The effect of TiB 2 content on the properties of AA6005/TiB 2 nanocomposites fabricated by mechanical alloying method

Abstract An A6005 aluminium alloy composite reinforced with different contents of titanium boride particles (2.5, 5 and 10 wt%) was produced by a mechanical alloying (MA) route. First, the aluminium alloy and titanium boride powders were blended by MA at different milling times, from 1 to 10 h. The samples obtained after MA processing were microstructurally and mechanically characterised by OM, SEM, TEM, LDS, XRD and micro-hardness tests. The optimum size distribution and suitable mechanical properties were obtained with 5 or 10 wt% of titanium boride particles after 8 h of MA, when the steady state is reached. Hot extrusion was employed as a consolidation process. An extruded sample of powders with a 5 wt% reinforcement content that was MA for 8 h was characterised by TEM, FE-SEM and nanoindentation tests. The results show a good distribution of the nano-reinforcement within the aluminium matrix. Nano-indentation test shows an increment in hardness values from 2.6 GPa for the reference extrusion of A6005 powders without MA and reinforcement to 3.3 GPa for the A6005 extrusion with 5 wt% TiB 2 and MA for 8 h.