The effect of magnetic field on precipitation phases of single-crystal nickel-base superalloy during directional solidification

Ren, Weili; Lu, Lerong; Yuan, Guangzhou; Wang, Xuan; Zhong, Yunbo; Ren, Zhongming

doi:10.1016/j.matlet.2013.03.023

Cited by 27 publications

(6 citation statements)

References 5 publications

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“…Figure 10 presents the element segregation coefficient k ’ of single crystal specimens at a temperature gradient of 80 K·cm −1 , drawing speed of 10 μm·s −1 , diameter of 12 mm as a function of intensities of magnetic field. Al and Ti show positive segregation behavior ( k ’ < 1), and Cr and Co show negative segregation behavior ( k ’ > 1), which agrees with that in Reference [ 15 ]. At the 0.5 T magnetic field, k ’ of Al and Ti increase by 11% and 13%, respectively, and k ’ of Cr and Co decrease by 27% and 25%, respectively.…”

Section: Discussionsupporting

confidence: 92%

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Directional Solidification Microstructure of a Ni-Based Superalloy: Influence of a Weak Transverse Magnetic Field

Wang

Zhang

et al. 2015

Materials

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A Ni-based superalloy CMSX-6 was directionally solidified at various drawing speeds (5–20 μm·s−1) and diameters (4 mm, 12 mm) under a 0.5 T weak transverse magnetic field. The results show that the application of a weak transverse magnetic field significantly modified the solidification microstructure. It was found that if the drawing speed was lower than 10 μm·s−1, the magnetic field caused extensive macro-segregation in the mushy zone, and a change in the mushy zone length. The magnetic field significantly decreases the size of γ’ and the content of γ-γ’ eutectic. The formation of macro-segregation under a weak magnetic field was attributed to the interdendritic solute transport driven by the thermoelectric magnetic convection (TEMC). The γ’ phase refinement could be attributed to a decrease in nucleation activation energy owing to the magnetic field during solid phase transformation. The change of element segregation is responsible for the content decrease of γ-γ’ eutectic.

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Section: Discussionsupporting

confidence: 92%

“…The nucleation activation energy of the γ′ phase precipitates is [ 15 ]:

where

is the interface energy between γ′ and γ phase,

is the volume free energy difference. The critical radius is given by:

…”

Section: Discussionmentioning

confidence: 99%

Directional Solidification Microstructure of a Ni-Based Superalloy: Influence of a Weak Transverse Magnetic Field

Wang

Zhang

et al. 2015

Materials

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“…These magnetic fields could affect the dendrites orientation or even break the dendrites. The effect of breaking dendrites was also shown by Ren et al [6]. This has to be proven for our setup by Scanning Electron Microscope (SEM) analysis.…”

Section: Resultssupporting

confidence: 72%

Crack Repair of Single Crystal Turbine Blades Using Laser Cladding Technology

et al. 2014

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The formation of cracks in single crystal (SX) turbine blades is a common problem for aero-engines. To repair cracks, which are located under the tip-area, a new method is to clad with single-crystal-technology. This technology use multi-layer cladding to replace the single crystal material. To regenerate cracked material it is necessary to remove the crack affected material. The used notch geometries to remove the crackaffected area must be weldable and also permit the material solidification in the same oriented plane as the original microstructure. To solidify in the original structure a thermal gradient has to be introduced in order to guide the grain growth. This required gradient can be established by inductive heating. To reduce the thermal effected zone, a laser source is used. In addition, it is also an efficient process to fill the notch. Also the small local heat input and controlled material supply support the epitaxial growth. However, there are requirements to achieve a SX structure without cracks and pores. Current achievements and further challenges are presented in this paper.

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“…From the above statement, each effect of magnetic fields plays the different role in the various alloy during the different solidification conditions. In our previous study, the destroying effects of TEMF on the SC integrity in nickel-based superalloy was investigated 35 , the TEMC and MHD effects on the primary dendrite-arm spacing 36 , 37 and precipitation phases 37 , 38 under the different parameters of solidification and magnetic fields. The present paper aims to develop and optimize the combination of the MHD, TEMC, and TEMF effects in the directional solidification of SC Nickel-based superalloys.…”

Section: Introductionmentioning

confidence: 99%

Improvement in creep life of a nickel-based single-crystal superalloy via composition homogeneity on the multiscales by magnetic-field-assisted directional solidification

Ren

Niu

Ding

et al. 2018

Sci Rep

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The improvement of the creep properties of single-crystal superalloys is always strongly motivated by the vast growing demand from the aviation, aerospace, and gas engine. In this study, a static magnetic-field-assisted solidification process significantly improves the creep life of single-crystal superalloys. The mechanism originates from an increase in the composition homogeneity on the multiscales, which further decreases the lattice misfit of γ/γ′ phases and affects the phase precipitation. The phase-precipitation change is reflected as the decrease in the γ′ size and the contents of carbides and γ/γ′ eutectic, which can be further verified by the variation of the cracks number and raft thickness near the fracture surface. The variation of element partition decreases the dislocation quantity within the γ/γ′ phases of the samples during the crept deformation. Though the magnetic field in the study destroys the single-crystal integrity, it does not offset the benefits from the compositional homogeneity. The proposed means shows a great potential application in industry owing to its easy implement. The uncovered mechanism provides a guideline for controlling microstructures and mechanical properties of alloys with multiple components and multiple phases using a magnetic field.

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The effect of magnetic field on precipitation phases of single-crystal nickel-base superalloy during directional solidification

Cited by 27 publications

References 5 publications

Directional Solidification Microstructure of a Ni-Based Superalloy: Influence of a Weak Transverse Magnetic Field

Directional Solidification Microstructure of a Ni-Based Superalloy: Influence of a Weak Transverse Magnetic Field

Crack Repair of Single Crystal Turbine Blades Using Laser Cladding Technology

Improvement in creep life of a nickel-based single-crystal superalloy via composition homogeneity on the multiscales by magnetic-field-assisted directional solidification

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