Interfacial phase induced load transfer in short carbon fiber reinforced Nb/Nb5Si3 composites

Load transfer is the main responsibility for improving mechanical properties of fiber reinforced metal composites, but it is significantly affected by interfacial phase. Short carbon fiber reinforced Nb/Nb₅Si₃ composites were successfully fabricated at different temperatures. Interfacial Nb₄C₃ is a nanoscale formed by in situ reaction, and the diameter and volume fraction of Nb₄C₃ phases increase with the fabrication temperature increasing. Due to the Nb₄C₃ phases are intimately attached to carbon fibers and tightly embedded in the matrix of composites, an anchor effect is induced between fibers and matrix. The load transfer of interface in composites was discussed, which is affected by the Nb₄C₃ phases. The interfacial Nb₄C₃ phases help to increase the load transfer efficiency, but also damage the carbon fiber, resulting in that carbon fiber can not effectively bear the transferred load but fracture. A relationship of the load transfer efficiency with the equivalent diameter of Nb₄C₃ phase was established. For regulating the load transfer efficiency, the control method of the equivalent diameter of Nb₄C₃ phase was established innovatively, which indicates that the equivalent diameter can be adjusted by fabrication temperature and time. This work provides new viewpoints for disclosing the load transfer in composites containing interfacial nano-sized phase.