Fabrication and performance of 3D co-continuous magnesium composites reinforced with Ti₂AlN_x MAX phase

Magnesium composites reinforced by N-deficient Ti₂AlN MAX phase were first fabricated by non-pressure infiltration of Mg into three-dimensional (3D) co-continuous porous Ti₂AlN_x (x = 0.9, 1.0) preforms. The relationship between their mechanical properties and microstructure is discussed with the assessment of 2D and 3D characterization. X-ray diffraction (XRD) and scanning electron microscopy detected no impurities. The 3D reconstruction shows that the uniformly distributed pores in Ti₂AlN_x preforms are interconnected, which act as infiltration tunnels for the melt Mg. The compressive yield strength and microhardness of Ti₂AlN_0.9/Mg are 353 MPa and 1.12 GPa, respectively, which are 8.55% and 6.67% lower than those of Ti₂AlN/Mg, respectively. The typical delamination and kink band occurred in Ti₂AlN_x under compressive and Vickers hardness (V_H) tests. Owing to the continuous skeleton structure and strong interfacial bonding strength, the crack initiated in Ti₂AlN_x was blocked by the plastic Mg matrix. This suggests the possibility of regulating the mechanical performance of Ti₂AlN/Mg composites by controlling the N vacancy and the hierarchical structure of Ti₂AlN skeleton.