Matrix-induced Cr2CTx MXene superlattice transforming coherent M23(C1-xOx)6 solid solution reinforced high-entropy alloy composite

High-entropy alloys (HEAs) exhibit robust strength and excellent ductility, rendering them well-suited for service as metal matrices. Adding 2D materials like MXene as reinforcements can further improve their properties. In this study, a specific HEA (AlCoCrFeNi₂) was combined with Cr₂CT_x MXene in different amounts. When 0.5 wt% of MXene was added, the composite had a yield strength of 822 MPa and 9 % elongation. At a concentration of 1 wt%, MXene forms spherical particles within the composite, resulting in a yield strength of 1088 MPa and an elongation of 7 %. Additionally, the composite exhibits a 50 % increase in high-temperature strength at 1023 K compared to the base HEA. These spherical particles have a structure of oxygen-interstitial M₂₃(C_1-xO_x)₆ solid solution. The study suggests that the MXene transforms into these spherical particles through an intermediate superlattice phase, which was confirmed by advanced microscopy and DFT calculations. This new composite material shows improved high-temperature strength, making it potentially useful for applications where heat and corrosion resistance are important.