In situ synthesis and properties of Zr2Al3C4/ZrB2 composites

The Zr2Al3C4/ZrB2 composites are in situ synthesized by spark plasma sintering using Zr, Al, graphite, and B4C powders as the initial materials. The introduction of ZrB2 can not only evidently hinder the coarsening of Zr2Al3C4 grains, but also benefit the densification and improve the hardness and Young’s modulus of the Zr2Al3C4/ZrB2 composites. When the ZrB2 content is 20 vol.%, the composite shows an optimum fracture toughness value of 4.37 MPa m1/2, about 20% higher than that of the monolithic Zr2Al3C4. The unique mechanical properties can be mainly ascribed to the contribution of ZrB2 as the reinforcing phase hindering the crack propagating. Compared with Zr2Al3C4, the Zr2Al3C4/20 vol.%ZrB2 composite also exhibits a relatively higher thermal conductivity and better oxidation resistance.