The effect of silicon on the microstructure and segregation of directionally solidified IN738 superalloy

“…In the last term of these three equations, the position of impurity in bulk material was always considered as substitutional, because this type of position of impurity is more stable than the interstitial one. After a deeper examination of this issue in Equation (24), it was found that the E seg Va bulk ;Va GB (X) quantity is, in case of the substitutional impurity, consistent with the X-GB binding energy at presence of Va, which is described by Equation (15). However, in case of the interstitial impurity, the results differ.…”

Section: Structure E B (Va;gb+x) E B (X;gb+va) E B (Gb+x;gb+va) E B (mentioning

confidence: 91%

“…We can also evaluate further energy-related quantities, which are described in the following text and defined using Equations (10)- (15). The first such quantity is the binding energy of a vacancy to couple of lattice defects GB+X (the tendency of vacancy to move from the bulk to the GB with impurity) which is evaluated as:…”

Section: Energeticsmentioning

confidence: 99%

“…However, in case of the interstitial impurity, the results differ. The reason for this difference is that we used the bulk material with interstitial Si as the reference state in case of Equation (15) and in case of the Equation (24), the bulk material with the more stable substitutional Si was used.…”

Section: Structure E B (Va;gb+x) E B (X;gb+va) E B (Gb+x;gb+va) E B (mentioning

confidence: 99%

“…The experimental results also reveal that the content of aluminum has a significant effect on the solvus temperature in nickel-based alloys. In IN738 superalloy, silicon segregates mainly in inter-dendritic regions and promotes the segregation of other elements [15].…”

Section: Introductionmentioning

confidence: 99%

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The Effect of Vacancies on Grain Boundary Segregation in Ferromagnetic fcc Ni

et al. 2020

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This work presents a comprehensive and detailed ab initio study of interactions between the tilt Σ5(210) grain boundary (GB), impurities X (X = Al, Si) and vacancies (Va) in ferromagnetic fcc nickel. To obtain reliable results, two methods of structure relaxation were employed: the automatic full relaxation and the finding of the minimum energy with respect to the lattice dimensions perpendicular to the GB plane and positions of atoms. Both methods provide comparable results. The analyses of the following phenomena are provided: the influence of the lattice defects on structural properties of material such as lattice parameters, the volume per atom, interlayer distances and atomic positions; the energies of formation of particular structures with respect to the standard element reference states; the stabilization/destabilization effects of impurities (in substitutional (s) as well as in tetragonal (iT) and octahedral (iO) interstitial positions) and of vacancies in both the bulk material and material with GBs; a possibility of recombination of Si(i)+Va defect to Si(s) one with respect to the Va position; the total energy of formation of GB and Va; the binding energies between the lattice defects and their combinations; impurity segregation energies and the effect of Va on them; magnetic characteristics in the presence of impurities, vacancies and GBs. As there is very little experimental information on the interaction between impurities, vacancies and GBs in fcc nickel, most of the present results are theoretical predictions, which may motivate future experimental work.

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Effect of Si on the Solidification Segregation Behavior of a New Ni–Co‐Based Superalloy

et al. 2021

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Herein, the effects of Si addition on the microstructure and solidification behavior of a new Ni–Co‐based superalloy are investigated. The microstructure of the as‐cast alloys is mainly composed of γ, γ′, (γ–γ′) eutectics, and MC‐type carbides. The results demonstrate that Si addition significantly decreases the size and volume fraction of (γ–γ′) eutectics, while promoting the formation of Si‐rich phase precipitated in front of the (γ–γ′) eutectics. The formation of a Si‐rich phase is induced by the rejection of Ti and Si into the residual liquid during the γ matrix formation. With the increase in Si content, the size distribution of (γ–γ′) eutectics decreases due to the formation of the Si‐rich phase consuming the forming element of (γ–γ′) eutectics. The solidus and liquidus temperatures of the alloy decrease with the increase in Si. However, the range of melting temperature increases. The Si addition promotes the segregation of alloying elements, and Si tends to segregate in the interdendritic region.

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The effect of silicon on the microstructure and segregation of directionally solidified IN738 superalloy

Cited by 13 publications

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Thermal–mechanical fatigue behaviour of a new single crystal superalloy: Effects of Si and Re alloying

Thermal–mechanical fatigue behaviour of a new single crystal superalloy: Effects of Si and Re alloying

The Effect of Vacancies on Grain Boundary Segregation in Ferromagnetic fcc Ni

Effect of Si on the Solidification Segregation Behavior of a New Ni–Co‐Based Superalloy

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