A reduction in the particle size is expected to improve the properties and increase the application potential of high-entropy alloys. Therefore, in this study, a novel sol–gel autocombustion technique was first used to synthesize high-entropy alloys. The average grain size of the prepared nanocrystalline CoCrCuNiAl high-entropy alloys showed was 14 nm with an excellent and uniform dispersion, exhibiting a distinct magnetic behavior similar to the superparamagnetic behavior. We show that the metal nitrates first form (Co,Cu,Mg,Ni,Zn)O high-entropy oxides, and then in situ reduce to CoCrCuNiAl high-entropy alloys by the reducing gases, and the chelation between citric acid and the metal ions and the in situ chemical reactions are the dominant reaction mechanisms. We demonstrate that the sol–gel autocombustion process is an efficient way to synthesize solid solution alloys eluding the restriction of a high mixing entropy.

An inequi-atomic CoCrFeNiMn_0.5Ti_0.5 high-entropy alloy (HEA) was synthesised by mechanical alloying. The structural and morphological evolution of the alloy powder during the mechanical alloying process and the thermal behaviour of 60 h ball-milled HEA powder were investigated systematically. A simple body-centred cubic solid solution HEA structure was obtained when the blended powder was ball-milled longer than 36 h. A 60 h ball-milled powder had an average particle size of 3 μm and consisted of hard agglomerated crystalline particles with a crystal size of < 20 nm. The body-centred cubic phase transformed into a face-centred cubic phase when the powder was annealed for 1 h at a temperature of 700°C; the liquidus point of the face-centred cubic phases was 1402.8°C.

The densification of ZrC ceramics doped with different contents of TiC prepared by spark plasma sintering at the temperatures between 1750 and 1850°C has been investigated. The microstructure and mechanical properties of the ceramics have been characterised. It was shown that TiC additions effectively promoted the densification process by forming (Zr,Ti)C solid solution. The relative densities and mechanical properties of ZrC samples increased with the increasing of TiC content or the sintering temperature. Ceramic with the content of TiC up to 10 vol.-% sintering at 1850°C showed an excellent combination of properties including a relative density of 98.7%, hardness of 20.8 GPa and flexural strength of 605 MPa.

This review establishes a comprehensive technical framework for aerogel-based fire-resistant coatings, from fundamental mechanisms to industrial applications. It analyses the multi-mode flame-retardant and thermal insulation mechanisms achieved through aerogels’ synergistic suppression of heat conduction, convection, and radiation, establishing their theoretical basis. The work compares the intrinsic characteristics of silica-based, carbon-based, and bio-based aerogels, providing rational selection criteria for fire protection systems. The study examines key integration challenges: balancing nanopore preservation with interfacial compatibility, inherent mechanical weaknesses, conflicts between high filler loading and workability, and scalability issues. It evaluates targeted strategies including interface engineering, mechanical reinforcement, workability optimization, and low-cost production routes. Application prospects in construction, tunneling, and cable protection are outlined. This review provides a coherent progression from mechanisms and material properties to challenges and solutions, offering theoretical guidance and a technical roadmap for developing next-generation high-performance fire-resistant coatings.