Heterogeneous fiberous structured Mg-Zn-Zr alloy with superior strength-ductility synergy

Here we reported a heterogeneous fiberous structured Mg-5.6Zn-0.6Zr (wt%) alloy obtained by conven-tional extrusion method, which exhibited high yield strength of -345 MPa, ultimate tensile strength of -370 MPa, and high tensile strain of -20.5%, superior to most of the Mg-Zn based alloys reported so far. The extraordinarily high mechanical properties were mainly attributed to the heterogeneous fiber-ous structure consisting of alternating coarse-and fine-grain layers. Grains in the different layers grew into the neighboring layers, ensuring a good layer bonding. A high Schmid factor and geometric compat-ibility factor for pyramidal slip led to full slip transfer between the neighboring coarse grains and fine grains, which could help to release the stress concentration and avoid early fracture. The profuse acti-vated < c + a > glide dislocations could render the unprecedented high tensile strain. The constraint by the hard fine-grain domains made the soft coarse-grain domains strong like the hard fine-grain domains, as well as the nanoscale precipitates pinning dislocations, contributed to the high strength. The hetero-geneous microstructure design was shown to have synergistic improvement in strength-ductility balance, which could be an inspiring strategy to improve mechanical properties of hexagonal close-packed (hcp) metals. (c) 2022 Published by Elsevier Ltd on behalf of The editorial office of Journal of Materials Science & Technology.

Automated summary

A heterogeneous fiberous Mg-5.6Zn-0.6Zr alloy with high strength and strain was reported, attributed to the alternating coarse-and-fine-grain layers and slip transfer mechanism. The heterogeneous microstructure design is of great significance for improving the mechanical properties of hexagonal close-packed metals.