Dual-scale (nano and micron) particle-reinforced TiB₂/6061Al matrix composites with different contents of TiB₂ were prepared using powder metallurgy, and then analyzed via microstructure observation and tests of microhardness, tensile properties, and friction and wear properties. The 6061Al powders’ particles changed from spherical to flaky after two rounds of high-energy ball milling, and the TiB₂ enhancer was embedded in or wrapped by the matrix particles after high-energy ball milling. Metallurgical bonding between TiB₂ particles and the matrix was achieved, and Al₃Ti was synthesized in situ during sintering. The hot-pressing process eliminated the internal defects of the composites, and the TiB₂ particles were diffusely distributed in the matrix. The best comprehensive mechanical properties (hardness and tensile strength) were achieved when the mass fraction of TiB₂ was 5% (1% micron + 4% nano); the hardness and tensile strength of the composites reached 131 HV and 221 MPa—79.5% and 93.9% higher than those of the pure matrix, respectively. The composites’ average coefficient of friction and volumetric wear rate were reduced. Composites with a TiB₂ mass fraction of 7% (3% micron + 4% nano) had the highest average coefficients of friction and the lowest volumetric wear rate of 0.402 and 0.216 mm³∙N⁻¹∙m⁻¹, respectively. It was observed that adhesion influences the friction mechanism, which transitions from adhesive wear with slight oxidative wear to abrasive wear.

In this study, FSW experiments were conducted on a 4 mm-thick A380 aluminium alloy plate and 6061 aluminium alloy using four different needle lengths (2.5 mm, 2.8 mm, 3.0 mm, and 3.5 mm) of H13 steel. The experiments were conducted at the same welding parameters (1000 rpm and 120 mm/min) to explore the effects of different stirring needle lengths on the microstructures and properties of the FSW joints. The experimental results show that FSW joints with varying lengths of needles have a significant effect on the microstructures and properties of welded joints, and the tensile strength increases and then decreases with increases in the needle length. A 2.8 mm needle length can achieve the maximum tensile strength of 203 MPa, about 85.3% of the base material. Too long or too short a needle leads to a decrease in joint performance. Furthermore, different needle lengths have a significant influence on the flowability of the weld core zone, and a suitable needle length will lead to better flowability in the weld core zone. With increases in the needle length, the heat production also increases, and the area of the RS-HAZ will increase with the heat production. When the joints achieve appropriate heat production, the weld core zone will experience grain refinement. At the same time, the grain will grow in the RS-HAZ; the hardness cloud diagram shows that, in the RS-HAZ, the material properties are weaker, and the tensile specimens are mainly fractured in the RS-HAZ. Finally, the tensile specimens exhibit mixed fracture.