Nanomechanical properties of spark plasma sintered multiwall carbon nanotubes reinforced Ti6Al4V nanocomposites via nanoindentation technique

In this study, nanoindentation tests were carried out to investigate the nanomechanical behaviours of Ti6Al4V and its nanocomposites comprising of multiwall carbon nanotubes (MWCNTs) fabricated via spark plasma sintering. Prior to the nanoindentation tests, the fabricated alloy and the nanocomposites comprising of 0.5 and 1.0 wt% of MWCNTs were observed under a scanning electron microscope (SEM) to reveal the morphology and the presence of the MWCNTs in the nanocomposites. The nanoindentation study was conducted using a Berkovich diamond indenter with a load of 75 mN to ascertain the nanohardness, reduced elastic modulus, plasticity index and elastic recovery index of the sintered materials. The SEM results revealed the dispersibility of the nanotubes in the titanium-based matrix and the presence of lamellar structures in the fabricated alloy. Furthermore, it was observed that the nanohardness and elastic modulus of the sintered materials ranges from 3.4-5.7 GPa and 27.6-38.9 GPa, which improved with the MWCNTs content. Also, the elastic recovery index increased with MWCNTs content in the nanocomposites. While the sintered Ti6Al4V displayed the maximum plasticity during the nanoindentation study.