Biennial Report 2005-2007 - Saha Institute of Nuclear Physics

160 Biennial Report 2005-075.1.3.7 The hardness study of oxygen implanted aluminum thin filmsSurface mechanical properties of metals are known to be dramatically modified by ion implantation.Implantation changes the composition and chemical bond structure of the target surface region toa depth comparable to the projectile range. In this work, effects of mass analyzed low energy O + 2implantation in thin Al films on the hardening and microstructure have been studied by nanoindentingatomic force microscopy (AFM). The fluence range was 1 x 10 17 1 x 10 18 O atoms/cm 2 . Amaximum increase of hardness about 90% of the implanted samples is observed. Apparently thereis no significant variation in the hardness values within the range of ion fluences investigated here.Fig.5.1.3.7. Typical AFM image of an array of nanoindentations on the 16.7 keV O + 2implanted Al sample at a fluence 1 × 10 18 O atoms/cm 2 . The applied loads are 74,82, 95 and 98µN, respectively (from right to left). The light area around the edges oftriangle is the piled-up material. The section analysis along the indicated line showsthe variations of the indentation depth at the above mentioned loads.It is supposed that tiny Al 2 O 3 precipitates behave as obstacles hindering the motion of dislocationsthereby leading to surface hardening. Finally, the surface roughness is found to decrease considerablyby oxygen irradiation.P Mishra, D GhoseSP5.1.3.8 Structural and Magnetic Property study of Magnetic MultilayersMagneto resistance (MR) of magnetic multilayers (ML) e.g of immiscible of Co/Ag is appreciable.As MR is highly dependent on film thickness and interface structure, [Co/Ag]n are prepared andthere are studied with X-ray reflectivity and AFM and magnetic measurements are made withSQUID. Some initial results are obtained and more systematic studies will be carried out with nextproject student.S KunduSP