Impact of Gold Ions on Nanohardness and Various Characteristics of G-metal Alloy Surface

Mechanically polished Gun-metal (G-metal) alloy specimens were irradiated using a 2 MeV Au+ beam of Pelletron Linear Accelerator. The range of Au+ fluence was 5 x 1011 to 1 x 1014 Au+/cm2. XRD patterns revealed the crystallographic peaks of Cu, Zn, and Sn. Harris analysis demonstrated that the Au+ fluence strongly influenced the preference of crystal plane alignment. The structural attributes like crystallite size, strain, etc. change as the Au+ fluence varies. Due to the low depth of ion-induced defects region, the estimation of ion irradiated material surface hardening is difficult. So, the technique of nanoindentation used in this work proves helpful for estimating the surface hardness of ion irradiated material. The surface hardness of specimens varied with the Au+ fluence and indentation depth. A significant increase in surface roughness, nanoindentation surface hardness, and elastic modulus values was observed at 5 x 1013 Au+/cm2 irradiation. Moreover, the surface hardness improves with decreasing crystallite size, reflecting the Hall-Petch relation. Energy dispersive X-ray (EDX) and Proton-induced X-ray emission (PIXE) were used for elemental analysis of specimens before and after Au+ irradiation.