Strengthening mechanisms in short carbon fiber reinforced Nb/Nb5Si3 composites with interfacial reaction

The understanding of strengthening mechanisms in composites is crucial to improve its mechanical properties. Strengthening mechanisms in Nb/Nb₅Si₃ composites reinforced by different contents of short carbon fiber (C_sf) were investigated. Interface and tensile properties of the composites were studied. Interfacial nano-sized Nb₄C₃ phase forms by in situ interfacial reaction, the Nb₄C₃ phase embedded intimately in the C_sf and matrix forms an anchor effect. The content of Nb₄C₃ phases in the composites increases because of the increase of C_sf content. Ultimate tensile strength and yield strength of the composite are improved because of the increase of C_sf content. When the content of C_sf is 1.0 wt%, the elongation reaches the maximum, but the elongation decreases slightly when the content of C_sf increases from 1.0 wt % to 2.0 wt %. The strengthening mechanisms in this composite were investigated according to grain refinement and load transfer. Load transfer is main strengthening mechanism and accounts for more than 95% of the improvement in yield strength. This indicates that the control of interfacial bonding state is crucial to improve the mechanical properties of the composites. This study can offer some valuable information to disclosing the strengthening behaviors in the C_sf reinforced metal matrix composites.