Influence of coconut shell powder organic reinforcement on chemical, microstructural and mechanical properties of spark plasma sintered Ti-Ni based metal matrix composite

Abstract

Metal matrix composites (MMCs) are currently used in place of pure alloys and polymer matrix composites because of their unique physical properties. Titanium and nickel powders were alloyed with coconut shell powder (CSP) as organic compound reinforcement to form a TiNi-based metal matrix composite (MMC) using spark plasma sintering (SPS) technique. The powders were mild-milled for 16 h and then axially consolidated at 850°C, heating rate of 100°C.min-1 and 50 MPa sintering pressure. Characterizations were done using field emission scanning electron microscope (FE-SEM-EDX) and x-ray diffractometer (XRD). Elemental and structural characterizations of the composites revealed the formation of the Ti-rich eutectic phase, Ni-rich dendrites, and TiNi-rich phase regions with dispersed distributions of carbides and oxide phases within the system. The Ni-rich “islands” appear to be depleted with increased CSP content. However, the relative density, tensile strength and microhardness improved in samples with higher amounts of CSP powder to the optimum values of 99.9%, 1022.91 MPa and 319.71 HV.