Abstract
Mullite/Molybdenum composites were sintered by Pulse Electric Current Sintering method with MgO as sintering aid. Densified samples achieved more than 98% of theoretical densities. Bend strength and fracture toughness increased to three to four times with monolithic mullite. Elastic moduli and the hardness of composites obeyed series-parallel models. Microstructure analysis of fractured specimens revealed the strengthening and toughening mechanism of composites. The strengthening was mainly attributed to refinement of mullite grains. Bridging of crack by plastic deformation of ductile particles and pinning in the frontal process zone and wake increased the toughness of composites.