Effect of nonstoichiometry of NbCy and TaCy powders on their high-energy ball milling

Nanocrystalline powders of nonstoichiometric carbides NbCy and TaCy are experimentally obtained by high-energy milling of coarse-grained powders. For the first time, the effect of nonstoichiometry of NbCy and TaCy carbides on the particle size of produced nanopowders is studied. It is shown that the effect of nonstoichiometry on milling is manifested by the concentration dependences of the main characteristics (crystal structure parameters, energy of interatomic bonds, elastic properties) of milled nonstoichiometric compound. The experimental results on NbCy (0.77 <= y <= 0.96) and TaCy (0.81 <= y <= 0.96) milling are compared with the theoretical model dependences of the particle size D of nanopowders on the duration of milling t and the composition y of nonstoichiometric cubic carbides NbCy and TaCy. It is established that the carbide powders with the average nanoparticle size of 20-30 nm and specific surface area of 25-30 m(2) g(-1) are produced by 15 h milling, all other factors being equal. (C) 2014 Elsevier Ltd. All rights reserved.