Parametric investigations to enhance the thermomechanical properties of CuAlNi shape memory alloy Bi-morph

Abstract The influence of growth substrate temperature on the development of CuAlNi shape memory alloy (SMA) over Kapton Polyimide sheet and its effect on tuning the thermomechanical behavior has been investigated. The SMA bi-morph was synthesized at varying substrate temperatures ranging from 100 °C–200 °C. Two-way shape memory effect could be demonstrated by the bi-morps without any post-processing and training, due to pre-straining of the flexible substrates. The deposited SMA film was responsible for the forward displacement and the return was achieved because of flexible kapton polyimide substrate. To investigate the life cycle behavior of the as developed SMA bi-morph, an in-house life cycle setup was developed with Joule heating as the actuation source. The cyclic behavior was investigated for 500 cycles, at three varying voltages of 2 V, 2.5 V and 3 V with an actuation frequency of 0.5 Hz. The film deposited with growth substrate temperature of 100 °C and 200 °C showed a maximum displacement of 0.6 mm and 0.9 mm, whereas samples prepared with substrate heating at 150 °C showed a maximum displacement of 2.6 mm with actuation voltage of 3 V. To probe the influence of substrate temperature in tuning the thermomechanical behavior, an analysis on the structural, morphological, and thermal properties of the bi-morphs has been investigated in detail.