Mxene-toughened Al₂O₃ ceramic at high temperature

The process of toughening brittle ceramics is challenging but important for broadening their range of applications. Extensive studies on toughening brittle alumina (Al₂O₃) ceramics at room temperature have been conducted; however, significantly increasing their toughness at high temperatures remains a challenge. Here, we propose the use of two-dimensional Ti₃C₂T_x MXene ceramics with high thermal stability to effectively toughen Al₂O₃ ceramics at high temperatures via a nacre-like structure strategy. The fracture toughness (K_Jc) of the as-prepared MXene/Al₂O₃ nanocomposite at 1000 °C is 6.02 MPa m^1/2, 2.4 times that of pure Al₂O₃ (2.51 MPa m^1/2). Moreover, it maintains relatively high strength at 1000 °C (∼193 MPa). The toughening mechanisms - crack deflection, bifurcation and bridging effects - are obtained via in situ observation of crack propagation and finite element simulation. Our novel strategy provides a universal solution to improve the toughness of brittle ceramics at high temperatures and in some special environments.