Bimodal microstructure evolution and strength-ductility co-enhancement of hot-extruded Al-La-Mg-Mn alloy

作者：Zhang, Xinkui; Li, Liejun; Wang, Zhi; Chen, Songjun; Peng, Hanlin; Gao, Jixiang; Peng, Zhengwu^*

来源：Materials Science & Engineering A: Structural Materials: Properties, Microstructure and Processing , 2022, 859: 144195.

DOI：10.1016/j.msea.2022.144195

• Al-La-Mg-Mn alloy
• Bimodal microstructure
• Mechanical properties
• Pre-existing microcracks
• Strong strain-hardening ability

Novel heat-resistant Al-(La, Ce) alloys are strengthened via alloying with high Mg; however, their ductility deteriorates due to the formation of coarse intermetallics. In this work, a conventional hot extrusion process was used to refine the microstructures of Al-La alloy with a high Mg addition. Bimodal intermetallic and grain structures were observed in the as-extruded alloy. Of note, the coarse intermetallics were decorated with highdensity microcracks. The as-extruded alloy achieved a good balance between strength and ductility, exhibiting a high ultimate tensile strength (360 +/- 2 MPa) and good elongation (9.6 +/- 0.6%). The high strength was mainly attributed to the strong strain-hardening ability and the load-transfer effect. Good elongation arises from the propagation of pre-existing microcracks, microstructure refinement, and increased strain-hardening ability. These findings reveal that a combination of pre-existing microcracks and a matrix with strong strain-hardening ability is a promising feature for microstructural design with increased ductility.

• 单位
  广东技术师范学院