Creep deformation mechanism mapping in nickel base disk superalloys

Smith, Timothy M.; Unocic, Raymond R.; Deutchman, H.; Mills, Michael J.

doi:10.1080/09603409.2016.1180858

Cited by 83 publications

(23 citation statements)

References 28 publications

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“…Similar results have been reported by Smith et al [17] for the case of SESFs on the disk-type alloy ME3. The same phenomenon is generalized in this work for CISFs/SISFs and APBs.…”

Section: A Segregation-assisted Shearingsupporting

confidence: 80%

“…Monotonic creep tensile tests were performed at 800°C under an applied tensile load of 650 MPa, consistent with a region where a rich variety of complex deformation mechanism appears (SISFs, SESFs, microtwins, and APBs). [15][16][17][18] Testing was conducted in an Instron electro-thermal mechanical testing (ETMT) machine with digital image correlation (DIC) as non-contact strain measurement. Three repetition tests were performed in order to validate the repeatability of the results.…”

Section: A Creep Testingmentioning

confidence: 99%

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Segregation-Assisted Plasticity in Ni-Based Superalloys

Barba

Smith

Miao

et al. 2018

Metall Mater Trans A

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Correlative high-resolution transmission electron microscopy and energy-dispersive X-ray spectroscopy are used to study deformation-induced planar faults in the single-crystal superalloy MD2 crept at 800°C and 650 MPa. Segregation of Cr and Co at microtwins, anti-phase boundaries (APB), and complex/superlattice extrinsic and intrinsic stacking faults (CESF/SESF and CISF/SISF) is confirmed and quantified. The extent of this is found to depend upon the fault type, being most pronounced for the APB. The CESF/SESF is studied in detail due to its role as a precursor of the microtwins causing the majority of plasticity under these conditions. Quantitative modeling is carried out to rationalize the findings; the experimental results are consistent with a greater predicted velocity for the lengthening of the CESF/ SESF-compared with the other types of fault-and hence confirm its role in the diffusion-assisted plasticity needed for the microtwinning mechanism to be operative.

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“…Similar results have been reported by Smith et al [17] for the case of SESFs on the disk-type alloy ME3. The same phenomenon is generalized in this work for CISFs/SISFs and APBs.…”

Section: A Segregation-assisted Shearingsupporting

confidence: 80%

Section: A Creep Testingmentioning

confidence: 99%

Segregation-Assisted Plasticity in Ni-Based Superalloys

Barba

Smith

Miao

et al. 2018

Metall Mater Trans A

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“…According to the research from National Institute for Materials Science in Japan (NIMS) [210], the longest creep rupture life at 900 °C is obtained by 70% γ′ alloys for TMS superalloys series (TMS is the designation of single crystal superalloy developed in NIMS). In the powder metallurgy processed nickel-based superalloys (widely used for the turbine disc applications), the volume fraction of γ′ is in the range of 40-60% [211][212][213]. Other conventionally cast nickel-based superalloys usually have a broad γ′ volume fraction range, e.g.…”

Section: Mad542: a Novel Nickel-based Superalloy For Am Processmentioning

confidence: 99%

Alloy Design and Characterization of γ′ Strengthened Nickel-based Superalloys for Additive Manufacturing

