Simultaneous synthesis and sintering of a nanocystalline AlCr₂-Al₂O₃ composite by rapid heating and its mechanical properties

A dense nanostuctured AlCr₂-Al₂O₃ composite was sintered by pulsed current activated heating up to 1200 °C within 2 min from mechanically milled powders. The advantage of this process is that it allows very quick densification to near theoretical density and prohibition of grain growth in nanostructured materials. A highly dense AlCr₂-Al₂O₃ composite with a relative density of up to 96% was produced under application of a 80 MPa pressure and a pulsed current of 2000 A. The fracture toughness and hardness of the AlCr₂-Al₂O₃ composite in this study was better than those of previous studies due to the grain refinement. The microstructure and mechanical properties of the composite were investigated using field emission scanning electron microscopy and a Vickers hardness tester.