The influence of nitrogen to hydrogen ratio and temperature on thickness and phase composition in plasma nitrided Ti-6Al-4V

Abstract

Ti-6Al-4V was plasma nitrided using several N 2 /H 2 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 -Ti 2 N, 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.

Isothermal oxidation kinetics of nitrided Ti-6Al-4V studied by infrared emissivity

“…These minor peaks hint at an α-like phase with similar cell parameters than both the original α and the hardened α, which is sometimes tentatively described as martensite α . Their stronger presence for the (002) peak (38 − 39 • ) is perhaps consistent with the larger breadth of this peak for the untreated sample, which is linked to the presence of residual martensite in the original sample [33].…”

Analysis of the Surface Treatments Effect on the Creep Behavior of Ti-6Al-4V Alloy

“…Just below it can be seen part of the second layer that has approximately 4.0 μm and can be called as diffusion layer. Lima et al 17 performed a phase identification of the Ti-6Al-4V samples nitrided layer, nitrided at 700 ºC for 4 hours with a nitrogen concentration of 50%, combining the results from Rietveld analysis, Grazing incidence x-ray diffraction in multiple angles (MA-GIXRD), and Nuclear reaction analysis (NRA). They found an upper fine-grained layer of δ-TiN in a layer of 0,5 μm followed by a layer of ~2 μm related to to ε-Ti 2 N with the possibility of δ-TiN extending to the lower layer.…”