Realization of CuAlMn SMA and its functional behavior for cryogenic application

Abstract

Cryogenic shape memory actuators are beneficial for various device applications, such as gas liquefiers (hydrogen, helium, and LNG storage and transportation), gas separation devices, compressors, cryostats, temperature controllers, and liquid pumps. Especially, shape memory alloys (SMA) are ideal actuator materials used for aforementioned applications in extreme environments. SMA actuator converts thermal energy into mechanical energy due to its unique characteristic of temperature-dependent actuation. Here, we have studied the extremely low-temperature actuation capability of Cu-based SMA bimorph. The CuAlMn SMAs with two different compositions (Cu-9Al-12.6Mn, Cu-9Al-11.8 M) were prepared and coated on a polyimide substrate (bimorph) by the thermal evaporation method. The varying compositions have a strong effect on achieving the martensitic transformation (MT) at ∼77 K where only a few SMAs can exhibit such transformation temperature below the boiling point of liquid nitrogen (LN2). Hence, the results indicated that the CuAlMn SMA could be favorable for cryogenic actuation and super-elastic applications. Moreover, we have observed maximum actuation of SMA bimorph of ∼ 4.5 mm during low-temperature (up to 77 K) exposure. Further, we have recorded that the response time of the actuator during cryogenic exposure is ∼60 msec which is quite faster than other actuation devices. © 2025 Elsevier B.V.