The effect of stress and radiation on the shape memory behaviour in copper based alloys

In this study, shape memory properties of Cu-13%Al-4%Ni; Cu-13.5%Al-4%Ni and Cu-12.7%Al-5%Ni-2%Mn alloys have been investigated. While these alloys having austenite phase have DO3 structure, martensite phase has long-period 18R structure. The alloys having martensitic phase at room temperature have been experienced with different stresses, neutron and gamma radiations. The variations in the ability of the shape memory of the alloys were determined by using electrical resistance, differential scanning calorimetry (DSC), X-ray diffraction and metallographic methods. It was seen from the electrical resistance and DSC measurements that the reverse transform temperatures of the martensite o austenite were decreased with the applied radiation and the transform temperatures increased with applied different stresses at the room temperature. X-ray diffraction measuremets show that three of the alloys have M18R structure. It was seen from the metallographic observations that the morphology of the samples subjected to radiation showed some distortions. Key Words: CuAINi and CuAlNiMn alloys, martensitic transformation, shape memory effect, radiation effect, electrical resistance, stress effect, transformation temperatures.