Turning characteristics of in situ formed TiB2 ceramic particulate reinforced AA7075 aluminum matrix composites using polycrystalline diamond cutting tool

This paper investigates the machining characteristics of AA7075/(0-12 wt.%) TiB2 aluminum matrix composites (AMCs) during dry turning using polycrystalline diamond cutting tool. AMCs were produced using in situ reaction between inorganic salts K2TiF6 and KBF4 with molten aluminum. TiB2 particles were observed to be uniformly distributed in the composite. The role of cutting speed and the content of TiB2 on machining forces and surface roughness was studied. The morphology of the cutting tool, chips and machined surface was observed using field emission scanning electron microscope (FESEM). The increase in cutting speed reduced the requirement for cutting forces due to thermal softening, deprivation of dislocation density and decrease in built-up edge (BUE). The length of the chips and plastic deformation increased with cutting speed. The cutting forces decreased with an increase in TiB2 particle content due to chip breaking action. The increase in cutting speed enhanced surface roughness due to reduction in transferred material. The reinforcement of TiB2 particles deteriorated the surface roughness due to micro cutting action of the pulled out TiB2 particles. Both cutting speed and TiB2 particles increased the tool wear respectively due to depletion of stable BUE and abrasive action.