Dependence of surface nano-structural modifications of Ti implanted by N ions on temperature

The surface modification of titanium thin foil/sheet samples (0.5 mm) implanted by nitrogen ions of 30 keV energy and a fluence of 1 × 10¹⁸ N⁺ cm⁻² at different temperatures is studied using XRD, AFM, SEM, and SIMS. XRD patterns showed the development of titanium nitride with different compositions in the implanted samples, while the presence of different titanium compositions such as titanium oxides was also observed. AFM images at 654 K showed the formation of grains, that after initial sputtering of the grain boundary at 728 K temperature, the morphology of the surface changed from small grains to a bimodal distribution of grains at 793 K which consisted of larger grains with bright hillocks within them. This was considered to be due to phase transformation/compositional changes, explained by correlating XRD and SIMS results. The SIMS results showed a maximum at about 730 K and a minimum at about 790 K for both N⁺ density and depth of N⁺ penetration in the Ti sample. The variation of these results with temperature was explained on the basis of the residual gas, substrate temperature, dissociation of water in the chamber and the gettering property of titanium.