Controlling the formation of microstructure at the melt-pool boundaries during directed energy deposition of aluminum alloy with a modified continuous growth restriction factor

Shanshan Xu, Bo Yin*, Jiale Wang, Liquan Jin, Yu Yin, Zhenhua Li, David H. StJohn*, Petro Pavlenko, Yueling Guo*

*Corresponding author for this work

Research output: Contribution to journalArticlepeer-review

Abstract

Understanding the formation of solidified microstructures adjacent to the fusion boundary of a melt pool can provide valuable insights for optimizing process parameters and achieving the desired microstructure in directed energy deposition (DED). However, existing analytical models fail to consider internal and external factors, particularly the solute concentration and scan speed, leading to low prediction accuracy of the solidified microstructure. A vc model of grain growth rate is developed based on the continuous growth restriction factor QC, that considers the coupling effect of both the internal factors and external factors. QC can also be used to describe the evolution of the growth restriction factor Q along the solidification path of liquid metal within the melt pool. The vc model can accurately predict variations in the rate of grain growth and evaluate the influence of solute concentration and scan speed on the Planar to Cellular Transition (PCT) of the Solid/Liquid interface and grain size. The QC value increases with the rise of solute concentration and scan speed, resulting in further growth resistance decreasing the vc value, thereby permitting secondary embryos to nucleate only after the S/L interface moves a short distance. This study fills the gap left by the inability of Q to explain the influence of solutes on the microstructure during DED, and presents a novel approach for analyzing the formation mechanism of solidified microstructure adjacent to the fusion boundary of the melt pool.

Original languageEnglish
Pages (from-to)2344-2357
Number of pages14
JournalJournal of Materials Research and Technology
Volume34
DOIs
Publication statusPublished - 1 Jan 2025

Keywords

  • Continuous growth restriction factor
  • Directed energy deposition
  • Grain growth rate
  • Planar to cellular transition
  • Solidified microstructure

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Xu, S., Yin, B., Wang, J., Jin, L., Yin, Y., Li, Z., StJohn, D. H., Pavlenko, P., & Guo, Y. (2025). Controlling the formation of microstructure at the melt-pool boundaries during directed energy deposition of aluminum alloy with a modified continuous growth restriction factor. Journal of Materials Research and Technology, 34, 2344-2357. https://doi.org/10.1016/j.jmrt.2024.12.249