In situ synthesis and properties of Zr_2Al_3C_4/ZrB_2 composites

摘要

The Zr_2Al_3C4/ZrB_2 composites are in situ synthesized by spark plasma sintering using Zr, Al, graphite, and B_4C powders as the initial materials. The introduction of ZrB_2 can not only evidently hinder the coarsening of Zr_2Al_3C_4 grains, but also benefit the densification and improve the hardness and Young's modulus of the Zr_2Al_3C_4/ZrB_2 composites. When the ZrB_2 content is 20 vol.%, the composite shows an optimum fracture toughness value of 4.37 MPa m~(1/2), about 20% higher than that of the monolithic Zr_2Al_3C_4. The unique mechanical properties can be mainly ascribed to the contribution of ZrB_2 as the reinforcing phase hindering the crack propagating. Compared with Zr_2Al_3C_4, the Zr2Al3G,/20 vol.%ZrB_2 composite also exhibits a relatively higher thermal conductivity and better oxidation resistance.