Effect of Impurities on the Phase Composition and Properties of a New Alloy of the Al–Y–Er–Zr–Sc System

Abstract

A comparative study is provided for the effect of Si and Fe impurities in relation to their concentration in the structure, phase composition, and mechanical properties of alloy Al–0.2Y–0.3Er–0.2Zr–0.05Sc. With a content of Fe and Si (in the amount of 0.15%), presence is noted of phases formed by iron and silicon impurities with an increased concentration of Zr, Er, and Y. These phases are not found in the structure of alloy with a lower concentration of Fe and Si (0.01%). Due to dilution of aluminum solid solution with Zr, Er and Y, alloy with an increased Fe and Si (0.15%) content shows a weaker hardening effect during annealing compared to alloy having a more supersaturated solid solution. Sc in both alloys is evenly distributed within the matrix of aluminum solid solution and does not form phases during crystallization. It is shown that the temperature for the start of recrystallization for these alloys is in the range 500–550 °C. The set of standard mechanical properties for sheet produced from these alloys is almost at the same level: yield strength of 155 MPa, ultimate strength of 166 MPa, elongation at 11.2% for alloy with 0.15% (Fe and Si) and 8.7% for alloy with 0.01% (Fe and Si). It is noted that after annealing (200 °C, 1 h) sheets hardness increases by 5 HV, which may point to aluminum solid solution decomposition.