THE EFFECT OF ROTARY SWAGING ON THE STRUCTURE, MECHANICAL AND CORROSION PROPERTIES OF THE Mg-1.1%Zn-1.7%Dy ALLOY

Abstract

In this work, the effect of rotary swaging (RS) with a deformation degree (ε) equal to 1.28 and 2.31 on the microstructure, corrosion resistance and mechanical properties of a potential medical alloy Mg-1.1%Zn-1.7%Dy was studied. It was shown that RS at ε = 1.28 leads to a grain refinement of the studied alloy by 10 times (from ~300–400 µm to ~30–40 µm). An increase in the deformation degree up to ε = 2.31 leads to the formation of an inhomogeneous microstructure with regions containing both grains ~30–40 µm in size and zones with grains ~5–10 µm in size. Grain refinement after Rs leads to an increase in resistance to electrochemical corrosion (corrosion potential increases from -1550 ± 9 mV in the quenched state to -1442 ± 23 and -1454 ± 35 mV after RS at ε = 1.28 and ε = 2.31, respectively), but does not cause a change in the current density. But the degradation rate of the alloy increases with an increase in the deformation degree up to 3.46 ± 1.06 mm/y. The structure refinement after RS at ε = 1.28 leads to a significant increase in the strength of the alloy in comparison with the quenched state (ultimate tensile strength (UTS) increases from 70 ± 13 to 273 ± 7 MPa) with a drop in ductility from 23.1 ± 5.1 to 14.0 ± 2.9%. An increase in the deformation degree up to ε = 2.31 does not lead to an increase in the strength of the alloy (UTS = 267 ± 4 MPa), but causes an increase in ductility (δ = 21.1 ± 1.6%), apparently due to texturechanges, occurring in the alloy.