We have fabricated single core superconducting wires and tapes using a process based on a chemical transformation from hexagonal (nonsuperconducting) to tetragonal (superconducting) via an optimal supply of Fe from the Fe sheath by annealing. This process enhanced a packing density of wire core inside the sheath, owing to an expansion of the lattice volume via a chemical transformation from high-density hexagonal to low-density tetragonal . An obvious correlation between annealing temperature and phase transformation was observed. Transformation of wire core from hexagonal to tetragonal was observed above 500 . Finally, the hexagonal phase completely transformed into the tetragonal phase by annealing at 700 . The obtained superconducting wire showed superconductivity below 13 K. The magnetic value of at 4.2 K was obtained for the sample annealed at 500 .