Experimental study and thermodynamic re-assessment of the Co–Sb system

• Published in: Calphad Vol. 68; p. 101694
• Main Authors: Brož, Pavel, Zelenka, František, Vřešťál, Jan, Zemanová, Adéla, Kroupa, Aleš, Buršík, Jiří, Svoboda, Milan, Šimoníková, Lucie, Pokorný, Tomáš
• Format: Journal Article
• Language: English
• Published: Elmsford Elsevier Ltd 01.03.2020; Elsevier BV
• Subjects: Computer simulation; Co–Sb system; Differential thermal analysis; Eutectic reactions; Liquidus; Phase analysis; Phase diagram; Phase diagrams; Thermal stability; Thermodynamic modelling; Thermoelectric materials; Differential thermal analysis; Phase analysis; Thermodynamic modelling; Phase diagram; Co–Sb system
• ISSN: 0364-5916; 1873-2984
• DOI: 10.1016/j.calphad.2019.101694

The Co–Sb system is of a special attention due to existence of CoSb3 skutterudite structure which is the key structure for doped skutterudite based thermoelectric materials. A critical review of this system, performed recently, shows the published thermodynamic assessment may not be fully correct compared to existing studies. Especially, there is a contradiction in the position of the liquidus line on the Sb-rich side of the phase diagram and of the eutectic reaction, liquid ↔ CoSb3 + (Sb). As these data are crucial for the study of thermal stability of skutterudite based thermoelectric materials, a good knowledge on phase relations in the Sb-rich part of the Co–Sb phase diagram is needed. To obtain reliable data, experimental alloys covering 80 to 100 at.% of Sb were prepared and investigated by differential thermal analysis and phase analysis. The data were compared with existing literature information and thermodynamic re-assessment of this binary system based on the CALPHAD approach was done. [Display omitted] •Phase constitution of Co–Sb alloys with xSb = 0.80–0.99 was determined by electron microscopy.•Phase transformation temperatures in the alloys were determined by differential thermal analysis.•Phase diagram based on this new information was constructed and compared with literature.•New assessment of parameters for CALPHAD-type modelling of the Co–Sb system is presented.