Effect of microalloying on the structure and mechanical properties of Al—Zn—Mg—Cu wrought alloys

Abstract

The possibilities of improving of the mechanical properties of Al—Zn—Mg—Cu alloys due to additional microalloying were studied. As an alloying additives used the next complexes: Sc + Zr and Sc + Zr + Hf + Cr. Semiproducts of investigated alloys were obtained as rods with a diameter of 8 mm (extraction ratio μ = 58) and as strips with cross-section of 7 × 32 mm (extraction ratio μ = 10,6). It is shown that microalloying of base alloy by Sc and Zr after heat treatment leads to the formation of secondary coherentbonded with matrix nanoparticles Al₃Sc(L1₂). With the microalloying by Sc, Zr and Hf these elements are part of intermetallic Al₃(Sc, Zr, Hf). Due to the applied technology the base alloy Al—Zn—Mg—Cu in the form of rods and strips demonstrated a high level of mechanical properties enough. Microalloying by Sc and Zr allowed increase the tensile strength properties of rods more than 30% and increase the fatigue strength at 65%. Alloying the base alloy by Sc, Hf, Zr, Cr can significantly improve all mechanical properties of semiproducts: for rods YS = 746 МPа, UTS = = 785 МPа, El = 11%, σ_0,1 = 510 МPа; for strips — YS = 670 МPа, UTS = МPа, El = 9,6%, σ_0,1 = 210 МPа. Full text download