Achieving synergistic strength-ductility-corrosion optimization in Mg-Li-Al-Zn alloy via cross-pass friction stir processing

In this study, the cross-pass friction stir processing method was applied to a duplex Mg-Li-Al-Zn alloy, and the mechanical and corrosion behaviors were systematically investigated. Through this method, the grain size of the Mg-Li-Al-Zn alloy was greatly refined with uniform distribution of equiaxed Mg-rich alpha (hexagonal close-packed, hcp) and Li-rich beta (body-centered cubic, bcc) phases. After friction stir processing, the tensile strength increased greatly, with an exceptional simultaneous increase in elongation. Moreover, the corrosion current density of the 2 cross friction stir processed alloys after immersion in 0.1 M NaCl solution for 48 h significantly decreased to 2.8 mu A/cm(2). Through microstructural analyses, it was inferred that the synergistic optimization in strength-ductility-corrosion was closely related to the unique distribution of the alpha/beta phases and ultrafine MgLi2Al precipitates introduced by cross-pass friction stir processing. (c) 2023 Elsevier B.V. All rights reserved.