Interfacial reaction induced mechanical behaviors in graphene reinforced Nb/Nb5Si3 composites

Abstract

Fabricating high-toughness Nb/Nb5Si3 composites without sacrificing their strength is a challenge. Here, a novel and promising strategy is suggested for developing the graphene reinforced Nb/Nb5Si3 composites with high performance by adjusting the nano-sized Nb4C3 interfacial phase, and their mechanical behaviors including toughening and strengthening mechanisms were reported for the first time. The generated nano-Nb4C3 interfacial phase is tightly bonded with the graphene and matrix, which reduces the interfacial stress concentration and improves the interfacial bonding strength because of the improvement of interfacial compatibility. The high interfacial bonding strength caused by the nano-Nb4C3 can effectively promote crack deflection and bridging, and consume the more propagating energy of cracks, thus increasing the toughness. The primary strengthening mechanism in this composite is the load transfer, which is influenced by the nano-Nb4C3 interfacial phase. An appropriate amount of nano-Nb4C3 interfacial phase is crucial for achieving a good strength-toughness balance in this composite. The excellent combination of strength and toughness demonstrates that the strategy used in this work can make this composite stand out from the dilemma of strength toughness inversion. This work paves a new path for breaking the inverted relationship between the strength and toughness in graphene/metal matrix composites.