Cryogenic nano-twinning engineering to mitigate the strength–hydrogen embrittlement trade-off in a high-entropy alloy

High-strength alloys are vulnerable to hydrogen embrittlement (HE), showing a trade-off between mechanical strength and HE resistance. In this work, a cryogenic nano-twinning strategy was proposed to overcome this trade-off relationship in a CoCrFeMnNi high-entropy alloy. The approach combines pre-straining at 77 K, which induces stable nanotwins, with recovery annealing at 773 K to decrease dislocation density. The nanotwin-engineered alloy exhibits ∼2.2-fold higher yield strength than fully recrystallized samples while retaining HE resistance. This cryo-twin engineering as a viable pathway to break the strength–HE resistance in HEAs, offering a design route for advanced structural materials in hydrogen environments.Impact statement This cryogenic nano-twinning engineering, which combines pre-straining at 77 K and heat treatment, can achieve superior synergy of mechanical strength and hydrogen embrittlement resistance.