The effects of sintering temperature and addition of Fe instead of Co into the matrix composition on the mechanical properties of diamond-reinforced MMC's have been studied. Diamond-reinforced MMC's based on Fe-Co compositions with and without boron carbide (B4C) have been processed. Three different matrix composites (with different Fe/Co ratios) have been produced with and without B4C at a pressure of 25 MPa and sintered in N-2 at various temperatures (800, 900, and 1000A degrees C). After sintering, mechanical properties of the resultant composites have been studied and the results discussed. Addition of B4C has been found to improve the hardness and wear resistance of the composites. Optical microscopy, SEM and EDS have been used to examine the microstructure and surface of the synthesized composites.