抄録
The fatigue behavior of monocrystalline Cu–Al–Ni shape memory alloys have been investigated by uniaxial fatigue tests under various deformation modes. Fatigue life, Nf, was found to depend on the deformation modes and to be long in the order of elastic deformation, reorientation of martensites and transformation pseudoelasticity, indicating that interphase boundaries have a most deleterious effect on Nf. Stress dependence of Nf was observed in all the deformation modes, but strain dependence was not in transformation pseudoelasticity, indicating that the principal factor controlling Nf was stress. No orientation and strain rate dependences were observed. These results were compared with those previously reported on polycrystalline Cu–Al–Ni alloys. Effect of grain boundaries was found to depend on the deformation modes within grains and the strain allowed for a certain Nf for single crystals was found to be larger than that for polycrystals.
