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

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)₈₆Al₇Ti₇ 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)₈₆Al₇Ti₇ HEA, comprising face-centered cubic (FCC) grains (averaging ∼33 μm), submicron island-like L2₁ phases along grain boundaries, and L1₂ precipitates (20–200 nm) embedded within the FCC matrix. This distinctive structure significantly enhances both corrosion and wear resistance. In 0.5 M H₂SO₄ solution, the alloy exhibits minimal pitting, which is attributed to micro-galvanic corrosion (MGC) between the FCC/L1₂ phases and the L2₁ phase, leading to the preferential dissolution of the L2₁ phase. Under tribocorrosion conditions, the SEBMed HEA shows a low wear rate of 2.19 × 10⁻⁵ mm³/(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.