Microstructure and mechanical properties of Mg/Mg bimetal composites fabricated by hot-pressing diffusion and co-extrusion

Abstract

In the present study, the bimetal composite rods composed of a softer AZ31 sleeve and a harder WE43 core were fabricated via a special process by combining hot-pressing diffusion with co-extrusion, with particular attention to the characterization of microstructure and mechanical properties. The results showed that a well-bonded interface with a diffusion layer of ~20 μm in thickness was achieved. The texture in the interfacial region adjacent to the WE43 core changed with the basal poles largely perpendicular to the extrusion direction. Compared with the monolithic Mg billet, the co-extruded AZ31/WE43 bimetal composite rods could achieve a gradient of both composition and microstructure. Such gradients along with the superior interfacial bonding led to a higher compressive and tensile yield strength of AZ31/WE43 bimetal composite rods compared with the AZ31 sleeve. This study indicated that combining hot-pressing diffusion with co-extrusion is an effective method to fabricate the bimetal composites with superior mechanical properties.