Evolution of microstructure and texture during hot rolling and subsequent annealing of the TZ73 magnesium alloy and its influence on tensile properties

摘要

The current focus of research in Mg alloys is to develop wrought Mg-based alloys suitable for automotive applications. The challenges to be overcome are low strength, poor ductility, and high cost associated with Mg-based alloys. With this objective, wrought Mg-7Sn-3Zn (TZ73) alloy has been developed in the present work, which does not contain expensive Rare-Earth (RE) elements and has much higher strength than the most commonly used commercial AZ31 alloy. The alloy was produced by squeeze casting process. The hot rolled (HR) sheet exhibited very high strength (0.2% PS: 315 MPa and UTS: 362 MPa) and reasonable elongation-to-failure (El): 9%, which are higher than any commercial rolled Mg-based alloy. The high strength is attributed to solid solution strengthening and fine grain size. Annealing of the HR sheet at 215 °C reduced strength (0.2% PS: 218 MPa and UTS: 311 MPa) and increased elongation-to-failure (18%). Annealing leads to 99% recrystallized grains, which resulted in higher elongation-to-failure for the hot rolled-annealed (HRA) sheet. The dissolved Zn and Sn atoms also activate non-basal slip systems, which leads to spreading/splitting of basal pole intensity along the rolling direction (RD) resulting in higher elongation-to-failure.