Segregation and Solid Evolution During the Solidification of Niobium-Containing Superalloys

Yang, Wulin; Chen, W.; Chang, Keh‐Minn; Mannan, S.; deBarbadillo, J.J.

doi:10.7449/2000/superalloys_2000_75_84

Cited by 12 publications

(3 citation statements)

References 19 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…This result is in accordance to the experimentally determined trend reported by Yang et al 20 for commercial superalloys with different amounts of Fe, and with the redistribution modeling results reported by DuPont et al 21 (a)…”

Section: Comparing With Theoretical Valuessupporting

confidence: 93%

Investigation of the Partition Coefficient in the Ni-Fe-Nb Alloys: A Thermodynamic and Experimental Approach

Valdés

Kim

Shang³

et al. 2008

Superalloys 2008 (Eleventh International Symposium)

View full text Add to dashboard Cite

The Nb containing Ni-based superalloys used for the production of large castings are highly sensible to the formation of macrosegregation defects like freckles and white spots. Production cost can be reduced by better prediction of the freckle formation. The most accepted freckling criterion is the one based on the Rayleigh number, which requires accurate determination of the partition coefficients for the solute elements. In this work, the partition coefficients of Nb and Fe on the ternary system Ni-FeNb were studied by experimental measurements and by thermodynamic calculations. Modified DTA experiments were performed for model alloys, and a thermodynamic database for the Ni-Fe-Nb ternary system was developed. Most of the calculated partition coefficients using the developed model agree well with the experimental data. One exception to this, as will be discussed later, is the partitioning coefficient of Fe for the alloy containing 36 wt. %Fe.

show abstract

Section: Comparing With Theoretical Valuessupporting

confidence: 93%

Investigation of the Partition Coefficient in the Ni-Fe-Nb Alloys: A Thermodynamic and Experimental Approach

Valdés

Kim

Shang³

et al. 2008

Superalloys 2008 (Eleventh International Symposium)

View full text Add to dashboard Cite

show abstract

“…The inclination of Re concentration is higher for 100 K/min in comparison with 1 K/min, especially in the adjacent area to the dendrite boundary. According to A. D. Patel and Y. V. Murty, 11) and Wanhong Yang et al, 12) at lower cooling rates, there is enough time for back diffusion in the solid (solidification time is greater than diffusion time); hence, a lower fraction of eutectic laves (Ni 2 Nb) phase. This suggests that in large ingots, the volume fraction of laves phase is the highest at the surface of ingot and decreases towards the center part.…”

Section: Effect Of Re On Solidification Of St-in718 Alloymentioning

confidence: 99%

Influence of Rhenium and Cooling Rate on the Solidification of Ni Base Superalloys, Inconel 718

et al. 2005

View full text Add to dashboard Cite

Influence of 2-6% Re additions has been investigated on the solidification phenomenon of a Ni base superalloy, In718. The solidification of each alloy proceeds in the order of primary , eutectic (+NbC) and eutectic (+Ni 2 Nb). Higher additions of Re increase the volume fraction of primary and enlarge the secondary dendrite arm spacing. The influence of cooling rates at 1, 10 and 100 K/min has also been studied on the solidification process of the alloy containing 3.5% Re. With increasing cooling rate, the crystallization start temperatures of primary and eutectic phases decrease and the volume fraction of NbC and Ni 2 Nb increase. EPMA analysis revealed that the distribution of alloy elements in microstructure also changed depending on cooling rate. The redistribution of alloy elements during solidification was evaluated by Clyne-Kurz and Ohnaka theories.

show abstract

“…This alloy is used widely in the parts of gas turbines and aeroplane engines due to its high strength as well as thermal and corrosion resistance. However, in spite of its good performance at high temperatures, the alloy elements added in Waspaloy, such as Mo, Ti, and Al, cause heavy microsegregation, even macrosegregation and freckles during solidification [1][2][3][4][5]. Once freckles form, the castings will be scrapped, which will limit the scale-up of the size and development of Waspaloy castings.…”

Section: Introductionmentioning

confidence: 99%

Effect of cooling rate on the phase transformation and stability of the mushy zone during the solidification of Waspaloy

Wang

Yao

Liu

et al. 2010

Int J Miner Metall Mater

View full text Add to dashboard Cite

Scanning electron microscopy (SEM) and energy dispersive X-ray analysis (EDAX) were used to study the microstructure, microsegregation, and fluid flow tendency of the superalloy Waspaloy in the mushy zone, which had been solidified at different cooling rates. The investigation was accompanied with the calculation of Rayleigh numbers. It is found that Ti is the main segregating element and the content of Ti is the highest in the final liquid at the cooling rates of 3-6°C/min. The eta phase (η ) precipitate presented in the residual liquid at the cooling rates higher than 6 °C/min is responsible for the fluctuations in the curves of Ti content. The dendrite arm spacing is found to markedly decrease with the increase of cooling rate. The maximum relative Rayleigh number occurs at 10-20°C below the liquidus temperature at a cooling rate of 1°C/min, where the mushy zone is most unstable and fluid flow is most prone to occur.

show abstract

Segregation and Solid Evolution During the Solidification of Niobium-Containing Superalloys

Cited by 12 publications

References 19 publications

Investigation of the Partition Coefficient in the Ni-Fe-Nb Alloys: A Thermodynamic and Experimental Approach

Investigation of the Partition Coefficient in the Ni-Fe-Nb Alloys: A Thermodynamic and Experimental Approach

Influence of Rhenium and Cooling Rate on the Solidification of Ni Base Superalloys, Inconel 718

Effect of cooling rate on the phase transformation and stability of the mushy zone during the solidification of Waspaloy

Contact Info

Product

Resources

About