Gradient microstructure and interfacial strength of CoCrFeMnNi high-entropy alloy in solid-state ultrasonic welding
Journal
Materials Science and Engineering A
Journal Volume
825
Date Issued
2021
Author(s)
Abstract
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 welding for 1.0 s and bonding strength reached about 1500 N (30 MPa of shear strength) after welding for 7.0 s. Such interfacial bonding was featured with the ultrafine microstructure with a grain size of 100–200 nm, which resulted from discontinuous dynamic recrystallization induced by severe plastic strain and a peak temperature of 511 °C. Strain and temperature due to severe plastic deformation in the ultrasonic sliding decreased with increasing distance from the interface. This contributed to a microstructural gradient from discontinuous dynamic recrystallization to continuous dynamic recrystallization and finally dislocation cells. This gradient microstructure was confined to areas within about 2 μm from the interface and showed no solidification defects or transformation of detrimental phases. ? 2021
Subjects
Electron backscattered diffraction
High-entropy alloys
Transmission kikuchi diffraction
Ultrasonic welding
Chromium alloys
Cobalt alloys
Dynamic recrystallization
Entropy
Iron alloys
Manganese alloys
Microstructure
Plastic deformation
Welding
Bonding strength
Discontinuous dynamic recrystallization
Electron back-scattered diffraction
Gradient microstructure
Gradient strength
High entropy alloys
Interfacial strength
Shears strength
Ultrasonic weldings
Diffraction
Type
journal article