A Review on Influence of Alloying Elements on the Microstructure and Mechanical Properties of Cu-Al-Ni Shape Memory Alloys

Cu–Al–Ni shape memory alloys (SMAs) have been developed for high temperatures engineering components such as sensor and actuators, due to their ability to work at temperatures near 200°C, rather than NiTi and Cu–Zn–Al alloys whose maximum working temperatures around 100°C. These alloys are widely used because they are much cheaper than NiTi/Cu-Zn-Al and do not require any complicated processing during their manufacturing as do for other shape memory alloys. In addition, these alloys have a small hysteresis and high transformation temperatures compared with other alloys. Despite all these advantages, these alloys have their limitations such as brittleness and low phase recovery strains and stress. The present review describes the role of alloying elements on the properties of Cu-Al-Ni shape memory alloys. It has been found that the additions of alloying elements have a significant effect on the formation, morphology, and structure of the obtained martensite, therefore, the properties of these alloys varied in accordance of these effects.