High-energy ball milling is successfully used to produce magnesium matrix nanocomposites reinforced with SiC nanoparticles. Changes in morphology and microstructural features of the milled powders were characterized in order to highlight advantages of the mechanical milling process and evaluate the role of the SiC nanoparticles. It was observed that with increasing volume fraction of SiC nanoparticles, a finer nanocomposite powder with more uniform particle size distribution is obtained. A homogeneous distribution of SiC nanoparticles, even up to 10% volume fraction, in magnesium matrix after 25 h milling was confirmed by elemental mapping and TEM results. The analysis of the XRD patterns accompanied by dark-field TEM images revealed that magnesium crystallites refine to fine nanocrystalline sizes after the mechanical milling. The results showed that the crystallite size of the magnesium matrix reduced with increasing SiC nanoparticle content in addition to the induced lattice strain. (C) 2018 Published by Elsevier B.V. on behalf of The Society of Powder Technology Japan. All rights reserved.