Strong and tough Mg-MAX phase composites with nacre-like lamellar and brick-and-mortar architectures

Bioinspired nacre-like structures are effective in toughening materials, yet are difficult to construct in Mg-ceramic systems. Here, a set of Mg-MAX phase composites with nacre-like lamellar and brick-and-mortar architectures were fabricated by pressureless infiltration of the Mg melt into ice-templated ceramic scaffolds. The structure and mechanical properties of the composites were elucidated with a special focus on the effects of the types of architectures (lamellar or brick-and-mortar) and matrices (pure Mg or Mg alloy) on the toughening mechanisms. The nacre-like architectures were found to play a role in blunting the cracks via plastic deformation and microcracking, and shielding the cracks from applied stress by promoting crack deflection and uncracked-ligament bridging mechanisms. These composites achieved a good combination of (specific) strength and fracture toughness which are superior to other reported Mg-ceramic and nacre-like metal-ceramic composite materials.