Achieving improved wear resistance and balanced strength-ductility in laser powder bed fused Al0.3CoCrFeNi alloy via L12 precipitation

Abstract

Synergistically enhancing the strength, ductility, and wear resistance of LPBF-fabricated Al_0.3CoCrFeNi alloy is critical for advancing its industrial applications. In this study, the effect of nano-scale precipitates, generated through annealing at 550 °C for durations ranging from 25 to 300 h, on the mechanical and tribological properties was systematically investigated. The as-fabricated alloy featured cellular structures with an average cell size of approximately 0.53 μm. Low-temperature annealing promoted the formation of spherical L1₂ precipitates, which had an average size of 1.85 ± 0.76 nm. These precipitates effectively accommodated and impeded dislocation motion, enabling an excellent combination of mechanical properties, including a tensile strength of 973.3 ± 15.6 MPa and an elongation of 20.6 %. Compared to the as-printed sample, the annealed material exhibits a 25.3 % increase in tensile strength and a 32.9 % improvement in elongation. After 150 h of annealing, the wear rate decreased to 0.798 × 10⁻⁴ mm³/N·m, representing a 30.8 % reduction compared to the as-printed sample. This enhancement in wear resistance primarily originates from the role of the L1₂ precipitates in facilitating the formation of a dense, protective oxide layer that exhibits both anti-wear and self-lubricating properties.