ZrB2/ZrC ceramic powders were fabricated by mechanical alloying (MA) of zirconium (Zr), amorphous boron (B) and graphite (C) powder blends prepared in the mole ratios of Zr/B/C: 1/1/1, 1/2/1, 1/1/2, 1/2/2 and 2/2/1. MA runs were carried out in a. vibratory ball mill using hardened steel vial/balls. The effects of Zr/B/C mole ratios and milling duration on the formation and microstructure of ZrB2/ZrC ceramic powders were examined. Gibbs free energy change-temperature relations of the reactions and moles of the products were interpreted by thermochemical software. Zr/B/C: 1/1/1, 1/2/1, 1/1/2 and 1/2/2 powder blends MA'd for 2 and 3 h contain unreacted Zr and C, ZrB2, ZrC and B4C particles. Synthesis of ZrB2/ZrC ceramic powders was completely accomplished after MA of Zr/B/C: 2/2/1 powder blend for 2 h. ZrC and ZrB2 particles wen: obtained ranging in size between 50 and 250 nm in the presence of FeB contamination (<1 wt.%). (C) 2011 Elsevier Ltd. All rights reserved.