This article reports the synthesis and microstructure characterization of nanocrystalline Si0.9Al0.1C powder obtained by mechanical milling the mixture of Si, Al and graphite powders at room temperature under inert atmosphere. XRD patterns of ball-milled powders clearly reveal the nucleation of Si0.9Al0.1C phase after 5 h of milling and the stoichiometric cubic Si0.9Al0.1C is formed after 10 h of milling with crystallite size of similar to 3 nm. Microstructure of ball-milled powders in terms of different lattice imperfections is characterized by employing both Rietveld's method of structure refinement using XRD data and high resolution transmission electron microscope (HRTEM). HRTEM micrographs of 10 h milled powder substantiate the formation of nanocrystalline Si0.9Al0.1C compound without any contamination and confirm the findings of Rietveld analysis using XRD data. (C) 2015 Elsevier B.V. All rights reserved.