Microstructure and mechanical properties of ZrB2-Nb composite

Abstract The high relative density of the ZrB 2 -based composite toughened by 25 vol.%Nb (ZN) was hot-pressed at reduced temperatures with low pressure of 30 MPa. Compared with the toughness of 2.3–3.5 MPa m 1/2 and strength of 350 MPa of the monolithic ZrB 2 , the toughness and strength of the ZN composite were improved to 6.7 MPa m 1/2 and 773 MPa, respectively, due to the addition of ductile Nb. The toughening mechanisms are crack deflection and branching as well as stress relaxation near the crack tip. Furthermore, the densification mechanism was analyzed and discussed. The results here pointed to a potential method for improving fracture toughness and strength of ZrB 2 -based ceramics.