Synchrotron X-ray imaging and ultrafast tomography in situ study of the fragmentation and growth dynamics of dendritic microstructures in solidification under ultrasound

DOI: 10.1016/j.actamat.2021.116796

Authors: Zhiguo Zhang (Jinan University; University of Hull) , Chuangnan Wang (University of Hull) , Billy Koe (University of Hull; Diamond Light Source) , Christian M. Schlepütz (Swiss Light Source) , Sarah Irvine (Diamond Light Source) , Jiawei Mi (University of Hull; Shanghai Jiao Tong University)
Co-authored by industrial partner: No

Type: Journal Paper
Journal: Acta Materialia , VOL 8

State: Published (Approved)
Published: March 2021

Abstract: High speed synchrotron X-ray imaging and ultrafast tomography were used to study in situ and in real time the fragmentation and growth dynamics of dendritic microstructures of an Al-15%Cu alloy in solidification under ultrasound. Under the studied condition, a strong swirling acoustic flow of ∼0.3 m/s was observed, resulting in efficient dendrite fragmentation due to thermal perturbation remelting plus mechanical fracture and separation effects. Acoustic flow fatigue impact and phase collision effects were found to play a minor role in causing dendrite fragmentation. Just 10 s of ultrasound application at the early stage of solidification produced ∼100% more dendrite fragments compared to the case without ultrasound, resulting in 20∼25% reduction in the average grain size in the solidified samples. Furthermore, the dendrite morphology and tip growth velocity were mainly affected by the initial dendrite fragment number density and their distribution. The systematic and real-time datasets obtained in near operando conditions provided valuable 4D information for validation of numerical models and assistance in developing optimisation strategy for ultrasound melt processing in industry.

Journal Keywords: Synchrotron X-ray imaging; Ultrafast synchrotron X-ray tomography; Ultrasonic melt processing; Dendrite fragmentation; Solidification; Al alloys

Diamond Keywords: Alloys

Subject Areas: Materials, Engineering

Facility: TOMCAT beamline X02DA at Swiss Light Source

Added On: 16/03/2021 15:32

Documents:
1-s2.0-S1359645421001762-main.pdf

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Materials Science Engineering & Technology Industrial Engineering Metallurgy

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