The nitrogen ion implantation was applied to modify TiNi shape memory alloy tape surface and the influence of implantation treatment on the tensile deformation and bending fatigue properties is investigated. The results obtained can be summarized as follows. (1) If the nitrogen ion was implanted, the transformation temperatures increase a little. Both upper and lower yield stresses therefore decrease and the partial superelasticity appears in place of the superelasticity. (2) The larger the maximum bending strain, the shorter the fatigue life is. If the nitrogen ion is implanted, the bending fatigue life becomes longer. (3) In the case of the non-implanted tape, the crack nucleates at a certain point in the central position of the surface and propagates towards the center in an ellipsoidal pattern. In the case of the ion-implanted tape, the crack nucleates at a corner of the tape and propagates towards the center and along the surface of the tape with the higher speed of progression.
