Siberian State Industrial University, Novokuznetsk, Russia:

I. F. Selyanin, Professor (Chair of Materials Science, Foundry and Welding)
A. I. Kutsenko, Assistant Professor, Head of Department of Scientific Researches
O. G. Prikhodko, Assistant Professor, Head of Education-Methodical Center

National University of Science and Technology “MISiS”, Moscow, Russia:
V. B. Deev, Chief Researcher of Engineering Center “Foundry Technologies and Materials”, Professor of a Chair of Foundry Processes Technology, e-mail: deev.vb@mail.ru

Absolute thermal e. m. f. of metals and alloys is functionally connected with parameter of electron-phonon interaction and linear expansion coefficient. This coefficient makes an influence on increase of a sample volume with its heating, which leads to difference of values of Fermi levels of hot and cold sides of the sample. At the same tine, this leads to a positive component in general thermal e. m. f. balance. The first temperature derivative of linear expansion coefficient, which is included in expression of positive thermal e. m. f. component, is calculated for copper, silver and gold, which have reliable experimental data of thermal e. m. f. and linear expansion coefficients (up to ultra low temperatures). Maximum of positive thermal e. m. f. sign (25 K for silver, 30 K for gold and 70 K for copper) completely coincides with maximum positive value of the first temperature derivative of linear expansion coefficient. The general expression for diffusive thermal e. m. f. is analytically proved. It is necessary to carry out the following operations for development of consistent theory of thermal e. m. f. of metals and alloys, suitable to experimental data:
— experiments for determination of thermoelectric properties and temperature dependence of thermal expansion coefficient in large temperature interval, including ultra low and above-melting temperatures;
— definition of difference of temperatures of hot and cold sides of the sample.
Thermal e. m. f. theory considers the main characteristic peculiarities of a power range of electrons at the Fermi level, and peculiarity of coefficient of volume expansion of metals and alloys in a wide interval of temperatures (including a liquid state). This theory allows metallurgists and metallographers to make the interpretation of received experimental results at microlevel, and to create the consistent modifying and alloying theories, where only macroscopic and phenomenological parameters are still used.

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