Microstructure and mechanical performance of the YSZ/Al₂O₃ hybrid surface composite on AZ31 Mg alloy by friction stir processing

Abstract This study aims to fabricate the hybrid yttria-stabilized zirconia (YSZ)/Al 2 O 3 surface composite on the AZ31 magnesium (Mg) alloy through friction stir processing (FSP). The base alloy center surface was turned to provide a 1 × 2 mm groove to fabricate the friction-stirred surface composite using the tapered cylindrical tool. The microstructural and mechanical behavior of the hybrid surface composite (FHSC) results were compared with the Al 2 O 3 -reinforced surface composite (FASC), the FSP-treated sample, and the base alloy. In terms of microhardness performance, the FHSC exhibits a 10% improvement over the FASC, a 32% improvement over the FSP treated alloy, and a 95% improvement over the base alloy. Additional FHSC samples exhibit improved impact resistance of around 30% over the FASC, 81% over the FSP treatment, and 226% over the base alloy. Furthermore, FHSC samples outperform FASC by about 15%, FSP-treated alloys by 59%, and base alloys by 95% in terms of tensile strength augmentation. This is due to the synergistic effects of both Al 2 O 3 and YSZ particles, which significantly strengthen the interfacial bonding between the matrix. This results in substantially enhanced interface adhesive behavior between the base alloy and ceramic particles and leads to enhanced mechanical characteristics.