## 3 Results and Discussion  
As defined in the prior sections, the nominal target composition for the Cu-Al-Mn shape memory alloy that was developed within this study was Cu-16 Al-10 Mn % at., which is due to the expectation of transformation temperatures within the desired range of 50-100 \({}^{\circ}\)C and a high level of workability due to a low level of aluminum content. A qualitative assessment of the microstructure for each SMA sheet was performed. This assessment was completed using optical microscopy to confirm that the obtained microstructure was indeed martensitic. An example of a successful martensitic transformation is provided in Figure 4. The laminar structure, which is characteristic of martensite, was dominant and observed in all samples within the study. Some composition measurements were also performed by generating EDX maps of the samples, which are laid out further in the text. Along with all the composition measurements performed on the Cu-Al-Mn SMA sheets, DSC analysis was used to evaluate the phase transformation capability and the transformation temperatures of the sheets. Additionally, several measurements were also performed using a DMA machine. Both the measured chemical compositions and the transformation properties of the obtained samples are summarized in Table 2 along with the corresponding thermomechanical treatment for each sample. The DSC analysis was performed within the range of -75 and 200 \({}^{\circ}\)C; hence, any samples that did not display signs of phase transformation within this range were considered \"nontransforming\". The lower temperature limit during DSC testing was based on the machine limitations. However, the upper limit temperature was selected because prior studies suggest that heating above the temperature range of about 240 to 300 \({}^{\circ}\)C results in martensitic stabilization and complete loss of the shape memory effect (SME) [7; 22; 23]. In Figure 5, an example of a DSC test performed on a specimen of Cu-Al-Mn sheet is given. \begin{table}
\begin{tabular}{c c c c c c c c c} \hline \hline \multicolumn{6}{c}{**Composition [\% at. ]**} & \multicolumn{6}{c}{**Transformation Temperatures [\({}^{\circ}\)C]**} \\ \hline
**Sample [\%]** & **Mn** & **Al** & **Cu** & **As** & **Af** & **Ms** & **Mf** & **Treatment** \\ \hline  
& 71.7 & 11.01 & 28.53 & 15.41 & 2.71 & HR/CR/AGG 4 \\
22 & 10.3 & 18.2 & 71.5 & & nontransforming & & HR/CR/AGG/T 5 [FOOTNOTE:5]Footnote 5: Data for the modelLooking at the data presented in Table 2, where the samples are sorted according to their respective manganese content and treatment histories, it is possible to see that the phase transformation temperatures of the Cu-Al-Mn SMA sheets are highly sensitive to small changes in the concentrations of alloying elements. The presence of the shape memory effect, or lack thereof, indicated a dependence on the ratio between the measured levels of manganese and aluminum within the Cu-Al-Mn alloy samples, respectively. Based on this observation, in Figure 6, it was possible to group samples according to their transformation capacity which was estimated through DSC/DMA testing. As a rule of thumb, it appears that samples with a ratio of Mn/Al which was above \(\sim\)0.62 retained a persistent shape memory effect across multiple DSC cycles within the range of \(-\)75 and 200 \({}^{\circ}\)C. Conversely, samples for which the ratio of Mn/Al was below \(\sim\)0.57 showed no transformation capacity within the above-mentioned range of testing temperatures. The Mn/Al ratio range between 0.57 and 0.62 of the was indicated separately as the range of \"inconsistent\" phase transformation performance. Testing of the samples within this composition ratio range has resulted in samples with both persistent phase transformation capability as well as those without any clear signs of transformation. Furthermore, three samples initially showed phase transformation behavior; however, it did not persist with further DSC cycling.