Extrusion Temperature-Dependent Mechanical and Degradation Behavior in a Cost-Effective and High-Performance Mg–0.6Zr Alloy

Developing cost-effective and high-performance magnesium alloys is a key focus in lightweight materials applications. In this work, a Mg extrusion alloy with a remarkable cost-performance advantage was prepared by microalloying with cost-effective zirconium and adjusting the deformation temperature. Investigations revealed that both the degree of dynamic recrystallization (DRX) and the average grain size increased with increasing extrusion temperature, developing a more homogeneous microstructure. Although all samples exhibited a typical basal texture, a progressive spreading of crystallographic orientations along the < 10–10 > – < 11–20 > arc became increasingly pronounced with elevated extrusion temperatures. At a low extrusion temperature of 200 °C, the heterogeneous microstructure and strong basal texture favored texture and grain boundary strengthening, resulting in the largest yield strength of ~ 244 MPa. However, the potential difference between coarse and fine grains aggravated localized corrosion with a higher corrosion rate of ~ 14.56 mm/y. Conversely, at a high extrusion temperature of 320 °C, the coarse grains and weak basal texture enhanced dislocation storage and the activation of multiple slip systems during axial tension, providing better strain hardening ability and the largest ductility of ~ 13.6%. Nevertheless, grain coarsening and texture weakening were detrimental to mechanical strength (~ 162 MPa). Interestingly, extrusion at 250 °C developed a good combination of grain size, microstructure homogeneity, and texture intensity, achieving synergistic enhancement in grain boundary strengthening, dislocation storage, and uniform corrosion. Thus, a balanced yield strength of ~ 185 MPa, ductility of ~ 12.9%, and corrosion rate of ~ 4.31 mm/y were obtained in this sample.