Unlocking the Mechanism for Achieving Excellent Thermal Stability in Ultra-Thin AZ61 Mg Alloy Foil

Excellent microstructure stability in ultra-thin Mg foils has been pursued for quite a long time. Both complex processing methods and various rare-earth (RE) elements have been tried, but either the minimum reliable thickness or the thermal stability still could not reach the desired result. Now, this work provides common plastic processing methods for preparing commercial AZ61 Mg alloy foil with more excellent thermal stability in comparison to the previously reported RE-containing Mg-rolled sheets and extruded bars. Meanwhile, the specific mechanism for synchronously realizing ultra-thin thickness and excellent thermal stability is unlocked. Prismatic <a> dislocations along different slip planes are responsible for the large rolling reduction at warm temperature. Strong basal texture and nano-scale precipitates collectively contribute to the slow grain growth during annealing treatment. Thus, this work is critical for tailoring ultra-thin RE-free Mg foil with high thermal stability in a low-cost way.