Influences of the Heating and Cooling Rates on the Dissolution and Precipitation Behavior of a Nickel-Based Single-Crystal Superalloy

Wang, Xiaoyan; Cheng, Hao; Gu, Shuning; Lu, Guangxian

doi:10.3390/met9030360

Cited by 4 publications

(4 citation statements)

References 13 publications

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“…Soucail et al [46,47] observed similar behavior for the dissolution rate of secondary γ' in Astroloy during heating. In particular, they found that the departure from equilibrium dissolution temperature was lower for smaller secondary γ' precipitates but increased with the heating rate in It has been reported [43][44][45] that changes in the heating rate modified the microstructure and the distribution of elements in the matrix resulting in changes in the chemical reaction temperatures and hence the DTA results. The results, reported in Table 3, quantify these changes for the examined samples in the present study and show that indeed the precipitation temperatures of γ , γ" and δ phases increased by increasing the heating rate because there was less time for elemental diffusion and chemical reactions for precipitation of each phase at higher rates.…”

Section: Low Heating Rate Testsmentioning

confidence: 99%

“…In this study, the focus was before liquation and melting because the melting temperature is principally independent of the heating rate. d 10 540 589 736 801 886 984 15 557 595 741 817 926 1008 25 560 614 754 831 962 1024 50 572 663 761 840 948 1035 80 596 678 776 860 965 1051 100 600 700 798 873 990 1057 It has been reported [43][44][45] that changes in the heating rate modified the microstructure and the distribution of elements in the matrix resulting in changes in the chemical reaction temperatures and hence the DTA results. The results, reported in Table 3, quantify these changes for the examined samples in the present study and show that indeed the precipitation temperatures of γ', γ" and δ phases increased by increasing the heating rate because there was less time for elemental diffusion and chemical reactions for precipitation of each phase at higher rates.…”

Section: Low Heating Rate Testsmentioning

confidence: 99%

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Microstructure Evolution of Selective Laser Melted Inconel 718: Influence of High Heating Rates

Tabaie

Rézaï-Aria

Jahazi

2020

Metals

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Inconel 718 (IN718) superalloy samples fabricated by selective laser melting (SLM) were submitted to different heating cycles and their microstructural characteristics were investigated. The selected heating rates, ranging from 10 °C/min to 400 °C/s, represent different regions in the heat-affected zone (HAZ) of welded additively manufactured specimens. A combination of differential thermal analysis (DTA), high-resolution dilatometry, as well as laser confocal and electron microscopy were used to study the precipitation and dissolution of the secondary phases and microstructural features. For this purpose, the microstructure of the additively manufactured specimen was investigated from the bottom, in contact with the support, to the top surface. The results showed that the dissolution of γ″ and δ phases were delayed under high heating rates and shifted to higher temperatures. Microstructural analysis revealed that the Laves phase at the interdendritic regions was decomposed in specific zones near the surface of the samples. It was determined that the thickness and area fraction of these zones were inversely related to the applied heating rate. A possible mechanism based on the influence of heating rate on Nb diffusion in the interdendritic regions and core of the dendrites is proposed to interpret the observed changes in the microstructure.

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Section: Low Heating Rate Testsmentioning

confidence: 99%

Section: Low Heating Rate Testsmentioning

confidence: 99%

Microstructure Evolution of Selective Laser Melted Inconel 718: Influence of High Heating Rates

Tabaie

Rézaï-Aria

Jahazi

2020

Metals

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“…While the lattice mismatch at room temperature was negative, its value was more negative at high-temperature. If the lattice mismatch degree was positive, its value decreased or became negative at high-temperature [ 23 ]. At the same time, the literature [ 27 ] also pointed out that the γ′ phase size distribution (PSD) was more consistent with the strain energy model in the early stage of heat treatment.…”

Section: Test Results and Discussionmentioning

confidence: 99%

The Effect of the Cooling Rates on the Microstructure and High-Temperature Mechanical Properties of a Nickel-Based Single Crystal Superalloy

2020

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The as-cast alloy of nickel-based single-crystal superalloy was used as the research object. After four hours of solution treatment at 1315 °C, four cooling rates (water cooling (WC), air cooling (AC) and furnace cooling (FC1/FC2)) were used to reduce the alloy to room temperature. Four different microstructures of nickel-based superalloy material were prepared. A high-temperature tensile test at 980 °C was carried out to study the influence of various rates on the formation of the material’s microstructure and to further obtain the influence of different microstructures on the high-temperature mechanical properties of the materials. The results show that an increase of cooling rate resulted in a larger γ′ phase nucleation rate, formation of a smaller γ′ phase and a greater number. When air cooling was used, the uniformity of the γ′ phase and the coherence relationship between the γ′ phase and the γ phase were the best. At the same time, the test alloy had the best high-temperature tensile properties, and the material showed a certain degree of plasticity. TEM test results showed that the test alloy mainly blocked dislocations from traveling in the material through the strengthening effect of γ′, and that AC had the strongest hindering effect on γ′ dislocation movement.

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“…However, the huge differences in composition between coating and underlying substrate can lead to element interdiffusion during long-term high-temperature service, resulting in the segregation of insoluble elements such as Ta in the substrate and the precipitation of harmful topological close-packed 2 of 10 phase [15][16][17]. The main components of topological close-packed phases are W, Mo and Re, which are added in the superalloy for strengthening the comprehensive performance of superalloys at high temperature [18][19][20].…”

Section: Introductionmentioning

confidence: 99%

Interdiffusion Behaviour of NiCoCrAlY Coating and N5 Single Crystal Superalloy

et al. 2020

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This paper aims at investigating the microstructure and phases evolution of single crystal superalloy/high temperature protective coating during high temperature static oxidation, and exploring the influence of element interdiffusion behaviour on microstructure and phase evolution of the single crystal superalloy substrate. A NiCoCrAlY high-temperature protective coating was deposited on the Ni-based single-crystal superalloy by low-pressure plasma spraying technology. The coated samples were subjected to static oxidation for 200 h at a constant temperature of 1100 • C. Scanning electron microscope, energy dispersive spectrometer and X-ray diffraction were used to characterise the microstructure and phase after interdiffusion between the coating and the substrate at high temperature. The results showed that a dense thermally grown oxide layer was formed on the surface of the NiCoCrAlY coating after oxidation for over 100 h. The only interdiffusion zone was formed after oxidation for 50 h, while both interdiffusion zone and secondary reaction zone could be observed after oxidation for over 100 h. The thickness of interdiffusion zone and secondary reaction zone is increased with the extension of oxidation time, and the grain growth of topological close-packed phase in the secondary reaction zone is found. Al, Cr and Co in the coating diffuse from the coating to the substrate, while Ni and refractory materials like Ta, Mo, Re and W diffuse from the coating to the substrate. The interdiffusion of coating and substrate leads to the instability of γ/γ phase in the substrate, which finally results in the formation of W, Re and Cr-rich needle-like topological close-packed phase in the substrate.

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Influences of the Heating and Cooling Rates on the Dissolution and Precipitation Behavior of a Nickel-Based Single-Crystal Superalloy

Cited by 4 publications

References 13 publications

Microstructure Evolution of Selective Laser Melted Inconel 718: Influence of High Heating Rates

Microstructure Evolution of Selective Laser Melted Inconel 718: Influence of High Heating Rates

The Effect of the Cooling Rates on the Microstructure and High-Temperature Mechanical Properties of a Nickel-Based Single Crystal Superalloy

Interdiffusion Behaviour of NiCoCrAlY Coating and N5 Single Crystal Superalloy

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