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

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. B...

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Published inMaterials science & engineering. A, Structural materials : properties, microstructure and processing Vol. 859; p. 144195
Main Authors Zhang, Xinkui, Li, Liejun, Wang, Zhi, Chen, Songjun, Peng, Hanlin, Gao, Jixiang, Peng, Zhengwu
Format Journal Article
LanguageEnglish
Published Lausanne Elsevier B.V 24.11.2022
Elsevier BV
Subjects
Al-La-Mg-Mn alloy
Alloying
Aluminum base alloys
Bimodal microstructure
Ductility
Elongation
Heat resistant alloys
Hot extrusion
Intermetallic compounds
Load transfer
Magnesium
Manganese base alloys
Mechanical properties
Microcracks
Microstructure
Pre-existing microcracks
Strain hardening
Strong strain-hardening ability
Ultimate tensile strength
Mechanical properties
Strong strain-hardening ability
Pre-existing microcracks
Bimodal microstructure
Al-La-Mg-Mn alloy
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Summary: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 high-density 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.
ISSN:0921-5093
1873-4936
DOI:10.1016/j.msea.2022.144195