Corrosion and wear behaviors of selective electron beam melted (FeCoNi)86Al7Ti7 high-entropy alloy with hierarchical microstructure

• Selective electron beam melting produced a unique hierarchical microstructure in (FeCoNi) 86 Al 7 Ti 7 HEA, consisting of FCC grains, submicron L2 1 precipitates, and nanoscale L1 2 phases. • Micro-galvanic coupling between the FCC/L1 2 matrix and L2 1 precipitates governed corrosion behavior, leading to preferential dissolution of the L2 1 phase in 0.5 M H 2 SO 4 . • The SEBMed HEA exhibited excellent tribocorrosion resistance, with a low wear rate of 2.19 × 10 −5 mm 3 /(N·m) under acidic conditions. High-entropy alloys (HEAs) have promising applications in environments with severe corrosion and wear. However, the corrosion and wear behavior, as well as their interaction mechanisms, of (FeCoNi) 86 Al 7 Ti 7 HEA fabricated by selective electron beam melting (SEBM) remain unclear. This study reveals that the SEBM process produces a unique hierarchical microstructure in the (FeCoNi) 86 Al 7 Ti 7 HEA, comprising face-centered cubic (FCC) grains (averaging ∼33 μm), submicron island-like L2 1 phases along grain boundaries, and L1 2 precipitates (20–200 nm) embedded within the FCC matrix. This distinctive structure significantly enhances both corrosion and wear resistance. In 0.5 M H 2 SO 4 solution, the alloy exhibits minimal pitting, which is attributed to micro-galvanic corrosion (MGC) between the FCC/L1 2 phases and the L2 1 phase, leading to the preferential dissolution of the L2 1 phase. Under tribocorrosion conditions, the SEBMed HEA shows a low wear rate of 2.19 × 10 −5 mm 3 /(N·m), with the primary degradation mechanism arising from the synergistic interaction between abrasive wear and corrosion. These findings underscore the unique microstructure and superior properties of the SEBMed HEA, indicating its suitability for demanding applications in marine and energy sectors.