Yihe Tian

To synergistically enhance the strength and toughness of low-alloy cast steels, a quenching–partitioning–tempering (Q-P-T) heat treatment process was specifically performed based on the “Constrained Carbon Equilibrium” thermodynamic model. The effects of partitioning temperature on microstructure and mechanical properties were examined. The Q-P(210)-T approach successfully produced an ultra-high strength cast steel (48SiNiMnCrMoAl6-4-4-3-8-14) with a tensile strength exceeding 2000 MPa and an elongation greater than 19.0%. The microstructure of this cast steel consists of tempered martensite (TM), bainite, ferrite, and retained austenite (RA). During tensile deformation, dislocations from adjacent martensite are absorbed by the film-like RA, thereby alleviating stress concentration induced by dislocations. Meanwhile, the transformation-induced plasticity (TRIP) effect of the RA significantly enhances the toughness of the cast steel. Furthermore, the ultra-high strength of the cast steel is jointly ensured by the fine crystalline strengthening of the martensite and the precipitation strengthening of the transitional carbides in the microstructure of the cast steel. This work provides a good reference for the development of high-performance cast steels.

High-entropy oxides (HEOs), as a new type of single-phase solid solution with a multi-component design, have shown great potential when they are used as anodes in lithium-ion batteries due to four kinds of effects (thermodynamic high-entropy effect, the structural lattice distortion effect, the kinetic slow diffusion effect, and the electrochemical “cocktail effect”), leading to excellent cycling stability. Although the number of articles on the study of HEO materials has increased significantly, the latest research progress in porous HEO materials in the lithium-ion battery field has not been systematically summarized. This review outlines the progress made in recent years in the design, synthesis, and characterization of porous HEOs and focuses on phase transitions during the cycling process, the role of individual elements, and the lithium storage mechanisms disclosed through some advanced characterization techniques. Finally, the future outlook of HEOs in the energy storage field is presented, providing some guidance for researchers to further improve the design of porous HEOs.