Internal friction and heat resistance of Al, Al–Ce, Al–Ce–Zr and Al–Ce–(Sc)–(Y) aluminum alloys with high strength and high electrical conductivity

Abstract

To study the application performances of new aluminum alloy conductors, dynamic mechanical analysis and microstructure observation were used to characterize the heat resistance and internal friction. Severe recrystallization occurred in Al and Al–0.2Ce alloy above 320 °C. The hardness and electrical conductivity of Al decreased from 40.3 to 22.2 HV and 61.58 to 60.87 %IACS after temperature scanning from 50 to 500 °C, which was mainly attributed to the enhancement of electron scattering by recrystallized grain boundaries. The co-addition of Sc and Y element can obtain the best heat resistance. The diameter of Al3Sc precipitates enriched with Y atoms is lower than 40 nm under high temperature (400–500 °C) and the recrystallization behavior can be effectively inhibited by Al3Sc precipitates. The internal friction of Al, Al–0.2Ce and Al–0.2Ce–0.1Y alloys mainly originates from dislocation motion before PR peaks and the growth of recrystallization grains after PR peaks. The internal friction of Al–0.2Ce–0.2Sc and Al–0.2Ce–0.2Sc–0.1Y alloys increases evenly because of the strong pinning effect of Al3Sc precipitates on dislocations and boundaries. The internal friction is composed of weak dislocation motion and boundaries relaxation. Finally, the internal friction of Al–0.2Ce–0.12Zr alloy under high temperature is complicated and affected by the precipitation behavior of Al3Zr precipitates, dislocations motion, the interaction between Al3Zr precipitates and dislocations, recrystallization processes.