In this study, a comprehensive examination of the deformation behavior of At particles impacting on Al substrate was conducted by using the Arbitrary Lagrangian Eulerian (ALE) method to clarify the deposition characteristics of Al powder and the effect of surface oxide films in cold spraying. It was found that the deformation behavior of At particles is different from that of Cu particles under the same impact conditions owing to its lower density and thus less kinetic energy upon impact. The results indicated that a higher velocity was required for Al particles to reach the same compression ratio as that of Cu particles. On the other hand, the numerical results showed that the oxide films at particle surfaces influenced the deformation and bonding condition between the particle and substrate. The inclusions of the crushed oxide films at the interfaces between the depostied particles inhibit the deformation. (c) 2006 Elsevier B.V. All rights reserved.