Improving mechanical properties of pure Zn by alloying with Mg and Zr and subsequent equal-channel angular pressing

A study of the effect of equal-channel angular pressing (ECAP) and alloying with 1.7 wt.% Mg and 0.2 wt.% Zr on microstructure, mechanical properties, and corrosion resistance of pure Zn was conducted in this article. The research showed that alloying leads to the formation in the Zn-1.7%Mg-0.2%Zr alloy of a two-phase state consisting of dendrites of α-Zn and an eutectic layer surrounding these dendrites, which is up to 30 μm thick and consists of Zn2Mg and Zn11Mg2 phases. After annealing of the Zn-1.7%Mg-0.2%Zr alloy, the thickness of the eutectic phase layer decreases to about 5 μm. This phase is still located along the boundaries of α-Zn grains, which have an average size of 20–30 μm. ECAP of the Zn-1.7%Mg-0.2%Zr alloy results in elongation of α-Zn grains along the deformation direction (grains width 5–7 μm) and formation of spherical inclusions of eutectic phase sized 3–5 μm. Alloying of pure zinc with Mg and Zr increases its yield stress (σ0.2) and ultimate tensile strength (σB) by three times but reduces elongation almost to zero level. At the same time, there is additional increase in strength to values of σ0.2 = 245 ± 2 MPa, σB = 295 ± 5 MPa, and slight improvement in ductility to value of δ = 2.3 ± 0.4% after ECAP. It was demonstrated that neither alloying nor ECAP affects the resistance of Zn to electrochemical and chemical corrosion. The average degradation rate of studied materials after 7 days incubation in solution based on DMEM (Dulbecco's Modified Eagle Medium) does not exceed 0.25 mm/year.