Effect of Fe and Si on the Structure and Mechanical Properties of Complex Al-Zn-Mg-Cu Alloys Produced by P/M and Casting Techniques

Abstract

In order to establish the possibility of using recycled aluminum, which usually has an increased content of Fe and Si, the structure and mechanical properties of high-strength Al-Zn-Mg-Cu alloys additionally alloyed with only Fe and Si as well as additionally alloyed with Mn, Zr, Sc, Fe and Si were studied. Rods were manufactured from ingots cast into water-cooled copper molds as well as by a P/M technique using powders atomized from the melt by high-pressure water. The microstructure and distribution of elements in the starting condition and in the T6 treated extruded rods were studied by OM and SEM techniques and compared with rod tensile properties. An addition of Fe up to 1 wt.% led to a 5–7% increase in strength. This increase was accompanied by a decrease in ductility in the cast and cast-and-wrought alloys. In alloys prepared by P/M the technique, the addition of Fe led to about 20% increase in strength, as compared to the baseline alloy, without any detrimental effect on elongation. An addition of ≥0.5 wt.% Si to the P/M alloys decreased strength and slightly increased ductility. Thus, reasonable properties were obtained in high strength Al-Zn-Mg-Cu alloys containing significant amounts of Fe and Si.