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

Ren, Weili; Niu, Chunlin; Ding, Biao; Zhong, Yunbo; Ren, Zhongming; Liu, Wenqing; Ren, Li; Liaw, Peter K.

doi:10.1038/s41598-018-19800-5

Cited by 18 publications

(8 citation statements)

References 46 publications

(84 reference statements)

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“…As far as the influence of a static magnetic field on solidification is concerned, there have been a great number of reports 24–27 , as Ren et al . 27 briefly reviewed.…”

Section: Discussionmentioning

confidence: 99%

“…As far as the influence of a static magnetic field on solidification is concerned, there have been a great number of reports 24–27 , as Ren et al . 27 briefly reviewed. For the present platelet immersing in the eutectic melt in the static magnetic field, the platelet with its longitude direction parallel to the direction of the Lorentz force does not imply that the c axis of the platelet can be aligned to a certain direction, some of them may be parallel while others may have certain degrees with the magnetic field.…”

Section: Discussionmentioning

confidence: 99%

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Crystalline orientation control of the platelet Nd2Fe14B phase to produce magnetic anisotropy via electromagnetic vibration processing

Tamura

2019

Sci Rep

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Controlled crystalline orientation of the discontinuous phase in a composite enables the production of improved anisotropic properties, e.g., well-aligned Nd 2 Fe 14 B platelets by hot pressing and then soaking in a low-melting Nd-Cu eutectic melt to infiltrate to grain boundary. Alternatively, an anisotropic magnet can be fabricated by sintering Nd 2 Fe 14 B powder pre-aligned with a static magnetic field. In this study, we used a two-step electromagnetic vibration (EMV) technique to solidify the Nd 70 Cu 30 -30wt% Nd 2 Fe 14 B alloy, by which the magnetic Nd 2 Fe 14 B compound could be segmented into short laths and the easy magnetisation axes of these discontinuous platelets could be highly aligned, as revealed by electron backscatter diffraction (EBSD) patterns. Magnetic properties showed that the alloy exhibited strong anisotropy in its magnetism. Our present results opened a new avenue for the simple production of anisotropic Nd 2 Fe 14 B magnets via solidification without the powder metallurgy routine. Moreover, the technique is highly expected to be applied to other systems, e.g., graphene-reinforced metallic and/or polymer composites in which the alignment of graphene can maximise the anisotropy in the thermal or electrical properties of the composites.

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“…As far as the influence of a static magnetic field on solidification is concerned, there have been a great number of reports 24–27 , as Ren et al . 27 briefly reviewed.…”

Section: Discussionmentioning

confidence: 99%

Section: Discussionmentioning

confidence: 99%

Crystalline orientation control of the platelet Nd2Fe14B phase to produce magnetic anisotropy via electromagnetic vibration processing

Tamura

2019

Sci Rep

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“…Methods have been devised to counter this, by employing solutes in grain boundaries, notably carbides to inhibit boundary sliding. A recent method adopted by [6] incorporates application of magnetic field to ensure homogeneous composition of the Nickel based super-alloy through two phases.…”

Section: Introductionmentioning

confidence: 99%

Thermo-Structural Analysis of Carbon Fibre-Ni Based Super Alloy Composite Employed in Gas Turbines

Dhoka¹

2020

AJMME

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A computational analysis was carried out on two different materials of turbine blades, namely Inconel MA754 and Nimonic 80A, in order to determine their structural and thermal properties at elevated temperatures. Long carbon fibers of uniform length were used and deposited at varying thicknesses ranging from 1 mm to 4 mm, on the top surface of turbine blades and then analyzed for its performance. It is seen that the carbon fibers (IM10) embedded in the super alloys drastically improve the load bearing parameters of the configurations being analyzed. The improvement in structural load carrying ability is a result of higher Young's modulus primarily. Subsequent analysis with higher volume fraction of the fibers indicated saturation of performance at about 70% volume fraction for 4 mm fibers and significant improvement beyond it for the 1 mm fibers. With improvement in the load bearing characteristics the blade with fibers embedded into a tube like structure at 3 sections were configured and A thermal analysis of the same underscores the effectiveness of the 4 mm fibers in undergoing much reduced principal strains than other configurations. This is seen to be a result of insulation of the top surface from increase in temperature, which significantly reduces the thermal expansion, especially at the free end. This is in contrast to other configurations, where the low volume fraction of fibers resulted in high principal strain.

