Effect of cryogenic temperature on the strengthening mechanisms of AZ61 Mg alloy extruded at different temperatures

• Published in: Journal of materials research and technology Vol. 33; pp. 335 - 348
• Main Authors: Tariq, Hafiz Muhammad Rehan, Masood Chaudry, Umer, Suh, Joung Sik, Kim, Young Min, Jun, Tea-Sung
• Format: Journal Article
• Language: English
• Published: Elsevier B.V 01-11-2024; Elsevier
• Subjects: Cryogenic deformation; Magnesium alloys; Stacking faults; Texture strengthening; Twin-twin interactions; Stacking faults; Cryogenic deformation; Twin-twin interactions; Texture strengthening; Magnesium alloys
• ISSN: 2238-7854
• DOI: 10.1016/j.jmrt.2024.09.068

This study investigates the influence of extrusion and deformation temperatures on the mechanical properties of the AZ61 Mg alloy. Increasing the extrusion temperature from 300 to 400 °C led to larger grain size and higher basal texture intensity. At 400 °C, the AZ61 alloy exhibited more Al–Mn phases and fewer Mg17Al12 phases, indicating enhanced dissolution of Mg17Al12 in the α-Mg matrix. Uniaxial tensile tests were conducted at room temperature (RT) and cryogenic temperature (CT, −150 °C). Despite grain growth, a higher yield strength (YS) was achieved at higher extrusion temperatures due to the texture-strengthening mechanism. However, during deformation at CT, the higher YS was primarily attributed to the formation of multiple twinning within individual grains, causing twinning interactions. These twin-interacting boundaries create additional barriers to dislocation movement. Notably, the AZ61 sample extruded at 400 °C demonstrated the formation of stacking faults during deformation at CT, with dislocations accumulating around the faults. This contributed to the best strength without compromising ductility in this sample.