Introducing the chemical potential of Cu–Mn–Al alloys for structural, electrical and thermal properties

Abstract

This study investigates the Martensite transition in Cu–Mn–Al alloys (CMAs) via the use of many methods, including scanning electron microscopy, temperature-dependent X-ray diffraction, resistivity and thermal measurements. The Martensite transition hysteresis and characteristic temperature are primarily determined by the alloy composition, crystal structure and residual stress. Furthermore, these alloys have been reported to have surface and crystallographic characteristics often associated with twinning structures. Resistivity experiments conducted during heating and cooling cycles demonstrate a 2.57-fold increase inside the phase change zone, emphasizing the influence of the transition on electrical conductivity. The Martensite transition temperature may be altered by 110 K by the manipulation of the electron-to-atom ratio (e/a), indicating the high susceptibility of this temperature to changes in chemical composition. Differential scanning calorimetry shows that the transition is accompanied by a maximum entropy shift of 48 J kg⁻¹. K, which offers valuable information on the thermodynamic driving factors involved. This work successfully attains a cooling power of 1350 W, which is equivalent to the cooling power of NiTi wire (1500 W), by using a theoretical manufacturing method and optimizing the CMAs. Overall, this work clarifies the Martensite transition in CMAs, highlighting its impact on their characteristics and indicating their potential for effective thermal energy storage and release applications. It is advisable to further optimize their performance and economic viability by considering the e/a ratio.