The effects of electron concentration on transformation temperature, crystal structure and thermal activation energy of Cu-Al-Fe shape memory alloys

In this study, CuAlFe and CuAlFe-X (X=Ni,Ti,Mn) shape memory alloys which have different electron concentration value were investigated. These Alloys were produced by arc melter furnace several times by using high purity elemental powders. Then, produced alloys were subjected to homogenize at 950 oC for 24 hours. The austenite-martensite transformation temperatures of CuAlFe ve CuAlFe-X (X=Ni,Ti,Mn) alloys were done by thermal anlysis method (by using Differatial Scanning calorimetry-DSC). All of alloys show high temperature shape memory alloys property. According to Kissinger and Ozawa methods activation energy of alloys calculated by using DSC measurement. The crystal structure and microstructure of alloys were determined with x-ray measurement and SEM-EDX measurement. It was seen that 18R martensite structure and Cu9Al4 precipitate phase at x-ray diffractograms. These phases seen at SEM images and also supported by EDX results. CuAlFe-Ti alloy have X-phase different from other alloys. The SEM image and Chemical ratio found at SEM-EDX results. Keywords: Shape Memory Alloys; High Temperature; Activation Energy; Austenite Phase; Martensite Phase