Synchronous manipulation of heterointerfaces and atomic hybrids in bimetallic MAX phase composites for advanced electromagnetic wave absorption

Rational constructing multi-phase interfaces and hetero-substituted sites structures holds extraordinary potential for harnessing tailorable electromagnetic (EM) responses and fascinating EM wave absorption. Herein, a series of new bimetallic MAX phase hybrid composites (Ti_1-xV_x)₂AlC_f with diverse dielectric behaviors integration are synthesized via a simple thermally driven gradient sintering strategy, using carbon fiber as the initial carbon source. Their chemical compositions, physical structures and EM properties are studied in detail, focusing on the resultant temperature and M-site vanadium atom substitutional engineering. Specifically, benefiting from the co-boosted interfacial/dipole polarization capabilities caused by the simultaneous manipulation of heterogeneous boundary states and intrinsic dipoles distribution at 1350 °C, the TiVAlC_f composite exhibits an ultrahigh minimum reflection loss of −59.13 dB and an effective absorption bandwidth of 4.93 GHz, with a matching thickness of only 1.53 mm. Furthermore, multilayer gradient metamaterial model and a high-temperature tail nozzle model are constructed to further highlight the advanced EM functional application capacity of these MAX-based materials. This work is expected to provide an innovative platform for understanding cooperative multi-dielectric coupling mechanisms in the controllable design of high-efficient hybrid composite absorbers.