2021

Linköping Studies in Science and Technology. Licentiate Thesis

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Nickel-based superalloys, an alloy system bases on nickel as the matrix element with the addition of up to 10 more alloying elements including chromium, aluminum, cobalt, tungsten, molybdenum, titanium, and so on. Through the development and improvement of nickel-based superalloys in the past century, they are well proved to show excellent performance at the elevated service temperature. Owing to the combination of extraordinary high-temperature mechanical properties, such as monotonic and cyclic deformation resistance, fatigue crack propagation resistance; and high-temperature chemical properties, such as corrosion and oxidation resistance, phase stability, nickel-based superalloys are widely used in the critical hot-section components in aerospace and energy generation industries. The success of nickel-based superalloy systems attributes to both the well-tailored microstructures with the assistance of carefully doped alloying elements, and the intently developed manufacturing processes. The microstructure of the modern nickel-based superalloys consists of a two-phase configuration: the intermetallic precipitates (Ni,Co)3(Al,Ti,Ta) known as γ′ phase dispersed into the austenite γ matrix, which is firstly introduced in the 1940s. The recently developed additive manufacturing (AM) techniques, acting as the disruptive manufacturing process, offers a new avenue for producing the nickel-based superalloy components with complicated geometries. However, γ′ strengthened nickel-based superalloys always suffer from the micro-cracking during the AM process, which is barely eliminated by the process optimization. On this basis, the new compositions of γ′ strengthened nickel-based superalloy adapted to the AM process are of great interest and significance. This study sought to design novel γ′ strengthened nickel-based superalloys readily for AM process with limited cracking susceptibility, based on the understanding of the cracking mechanisms. A two-parameter model is developed to predict the additive manufacturability for any given composition of a nickel-based superalloy. One materials index is derived from the comparison of the deformation-resistant capacity between dendritic and interdendritic regions, while another index is derived from the difference of heat resistant capacity of these two spaces. By plotting the additive manufacturability diagram, the superalloys family can be categorized into the easy-to-weld, fairly-weldable, and non-weldable regime with the good agreement of the existed knowledge. To design a novel superalloy, a Cr-Co-MoW -Al-Ti-Ta-Nb-Fe-Ni alloy family is proposed containing 921,600 composition recipes in total. Through the examination of additive manufacturability, undesired phase formation propensity, and the precipitation fraction, one composition of superalloy, MAD542, out of the 921,600 candidates is selected. Validation of additive manufacturability of MAD542 is carried out by laser powder bed fusion (LPBF). By optimizing the LPBF process parameters, the crack-free MAD542 part is achieved. I...

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“…Maintaining the microstructural integrity of these materials during operation is a paramount challenge in this field [1,2]. Most investigations of the microstructural changes during high temperature deformation focus on the main precipitation strengthening phase in the superalloys, the γ' precipitates, and its evolution over time in terms of size [3,4], volume fraction [5,6], shape [7,8], composition [9][10][11] and its different deformation mechanisms occurring under various thermal loading scenarios [12][13][14][15][16]. However, little attention has been paid so far to the minor elements, such as carbon and boron and their associated phases, which can also have major consequences for the mechanical performance of superalloys.…”

Section: Introductionmentioning

confidence: 99%

Influence of composition and precipitation evolution on damage at grain boundaries in a crept polycrystalline Ni-based superalloy

et al. 2019

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The microstructural and compositional evolution of intergranular carbides and borides prior to and after creep deformation at 850 °C in a polycrystalline nickel-based superalloy was studied. Primary MC carbides, enveloped within intergranular γ' layers, decomposed resulting in the formation of layers of the undesirable  phase. These layers have a composition corresponding to Ni3Ta as measured by atom probe tomography and their structure is consistent with the D024 hexagonal structure as revealed by transmission electron microscopy. Electron backscattered diffraction reveals that they assume various misorientations with regard to the adjacent grains. As a consequence, these layers act as brittle recrystallized zones and crack initiation sites. The composition of the MC carbides after creep was altered substantially, with the Ta content decreasing and the Hf and Zr contents increasing, suggesting a beneficial effect of Hf and Zr additions on the stability of MC carbides. By contrast, M5B3 borides were found to be microstructurally stable after creep and without substantial compositional changes. Borides at 850 °C were found to coarsen, resulting in some cases into γ'depleted zones, where, however, no cracks were observed. The major consequences of secondary phases on the microstructural stability of superalloys during the design of new polycrystalline superalloys are discussed.

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Creep deformation mechanism mapping in nickel base disk superalloys

Cited by 83 publications

References 28 publications

Segregation-Assisted Plasticity in Ni-Based Superalloys

Segregation-Assisted Plasticity in Ni-Based Superalloys

Alloy Design and Characterization of γ′ Strengthened Nickel-based Superalloys for Additive Manufacturing

Influence of composition and precipitation evolution on damage at grain boundaries in a crept polycrystalline Ni-based superalloy

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