The Relationship Between Thermo-Mechanical Treatment and the Properties of CuAlNi Shape Memory Alloys

This study seeks to explore the influence of thermomechanical processing on various aspects, including transformation temperature, shape memory effect, and thermal properties such as enthalpy and entropy. The alloys underwent a casting process at 1200 ℃, followed by homogenization at 950 ℃. Subsequently, they underwent treatment at temperatures of 250 ℃, 300 ℃, and 350 ℃ with a 25 KN load, followed by machining using an EDM wire-cutting machine. A thermomechanical test involving a 25 KN load was applied for the calculation of the recovery strain. Also, a Differential Scanning Calorimetry (DSC) test was conducted within the temperature range of 25 ℃ to 350 ℃ and in reverse. The thermal characteristics were computed using MATLAB and the area under the curve of the thermogram. The findings indicate an increase in different domain conversion temperatures with higher aging temperatures. Furhermore, the recovery strain exhibits a decline in the near-hyperplastic state, concurrent with an increase in enthalpy and a decrease in entropy as the treatment temperature rises.