Improving mechanical properties of heterogeneous Mg-Gd alloy laminate via accumulated extrusion bonding

In this study, accumulative extrusion bonding (AEB) was used to process Mg-1Gd/Mg-13Gd laminated composites, in which the Mg-13Gd layers had much finer grains than the Mg-1Gd layers. This grain size difference was maintained after 2-pass, but diminished after the 3-pass. The 2-pass composite samples exhibited an excellent combination of ultimate tensile strength (291 MPa), elongation (20.6%) and yield strength (144 MPa), which are much superior than the individual component materials. Moreover, the 2-pass samples also exhibited maximum extra strength and ductility that is higher than what is predicted by the rule-of-mixture. The observed high strength and ductility are mainly attributed to back-stress strengthening and work hardening, respectively. The 2-pass samples exhibited the highest back stress, indicating an optimum laminate thickness for producing the highest back stress hardening. This work provide a new understanding on the design of heterogeneous laminated Mg alloys for improving mechanical properties.