Journal of Chemical Technology and Metallurgy, 54, 1, 2019 204 COOLING CONDITION EFFECTS ON TRANSFORMATION TEMPERATURE AND MICROSTRUCTURE OF Cu 81 Al 13 Ni 4 Ti 2 SMA Fethi Dagdelen 1 , M.Sait Kanca 1 , Mustafa Boyrazli 2 ABSTRACT The present communication reports the production of Cu 81 -Al 13 -Ni 4 -Ti 2 shape memory alloy (SMA) by an arc- melting method. A piece of this alloy is subjected to heat treatment at 930 o C for 30 min and then shock-cooled in liquid nitrogen (-196 o C), alcohol (0 o C) and saline ice water (+6 o C). Differential Scanning Calorimetry (DSC) is performed on samples with no heat treatment and on those subjected to three different heat treatments. It is found that the cho- sen heat treatments increase signifcantly the phase transformation temperatures of the shape memory alloy. Some changes in the microstructure of the alloy are also observed after the heat treatment. The grain boundaries become more pronounced, while the martensite plates increase in the samples which are shock-cooled in alcohol and saline ice water. The crystalline structures of the samples are investigated at room temperature. The XRD diffractograms reveal that b ı phase (martensite phases) increases in the alloys subjected to heat treatment. Keywords: shape memory alloy, transformation temperature, martensite phase. Received 21 December 2017 Accepted 27 July 2018 Journal of Chemical Technology and Metallurgy, 54, 1, 2019, 204-208 1 Fırat University, Faculty of Science Department of Physics Elazıg, Turkey E-mail: fdagdelen@frat.edu.tr 2 Fırat University, Faculty of Engineering, Department of Metallurgy and Material Engineering Elazıg, Turkey INTRODUCTION Cu-based shape memory alloys (SMAs) are meta- stable in the β-phase region. They are very sensitive to heat treatment, that is, the heat treatment changes signif- cantly the martensite transformation temperatures [1]. It is also well recognized that the heat treatment affects the microstructure and changes the microhardness of the shape memory alloys. That is why it is essential to select an appropriate heat treatment for such alloys aiming to exhibit the desired transformation temperature [2 - 5]. This study is focused on the production of quater- nary Cu based shape memory alloy by an arc-melting method. The product is subjected to different heat treat- ments, and the subsequent changes in its phase trans- formation temperatures, microstructure and enthalpy values are determined. EXPERIMENTAL 99.9 % pure Cu, Al, Ni and Ti metal powders were mixed with a ceramic ball of 8 mm - 10 mm diameter at determined ratios using a Merck mechanical mixer. These metal powders were pressed into pellets (disc) with a diameter of 13 mm under a pressure of 10 MPa. The pellets were melted in argon atmosphere in an arc-melting system. This process was repeated several times to achieve a homogeneous Cu 81 -Al 13 -Ni 4 -Ti 2 (% by mass) alloy. The latter was cut in separate experimental specimen with a dremel tool. They were heat-treated at 800°C for 1 h in order to remove the cutting hard-strain effect and to ensure homogenization. A specimen was heat-treated at 930 o C for 30 min and then shock-cooled in liquid nitrogen (-196 o C) (sample B1), alcohol (0 o C) (sample B2) and saline ice water (+6 o C) (sample B3). Perkin Elmer Sapphire DSC (Differential Scanning Calorimetry) was used to determine the transformation temperatures and the activation energies of these alloys. Nikon Eclipse MA200 optical microscope measurement systems were used to observe the changes in the alloys microstructure. A methanol solution of 20 ml HCl + 5 gr FeC 3 H 2 O + 96 ml was used as an etchant. The crystal structures were determined at room temperature using an X-ray diffractogram (Bruker Discover D8).