Jiang-Hua Chen

Materials with excellent high-temperature strength are now sought for applications in hypersonics, fusion reactors, and aerospace technologies. Conventional alloys and eutectic multiprincipal-element alloys (MPEAs) exhibit insufficient strengths at high temperatures due to low melting points and microstructural instabilities. Here, we report a strategy to achieve exceptional high-temperature microstructural stability and strength by introducing eutectic carbide in a refractory MPEA. The synergistic strengthening effects from the multiprincipal-element mixing and strong dislocation blocking at the interwoven metal-carbide interface make the eutectic MPEA not only have outstanding high-temperature strength (>2 GPa at 1473 K) but also alleviate the room-temperature brittleness through microcrack tip blunting by layered metallic phase. This strategy offers a paradigm for the design of the next-generation high-temperature materials to bypass the low–melting point limitation of eutectic alloys and diffusion-dominated softening in conventional superalloys.

Traditional absorbers are usually sandwich structures in which a metallic ground plane is employed to prevent the transmission. Such absorbers suffer from a major drawback that incident light can only irradiate from the front of the absorbers. In this paper, a novel absorber with bulk Dirac semimetal (BDS)-AlCuFe quasicrystals is proposed to realize bidirectional and dynamically tunable terahertz (THz) perfect absorption. The proposed structure consists of two layers of AlCuFe plates with rectangular apertures and a dielectric spacer. By adjusting transverse distance between the top and bottom rectangular apertures, perfect absorption could be realized under TM polarization. Simulation results show that perfect absorption can be obtained whether light irradiates from the front or back of the system, indicating a performance of bidirectional absorption. In addition, benefiting from the variable Fermi level of AlCuFe, the resonance frequency can be dynamically tuned in the THz range. Our work will stimulate more investigations on BDS-based bidirectional absorbers and optical modulators.