Influence of withdrawal rate on the porosity in a third-generation Ni-based single crystal superalloy

Yue, Quanzhao; Liu, Lin; Yang, Wenchao; Huang, Taiwen; Zhang, Jun; Fu, Hengzhi; Zhao, Xinbao

doi:10.1016/j.pnsc.2017.02.008

Cited by 24 publications

(11 citation statements)

References 24 publications

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“…The primary spacing controls the maximum length scale for the microsegregation [7], the solutioning heat treatment times [8,9], and the mechanical properties of the directionally solidified material [10][11][12][13][14][15][16][17][18][19][20][21][22][23][24]. In addition, the λ 1 directly influences the mushy zone convection, the formation of low melting point secondary phase eutectics, as well as incoherent precipitates and pores in the interdendritic region [25][26][27][28][29][30][31][32]. Consequently, the mechanical properties of unidirectional solidified crystals are strongly dependent on the temperature and convection within the melt, as this controls the concentration of solute at the solid-liquid interface.…”

Section: Introductionmentioning

confidence: 99%

On Directional Dendritic Growth and Primary Spacing—A Review

2020

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The primary spacing is intrinsically linked with the mechanical behavior of directionally solidified materials. Because of this relationship, a significant amount of solidification work is reported in the literature, which relates the primary spacing to the process variables. This review provides a comprehensive chronological narrative on the development of the directional dendritic growth problem over the past 85 years. A key focus within this review is detailing the relationship between key solidification parameters, the operating point of the dendrite tip, and the primary spacing. This review critiques the current state of directional dendritic growth and primary spacing modelling, briefly discusses dendritic growth computational and experimental research, and suggests areas for future investigation.

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Section: Introductionmentioning

confidence: 99%

On Directional Dendritic Growth and Primary Spacing—A Review

2020

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“…Two distinct pore types can be seen in Fig.2 (c). The elongated, irregular shaped pores, are known as shrinkage porosities which form during the final stages of the solidification process[45]. The more spherical, smaller pores are known as gas pores[46].…”

mentioning

confidence: 99%

Strain accumulation and fatigue crack initiation at pores and carbides in a SX superalloy at room temperature

Jiang

Bull

Evangelou

et al. 2018

International Journal of Fatigue

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Pores and carbides inherited from SX superalloy manufacturing processes usually act as stress concentrators and are preferential sites for fatigue crack initiation. In this study, pore & carbide size, morphology and distribution in a SX superalloy MD2 has been evaluated by X-ray CT. Strain accumulation and fatigue cracking behaviour in MD2, particularly around the pores and carbides, has been investigated by ex-situ SEM-DIC at room temperature along with image-based modelling of the observed MD2 defect populations obtained through X-ray CT imaging. The deformation structures have also been examined by electron channelling contrast imaging under controlled diffraction conditions. The results indicate that the pores & carbides with complicated three-dimensional features are the dominant fatigue crack initiation sites. Deformation is concentrated within intense slip bands and an enhanced strain accumulation around pores is captured by SEM-DIC. Dislocation motion is mainly confined to the γ matrix channels with some dislocation shear cutting of γʹ precipitates also observed ahead of the crack tip. As the crack propagates, strain band density and dislocation density at the crack tip increases correspondingly. Image-based modelling using the observed defect populations in MD2 (micro)structure can effectively predict the stress concentrations and the resultant hot spot for subsequent fatigue crack initiation, which is consistent with the experimental observations.

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“…The microstructure evolution trends are consistent with conventional alloys reported in literature. 24,31) It should be noted that the microstructure is different from Zhang et al's work 26) with similar withdrawal velocities, which could be related to superheat and temperature gradient. The melting temperatures of the elements in HEAs are significantly varied, which leads to a wide solidification range, and thus large superheat is required.…”

Section: Methodsmentioning

confidence: 73%

Effect of Solidification Rate on the Microstructure and Strain-Rate-Sensitive Mechanical Behavior of AlCoCrFeNi High-Entropy Alloy Prepared by Bridgman Solidification

et al. 2019

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AlCoCrFeNi high-entropy alloys (HEAs) were prepared by Bridgman solidification with different solidification rates, and the mechanical behavior of the HEAs was investigated over a wide strain rate range (³10 ¹3 ³10 3 s ¹1). Microstructure observations suggest that, with increasing solidification rate, the microstructure evolves from coarse columnar grains to fine equiaxed ones. Through compression tests under both quasistatic and dynamic strain rates, the AlCoCrFeNi HEAs were found to possess positive strain-rate sensitivity (SRS), and the HEA with lower solidification rate exhibits higher SRS, which are attributed to the coarse grain size.

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Influence of withdrawal rate on the porosity in a third-generation Ni-based single crystal superalloy

Cited by 24 publications

References 24 publications

On Directional Dendritic Growth and Primary Spacing—A Review

On Directional Dendritic Growth and Primary Spacing—A Review

Strain accumulation and fatigue crack initiation at pores and carbides in a SX superalloy at room temperature

Effect of Solidification Rate on the Microstructure and Strain-Rate-Sensitive Mechanical Behavior of AlCoCrFeNi High-Entropy Alloy Prepared by Bridgman Solidification

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