Insight into corrosion and tribological behavior of solid-state recycling Mg-Gd-Y-Zn-Zr alloys through spark plasma sintering

The paper achieved solid-state recycling of Mg-13Gd-4Y-2Zn-0.6Zr alloy through spark plasma sintering, and investigated the effects of heat treatment and 3 wt.% BN doping on the corrosion and tribological mechanisms of the solid-state recycling billets. The results indicated that microstructural homogenization is the key to enhancing the corrosion resistance of the recycled alloy. The heat treatment facilitated sufficient diffusion of solute atoms, leading to dissolution of the block long-period stacking ordered (LPSO) phase. This reduced the potential difference between the α-Mg matrix and block LPSO phase by 0.1 V (for the SPS-480°C/8 h sample), thereby lowering the driving force for micro-galvanic corrosion. The formation of a dense rare-earth (RE) oxide mechanically mixed layer was induced on the contact surface during shear friction, transforming the wear mechanism into mild oxidative wear with a 0.15 mm 3 reduction in wear volume. In contrast, BN doping provided certain corrosion protection in NaCl solution by forming a physical barrier layer, which improved the Rp to 45.48 Ω·cm 2 , the introduction of heterogeneous interfaces accelerated the corrosion exfoliation of the matrix in Na 2 SO 4 environments. Additionally, the weak bonding interfaces and the detachment of hard BN particles induced three-body abrasion, resulting in significant material loss and deep groove damage. In summary, the heat treatment synergistically enhances the corrosion resistance and wear resistance of solid-state recycled alloys. While BN doping provides localized barrier protection in Cl − environments, the resulting weak and heterogeneous interfaces severely deteriorate both the tribological reliability under sliding wear and the overall structural integrity in SO 4 2− environments.