Grain structure and texture evolutions during single crystal casting of the Ni-base superalloy CMSX-4

Seo, Seong Moon; Kim, In Soo; Lee, Je Hyun; Jo, Chang-Yong; Miyahara, Hirofumi; Ōgi, Keisaku

doi:10.1007/s12540-009-0391-2

Cited by 49 publications

(32 citation statements)

References 24 publications

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“…Note that the DSC exothermic peak at 1402 K could not be observed in the DSC curve of the alloy CM247LC, whose as-cast microstructure is composed of primary c, MC carbide, c/c¢ eutectic, and c¢ precipitates. [14] However, because the onset temperatures of MC carbide, c/c¢ eutectic, c¢ precipitation, and eta and boride phases were concealed by the trail of primary c solidification peak, the exact phase transformation temperature of these phases could not be determined by the DSC analysis. Nevertheless, assuming that the formation of eta and boride phases continues below their peak temperature (1402 K), the solidification range, which is defined as the temperature difference between the primary c formation and the end of solidification, might be about 196 K.…”

Section: Solidification Sequence Of Eta and Boride Phasesmentioning

confidence: 99%

Eta Phase and Boride Formation in Directionally Solidified Ni-Base Superalloy IN792 + Hf

Seo

Kim

Lee

et al. 2007

Metall Mater Trans A

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A series of directional solidification experiments have been conducted to elucidate the formation mechanism of eta and Cr-rich phases in the Ni-base superalloy IN792 + Hf. Both eta and Cr-rich phases were found to be the final solidification products developed from the remaining liquid after c/c¢ eutectic reaction. The (Ti + Ta + Hf)/Al ratio in the residual liquid played a significant role in the nucleation of eta phase. During the solidification of c/c¢ eutectic, the continual increase of (Ti + Ta + Hf)/Al ratio in the residual liquid eventually led to the completion of c/c¢ eutectic reaction and caused the nucleation of eta phase. The results of electron probe microanalysis and transmission electron microscopy revealed that the Cr-rich phase was Cr, Mo, and W containing M 5 B 3 and M 3 B 2 type borides. The formation of these boride phases was found to be strongly influenced by the formation of c/c¢ eutectic. Because of the limited solubility of Cr, Mo, and W in c¢ phase, these elements were enriched in the residual liquid during the solidification of c/c¢ eutectic. In addition, boron would preferentially segregate into liquid due to its very limited solubility in both c and c¢ phases so that the possibility of boride formation in the residual liquid ahead of the c/c¢ eutectic was increased. A modified Scheil model was adopted to explain the influence of solidification rate on the formation of eta phase and borides, and the results were discussed.

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Section: Solidification Sequence Of Eta and Boride Phasesmentioning

confidence: 99%

Eta Phase and Boride Formation in Directionally Solidified Ni-Base Superalloy IN792 + Hf

Seo

Kim

Lee

et al. 2007

Metall Mater Trans A

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“…However, the relative growth directions significantly influence the competitive growth of grains. It was found that grains with larger misorientations were preserved on top of the starter block for improper geometry design [18,19], meaning that unfavorable grains were not overgrown through a long competitive growth distance. This illustrated that the misaligned grains would have great growth advantage and can overgrow the well-aligned grains under special conditions.…”

Section: Grain Competitive Growth Mechanismmentioning

confidence: 99%

Investigation of grain competitive growth during directional solidification of single-crystal nickel-based superalloys

2015

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Grain competitive growth of nickel-based single-crystal superalloys during directional solidification was investigated. A detailed characterization of bi-crystals' competitive growth was performed to explore the competitive grain evolution. It was found that high withdrawal rate improved the efficiency of grain competitive growth. The overgrowth rate was increased when the misorientation increased. Four patterns of grain competitive growth with differently oriented dispositions were characterized. The results indicated that the positive branching of the dendrites played a significant role in the competitive growth process. The effect of crystal orientation and heat flow on the competitive growth can be attributed to the blocking mechanism between the adjacent grains.

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“…The mechanism of grain selection during directional solidification and the opting of one grain from a set of columnar grains have been studied by various researchers both experimentally and theoretically . Initially, Schneider et al.…”

Section: Introductionmentioning

confidence: 99%

Optimizing Grain Selection Design in the Single‐Crystal Solidification of Ni‐Based Superalloys

Sadeghi

Kermanpur

Norouzi‬

2018

Crystal Research and Technology

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An attempt is made to model the design of grain selection during single‐crystal solidification of an Ni‐based superalloy by the Bridgman method. Various geometrical designs of the starter block and spiral grain selector are chosen and their effects on crystal orientation of the single‐crystal part are studied. The competitive grain selection is simulated utilizing the cellular automaton finite element module of the ProCAST software. The simulated results are validated against the experimental observation of grain structure along with the crystal orientation measured by the electron backscatter diffraction (EBSD) and rotational orientation X‐ray diffraction (RO‐XRD) techniques. The results show that in order to obtain the single crystal with a minimum deviation from longitudinal axis, the height and diameter of the starter block as well as the height and the take‐off angle of the spiral should be optimized. It is found that the diameter/height ratio of the starter block should be less than 0.6 to obtain a well‐oriented single crystal prior to entrance of solidification front into the spiral. The height of starter block is found to be more influential than its diameter in selecting the suitable single grain.

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Grain structure and texture evolutions during single crystal casting of the Ni-base superalloy CMSX-4

Cited by 49 publications

References 24 publications

Eta Phase and Boride Formation in Directionally Solidified Ni-Base Superalloy IN792 + Hf

Eta Phase and Boride Formation in Directionally Solidified Ni-Base Superalloy IN792 + Hf

Investigation of grain competitive growth during directional solidification of single-crystal nickel-based superalloys

Optimizing Grain Selection Design in the Single‐Crystal Solidification of Ni‐Based Superalloys

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