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

摘要

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 ℃. Tensile data also showed enhancement of yield stress and ultimate tensile strength up to 150 ℃. But from 200 ℃ 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 ℃. The present study reveals that Ni-Tf nanocomposite possess better strength and ductility compared to nc-Ni up to 200 ℃.