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

Abstract

Bioinspired nacre-like structures are effective in toughening materials, yet are difficult to construct in magnesium-ceramic systems. Here, a set of magnesium-MAX phase composites with nacre-like lamellar and brick-and-mortar architectures are fabricated by pressureless infiltration of the magnesium melt into ice-templated Ti3AlC2 ceramic scaffolds. The structure and mechanical properties of the composites are elucidated with a special focus on the effects of the types of architectures (lamellar or brick-and-mortar) and matrices (pure magnesium or AZ91D alloy) on the toughening mechanisms. The nacre-like architectures are 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 achieve a good combination of specific strength and fracture toughness, which are superior to many other reported magnesium-ceramic and nacre-like metal-ceramic composite materials.