High-Strength β-Phase Magnesium-Lithium Alloy Prepared by Multidirectional Rolling.

Area of Science:

• Materials Science
• Metallurgical Engineering

Background:

• Magnesium-lithium (Mg-Li) alloys are valued for low density in lightweight applications.
• Increased lithium content in Mg-Li alloys often compromises alloy strength.
• Enhancing the mechanical properties of beta-phase Mg-Li alloys is a critical research area.

Purpose of the Study:

• To investigate the effects of multidirectional rolling (MDR) on the mechanical properties of Mg-16Li-4Zn-1Er alloy.
• To compare MDR with conventional rolling (CR) in improving alloy strength.
• To explore the influence of various rolling temperatures, including cryogenic conditions, on alloy microstructure and performance.

Main Methods:

• The Mg-16Li-4Zn-1Er alloy was subjected to multidirectional rolling at different temperatures (e.g., 200 °C, -196 °C) and compared to conventional rolling.
• Finite element simulations were employed to analyze stress distribution and metal flow during rolling processes.
• Microstructural analysis focused on dynamic recrystallization and dislocation movement, with specific attention to nanograin formation.

Main Results:

• Multidirectional rolling demonstrated superior stress absorption and controlled metal flow compared to conventional rolling, leading to improved mechanical properties.
• Both high-temperature (200 °C) and low-temperature (-196 °C) MDR significantly enhanced alloy strength by modifying dynamic recrystallization and dislocation behavior.
• Cryogenic MDR at -196 °C resulted in the formation of numerous nanograins (56 nm diameter) and achieved a peak strength of 331 MPa.

Conclusions:

• Multidirectional rolling is an effective strategy for enhancing the strength of Mg-Li alloys.
• Cryogenic processing via MDR offers a promising route to achieving ultra-high strength in Mg-Li alloys through nanostructure refinement.
• The findings provide a pathway for developing stronger, lightweight Mg-Li alloys for demanding applications.