Enhancement of plasticity in Mg–3Al–1Zn alloy at cryogenic temperature

Abstract

Compression tests were conducted at room and cryogenic temperatures to investigate the low-temperature plasticity in Mg–3Al–1Zn alloy. The strain to failure and fracture strength in Mg–3Al–1Zn alloy increase by 21.4% and 51.6% from room to cryogenic temperature. Using a quasi-in-situ EBSD method, it is found that {10 1¯ 2} tension twins dominate at room temperature, while abundant (10 1¯ 2)-(01 1¯ 2) twin-twin interactions are observed at cryogenic temperature. Multiple slips, including pyramidal and basal slips, occur in twin-twin interactions, enhancing the strain to failure and flow stress at cryogenic temperature. The high dislocation density near twin-twin interactions boundaries would contribute to the high hardening rate and flow stress at cryogenic temperature. This work would provide a novel way to enhance plasticity in magnesium alloys and gain an in-depth understanding of twin-twin interactions.

Keywords

• Cryogenic deformation
• Twin-twin interactions
• Magnesium alloys
• Plasticity
• Electron backscatter diffraction (EBSD)