Neutron Diffraction Study of Microstructure of Nanocrystalline Cubic Niobium Carbides from NbC0.77 to NbC0.96

Abstract

The microstructure of nanocrystalline nonstoichiometric niobium carbides NbC0.77, NbC0.84, NbC0.96 powders produced by high-energy ball milling has been investigated by time-of-flight (TOF) high resolution neutron diffraction. The diffraction patterns have been collected with the high resolution Fourier diffractometer HRFD by using the TOF mode of data acquisition. The nanocrystalline ball-milled powders have a microinhomogeneous structure, in which two fractions with different particle size and composition can be identified. The average sizes of the coherent scattering regions and microstrains in nanocrystallites with allowance for the anisotropy of the deformation distortions have been estimated. It is shown that TOF neutron diffraction patterns can provide the very accurate data for microstructure analysis of nanocrystalline powders.

Keywords:

Time-of-flight neutron diffraction, high-energy ball milling, niobium carbide, nanocrystalline materials, microstructure

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