Thermodynamic properties of liquid alloys of the Sb-Sc system

DOI: 10.62564/M4-VS1639

Valentina Sudavtsova¹, Larysa Romanova¹, Michael Ivanov¹, Volodymyr Kudin<sup>2

1</sup>Frantsevich Institute for Problems of Materials Science National Academy of Science of Ukraine
²Taras Shevchenko National University of Kyiv, Ukraine


Enthalpies of alloy formation in the Sb-Sc system have not been previously studied because scandium is refractory metal whereas stibium is extremely volatile. In this study, for the first time, the mixing enthalpies of melts in the Sb-Sc system were determined by the calorimetric method in wide concentration regions at 1413-1423 K. The minimum of the integral enthalpy of mixing is –44.8 ±2.3 kJ/mol is observed near the equiatomic composition. Such significant exothermic effects are explained by the large difference in electronegativities of the components. The limiting partial enthalpies of the components are –125±4 kJ/mol for scandium and –129±9 kJ/mol for stibium. In order to monitor how ΔН min of liquid alloys and Δ f H of monostibides in the Sb–3d-metal systems change, as well as predict similar data for unstudied systems, we presented them depending on the serial number of the transition metal. For this purpose, we used the most reliable literature data as well as our data obtained in the present study. It was established that ΔН of melts of the Sс–Sb system obtained in the work correlate with similar data for the Sb–3d-metal systems. In addition, they are the most exothermic. This can be explained by the electronic structure of 3d metals. It is known that there are 9 electrons on the 3d-orbitals of Ni, therefore, when forming alloys with Sb, nickel accepts the outer electrons of the latter, forming a donor-acceptor bond. On the contrary, at the formation of liquid alloys of the Sc–Sb system, most likely, occurs the transition of one electron from the 3d-orbitals of Sc to the outer orbital of Sb. Based on the values of ΔНmin of melts of Sb–3d-metal systems, it can be concluded that the formation of bonds in liquid alloys of the Sc–Sb system is energetically more advantageous than even in melts of the Ni–Sb system.

Keywords
Enthalpies, alloy, Sb-Sc system

Acknowledgments
Not provided

References
[1] Bondarenko T.P., Sudavtsova B.C., Batalyn G.I., Ulyanov V.I. Enthalpies mixing of liquid Fe-Si-Mn alloys // Izv. Academy of Sciences of the USSR. Metals. – 1984. – No. 3. – S.81-82.