Gradient microstructure and interfacial strength of CoCrFeMnNi high-entropy alloy in solid-state ultrasonic welding

This study investigated the microstructure gradient and interfacial strength of CoCrFeMnNi high-entropy alloy bonded by ultrasonic welding (USW). It was found that bonding occurred after for 1.0 s reached about 1500 N (30 MPa shear strength) 7.0 s. Such featured with ultrafine a grain size 100–200 nm, which resulted from discontinuous dynamic recrystallization induced severe plastic strain peak temperature 511 °C. Strain due to deformation in sliding decreased increasing distance interface. contributed microstructural continuous finally dislocation cells. confined areas within 2 μm interface showed no solidification defects or transformation detrimental phases.