Severe plastic deformation (SPD) with deformation strain significantly larger than one is effective to strengthen metals and alloys. However, such a method will not work for Mg alloys due to their low deformability. In view of this problem, we propose a new alloy strengthening scheme of low-strain deformation, which is to introduce massive twins and stacking faults in coarse grain interior by rotary swaging (RS) at room temperature. By using this scheme, we successfully prepared an ultra-light bulk Mg-Li alloy with new strength record. GRAPHICAL ABSTRACT IMPACT STATEMENT This paper explored a new strengthening way of low deformation strain for metals and alloys and successfully prepared a strongest ultra-light Mg–Li alloy by low-strain rotary swaging process.

Al(1060)/Mg(AZ31)/Al(1060) multilayered composite was successfully produced using an accumulative roll bonding (ARB) process for up to four cycles at an elevated temperature (400 °C). The microstructure evolution of the composites and the bonding characteristics at the interfaces between Al and Mg layers with increasing ARB cycles were characterized through optical microscopy, field emission scanning electron microscopy (FESEM) and transmission electron microscopy (TEM). It was found that the grains of Al and Mg layers were significantly refined and Al₃Mg₂ and Al₁₂ Mg₁₇ intermetallic compound layers formed at the Al/Mg bonding interfaces. The strength increased gradually and the ultimate tensile strength (UTS) reached a maximum value of about 240 MPa at the third pass. Furthermore, the strengthening mechanism of the composite was analyzed based on the fracture morphologies.