United Company “RUSAL”, Moscow, Russia.:

A. N. Alabin, Head of a Project

National University of Science and Technology “MISiS”, Moscow, Russia:
N. A. Belov, Professor of a Chair Casting Technologies and art metal processing
N. Yu. Tabachkova, Assistant Professor of a Chair of Materials Science of Semiconductors and Dielectrics

Baikov Institute of Metallurgy and Materials Science, Moscow, Russia:
T. K. Akopyan, Researcher of Engineering Center “Casting Technologies and Materials” e-mail: aktorgom@gmail.com

Aluminium, possessing a high electrical conductivity, is widely used in electrical products, where this quality is the basic one. Recently, there has been increased the interest from power industry in thermally stable aluminium alloys, which should combine high electrical conductivity and strength stability after the heatings up to 300 ^oC. To solve this problem, the most promising approach is to develop alloys with zirconium and scandium additives. These elements promote the formation of L1₂ nanoparticles (Al₃Zr, Al₃Sc and Al₃(Zr, Sc)), which enables both the required strengthening and thermal stability. In the present work there was studied the influence of composition and parameters of strain-thermal treatment on the structure (OM, SEM, TEM), strength (UTS, YS), electrical resistivity (ρ) and thermal stability of Al – Zr – Sc alloys containing up to 0.64% (wt.) Zr and up to 0.30% (wt.) Sc. The Thermo-Calc software was used for calculation of liquidus temperatures, the solubilities of Zr and Sc in aluminium solid solution and volume fractions of L12 nanoparticles. In hardened state the additions of Zr and Sc significantly increase  value, which is possible to decrease by application of annealing. Parameters of annealing have to be chosen proceeding from ultimate concentration of Zr and Sc in aluminium solid solution and rate of decomposition of the last one. Using desirability function it is shown that ternary alloy Al – 0.24% Zr – 0.1% Sc has the best combination of strength, electrical resistance and thermal stability. After holding at 300 ^oC during 500 hours, it has the following properties: ρ = 28.3.10^–9 Ωm·m, YS = 165 MPa, UTS = 186 MPa.

This scientific work was carried out with the support of the grant of the Russian Scientific Funds No. 14-19-00632.

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