Ti-6Al-4V, has an excellent combination of strength, toughness, and corrosion resistance [1] and is applied in aircraft-turbines, pressure vessels, compressor blades [2], and in biomedical applications [3]
In order to investigate the combined influence of these parameters on phase composition and thickness of the coatings, the phases in the as received, annealed, and nitrided Ti-6Al-4V samples were identified with Rietveld refinement
In plasma nitriding several process parameters affect the phases that are formed in the coating, such as substrate temperature, gas composition, gas pressure, gas flow, voltage, current, current density, and deposition time
Summary
The most widely used titanium alloy, Ti-6Al-4V, has an excellent combination of strength, toughness, and corrosion resistance [1] and is applied in aircraft-turbines, pressure vessels, compressor blades [2], and in biomedical applications [3]. In plasma nitriding several process parameters affect the phases that are formed in the coating, such as substrate temperature, gas composition, gas pressure, gas flow, voltage, current, current density, and deposition time. SILVA et al [6] used 20% and 60% N2 in N2+H2, varying temperature between 400 °C and 670 °C They conclude that at temperatures below 500 °C, -Ti2N and -TiN are present only in samples nitrided in 60% N2 atmosphere. BRADING et al [7] used a wide compositional range of N2 in N2+H2 at 700 oC, their substrate was commercially pure titanium. They observed the thickest TiN layers on samples nitrided in atmospheres with less than 30% N2
Sign-in/Register to view highlights & summary Sign-in/Register to access full text options 
Free) 
Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a call
