ZrN-sialon composites were synthesized from zircon and gamma-Al2O3 via carbothermal reduction-nitridation. The effects of reaction temperature on the phase compositions and product morphologies were studied. The equilibrium relationship curves of the condensed phases were drawn and the temperature dependence of the phase stability was investigated. The results show that products with different phase compositions and morphologies can be obtained at different temperatures. The optimum temperature for acquiring ZrN-sialon composites was 1550 degrees C. Granular ZrN and short prismatic beta-sialon (Si3Al3O3N5) were formed at 1500 degrees C, accompanied by surplus Al2O3 and ZrO2. The dominant products at 1550 degrees C were ZrN and Si3Al3O3N5, whereas they were ZrN and 15R-SiAl4O2N4 at 1600 degrees C. beta-sialon had perfect crystals with a long-column morphology, whereas 15R-SiAl4O2N was plate-like. (C) 2012 Elsevier Ltd. All rights reserved.