Comparative study of mechanical properties of pure nanocrystalline Ni and Ni-Tf nanocomposite

Mechanical properties of nanocrystalline (nc) Nickel (Ni) and Ni-Teflon (Ni-Tf) nanocomposite has been studied in detail using nanoindentation and conventional tensile tests. Nanoindentation tests carried out at room temperature over a range of loading rate exhibited higher hardness for the nanocomposite as compared to the nc-Ni due to Tf dispersion. An increase in strain rate sensitivity (SRS) and decrease in activation volume of the nanocomposite as compared to nc-Ni was also observed. Tensile tests were carried out over a temperature regime of room temperature (RT) to 500 degrees C. Tensile data also showed enhancement of yield stress and ultimate tensile strength up to 150 degrees C. But from 200 degrees C and above, Tf dispersion is unable to provide superior strength over nc-Ni as both the materials show almost similar strength. However, the ductility of the Ni-Tf nanocomposite was observed to be higher at all temperature compared to the pure nc-Ni. SRS was found to increase with temperature while SRS in nanocomposite had higher value below 200 degrees C. The present study reveals that Ni-Tf nanocomposite possess better strength and ductility compared to nc-Ni up to 200 degrees C.