Magnesium matrix composites (MMCs) combine exceptional low density, high specific strength, and stiffness, positioning them as critical materials for aerospace, automotive, and electronics industries. This review highlights recent progress in the fabrication of Ti-Mg composites and analyzes the mechanisms behind their enhanced mechanical properties. A key focus is the interfacial deformation incompatibility between Ti and Mg phases, which generates strain gradients and promotes the accumulation of geometrically necessary dislocations (GNDs) at the interface. This process not only improves strain hardening and ductility but also reveals the need for advanced micromechanical models to capture the plastic behavior of both phases. The review critically examines the impact of different Mg matrix types (AZ, AM, VW series) and the role of interfacial product morphology and size on bonding and overall performance. Furthermore, Ti reinforcement endows the composites with superior wear resistance and thermal conductivity, indicating broad application potential.

While early transition metal-based materials, such as MXene, has emerged as an efficient catalyst for the Mg-based hydrogen storage materials, their strong interaction with hydrogen resulted in the high hydrogen diffusion barrier, hindering further improvement of catalytic activity. A MXene is characterized by rich anionic groups on its surface, significantly affecting electronic and catalytic functionalities. Using Nb₂CT_x as an example, we herein illustrate the critical role of anionic T_x defects on controlling hydrogen dissociation and diffusion processes in Mg-based hydrogen storage materials. The hydrogen desorption properties of MgH₂ can be significantly enhanced by utilizing T_x controllable Nb₂CT_x, and it can release 3.57 wt.% hydrogen within 10 min under 240 °C with the reduced dehydrogenation activation barrier. It also realized stable de/hydrogenation reactions for at least 50 cycles. DFT studies combined with kinetic analysis revealed that the catalyst–hydrogen interaction could be systematically controlled by optimizing surface T_x defect density, accelerating the hydrogen dissociation and diffusion processes at the same time. These results demonstrate that the T_x defects serve as the effective catalytically active centers of Nb₂CT_x, offering a flexible catalyst design guideline.