Martensitic transformation and thermal cycling effect in Cu–Co–Zr alloys

Cu50−xCox Zr50 (x = 0, 0.5, 1, 2, 3, 4 and 5 at.%) alloys were cast in a cylindrical copper mold by a suction casting device. In order to investigate the thermal behavior of the as-cast rods, the samples were heated from 313 to 573 K and then cooled down to about 253 K. The structure of the samples was studied by X-ray diffraction and optical microscopy. Thermal cycling measurements were also done for alloys with 2, 3, 4 and 5 at.% cobalt. It was found that increasing the cobalt content decreases martensite (Ms) and austenite (As) start temperatures, while it increases the temperature region in which austenite is stable. Thermal cycling measurements revealed that by increasing the number of cycles, the austenite start temperature increases while martensite start temperature shifts to lower temperatures.