Microstructure, mechanical properties and wear behaviour of Zn-Al-Cu-TiB2 in situ composites

Zn-Al-Cu-TiB2 (ZA27-TiB2) in situ composites were fabricated via reactions between molten aluminum and mixed halide salts (K2TiF6 and KBF4) at temperature of 875 degrees C. The microstructure, mechanical properties and wear behavior of the composites were investigated. Microstructure analysis shows that fine and clean TiB2 particles distribute uniformly through the matrix. The mechanical properties of the composites increase with the increase in TiB2 content. As TiB2 content increases to 5% (mass fraction), an improvement of HB 18 in hardness and 49 MPa in ultimate tensile strength (UTS) is achieved. The overall results reveal that the composites possess low friction coefficients and the wear rate is reduced from 5.9x10(-3) to 1.3x10(-3) mm(3)/m after incorporating 5% TiB2. Friction coefficient and worn surface analysis indicate that there is a change in the wear mechanism in the initial stage of wear test after introducing in situ TiB2 particles into the matrix.