Preparation of Nanocrystalline NbN and (Nb, Al)N Powders by Mechanical Alloying under Nitrogen Atmosphere

Abstract

Elemental niobium powder and Nb 50 Al 50 elemental powder mixture were milled in a vibrational ball mill, Spex 8000, under nitrogen atmosphere, and the structures of milled powders and their sintered materials were examined by means of X-ray analysis, SEM and HRTEM observations. The niobium powder absorbed 50 at% of nitrogen during milling. Several types of nitrides were formed during milling, i.e., γ-Nb 4 N 3 (FCT), δ-NbN (FCC) and δ'-NbN (hexagonal) with increasing nitrogen content. The mean grain size of these nitrides were about 5 nm