Microstructure and mechanical properties of the AZ31/GW103K bimetal composite rods fabricated by co-extrusion

The AZ31/GW103K bimetal composite rods consisting of a soft AZ31 sleeve and a hard GW103K core were fabricated by the co-extrusion at 350 °C, 400 °C and 450 °C, and their microstructure and mechanical properties were investigated. The results show that the AZ31/GW103K bimetal composite rods have favorable bonding interfaces at above three extrusion temperatures, and the interfacial layer thickness thickens with the increase of the extrusion temperature. Compared with the monolithic extrusion, the co-extrusion promotes the growth of grains in the AZ31 sleeve but makes grains in the GW103K core to be refined. The AZ31/GW103K bimetal composite rod has higher compressive yield strength and compressive strength than the monolithic AZ31 rod, and the plasticity is similar to that of the monolithic AZ31 rod. Compared with the monolithic GW103K rod, the AZ31/GW103K bimetal composite rod has better plasticity. As the volume fraction of GW103K in the AZ31/GW103K bimetal composite rod increases, its strength gradually increases. Compared with the monolithic AZ31 and GW103K rods, the co-extrusion enhances the texture intensity of the AZ31 sleeve and the GW103K core, but their texture types are hardly changed. The AZ31/GW103K bimetallic composite rod extruded at 350 °C has the thinnest interfacial layer and its yield strength is nearest to the rule of mixture (ROM) predicted value when co-extruding at this extrusion temperature.