The coarse insoluble intermetallic phase in 2024Al was refined to nanometer scale by an effective powder metallurgy approach, which involved atomization to form oversaturated solution powder, high energy ball milling to produce a high dislocation density and fine grains in the powder, and sintering to generate highly dispersed nanosized intermetallic particles. The structure of refined nanosized intermetallic particles have been determined to be an ordered body center cubic with a lattice parameter of a = 12.65 angstrom for the first time. The nanosized intermetallic particles play a positive role in enhancing dispersion-strengthening effect and thermal stability of 2024Al alloy. This refined approach can be applied to many commercial alloy systems that contain insoluble coarse intermetallic phases. (C) 2010 Elsevier B.V. All rights reserved.