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 (Al 2 O 3 ) 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 Ti 3 C 2 T x MXene ceramics with high thermal stability to effectively toughen Al 2 O 3 ceramics at high temperatures via a nacre-like structure strategy. The fracture toughness (K Jc ) of the as-prepared MXene/Al 2 O 3 nanocomposite at 1000 °C is 6.02 MPa m 1/2 , 2.4 times that of pure Al 2 O 3 (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.