In　this　study,　the　effect　of　the　addition　of　carbon　fibres　as　an　alternative　carbon　source　on　the　microstructure　and　mechanical　properties　of　reaction　bonded　B4C/SiC　(RBSC)　composites　was　investigated.　The　phase　composition　and　morphology　were　studied　by　X-ray　diffraction,　scanning　electron　microscopy　and　energy-dispersive　X-ray　spectroscopy.　The　sintered　bodies　were　found　to　consist　of　alpha-SiC,　beta-SiC,　B4C,　Si　and　B-12(B,C,Si)(3).　Furthermore,　two　types　of　core-rim　structure　were　observed,　as　well　as　the　fibre　like　extensions　of　silicon　particles.　The　B4C　phase　was　found　to　replace　the　residual　silicon,　resulting　in　a　lower　bulk　density　and　a　more　refined　structure,　whereas　the　fibre-like　extensions　of　silicon　particles　led　to　a　reduction　of　the　size　of　the　silicon　islands.　The　flexural　strength　and　fracture　toughness　of　the　prepared　composites　were　higher　than　those　of　conventional　RBSC　composites,　reaching　peak　values　of　465　+/-　17　MPa　and　7.5　+/-　0.4　MPam(1/2),　respectively.　(C)　2016　Elsevier　Ltd.　All　rights　reserved.