Synthesis, microstructure and mechanical properties of (Zr,Ti)B2-(Zr,Ti)N composites prepared by spark plasma sintering

(Zr,Ti)B2-(Zr,Ti)N composites were fabricated by spark plasma sintering (SPS) using ZrB2 and TiN powders as initial materials. The adopted TiN contents in the initial compositions were 0, 4, 9, and 18 wt%, respectively. During the sintering process, the reaction between ZrB2 and TiN first produced TiB2 and ZrN and then (Zr,Ti)B2 and (Zr,Ti)N were formed through the solid solutions between ZrB2 and TiB2, and between ZrN and TiN, respectively. When using 18 wt% TiN, the solid solutions of (Zr,Ti)B2 and (Zr,Ti)N finished at 1600 °C. Above 1900 °C, the solid solution of (Zr,Ti)N reached saturation in all the composites. With the increasing (Zr,Ti)N content in the composites, the finer microstructure was obtained due to the inhibiting effect of (Zr,Ti)N particles on the growth of (Zr,Ti)B2 grains. The mechanical properties investigation showed that fracture toughness of composites increased with the increment of (Zr,Ti)N content.