No abstract

No abstract

The cyclic deformation and fatigue of a TiNi shape-memory alloy wire were studied by carrying out rotating-bending fatigue tests at various strain amplitudes, temperatures, and rotational speeds in air and in water. The results were summarized as follows: (1) for strain amplitudes in the rhombohedral-phase transformation region, the fatigue life was longer than 107 cycles and the deformation properties did not change under cyclic deformation; (2) for the strain amplitudes in the martensitic transformation region, the fatigue life was shorter than 105 cycles and the higher the temperature, the shorter was the fatigue life; (3) the rotational speed did not affect the fatigue life in water but a higher rotational speed led to a shorter fatigue life in air.

The thermomechanical properties of the shape memory effect and superelasticity due to the martensitic transformation and the R-phase transformation of a TiNi shape memory alloy were investigated experimentally. The transformation line, recovery stress and fatigue property due to both transformations were discussed for cyclic deformation. The thermomechanical properties due to the R-phase transformation were excellent for deformation with high cycles.

No abstract