“…5 shows the grain size of untreated and plasma nitrided samples as a function of treatment time at a filling pressure of 2 and 3 mbar of reflection (1 1 0). It can be observed that the grain size of nitrided samples increases with pressure (Pandis et al, 2006), whereas, it decreases in comparison with the grain size of untreated sample with nitriding time owing to the diffusion of nitrogen atoms causing the peak broadening due to variation of d-spacing (Badawi et al, 2000;Aouadi et al, 2005). …”