PROBLEM TO BE SOLVED: To provide: a nickel-titanium-rare earth alloy with better workability, radiopacity, superelasticity and the like than conventional Ni-Ti-RE alloys； and a method of processing the same.SOLUTION: A nickel-titanium-rare earth alloy comprises: nickel at a concentration from 35 at.% to 65 at.%； a rare earth element at a concentration from 1.5 at.% to 15 at.%； and boron at a concentration up to 0.1 at.%； with the balance of the alloy being titanium. A method of processing the alloy includes: providing a nickel-titanium-rare earth alloy comprising nickel at a concentration from about 35 at.% to about 65 at.% and a rare earth element at a concentration from about 1.5 at.% to about 15 at.%, with the balance being titanium； heating the nickel-titanium-rare earth alloy in a homogenization temperature range at or below a critical temperature； and forming spheroids of a rare earth-rich second phase in the alloy while keeping it in the homogenization temperature range.SELECTED DRAWING: Figure 1【課題】加工性、放射線不透過性、超弾性等において従来のＮｉ－Ｔｉ－ＲＥ合金類よりも優れたニッケル－チタン－希土類元素合金及びその加工方法の提供。【解決手段】３５at.%から６５at.%の濃度のニッケル；１．５at.%から１５at.%の濃度の希土類元素；０．１at.%までの濃度のホウ素；及び残部のチタンを含むようにする。また、約３５at.%から約６５at.%の濃度でニッケル、約１．５at.%から約１５at.%で希土類元素を含み、残部がチタンであるニッケル－チタン－希土類元素の合金を提供し、臨界温度以下の均質化処理温度領域で該ニッケル－チタン－希土類元素合金を加熱し、該均質化処理温度領域に維持しつつ、合金中に球体の希土類元素リッチ(rare earth-rich)な第２の相を形成することを含む合金加工方法。【選択図】 図１
