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Multiscale characterization of the nucleation and 3D structure of Al3Sc phases using electron microscopy and synchrotron X-ray tomography

DOI: 10.1016/j.matchar.2020.110353 DOI Help

Authors: Yuliang Zhao (Dongguan University of Technology; South China University of Technology) , Weiwen Zhang (South China University of Technology) , Billy Koe (University of Hull; Diamond Light Source) , Wenjia Du (University of Hull) , Mengmeng Wang (Shanghai Jiao Tong University) , Weilin Wang (Shanghai Jiao Tong University) , Elodie Boller (ESRF-The European Synchrotron) , Alexander Rack (ESRF-The European Synchrotron) , Zhenzhong Sun (Dongguan University of Technology) , Da Shu (Shanghai Jiao Tong University) , Baode Sun (Shanghai Jiao Tong University) , Jiawei Mi (University of Hull; Shanghai Jiao Tong University)
Co-authored by industrial partner: No

Type: Journal Paper
Journal: Materials Characterization

State: Published (Approved)
Published: April 2020

Abstract: Scandium (Sc) has been long recognized as one of the most effective grain refining elements for Al alloys because of the Al3Sc phases formed in an Al melt containing Sc. However, there are still lack of comprehensive studies on the exact mechanism of how Al3Sc phases are nucleated in Al melt and their true 3D structures. In this paper, we used scanning/transmission electron microscopy and synchrotron X-ray tomography to study the nucleation and true 3D structure of primary Al3Sc phases in an Al-2wt%Sc alloy. The multiscale characterization approach revealed that the micrometre α-Al2O3 particles present in the Al melt can facilitate the formation of stacking faults at the α-Al2O3/Al3Sc interface and therefore promote heterogenous nucleation of Al3Sc phases. SEM and tomography clearly revealed that individual primary Al3Sc phases were simple cubes with the edge length of 10–35 μm; and majority of them were interconnected to form clusters with the peak value of 10,000 μm3. At the interface between an Al matrix and an Al3Sc cube, the Al3Sc phases can also grow into nanometre size particle clusters due to the depletion of Sc.

Journal Keywords: Multiscale characterization; Al3Sc intermetallics; Al alloy; Electron microscopy; Synchrotron X-ray tomography

Subject Areas: Materials

Facility: ID19 at ESRF