Effect of Al addition on the room and cryogenic temperature deformation of Mg-xAl-1Zn-1Ca alloy (x = 2, 3 wt.%)

• Room and cryogenic mechanical behavior of Mg-xal-1Zn-1Ca alloy ( x = 1, 2 wt.%). • Superior tensile strength achieved in AZX311 alloy without ductility trade-off. • Increased barriers to dislocation movement lead to significant hardening at CT in AZX311. • Strength-ductility synergy in AZX311 alloy at CT due to formation of stacking faults. • Higher twinning interactions during CT deformation lead to higher hardening in AZX311. This study explores the influence of Al addition on the microstructure, texture and mechanical deformation behavior of Mg-xAl-1Zn-1Ca ( x = 1, 2 wt.%) alloy (referred as AZX211 and AZX311, respectively). Tensile tests were performed at room (24 °C, RT) and cryogenic temperature (-150 °C, CT) to probe the dislocation and twinning evolution and its consequent effect on the strength, ductility and hardening characteristics. The results revealed that AZX311 exhibited an outstanding combination of superior strength and excellent ductility at both temperatures. This unique balance of high tensile strength and consistent ductility outperforms previously documented magnesium alloys, positioning AZX311 as an ideal material for applications that demand both robust mechanical properties and reliable ductility, particularly under low-temperature conditions. The exceptional strength at cryogenic temperatures in this alloy is attributed to the synergistic effect of dislocation strengthening and boundary strengthening, where the increased barriers to dislocation movement lead to significant hardening. The presence of nano-stacking faults and greater activation of pyramidal slip, along with their interactions, result in a substantial increase in tensile strength while maintaining ductility at cryogenic temperature making it a suitable fit for cryogenic applications.