A radiopaque composite wire for medical applications comprises a core comprising a rare earth metal, an outer layer comprising a nickel-titanium alloy disposed over the core, and a diffusion barrier comprising a barrier material between the core and the outer layer. A method of making a radiopaque composite wire includes cold drawing a composite billet through a die, where the composite billet includes a tube comprising a nickel-titanium alloy disposed about a rod comprising a rare earth metal, and a barrier layer comprising a barrier material disposed between the tube and the rod. After cold drawing, the composite billet is annealed to relieve strain. After multiple passes of the cold drawing and annealing, a radiopaque composite wire having a core comprising the rare earth metal, an outer layer comprising the nickel-titanium alloy, and a diffusion barrier comprising the barrier material between the core and the outer layer is formed.
