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Formation of intermetallic phases in unrefined and refined AA6082 Al alloys investigated by using SEM-based ultramicrotomy tomography

Journal Article


Abstract


  • The spatial arrangement, distribution and morphology of Fe-bearing intermetallics in AA6082 alloys depends on the manufacturing process of the alloy and thus influences the macroscopic properties. Here, the microstructure of a near industrial scale casting AA6082 Al alloy fabricated by: (a) direct chill casting, (b) Al-5Ti-1B grain refiner addition and (c) intensive melt shearing has been investigated by three-dimensional visualization using SEM-based serial ultramicrotomy tomography. The formation sequence of phases in AA6082 alloys is generally categorized into four stages: formation of ��-Al grains, Fe-bearing intermetallics, Mg2Si phase, and eutectic rosettes. Results of three-dimensional visualization of the microstructure indicated that TiB2 particles not only could nucleate Fe-bearing ��-intermetallics, but also could provide substrate for the formation of Fe-bearing ��-intermetallics and Mg2Si. A further deep analysis reveals that the essential condition for the formation of secondary phases such as Fe-bearing intermetallics and Mg2Si phase is the build-up of a supersaturated solute front at the ��-Al solid-liquid interface irrespective of the specific nucleation site. In addition, the results indicate that grain refinement processing causes the severe interconnectivity of Fe-bearing ��-intermetallics. However, the intensive melt shearing is a better manufacturing process because the intermetallics are more evenly distributed and refined than with the addition of the grain refiner, thereby improving the properties of the alloy.

Publication Date


  • 2022

Citation


  • Yu, J. M., Hashimoto, T., Li, H. T., Wanderka, N., Zhang, Z., Cai, C., . . . Wang, X. N. (2022). Formation of intermetallic phases in unrefined and refined AA6082 Al alloys investigated by using SEM-based ultramicrotomy tomography. Journal of Materials Science and Technology, 120, 118-128. doi:10.1016/j.jmst.2022.02.007

Scopus Eid


  • 2-s2.0-85126632635

Start Page


  • 118

End Page


  • 128

Volume


  • 120

Issue


Place Of Publication


Abstract


  • The spatial arrangement, distribution and morphology of Fe-bearing intermetallics in AA6082 alloys depends on the manufacturing process of the alloy and thus influences the macroscopic properties. Here, the microstructure of a near industrial scale casting AA6082 Al alloy fabricated by: (a) direct chill casting, (b) Al-5Ti-1B grain refiner addition and (c) intensive melt shearing has been investigated by three-dimensional visualization using SEM-based serial ultramicrotomy tomography. The formation sequence of phases in AA6082 alloys is generally categorized into four stages: formation of ��-Al grains, Fe-bearing intermetallics, Mg2Si phase, and eutectic rosettes. Results of three-dimensional visualization of the microstructure indicated that TiB2 particles not only could nucleate Fe-bearing ��-intermetallics, but also could provide substrate for the formation of Fe-bearing ��-intermetallics and Mg2Si. A further deep analysis reveals that the essential condition for the formation of secondary phases such as Fe-bearing intermetallics and Mg2Si phase is the build-up of a supersaturated solute front at the ��-Al solid-liquid interface irrespective of the specific nucleation site. In addition, the results indicate that grain refinement processing causes the severe interconnectivity of Fe-bearing ��-intermetallics. However, the intensive melt shearing is a better manufacturing process because the intermetallics are more evenly distributed and refined than with the addition of the grain refiner, thereby improving the properties of the alloy.

Publication Date


  • 2022

Citation


  • Yu, J. M., Hashimoto, T., Li, H. T., Wanderka, N., Zhang, Z., Cai, C., . . . Wang, X. N. (2022). Formation of intermetallic phases in unrefined and refined AA6082 Al alloys investigated by using SEM-based ultramicrotomy tomography. Journal of Materials Science and Technology, 120, 118-128. doi:10.1016/j.jmst.2022.02.007

Scopus Eid


  • 2-s2.0-85126632635

Start Page


  • 118

End Page


  • 128

Volume


  • 120

Issue


Place Of Publication