Application of metallic phase change materials (PCMs) in latent heat storage systems has been limited by the absence of appropriate packaging technology. Compared to other PCMs, metallic PCMs generally possess extremely high thermal conductivity, high energy density and high phase change temperature. As one of the best metallic PCM candidates, Cu-based encapsulated metallic phase change materials (EM-PCMs) with a typical Fe-shell/Cu-core structure have been prepared by an aerodynamic levitation method in this work, which provided a solution to the packaging issue. Cu-based EM-PCMs were formed based on the liquid phase separation phenomenon of undercooled Fe-Cu immiscible alloys. Results show that the morphology evolution of Fe-Cu alloys could be attributed to the combined effects of liquid phase fraction of the two immiscible liquids, Stokes and Marangoni velocities of droplets, and the rotation direction of the alloy samples during solidification. This kind of EM-PCM is nearly spherical with a diameter of about 2 mm and coated by an iron oxide layer which can improve the wear resistance of EM-PCMs. (c) 2014 Elsevier Ltd. All rights reserved.