Assessment of microstructure, nanomechanical and tribological properties of Ti-xNi alloys fabricated by spark plasma sintering

Abstract

This work employed the nanoindentation and conventional dry sliding wear techniques to study the nanomechanical and tribological properties of the spark plasma sintered Ti-xNi (x = 2, 6 and 10 wt%) alloys. The microstructure and phase composition of the fabricated alloys were studied. The results indicated the presence of hexagonal close-packed (hcp) α-Ti and face-centred cubic (fcc) Ti2Ni intermetallic phases within the matrix of the Ti-xNi alloys. Nanoindentation measurements under varying loads showed that the hardness (H), elastic modulus (Er) and elastic recovery index (We/Wt) of the developed alloys increased with increasing nickel contents. At a constant load, the hardness trend aligns perfectly with the indentation size effect phenomenon. The H and Er decreased upon transition from lower to higher loads. The H/Er and H3/Er2 ratios obtained from nanoindentation are higher for Ti-xNi alloys compared to pure Ti. This shows that the Ti-xNi alloys possessed better anti-wear characteristics than pure Ti. The wear analysis results show that the wear resistance increased with increasing volume fraction of the Ti2Ni intermetallics in the sintered samples. Ti–10Ni alloy displayed the best nanomechanical and wear performances among the sintered samples.