Enhanced hardness and fracture toughness of the laser-solidified FeCoNiCrCuTiMoAlSiB0.5 high-entropy alloy by martensite strengthening

A FeCoNiCrCuTiMoAlSiB0.5 high-entropy alloy (HEA) comprised of a lath-like martensite phase was fabricated by laser cladding. The alloy combines attractive properties including hardness (11.6 GPa), elastic constant (187.1 GPa), fracture toughness (50.9 MPa m0.5) and softening resistance (up to 900 °C). The nucleation of the martensite phase is co-triggered by laser rapid solidification and interstitial boron solute, owing to the improved lattice strain energy. The designed strengthening by martensite and interstitial solutes may enhance both hardness and toughness in other rapidly solidified HEAs.