RAPID COMMUNICATION Thermal and structural characterization of Cu–Al–Mn–X (Ti, Ni) shape memory alloys C. Aksu Canbay • Z. Karagoz Genc • M. Sekerci Received: 15 January 2014 / Accepted: 9 March 2014 / Published online: 3 April 2014 Ó Springer-Verlag Berlin Heidelberg 2014 Abstract In this study, the Cu–Al–Mn–X (X = Ni, Ti) shape memory alloys at the range of 10–12 at.% of alu- minum and 4–5 at.% manganese were produced by arc melting. We have investigated the effects of the alloying elements on the transformation temperatures, and the structural and the magnetic properties of the quaternary Cu–Al–Mn–X (X = Ni, Ti) shape memory alloys. The evolution of the transformation temperatures was studied by differential scanning calorimetry with different heating and cooling rates. The characteristic transformation tem- peratures and the thermodynamic parameters were highly sensitive to variations in the aluminum and manganese content, and it was observed that the nickel addition into the Cu–Al–Mn system decreased the transformation tem- perature although Ti addition caused an increase in the transformation temperatures. The effect of the nickel and the titanium on the thermodynamic parameters such as enthalpy and entropy values was investigated. The struc- tural changes of the samples were studied by X-ray dif- fraction measurements and by optical microscope observations at room temperature. It is evaluated that the element Ni has been completely soluble in the matrix, and the main phase of the Cu–Al–Mn–Ni sample is martensite, and due to the low solubility of the Ti, the Cu–Al–Mn–Ti sample has precipitates, and a martensite phase at room temperature. The magnetic properties of the Cu–Al–Mn, Cu–Al–Mn–Ni and Cu–Al–Mn–Ti samples were investigated, and the effect of the nickel and the titanium on the magnetic properties was studied. 1 Introduction The martensitic transformation is a diffusionless phase transition in the solid state. In this transformation, the atoms keep on moving comparatively in regard to their neighbours. The thermoelastic martensitic transformations are responsible for the shape change from martensite to the austenite phase or from austenite to martensite phase (M$A) in the shape memory alloys (SMAs). The phase change process occurred in these materials, which was obtained repeatedly on cooling and heating. In this respect, the shape memory effect is linked from an ordered aus- tenite phase (b-phase) to the martensite phase [1, 2]. With the development of the technology, the SMAs have been considered as a possible alternative to the tra- ditional materials because of their excellent properties such as shape memory effect (SME), pseudoelasticity (PE), low manufacturing cost and their advantages with regard to the electrical and thermal conductivities [3]. Among the shape memory alloy systems, the Cu–Al binary systems are paid conspicuous attention to by researchers in the SMA research field [4–7]. However, the Cu–Al-based SMAs have high elastic anisotropy leading to poor mechanical properties, easy intercrystalline failure and the short fatigue cycle life. In recent years, many studies have been carried out in order to improve the properties of Cu–Al systems by adding other elements such as Mn, Ni and Be [8]. The addition of the Mn to the binary Cu–Al system has resulted in enhanced ductility, which is very important for practical applications [9]. In the Cu–Al–Mn SMAs, the low alumi- num and the high manganese content showed good C. A. Canbay (&) Department of Physics, Faculty of Science, University of Firat, 23119 Elazig, Turkey e-mail: caksu@firat.edu.tr Z. K. Genc  M. Sekerci Department of Chemistry, Faculty of Science, University of Firat, 23119 Elazig, Turkey 123 Appl. Phys. A (2014) 115:371–377 DOI 10.1007/s00339-014-8383-6