CHEM02200704003 Nilamadhab Pandhy - Homi Bhabha National ...

Chapter 5
minor decrease in root mean squre roughness value (R q ) is mainly due to homogenization of
surface in the process of implantation due to preferential sputtering from the grain boundaries
[143,152] overcoming the effect of surface inhomogenities. Chico et al [153] have reported the
formation of pinhole like structures, and unidentified surface structures of peculiar shape at a dose
of 1×10 15 N + /cm 2 at 80 keV energy. The occurrence of such surface features were also attributed to
possible formation of interstitial nitrides of Cr and Fe. However, in the present study at a dose of
1×10 15 N + /cm 2 (Fig. 5.1a) such structures were not visible and the surface remained in as polished
condition [21].
5.2. 2 Elemental analysis using secondary ion mass spectroscopy
The elemental depth profile analysis using SIMS of unimplanted, and nitrogen ion
implanted (2.5×10 17 N + /cm 2 ) 304L SS are shown in Fig. 5.2a-b [21]. Contrast features were
observed in the profiles for iron (Fe 54 ), chromium (Cr 50 ), nickel (Ni 58 ), and nitrogen (N 14 ) prior to
and after nitrogen ion implantation. In case of unimplanted 304L SS specimens, iron, chromium,
and nickel showed steady state with increase in depth sputtering (Fig. 5.2a).
Intensity (Arbitrary units)
Fe 54
Cr 50
Ni 58
O 16
C 12
N 14
0 200 400 600 800
Depth (nm)
Fig. 5.2a: SIMS analysis of unimplanted 304L SS [21].