Enhanced strength and toughness of bulk ultrafine grained Cu by nacre-inspired lamellar structure

An ultrafine grained (UFG) bulk Cu with a novel nacre-inspired lamellar structure containing nano-bridges and aligned nanopores at inter-lamellar interfaces was fabricated by consolidation of a nanocrystal-attached ultrathin Cu flake powder by spark plasma sintering with a relatively lower pressure (50 MPa) followed by hot rolling. It was discovered that the bulk UFG Cu with such a novel structure has both higher strength and higher toughness (static toughness) than its counterpart with a conventional UFG structure, despite the latter has a perceived better metallurgical quality as evidenced by a lower content of pores. The formation mechanism of the nacre-inspired microstructure in bulk Cu and its correlation with strengthening and toughening mechanisms were illustrated. (C) 2020 Elsevier B.V. All rights reserved.