Microstructure and mechanical properties of MoAlB particles reinforced Al matrix composites by interface modification with in situ formed Al12Mo

The interfacial bonding between reinforcement particles and metal matrix is vital significant to the mechanical properties of composites. In this study, a new MoAlB/Al composites with interface modification by in situ formed Al12Mo were prepared from MoAlB and Al powders for the first time. The thermal stability of MoAlB in MoAlB–Al system was investigated by differential scanning calorimetry and thermogravimetry analysis. It was found that the MoAlB can react with Al to form Al12Mo and a small quantity of AlB2 and MoB2. The formed Al12Mo can suppress the Al atoms diffusion and thus to hinder the reaction progress. The modified interfacial bond by in situ formed Al12Mo effectively improved the mechanical properties of the MoAlB/Al composites. The Vickers hardness increases linearly as the MoAlB volume content increases from 5% to 20%, the hardness value increases by approximate 11 H V for every 5% reinforcements increment. The yield stress and Vickers hardness of 20MoAlB/Al composites are 124.2 MPa and 70.1 H V, respectively. The mechanical properties and failure mechanism of the composites with different initial MoAlB contents were also estimated and analyzed, the excessive MoAlB particles will be detrimental to the mechanical properties due to the premature microcracks initiation, rapid propagation and coalescence of the microcracks in the composites.