An experimental study on preparation and properties of Zirconium boride reinforced NbMo-matrix composites

Abstract:

Zirconium boride reinforced NbMo-matrix composites with a composition of 42.5%Nb+42.5%Mo+15%ZrB₂ (Vol.%) and SiC doped with a composition of 42.5%Nb+42.5%Mo+10.5%ZrB₂+4.5% SiC (Vol.%) was fabricated by hot-pressing under an uniaxial load of 30 MPa at 1600℃ in Ar atmosphere with two kind of holding time. The microstructure and phase compositions were analyzed by means of scanning electron microscopy (SEM), energy-dispersive spectroscopy (EDS) and X-ray diffraction (XRD). The mechanical properties were measured by Micro Vickers and hydraulic universal tester. NbMo solid solution was observed with small ZrB particles distributed uniformly in it. No SiC particle was founded. The compressive strength was improved to 1974.17MPa compared to the NbMo solid solution 1380.15MPa. The yield stress was improved to 1664.13MPa and the hardness was 3~5 times higher than NbMo. The increase in strength and hardness of the composites is a consequence of the solid solution strengthening mechanism and the excellent interface bonding between ZrB and Nb-Mo solid solution.