Milling of nonstoichiometric niobium carbide powder to a nanocrystalline state

Abstract

Using high-energy ball milling, we obtained nanocrystalline nonstoichiometric NbC y niobium carbide powders. The crystal structure, microstructure, and particle size distribution of the starting and milled powders were determined using X-ray diffraction, laser diffraction, and scanning electron microscopy. Experimental data on the milling of NbC y (0.77 ≤ y ≤ 0.96) niobium carbides were compared to theoretical model dependences of the particle size D of the nanopowders on milling time τ and composition y for nonstoichiometric cubic NbC y carbides. Our results demonstrate that 15-h milling of niobium carbide powder with an average particle size of ≃6 μm yields nanopowder with an average particle size of 20–30 nm and a specific surface area of 25–30 m2/g.