Enhanced structural refinement on eutectic medium-entropy alloy CrCoNiNb0.48 by laser remelting

• CrCoNiNb 0.48 eutectic medium-entropy alloy is successfully designed. • The lamellar spacing is reduced by an order of magnitude after laser remelting. • The hardness of CrCoNiNb 0.48 with laser remelting are approximately 50% increase over as-cast. A novel efficient method to design eutectic medium-entropy alloys with typical lamellar structure is successfully proposed. The CrCoNiNb 0.48 alloy is prepared with microstructure comprised of FCC and Laves phases. After laser remelting, the nano-scale eutectic lamellar is formed and the eutectic lamellar spacing is refined to approximately 30 nm from 300 nm (as-cast). Thus, the hardness of CrCoNiNb 0.48 with laser remelting is approximately 50% increase over as-cast. Moreover, through calculation, the strain hardening exponent of the laser-treated alloy is almost twice of that in the as-cast alloy.