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INTRODUCTION

THE electrochemical codeposition is a process in which a particle-dispersed metallic-matrix film is electroplated on a cathodic substrate from an electroplating bath containing insoluble particles. The technique has emerged as a potential route to form a metallic-matrixcomposite coating dispersed with hard and inert particles, e.g., Al2O3, TiC, and WC, that contribute to the improvement of the mechanical and chemical properties of the host metals.[1–5] Furthermore, the technique can also be employed to fabricate an intermetallic-contained layer which generally requires two processing steps including (i) codeposition of metals and active particles and (ii) heat treatment for a formation of intermetallic phases or compounds. For example, a film of Ni matrix and Ni3Al intermetallic alloys was successfully fabricated by codepositing a Ni matrix layer containing Al particles and subsequently annealing under a vacuum at 823 K to 1073 K (550 C to 800 C) for 2 hours.[6] SANGTHUM SRIKOMOL, Graduate Student, is with the Department of Materials Engineering, Faculty of Engineering, Kasetsart University, 50 Phaholyothin Rd., Chatuchak, Bangkok, 10900, Thailand. YUTTANANT BOONYONGMANEERAT, Assistant Professor, is with the Metallurgy and Materials Science Research Institute, Chulalongkorn University, Bangkok, 10330, Thailand. RATCHATEE TECHAPIESANCHAROENKIJ, Lecturer, with the Department of Materials Engineering, Faculty of Engineering, Kasetsart University and also Researcher, with the Center of Advanced Studies in Industrial Technology, Faculty of Engineering, Kasetsart University, Bangkok, 10900, Thailand. Contact e-mail: fengrct@ku. ac.th Manuscript submitted May 24, 2012. Article published online October 10, 2012. METALLURGICAL AND MATERIALS TRANSACTIONS B

Another important intermetallic alloy system with interesting functional properties in which the codeposition could be utilized as its alternative processing technique is nickel-titanium (NiTi). Due to their relatively high mechanical strain outputs under thermal stimulus as well as their superelasticity within room temperature proximity,[7,8] NiTi alloys are excellent candidates for active components in engineering devices and medical applications that require less invasive parts with improved functionality. Typically, a NiTi film is fabricated on a substrate by the physical vapor deposition method (PVD),[9–12] which demands expensive setups, limited maximum sizes and shapes, and yields low deposition rates.[10,11] Alternatively, a powder metallurgy process is typically applied to fabricate larger NiTi components at faster production rates and lower manufacturing costs. However, such processes have limitations of potential minimum sizes, limited to submillimeter ranges. On the other hand, the electrodeposition technique potentially serves as a more cost-efficient technique that can fabricate a NiTi component within the size range between micron and sub-millimeter. As opposed to PVD, the electrodeposition technique can potentially fabricate a film of a larger size