The synergy of boundary engineering and segregation strategy towards high strength and ductility Mg-3Gd alloy

Abstract Nanostructured materials prepared by severe plastic deformation processing were puzzled by the trade-off between strength and ductility. With the synergy of boundary engineering and segregation strategy, a nanostructured Mg-3Gd (wt. %) alloy with simultaneously enhanced strength and ductility was fabricated by accumulative roll-bonding processing and subsequent annealing treatment. Based on transmission electron microscopy observations, clear evidences of Gd segregation at grain boundaries, twin boundaries, stacking faults and dislocations can be observed in annealed samples. Meanwhile, the activation of non-basal slip and intensive interaction between dislocations and Gd atoms were determined in the annealed sample after tensile testing. Boundary segregation and pinning of dislocations were considered to be the main reason for the strength enhancement, while the increase in ductility was attributed to the inhibition of premature failure by Gd segregation at twin boundaries and the activation of non-basal slip.