Cryogenic Tribological Breakthroughs in Medium-Entropy Alloy Composites via Regulated Partial Recrystallization

• • The optimized (CoCrNi)90Mo10 MEA with regulated partial recrystallization achieves a wear rate at 113 K that is less than half of its as-cast and fully recrystallized counterparts, demonstrating a significant improvement in cryogenic wear resistance. • • The engineered microstructure comprises a fully recrystallized FCC phase embedded within a continuous skeleton of hard, non-recrystallized σ phase, providing a synergistic combination of structural support and strain accommodation. • • The σ skeleton distributes stress deeply, while the recrystallized FCC phase, with its high density of grain boundaries and annealing twins, suppresses interfacial cracking, addressing the fundamental trade-off between strength and damage tolerance. • • This microstructural design strategy offers a practical pathway for developing high-performance, crack-resistant dual-phase composites for extreme cryogenic environments, overcoming the limitations of conventional second-phase strengthening.