We recently reported that the columnar grain width of Cr 2 AlC MAX phase coatings increases during oxidation (4 h at 1120°C) by 80%, while for 0.7 at.% Si additions to Cr 2 AlC, coarsening of only 12% was observed. Here, we use nm scale compositional and microstructural investigations to identify significant differences between Cr 2 AlC and Cr 2 Al(Si)C. In particular, needle-shaped precipitates coarsen into globular Cr 3 Si precipitates upon oxidation in the Si-containing MAX phase. We infer that the presence of these precipitates, which are located predominantly along grain boundaries in the MAX phase, retards coarsening during oxidation by Zener pinning. © 2019, © 2019 The Author(s). Published by Informa UK Limited, trading as Taylor & Francis Group.