TY - JOUR
T1 - Controlling the formation of microstructure at the melt-pool boundaries during directed energy deposition of aluminum alloy with a modified continuous growth restriction factor
AU - Xu, Shanshan
AU - Yin, Bo
AU - Wang, Jiale
AU - Jin, Liquan
AU - Yin, Yu
AU - Li, Zhenhua
AU - StJohn, David H.
AU - Pavlenko, Petro
AU - Guo, Yueling
N1 - Publisher Copyright:
© 2024 The Authors
PY - 2025/1/1
Y1 - 2025/1/1
N2 - 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.
AB - 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.
KW - Continuous growth restriction factor
KW - Directed energy deposition
KW - Grain growth rate
KW - Planar to cellular transition
KW - Solidified microstructure
UR - http://www.scopus.com/inward/record.url?scp=85213265316&partnerID=8YFLogxK
U2 - 10.1016/j.jmrt.2024.12.249
DO - 10.1016/j.jmrt.2024.12.249
M3 - Article
AN - SCOPUS:85213265316
SN - 2238-7854
VL - 34
SP - 2344
EP - 2357
JO - Journal of Materials Research and Technology
JF - Journal of Materials Research and Technology
ER -