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CoPt and FePt nanowire arrays were successfully prepared by electrodeposition into nanochannels of porous alumina membranes. The as-deposited CoPt alloy has a face centred cubic structure and displays soft magnetic properties. Heat treatment at 700?°C for different durations, under vacuum condition was carried out in order to obtain the ordered face centred tetragonal phase L10, exhibiting hard magnetic properties. After annealing, arrays of nanowires actually show hard magnetic properties with coercive fields up to 1.1?T at room temperature. Phase transformation, structural and magnetic properties were analysed and necessary conditions to obtain optimum magnetic properties are concluded.The first results obtained with FePt nanowires denote a more complicated system since the as-deposited material shows no magnetization. Magnetism appears only after annealing at 700?°C minimum. Coercivity up to 1.1?T has been obtained at room temperature but with inhomogeneous phase composition. [ABSTRACT FROM AUTHOR]