Effects of sintering temperature on interface and mechanical properties of short carbon fiber reinforced Nb/Nb5Si3 composites fabricated by spark plasma sintering

Abstract

Short carbon fiber reinforced Nb/Nb5Si3 composites were innovatively fabricated by spark plasma sintering. The effects of sintering temperatures (1450 °C, 1500 °C, and 1550 °C) on the interface microstructure and mechanical properties of the composites, including hardness, tensile property, and fracture toughness, were investigated. The relative density of the composites exceeded 99%, and a nearly uniform distribution of short carbon fibers was observed throughout the composite. Results indicated that short carbon fiber reinforced Nb/Nb5Si3 composites were successfully fabricated by this technology. The Nb4C3 phase was detected at the interface between carbon fiber and matrix alloy, and dislocations were also found near interface zone. In this study, the composite fabricated at 1500 °C sintering temperature has the best mechanical properties owing to its high density, low fiber damage, and satisfying interface bonding strength. With increased sintering temperature to 1550 °C, the mechanical properties of composites decreased, which can be attributed to the damage of carbon fibers arising from interface reaction.