Nonisothermal calorimetric study of the precipitation processes in a Cu–1Co–0.5Ti alloy

• Published in: Journal of thermal analysis and calorimetry 2010-06, Vol.100 (3), p.975-980
• Main Authors: Donoso, E., Zúñiga, A., Diánez, M. J., Criado, J. M.
• Format: Article
• Language: English
• Subjects: Analysis; Analytical Chemistry; Applied sciences; Calorimetry; Chemistry; Chemistry and Materials Science; Cobalt; Copper base alloys; Differential scanning calorimetry; Engineering techniques in metallurgy. Applications. Other aspects; Exact sciences and technology; Inorganic Chemistry; Mathematical analysis; Measurement Science and Instrumentation; Metals. Metallurgy; Nucleation; Others aspects; Physical Chemistry; Polymer Sciences; Precipitation; Rain and rainfall; Specialty metals industry; Titanium alloys; Transmission electron microscopy
• ISSN: 1388-6150; 1588-2926; 1572-8943
• DOI: 10.1007/s10973-009-0642-y

The precipitation processes in a Cu–1.0 at.%Co–0.5 at.%Ti (Cu–1.5 at.%Co 2 Ti) alloy were studied using differential scanning calorimetry (DSC), transmission electron microscopy (TEM), and microhardeness measurements. The analysis of the calorimetric curves from room temperature to 900 K shows the presence of two exothermic reactions attributed to the formation of CoTi and Co 2 Ti particles in the copper matrix. On the basis of enthalpy calculations, it was found that the decomposition begins with the precipitation of CoTi, followed by the formation of Co 2 Ti particles. The activation energies calculated using the modified Kissinger method were lower than the ones corresponding to diffusion of cobalt and titanium in copper. Kinetic parameters were obtained by a convolution method based on the Johnson–Mehl–Avrami (JMA) formalism. The values obtained for the parameter n were indicative of a particle nucleation process from preexistent nuclei. Microhardness measurements and TEM micrographs confirmed the formation of the mentioned phases.