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<p>To mitigate the precipitation of coarse MC and Laves phases during the solidification of Inconel 718 alloy, this study investigates the dendritic structure, microsegregation behavior, and precipitates in the as-cast Inconel 718 alloys with varying Mg contents. The results indicate that the appropriate Mg addition content for the as-cast alloy is 0.013&#xa0;wt pct. The addition of an appropriate content of Mg enhances constitutional undercooling and restricts the migration of the solid–liquid interfaces, leading to a significant refinement of primary dendritic arm spacing (PDAS) by about 30&#xa0;pct. This refinement shortens the diffusion distance of solute elements and promotes back-diffusion, thereby alleviating microsegregation—specifically reducing the interdendritic segregation of C, Mo, Nb, and Ti, and the dendritic segregation of Cr and Fe. Furthermore, the addition of Mg effectively modifies the size, distribution, and morphology of precipitates. The continuous script-like MC phases (enriched in C, Ti, and Nb) and clustered Laves phases (enriched in Mo and Nb) are notably refined and dispersed. The average diameter and area fraction of the MC phase decrease by approximately 30 and 18&#xa0;wt pct, respectively. For the Laves phase, the corresponding values decrease by about 35 and 37&#xa0;wt pct, respectively. Meanwhile, the morphologies of both MC and Laves phases transform into elongated and blocky shapes.</p>

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Effects of Mg Content on the Dendritic Structure, Microsegregation Behavior, and Precipitates in As-Cast Inconel 718 Alloy

  • 期刊论文

  • 发表日期：

    2026年3月23日

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  • Yong-Sheng Wei,
  • Wei Gong,
  • Pu-Tong Liu,
  • Zi-Hang Mo,
  • Xiao-Long Chen,
  • Yu-Han Weng

摘要

To mitigate the precipitation of coarse MC and Laves phases during the solidification of Inconel 718 alloy, this study investigates the dendritic structure, microsegregation behavior, and precipitates in the as-cast Inconel 718 alloys with varying Mg contents. The results indicate that the appropriate Mg addition content for the as-cast alloy is 0.013 wt pct. The addition of an appropriate content of Mg enhances constitutional undercooling and restricts the migration of the solid–liquid interfaces, leading to a significant refinement of primary dendritic arm spacing (PDAS) by about 30 pct. This refinement shortens the diffusion distance of solute elements and promotes back-diffusion, thereby alleviating microsegregation—specifically reducing the interdendritic segregation of C, Mo, Nb, and Ti, and the dendritic segregation of Cr and Fe. Furthermore, the addition of Mg effectively modifies the size, distribution, and morphology of precipitates. The continuous script-like MC phases (enriched in C, Ti, and Nb) and clustered Laves phases (enriched in Mo and Nb) are notably refined and dispersed. The average diameter and area fraction of the MC phase decrease by approximately 30 and 18 wt pct, respectively. For the Laves phase, the corresponding values decrease by about 35 and 37 wt pct, respectively. Meanwhile, the morphologies of both MC and Laves phases transform into elongated and blocky shapes.