Abstract
Two quaternary Cu-Al-Mn-Ag shape memory alloys with nearly constant Al and Ag contents and variable content of Mn were prepared by arc melting of pure metals. Experimentally determined overall compositions of the investigated alloys were Cu-9.4%Al-1.1%Mn-3.7%Ag (alloy 1) and Cu-9.5%Al-5.6%Mn-3.9%Ag (alloy 2) (in wt.%). Microstructures of the prepared samples were investigated in the as-prepared condition and after heat treatment, which included solution annealing at 850 °C and quenching into the ice water.
The effects of alloy composition and heat treatment on the microstructure and transformation temperatures of the investigated shape memory alloys were investigated using scanning electron microscopy with energy dispersive spectroscopy (SEM-EDS) and differential scanning calorimetry (DSC). It was determined that alloy with low Mn content (alloy 1) exhibits martensite + α microstructure in the as-prepared state and the as-quenched state. The volume fraction of α-phase was much larger in the as-prepared condition. Ag was uniformly distributed between the co-existing phases. The microstructure of the alloy with a higher content of Mn (alloy 2) was fully martensitic in both investigated conditions. Martensite and austenite transformation temperatures were investigated using DSC.

Key words
shape memory alloy, Cu-Al-Mn-Ag alloy, microstructure, martensitic transformation

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