Synthesis of a composite in situ using a solid state displacement reaction between Mo2C and Si

Combustion Synthesis of Dense Functionally Graded B4C Reinforced Composites

Dense FGMs with gradually changing fraction of very hard and light-weight B4C particles were fabricated employing an original Reactive Forging (RF) combustion synthesis method. In RF, a self-sustained reaction (thermal explosion, TE) is ignited by placing a powder blend between preheated press rams and the high temperature achieved is utilized for consolidation of the combustion product. The reported FGMs were prepared by stacking layers of highly exothermic Ti-C-Ni powder blend diluted with varying fractions of non-reacting B4C particles. Only a limited amount of B4C could be added as its diluting action reduces the overall exothermicity of the blend. In some cases, B4C particles were precoated in order to prevent their interaction with Ti during combustion. Temperature evolution in (Ti-Ni-C)-B4C powder compacts corresponding to different FGM layers was measured separately and in the stacked form. The better understanding of combustion process in B4C-diluted blends coupled with well-devised geometrical design allowed us to fabricate FGMs with high volume fractions of B4C in the surface layer.