The influence of Cu additions on the microstructure and properties of Al–Fe system alloys produced by casting into electromagnetic crystallizer

The modern electrical engineering industry requires cheap and easily reproducible aluminum alloys with advanced mechanical strength and electrical conductivity. This work studies the influence of small (up to 0.3 wt. %) copper additions on the microstructure and physical and mechanical properties, as well as phase transformations in the Al–Fe system alloys with an iron content of 0.5 and 1.7 wt. %, produced by continuous casting into electromagnetic crystallizer. Alloys of the above chemical compositions were produced, and subsequently annealed at 450 °C for 2 h. In all states, the microstructure (via SEM), yield strength, ultimate tensile strength, elongation to failure, and electrical conductivity were studied. It has been shown that copper additions lead to an increase in the strength of both alloys and a slight decrease in their ductility compared to similar materials without copper. An increase in strength and a decrease in ductility due to the copper addition is associated with the formation of more dispersed intermetallic particles in copper-containing Al–Fe system alloys. Additional spheroidizing annealing leads to a decrease in the length of the interphase boundary between the aluminum matrix and iron aluminide particles due to a change in their morphology, which leads to an increase in electrical conductivity. In general, copper-containing alloys showed higher mechanical strength with lower electrical conductivity, as well as higher thermal stability.