Abstract
TiB2 and Al2O3 particulates reinforced AA6061 aluminum matrix composites (AMCs)
were synthesized by in-situ reaction of titanium (Ti) and boric acid (H3BO3) powders with
molten aluminum. AMCs were fabricated using an electric stir casting furnace under a
controlled environment. Heat flow curves of differential thermal analysis (DTA) showed that
the synthesis temperature for the formation of TiB2 and Al2O3 using Al-Ti-H3BO3 reaction
system was 950°C. The in-situ synthesized composites were characterized using XRD,
FESEM, TEM and EBSD. XRD results revealed the formation of TiB2 and Al2O3 particulates
in the composite. FESEM micrographs revealed a homogenous distribution of both the
particulates with good interfacial bonding. EBSD maps showed that the in-situ formed TiB2
and Al2O3 particulates refined the grains of the aluminum matrix from 103 μm at 0 wt.% to
14 μm at 15 wt.%. Al2O3 particles exhibited spherical shape while TiB2 particles displayed
hexagonal and cubic shapes. The formation of ultrafine and nano scale thermodynamically
stable TiB2 and Al2O3 particles enhanced the microhardness and the tensile strength of the
2
AMCs. The microhardness and the tensile strength were respectively 122 HV and 287 MPa at
15 wt.%.