Improved cryogenic properties of the Al-xMg alloys enabled by twin-roll strip casting

Abstract

High strength and ductility are vital material properties required in alloys used for structural applications at cryogenic temperatures. However, the simultaneous provision of these characteristics is challenging because the two properties are mutually contrasting from the perspective of dislocation motion. Herein, we prepare binary Al-xMg alloys supersaturated with Mg using a combined technique of twin-roll strip casting and subsequent thermo-mechanical treatment; this produces Al alloys with both high strength and ductility at cryogenic temperatures. Experiments show that gradually adding Mg to Al significantly improves cryogenic tensile properties of the alloys. At the cryogenic temperature of the liquid N2 (−196 °C), the Al-5Mg and Al-7Mg alloys exhibit the ultimate tensile strength (UTS) of 370 and 450 MPa with the corresponding ductility of 93% and 87%, respectively. Comparing Al-xMg alloys with differing Mg contents elucidates avenues of simultaneously improving these properties for utilization at cryogenic temperature. This study provides a simple and robust approach for producing low-cost Al-xMg alloys with excellent cryogenic properties for structural applications.

Keywords

• Al-Mg alloys
• Cryogenic properties
• Stacking fault energy
• Hardening mechanism
• Dislocation density