Fabrication of toughened B4C composites with high electrical conductivity using MAX phase as a novel sintering aid

MAX phase Ti3AlC2 was chosen as a novel sintering aid to prepare electrically conductive B4C composites with high strength and toughness. Dense B4C composites can be obtained at a hot-pressing temperature as low as 1850 degrees C with 15 vol% Ti3AlC2. The enhanced sinterability was mainly ascribed to the in situ reactions between B4C and Ti3AlC2 as well as the liquid phase decomposed from Ti3AlC2. Both the Vickers hardness and fracture toughness increase with increasing Ti3AlC2 amount, and high hardness and toughness values of 28.5 GPa and 7.02 MPa m(-1/2) respectively were achieved for B4C composites sintered with 20 vol% Ti3AlC2 at 1900 degrees C. Crack deflection by homogenously distributed TiB2 particles was identified as the main toughening mechanism. Besides, B4C composites sintered with Ti3AlC2 show significantly improved electrical conductivity due to the percolation of highly conductive TiB2 phase, which could enhance the machinability of B4C composites largely by allowing electrical discharge machining. (C) 2016 Elsevier Ltd and Techna Group S.r.l. All rights reserved.