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“…One such example is the work of Weili Ren et. Al (Ren et al, 2018) who found that the application of a magnetic field to the material during directional solidification of a single crystal part lead to an increase in creep life. The cause of this improvement is a combination of effects that the magnetic field have on the molten material.…”

Section: Novel Methods Of Improving Stress Rupture In Nickel Superalloymentioning

confidence: 99%

“…The result was material with better solute distribution and smaller strengthening phase precipitates more coherent with the y matrix. The use of such a magnetic field led to a reduction in the quantity of dislocations present in the material during creep and a maximum of a 5x increase in stress rupture life of the material (Ren et al, 2018).…”

Section: Novel Methods Of Improving Stress Rupture In Nickel Superalloymentioning

confidence: 99%

Powder Characterisation, Microstructure, and Mechanical Property Evolution of IN625 and IN718 During Selective Laser Melting and Heat Treatment

Pleass¹

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Additive layer manufacturing is a blanket term for a wide range of processes operating on the same underlying principle. 3D geometry is created by depositing material, layer by layer to create a final 3D geometry. Selective laser melting (SLM) is a branch of additive layer manufacturing, using a laser to fuse a powder bed of metal into each layer. This thesis investigates the SLM process and its application to nickel based superalloy materials, IN625 and IN718. IN625 and IN718 are similar nickel-based superalloys developed for use in aerospace gas turbine engines. In their conventionally manufactured form, these materials have excellent high temperature mechanical properties which make them idea for use in the hot section of gas turbine engines. The aim of this thesis was to investigate how these materials interact with the SLM process and how the material produced can be optimised to improve the range of applications it can be used for. A gap in knowledge regarding a detailed understanding of how the powders morphological and rheological properties influence its ability to be processed by SLM was identified and investigated. A wide range of characterisation methods were implemented with certain important properties being identified to assess a powders processability, namely the particle size distribution and how a significant content of fine particles below 10 μm in size can be detrimental to processability. There is also a lack of a standard powder characterisation methodology specifically for SLM applications. This is addressed with certain methods and measurements being suggested as most promising for wider SLM application. Avalanche flow testing is found to be most applicable to the critical recoating process in SLM and most able to differentiate suitable and unsuitable SLM powders. Following characterisation of the raw material feedstock powder, this thesis also investigates the influence of processing parameters on the microstructure of the material produced by the SLM process. Significant microstructural changes were observed as a result of process parameter changes. This was identified to potentially enable for in-situ modification of material microstructure to suit a manufactured material to its end application. Of the process parameters investigated, laser scan speed was most interesting, suggesting that a faster laser scan speed was able to create a similar microstructure to a much slower one. This was attributed to the reheating effect of the laser beam returning quickly to the adjacent scan line. The validity of this explanation was investigated using a simple, computational thermal model. The result is a new understanding of laser scan speed SLM and its nonlinear relationship with material temperature and microstructure evolution. Finally, post process heat treatments of SLM manufactured IN718 material were investigated. This investigation was in response to a gap in current knowledge regarding heat treatments designed specifically for SLM material. SLM IN718 has been found to have reduced high temperature mechanical properties, specifically stress rupture, which limits its application in demanding environments. In this thesis a range of post process homogenisation heat treatments were investigated, with treatments between 1030 °C and 1060 °C being found to produce material with characteristics consistent with material with excellent stress rupture properties. This novel heat treatment route could provide a method for SLM IM718, and the increased design and geometric freedoms, to be applied in more demanding applications. An evolution of the grain structure in the material was also observed and measured during high temperature homogenisation treatments. This was investigated in the final chapter, and a novel mechanism is suggested for the process of grain coarsening observed. Previously published literature explains similar evolutions as recrystallisation however this did not fit the observations during this thesis. The evolution of grain structure was observed using a process of quasi in-situ electron back scatter diffraction, and a mechanism of grain boundary length reduction, followed by grain growth, is suggested to better fit the observations. It was determined that grains are preferentially selected for growth based on their proximity to a ‘path of least resistance’ of lower angle grain boundaries. The results of this work should benefit industrial users of SLM in the fabrication of Nickel-Based Superalloy material for aerospace applications. The conclusions on powder characterisation offer an insight into available methods to better control and characterise powder feedstock materials for consistent production. Aerospace users especially may find the work regarding post process heat treatments designed specifically for SLM material, to recover lost stress rupture performance, useful in enabling the use of SLM materials, and the design freedom that brings with it, in mor demanding environments than are currently possible.

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

Cited by 18 publications

References 46 publications

Crystalline orientation control of the platelet Nd2Fe14B phase to produce magnetic anisotropy via electromagnetic vibration processing

Crystalline orientation control of the platelet Nd2Fe14B phase to produce magnetic anisotropy via electromagnetic vibration processing

Thermo-Structural Analysis of Carbon Fibre-Ni Based Super Alloy Composite Employed in Gas Turbines

Powder Characterisation, Microstructure, and Mechanical Property Evolution of IN625 and IN718 During Selective Laser Melting and Heat Treatment

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