Effect of texture and twinning on mechanical properties and corrosion behavior of an extruded biodegradable Mg–4Zn alloy

Abstract

Microstructure, texture, mechanical properties and corrosion behavior of the extruded Mg–4Zn alloy, as a biodegradable material, were investigated. A refined microstructure caused by dynamic recrystallization (DRX), and a general fiber texture were achieved after extrusion. Mechanical properties along different directions of the extruded samples were investigated using shear punch test (SPT). The shear yield stress (SYS) of 113.8 MPa obtained in the transverse direction (TD) was higher than the 106 MPa achieved for the extruded direction (ED) and 45˚ samples. This was attributed to the higher amounts of twins and also lower Schmid factor (SF) in the TD. On the other hand, encouraged activation of the basal slip system in the 45˚ samples resulted in improved room temperature formability, as indicated by the normalized displacement in the SPT diagram. Electron back scattered diffraction (EBSD) analysis of the surfaces corroded in the phosphate buffered saline (PBS) solution, showed that despite having similar grain sizes and second phase particles shape and volume fractions, surfaces containing grains near (0001) orientations and extension twins (TD and 45˚ samples) have lower corrosion rates, as compared to the ED specimens. Keywords: Mg–Zn alloy, Corrosion rate, Dynamic recrystallization, Texture, Twinning