The effect of post-rolling annealing time on the microstructural evolution and room-temperature mechanical properties of a hot-rolled Cu–Zn–Sn alloy was systematically investigated. The alloy was isothermally annealed at 500 °C for 4, 5, and 6 h. Results reveal that annealing time non-monotonically governs the recrystallization of the α and β phases and the final content of the Sn-rich intergranular phase, coupled with the α/β phase transformation and Sn partitioning. The as-hot-rolled microstructure comprises a dual α + β structure without the Sn-rich intergranular phase. After 4 h, the α phase recrystallizes completely, and the β phase fraction decreases, leading to Sn rejection and Sn-rich intergranular phase formation after furnace cooling; hardness and strength are minimum, while ductility is high. At 5 h, the β phase fraction recovers and Sn partitions into the β phase, decreasing the final Sn-rich intergranular phase content. The β phase transforms into fine short-rod and lath-like morphologies, refining grains and yielding optimal strength–ductility synergy, with an ultimate tensile strength (UTS) of 451.6 MPa and an elongation of 41.7%. At 6 h, the β phase fraction decreases and grains coarsen, leading to re-formation of the Sn-rich intergranular phase and degraded strength. Quantitative analysis reveals that solid-solution strengthening provides a stable baseline, while variations in yield strength are dominated by dislocation and grain-boundary strengthening. The β phase provides load-transfer strengthening, and the Sn-rich intergranular phase acts primarily as a damage source. Fracture changes from ductile dimples to mixed ductile–brittle with local flat features, depending on the Sn-rich intergranular phase distribution. This study links processing, microstructure, and properties for optimizing tin brass heat treatment.

This study prepares Ni₅₀(AlNbTiV)₅₀-xY₂O₃ complex concentrated alloy composite coatings and analyzes their microstructure, phase composition, and high-temperature performance. The results indicate that each coating is composed of FCC phases, including γ-FeNi, Ni₃Al, and Ni₃(Al, Ti), as well as BCC phases such as Ni₃Nb and Ni₃Ti. With increasing Y₂O₃ content, the lamellar structure in the inter-dendritic regions of the coatings first decreases and then increases. The wear mechanism of the coating without Y₂O₃ addition under high-temperature conditions involves the combined effects of abrasive wear and adhesive wear. The coating with a 0.6 wt.% addition exhibits the smallest cracks and the lowest oxidation rate in high-temperature oxidation and thermal shock tests, with the oxidation weight gain reduced by 26.2% compared to the coating without Y₂O₃ addition. The abrasive and adhesive wear of this coating is mitigated, and the average friction coefficient and mass loss are decreased. When the mass fraction of Y₂O₃ is 0.4 wt.%, the coating structure shows a significant refinement effect and exhibits the best performance in tensile strength and high-temperature friction and wear tests.