Mechanical and corrosion properties of Zn-0.5 Mg and Zn-1.0 Mg alloys processed by HPT

In the present study the structural, mechanical, and corrosion properties of Zn alloys with Mg after severe plastic deformation by high pressure torsion (HPT) were investigated. The structural investigations included techniques such as electron back scatter diffraction, scanning electron microscopy, and X-ray texture measurements. Mechanical properties were studied by tensile tests along and perpendicular to the extrusion direction, not only at room temperature (RT) but also at 40 °C to simulate human body conditions. The corrosion properties were determined by the immerse method in a simulated body fluid solution. It was found that HPT significantly increases the tensile strength and reduces the strong mechanical anisotropy of the as-extruded material due to strong grain refinement and texture transformations. The tensile strength in the samples tested at 40 °C was lower than that tested at RT but still much higher than in as-extruded samples, and the plasticity was higher. However, all tension tests of HPT-processed alloy samples showed significant dynamic recrystallization. The observed steady drop of stress can be related to heterogenous dynamic recrystallization with nuclei out of Zn2Mg11. The corrosion investigations revealed that HPT increases the corrosion rate of the ZnMg alloys which, however, stabilizes at longer corrosion times.