Material having a high elastic deformation and process for producing the same

A material having a high elastic deformation composed of Co-based alloy comprising, on the basis of mass percent, one or more members selected from 0.01 to 10% of Fe, 0.01 to 30% of Ni, 0.01 to 25% of Mn, and the balance being cobalt without inevitable impurities, wherein

• the Co-based alloy is Co-based alloy having a high elastic deformation in which ε-phase of h.c.p. structure thermally induced and/or stress-induced from γ-phase of f.c.c. structure occupies 10% or more by volume of an total metallic structure.

A process of producing a material having a high elastic deformation, wherein

• Co-based alloy including, on the basis of mass percent, one or more members selected from 0.01 to 10% of Fe, 0.01 to 30% of Ni, and 0.01 to 25% of Mn, and the balance being cobalt without inevitable impurities, is first subjected to solution treatment at 900 to 1,400° C., and
• ε-phase of h.c.p. structure is then thermally induced and/or stress-induced.