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The microstructure, mechanical and tribological properties of thermomechanical processed (CoNiCr0.5)95AlxTiy (x = 1, 3, 4 and y = 4, 2, 1 (at.%)) high-entropy alloys (HEAs) were systematically investigated. The low Al and Ti addition is designed to inhibit the formation of precipitation, which is aimed to reach solution strengthening, so as to realize its engineering processing better. The results show that the HEAs mainly contain face-centered cubic (FCC) structure without precipitation. As the Ti/Al ratio increases from 1/4 to 4/1, the average geometrically necessary dislocations (GNDs) density of the HEAs increases from 1.04 × 1014 m−2 to 1.11 × 1014 m−2, and the average Schmid factor decreases from 0.442 to 0.288. Moreover, the ductility, strength, and microhardness of the HEAs change from 13.87%, 910.31 MPa, and 306.12 HV to 10.62%, 1221.09 MPa, and 382.97 HV, respectively. The sliding wear mechanism of HEAs against SiC is mainly composed of abrasive wear and adhesive wear. The increment of Ti/Al ratio improves the tribology performance of HEAs, e.g. the wear rate decreases from 3.95 × 106 mm3/(N·m) to 2.58 × 106 mm3/(N·m) with the increased Ti/Al ratio at a normal load of 7 N.

Interface considerably influences the properties of copper (Cu)–graphite composites. Therefore, considerable understanding of the interface is required to improve the mechanical and tribological properties of these composites. Because the graphite (0001) and Cu (111) interfaces are a good match, this study focuses on calculating the related properties of the interface structure using first–principles calculations. The parameter setting of this work is reasonable when comparing the theoretical and experimental results of the bulk Cu and graphite. Slabs of the nine-layer graphite (0001) and seven-layer Cu (111) surfaces have excellent convergence. The order of interfacial configuration stability is HCP > OT > MT and HCP possesses the largest work of adhesion and smallest interface energy among the studied interface structures. Furthermore, the electron density and Mulliken population method are used to examine the interfacial bonds. [ABSTRACT FROM AUTHOR]

State‐of‐the‐art perovskite solar cells (PSCs) continue to encounter stability challenges throughout their current commercialization process, primarily due to the instable organic components. Especially, surface (interface) imperfections, like the undercoordinated Pb2+ and halide sites, further compromise the confinement of organic cations at the surface (interface) and provide a rapid pathway for ion migration and volatilization, decreasing stability and efficiency. Herein, the study has developed a surface Formamidine (FA) cation immobilization strategy through hydrogen bond effect, achieved by a post‐treatment of piperazine dihydrochloride (PDCl2), to obtain stable FA‐based perovskites. The piperazine can immobilize surface FA+ cation through hydrogen bond. Moreover, the post‐treatment of PDCl2 can induce surface Cl– doping to establish strong coordinating bond with the uncoordinated Pb2+, reducing the imperfections of surface octahedral cage. Such a synergistic effect effectively constrains surface FA+ cations, simultaneously alleviates surface lattice stress. Because of improved surface properties, the resultant perovskite demonstrates not only outstanding light/thermal stability, but also more pronounced n‐type characteristics and uniform potential distribution for improving charge transfer dynamics. Finally, the champion PSCs exhibit a significantly enhanced efficiency from 23.15% to 25.52%. Moreover, these PSCs exhibit excellent stability: retain 91% of their initial efficiency after over 1000 h maximum power point test. [ABSTRACT FROM AUTHOR]