Synergistically improved mechanical and tribological properties in laser powder bed fused Al0.3CoCrFeNi high-entropy alloy via tailored precipitation

Al0.3CoCrFeNi alloy has excellent plasticity, toughness, and corrosion resistance, making it promising for aerospace, defense, and energy applications. However, its low strength and poor wear resistance limit broader industrial adoption, making the synergistic enhancement of its mechanical and tribological properties a key focus of current research. Here, the alloy was fabricated via laser powder bed fusion (L-PBF) and subsequently annealed at 800 °C for 1-50 h, to systematically investigate the precipitation behavior of the B2 phase and its corresponding effects on mechanical and tribological performance. The results demonstrate that the volume fraction of B2 precipitates initially increases and then decreases with increasing annealing time, reaching its peak at 10 h. High-temperature annealing also facilitates recrystallization, in which newly formed equiaxed grains gradually propagate inward from the melt pool boundaries. After 50 h of annealing, the original cellular structure disappears completely, replaced fully by fine equiaxed grains. Texture analysis shows that the as-deposited alloy exhibits a typical {001}<100> texture with an intensity of 7.29, while annealing improves microstructural isotropy, reducing the texture intensity to 3.68 after annealing for 50 h. Benefiting from B2 phase precipitation strengthening and recrystallization-induced grain refinement strengthening, the 10 h and 50 h annealed samples show excellent mechanical properties, with yield strengths of approximately 670-673 MPa, tensile strengths of around 1289-1312 MPa, and elongations of 25.3% and 25.1%, respectively. Further ODF analysis of the fracture surfaces reveals that the as-deposited alloy possesses a strong F-type texture, with weak Goss and R-Cu textures. With extended annealing, the F-type texture weakens, while Goss and R-Cu textures are markedly strengthened. These two textures originate from the preferential growth of recrystallized grains, improving deformation compatibility and retaining work-hardening capacity. Both annealed states exhibit good wear resistance because the high-fraction B2 phase or fine equiaxed grains significantly enhance resistance to plastic deformation and effectively maintain the continuity and integrity of the self-lubricating oxide layer. The dominant wear mechanisms are plastic deformation, abrasive wear, fatigue wear, and oxidative wear.