Ultrahigh compressive-strength (TiZrNbTa)2AlC MAX phase enabled by high-entropy design and its derivative MXene

High-entropy MAX (HE-MAX) phases and their derivative MXenes (HE-MXenes) have attracted widespread attention due to multicomponent modulation effects. Herein, a (TiZrNbTa) 2 AlC HE-MAX phase with high purity of 96.18 wt.% was synthesized. The ceramic exhibits a low lattice thermal conductivity of 4.56 W/(m K) because of strong phonon scattering at the M-site. Superior mechanical performances were achieved, including Vickers hardness of 7.2 GPa, flexural strength of 494 MPa, compressive strength of 1643 MPa, and fracture toughness of 6.8 MPa m 1/2 . The strength enhancement is attributed to local chemical fluctuations and wavy-distributed lattice strain fields that create rugged energy landscapes and impede dislocation motion. Whereas the nearly cubic stacking of [M 6 X] octahedron promotes homogeneous deformation and achieves a comparable fracture toughness to Ti 2 AlC. The derived HE-MXene maintains hexagonal symmetry with enlarged interlayer spacing and mixed M-site valence states. Density functional theory calculations reveal a Young’s modulus of 252 GPa and metallic character with Nb serving as the dominant redox‑active center. This work offers a generalizable strategy for strengthening MAX phases via a high-entropy design, highlighting their potential for lightweight structural applications.