Fabrication and Characterization of Ternary CuAlMn Shape Memory Alloy with Novel Operation Temperatures
Shape memory alloys (SMAs) have reached a numberless utilization in a wide range areas of modern technology over the last few decades. This is mostly because these smart materials have some very useful distinctive properties such as shape memory effect (SME), and superelasticity (SE), or damping. The most commonly preffered SMAs due to the superior SME and SE properties are the expensive NiTi alloys that constitute a majority commercial SMAs. Therefore, been regarded as the closest alternative to NiTi SMAs, the cost effective and easierly processable Cu-based SMAs are focused by researchers in SMA related areas in order to improve their SMA properties by some methods. Adding one or more grain refining alloying elements (Mn, Ni) to binary Cu-based SMAs (e.g. Cu-Al) is one of such ways. One of the resultants, the ternary CuAlMn Heusler SMAs have already proved their good SMA properties and these SMAs can potentially be improved more by future research. In this work, the Cu-rich ternary CuAlMn SMA with minor amount of Mn content was fabricated by arc melting technique. After homogenizing the alloy in β-phase region and quenching it in ice-brine water to form the β1’ martensite phase in the alloy, the SME properties were loaded in the alloy. The SME features of the produced CuAlMn SMA were studied by conducting some calorimetric and structural measurements. The differential scanning calorimetry (DSC) tests were performed to reveal the pairs of interchanging opposite-way endo/exo martensitic phase transformation peaks on the heating and cooling fragments of the DSC curves of the alloy as a sign of SME property of the alloy. The characteristic martensitic transformation temperatures and the enthalpy change values of the alloy were directly obtained by DSC peak analyses. Some other thermodynamical parameters of martensitic transformations of the alloy such as the hysteresis gap, entropy change values and equilibrium temperature were also calculated. The high temperature behavior of the CuAlMn alloy was observed by doing differential thermal analysis (DTA) measurement. The composition of the alloy (at.%) was determined by EDX test performed in room conditions. The X-ray measurement conducted at room temperature displayed and proved the successful formation of martensite structures. The results showed that the produced CuAlMn alloy has SME properties and its own martensitic transformation temperatures that can be included in the SMA properties spectrum of CuAlMn SMAs present in the literature.