Reinforcement size dependence of mechanical properties and strengthening mechanisms in diamond reinforced titanium metal matrix composites

Abstract

Diamond particulates reinforced titanium matrix composites (TiMMCs) were fabricated by spark plasma sintering technique at different reinforcement sizes of 5, 100, 200 nm and 3 μm. The dependence of reinforcement size on the mechanical and tribological properties in the TiMMCs was studied, paying particular attention to the nanoscale effects. The enhancement in strength of the composites was elucidated on the basis of strengthening mechanisms characterized by load transfer, thermal mismatch, grain size, and Orowan strengthening. The strengthening mechanisms were quantitatively analyzed and evaluated as a function of particle size. The results revealed that the presence of 5 nm diamond particles enhance strength by interacting with dislocations, while simultaneously retarding grain growth. Although the micro-composite has a little higher strength than the nanodiamonds reinforced composite, the latter has a combination of high strength and high ductility as wells excellent tribological properties.