In this study, the surface properties of marine structures were improved by applying a twin wire arc spray process to high-strength low alloys. The effect of Al and Mo contents in Ni-Al coatings on their mechanical and corrosion behaviors was analyzed using hardness tests, electrochemical experiments, and immersion tests. The increase in Al content resulted in the formation of oxides and intermetallic compounds, leading to a significant improvement in the mechanical properties by approximately 222 HV. Despite a fine galvanic phenomenon causing a decrease in corrosion resistance by up to 8.91%, a higher Al content demonstrated the highest corrosion resistance after high-temperature exposure, with an enhancement of approximately 20.9%, attributed to the formation of an oxide film generated by intermetallic phase transformation. However, the mechanical properties experienced a reduction of 134.3 HV. This study demonstrated a correlation between the microstructure of the coating layers that form passivation films and their respective mechanical and corrosion properties. It also revealed that the content of Al and Mo significantly affects the mechanical and corrosion behavior of Ni-Al coatings.

This study comparatively analyzed the wear characteristics and adhesion properties of 86WC–10Co–4Cr (WC) coatings deposited using the high velocity oxygen fuel process and 75Cr₃C₂–25NiCr (CrC) and Al₂O₃–3TiO₂ (Al₂O₃) coatings deposited using the atmospheric plasma spray process on an A390 aluminum alloy substrate. The adhesion strength and wear test results demonstrated that the WC coating exhibited superior wear resistance. In contrast, the CrC and Al₂O₃ coatings showed lower adhesion properties and unstable frictional variations due to a higher number of defects compared to the WC coating. The WC coating layer, protected by WC particles, exhibited minimal damage and a low wear rate, followed by CrC and Al₂O₃. Ultimately, WC coating is highlighted as the optimal choice to enhance the wear resistance of A390 aluminum alloy.

Enhancing damage tolerance and wear resistance in Al–Si-based alloys under thermomechanical stress remains a key challenge in lightweight structural applications. This study investigates the microstructural and tribomechanical behavior of hypoeutectic Al–Si–(Cu)–Mg alloys with varying Cu:Mg ratios (3:1 vs. 1:3) under a T6 heat treatment. Alloys A and B, with identical Si contents but differing Cu and Mg levels, were subjected to multiscale microstructural characterization and mechanical and wear testing at 25 °C, 150 °C, and 250 °C. Alloy A (Cu-rich) exhibited refined α-Al(FeMn)Si phases and homogeneously dissolved Cu in the Al matrix, promoting lattice contraction and dislocation pinning. In contrast, Alloy B (Mg-rich) retained coarse Mg₂Si and residual β-AlFeSi phases, which induced local stress concentrations and thermal instability. Under tribological testing, Alloy A showed slightly higher friction coefficients (0.38–0.43) but up to 26.4% lower wear rates across all temperatures. At 250 °C, Alloy B exhibited a 25.2% increase in the wear rate, accompanied by surface degradation such as delamination and spalling due to β-AlFeSi fragmentation and matrix softening. These results confirm that the Cu:Mg ratio critically influences the dominant hardening mechanism—the solid solution vs. precipitation—and determines the high-temperature performance. Alloy A maintained up to 14.1% higher tensile strength and 22.3% higher hardness, exhibiting greater shear resistance and interfacial stability. This work provides a compositionally guided framework for designing thermally durable Al–Si-based alloys with improved wear resistance under elevated temperature conditions.

This study investigates the synergistic effects of Cr–Zr and Mn–Zr additions on the microstructural evolution and mechanical properties of Al–6 wt.%Cu alloys. Alloys were designed with solute concentrations positioned below, near, and above their maximum solubility limits, and were evaluated under as-cast, T4, and T6 heat treatment conditions. Mechanical testing revealed distinct behavioral trends depending on the heat treatment: the T4 heat treatment condition generally exhibited superior hardness and yield strength, whereas the T6 heat treatment condition resulted in a slight reduction in hardness but facilitated a significant recovery in tensile strength and structural stability, particularly in alloys designed near the solubility limit. To elucidate the crystallographic origins of these mechanical variations, X-ray diffraction analysis was conducted to monitor changes in lattice parameters, dislocation density, and micro-strain. The results showed that T4 heat treatment induced lattice contraction and a decrease in dislocation density, suggesting that the high strength under T4 heat treatment conditions arises from lattice distortion caused by supersaturated solute atoms. Conversely, T6 aging led to lattice relaxation approaching that of pure aluminum, yet simultaneously triggered a re-accumulation of dislocation density and micro-strain due to the coherency strain fields surrounding precipitates, which effectively impede dislocation motion. Therefore, rather than proposing a single, definitive optimization condition, this study aims to secure foundational data regarding the correlation between these microstructural descriptors and mechanical behavior, providing a guideline for balancing the strengthening contributions in transition metal-modified Al–Cu alloys.