MXene defect engineering for optimizing the mechanical properties of Ti3C2TX/ZK61 composites

A MXene defect engineering strategy was proposed to tailor the thermal stability of Ti₃C₂T_X and mechanical properties of Ti₃C₂T_X/ZK61 composites. Surface defects were introduced in the reinforcement MXene Ti₃C₂T_X using H₂O₂ followed by HCl treatment, creating defects without significantly compromising its structure. MgO was induced at the grain boundary to restrain the interfacial reaction. The introduction of defects in Ti₃C₂T_X reduced its thermal stability, leading to the decomposition of defective Ti₃C₂T_X flakes during sintering. However, these defective Ti₃C₂T_X flakes surrounded by MgO significantly enhanced the toughness of the Ti₃C₂T_X/ZK61 composites. Treating Ti₃C₂T_X with H₂O₂ (10 min) and HCl introduced an appropriate number of defects, resulting in a remarkable 36.1 % increase in ultimate compressive strength (UCS) and a 38.0 % enhancement in failure strain. Treating Ti₃C₂T_X with H₂O₂ (20 min) and HCl introduced an excess number of defects, resulting in a 10.7 % increase in UCS and a 27.0 % enhancement in failure strain. The defective Ti₃C₂T_X surrounded by MgO facilitated coordinated dislocation motion, alleviating local dislocation pile-up and delaying crack formation at grain boundaries. This work provides a new way to enhance the toughness of Ti₃C₂T_X/ZK61 composites.