Order-disorder phase transition in silicon-containing high-entropy materials

<sec>High-entropy alloys (HEAs), representing a significant category of multi-component alloys, have attracted significant attention due to their outstanding mechanical and functional properties. This review focuses on the order-disorder phase transition mechanisms in silicon-based HEAs, systematically addressing the thermodynamic and kinetic regulation principles and their effects on material performance. The research has shown that adding silicon improves atomic size matching and mixing enthalpy, allowing high-entropy alloys to have both ordered and disordered phases, thereby significantly enhancing their mechanical and physicochemical properties.</sec><sec>The evolution of ordered and disordered phases is strictly controlled by fabrication processes. Advanced fabrication techniques, such as laser cladding and powder metallurgy, as well as temperature/pressure modulation, can precisely control phase formation and layered structure, achieving synergistic strengthening through multiphase structures. Rapid cooling techniques such as laser cladding suppress the nucleation and growth of brittle intermetallic compounds, which is beneficial for single-phase FCC structures. On the contrary, controlled annealing treatments can induce phase transitions towards ordered BCC/B2 structures, enhancing high-temperature stability. Advanced techniques such as powder plasma arc additive manufacturing (PPA-AM) utilize rapid solidification to refine grain size and effectively disperse second phases. Thermodynamic drivers, particularly the competition between entropy and enthalpy quantified by the parameter <i>Ω</i>, as well as external stimuli such as pressure, provide precise control over the phase transition pathways and final microstructures. </sec><sec>Furthermore, the incorporation of sillicon enhances functional performance, including increasing electrical resistivity, customizing magnetic responses, and improved high-temperature oxidation resistance through the formation of Al<sub>2</sub>O<sub>3</sub>/SiO<sub>2</sub> layers. Despite these advancements, there are still challenges in understanding atomic-scale dynamics of phase transitions and expanding cost-effective manufacturing processes. Future efforts should integrate multiscale characterization, computational modeling, and performance validation under extreme conditions to accelerate the engineering applications of silicon-based HEAs in aerospace, energy storage, and electronic devices.</sec>