Metallurgical and Materials Transactions B

, Volume 49, Issue 4, pp 1883–1897 | Cite as

Effect of Cooling Rate on Microsegregation During Solidification of Superalloy INCONEL 718 Under Slow-Cooled Conditions

  • Xiao Shi
  • Sheng-Chao Duan
  • Wen-Sheng Yang
  • Han-Jie Guo
  • Jing Guo


The solidification sequence, microstructural evolution, solid-liquid interface variation, interdendritic segregation, and elemental distribution of as-cast IN718 alloy at three slow-cooling rates (5, 10, and 20 °C/min) were investigated by differential scanning calorimetry (DSC), confocal laser scanning microscopy (CLSM), optical microscopy (OM), field-emission scanning electron microscopy (FESEM), and electron-probe microanalysis (EPMA) techniques. The results indicate that as the cooling rate decreases, the constitutional supercooling at the solidification front affects the solid-liquid interface more significantly, and the size and quantity of the Laves phase increase. However, the composition of the Laves phase is insensitive to the cooling rate in the range of conditions studied here. In dendrite core, the contents of Ni, Cr, Fe, and Al follow a slight downward trend with an increasing cooling rate, whereas the Nb, Mo, and Ti contents show an upward trend. Additionally, Mo shows a stronger propensity to segregate under slow-cooling conditions because its effective partition coefficient almost linearly decreased with decreasing cooling rate, which is same as Nb. Using the parameters experimentally determined in this study and the Clyne–Kurz equation, we achieved reasonable agreement between the calculated and measured liquid composition change during the solidification process at different cooling rates. All experimental and theoretical programs in this research were undertaken with the aim of gaining further understanding of the microsegregation behaviors in large-scale IN718 ingots, whose cooling rates are within a lower range.



This work was financially supported by the National Natural Science Foundation of China (NSFC) Grant No. U1560203 and the Fundamental Research Fund for the Central Universities of China No. FRF-TP-16-079A1.


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Copyright information

© The Minerals, Metals & Materials Society and ASM International 2018

Authors and Affiliations

  • Xiao Shi
    • 1
    • 2
  • Sheng-Chao Duan
    • 1
    • 2
  • Wen-Sheng Yang
    • 1
    • 2
  • Han-Jie Guo
    • 1
    • 2
  • Jing Guo
    • 1
    • 2
  1. 1.School of Metallurgical and Ecological EngineeringUniversity of Science and Technology BeijingBeijingChina
  2. 2.Beijing Key Laboratory of Special Melting and Preparation of High-End Metal MaterialsBeijingChina

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