Microstructure and properties of TiB_2P/Al composites fabricated by squeeze casting technology

TiB_2P/Al composites were fabricated by squeeze casting technology, and their microstructures and properties were investigated by XRD, SEM, TEM, three-point bending tests, friction and wear tester. The results showed that TiB₂ reinforcements distributed homogeneously in the dense TiB_2P/Al composites, and the main phases in composites were composed of Al and TiB₂ phase. TEM observation reveals that after peak aging (T6) treatment, many β′ precipitates and dislocations were found in the matrix alloy. Some massive and discontinuous reactants, MgAl₂O₄, were observed on some interfaces of TiB_2P/Al composites. For 45% TiB_2P/Al composite, its bending strength was 934 MPa and the elastic modulus was 1823 GPa, which increased by 34% and 27% respectively, compared with those of the composite with 30% TiB₂. In dry sliding mode, sliding with GCr15 bearing steel, friction coefficient of TiB_2P/Al composites had no obviously change (fluctuated about 0.2), which is obviously lower than that of the Al alloy under the same friction condition. No clear plastic deformation and adhesive wear were observed at the worn surfaces of TiB_2P/Al composites. TiB_2P/Al composites show the self-lubricating properties.