Effect of nickel addition on densification, microstructure and wear behaviour of spark plasma sintered CP-titanium

Titanium alloys with varying amounts of nickel additions (2, 6 and 10 wt%) were prepared through the spark plasma sintering technique. The influence of nickel additions on densification, microstructure and wear behaviour of the sintered alloys was investigated, against commercially-pure titanium (CP–Ti). SEM analysis results showed a mixed portion of dark background (α-Ti), white patches and bright spots within the matrix of the sintered binary alloys compared to sintered CP-Ti matrix. These white patches and bright spots were confirmed by the X-ray diffraction (XRD) results to be a mixture of intermetallic phases of Ti₂Ni (FCC) and TiNi₂ (HCP). The relative density and the microhardness value were found to increase from 91.42% to 99.6% and 212 HV_0.1 to 343 HV_0.1 respectively. Estimated yield and tensile strength values were observed to vary linearly with increasing concentration of Ni in the sintered alloys. Analysis of the worn surfaces indicated improved resistance to adhesive and abrasive wear with increasing nickel content in the sintered alloys.