Core structure of a〈100〉 superdislocations in a single-crystal superalloy during high-temperature and low-stress creep

Huang, Ming; Zhuo, Longchao; Xiong, Jichun; Li, Jiarong; Zhu, Jing

doi:10.1080/09500839.2015.1100763

Cited by 18 publications

(5 citation statements)

References 25 publications

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“…They show the double-line contrast when viewed along [100] direction. The Burgers vector of these dislocations is identified as a[100], based on the diffraction contrast analyses [19][20][21]. They are formed according to Eq.…”

Section: Superdislocations In γʹ Phasementioning

confidence: 99%

“…With the development of advanced aircraft engines, new generations of SX nickel-based superalloys operate at higher temperatures over 1000 °C. High-temperature deformation of SX superalloys is dominated by several prominent features, such as directional coarsening of γʹ precipitates [12][13][14], formation of dislocation networks at γ/γʹ interface [15,16] and γʹ phase cutting by a<110> or a<100> superdislocations [17][18][19][20][21], but most of the studies focus on the deformation in [001]-oriented SX superalloys. The creep deformations of [011] and [111] specimens have so far received sporadic attention [9][10][11][22][23][24][25][26][27].…”

Section: Introductionmentioning

confidence: 99%

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Anisotropic Stress Rupture Properties of a 3rd-Generation Nickel-Based Single-Crystal Superalloy at 1100 °C/150 MPa

Wang

Gong

et al. 2019

Acta Metall. Sin. (Engl. Lett.)

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The influence of orientation on the stress rupture behaviors of a 3rd-generation nickel-based single-crystal superalloy was investigated at 1100 °C/150 MPa. It is found that the stress rupture anisotropy is shown at 1100 °C, but not so obvious compared with that at intermediate temperatures. The [001] specimens display the longest rupture life, [111] specimens show the shortest rupture life, and [011] specimens exhibit the intermediate life. Detailed observations show that the final fracture is caused by crack initiation and propagation, and the anisotropy of three oriented specimens is related to the fracture modes, γ/γʹ microstructures, interfacial dislocation networks and cutting mechanisms in γʹ phase. For [001] specimens, N-type rafted structures are formed which can well hinder the slip and climb of dislocations. Besides, the regular interfacial dislocation networks can prevent dislocations from cutting into γʹ phase, leading to the improvement of the creep resistance. For [011] specimens, ± 45° rafted structures and irregular networks result in less strain hardening. For [111] specimens, a large number of crack propagation paths and inhomogeneous deformations caused by irregular rafted structures deteriorate the property and result in the shortest life. Furthermore, a[100] superdislocations with low mobility are widely formed in [001] and [011] specimens which suggests the low creep strain rate during steady creep stage, whereas superdislocations in [111] specimens possess high mobility, which indicates the high strain rate and corresponding poor stress rupture property.

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Section: Superdislocations In γʹ Phasementioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Anisotropic Stress Rupture Properties of a 3rd-Generation Nickel-Based Single-Crystal Superalloy at 1100 °C/150 MPa

Wang

Gong

et al. 2019

Acta Metall. Sin. (Engl. Lett.)

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“…Plasticity within the rafts is known to take place mainly by climb of pairs of dislocations [13][14] with a total . 〈001〉 Burgers vector.…”

Section: Introductionmentioning

confidence: 99%

High-Temperature Dislocation Climb in the γ′ Rafts of Single-Crystal Superalloys: The Hypothesis of a Control by Dislocation Entry into the Rafts

Jacques

Tréhorel

Schenk

2018

Metall Mater Trans A

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The good mechanical resistance to high temperature creep of [001] oriented single crystal superalloys is due to the properties of the rafts, i.e. platelets of the L12 γ' phase embedded in a γ matrix. At temperatures higher than 900°C, the plastic strain of the rafts results from the climb of dislocation pairs with a total. < 100 > Burgers vector and/or from the climb at the γ/γ' interfaces of 2 ⁄. < 110 > dislocation segments. This climb motion involves the exchange of vacancies between these dislocations and vacancy sinks such as pores and the specimens' surfaces. In this paper we suggest that the entry of. < 100 > into the rafts requires the overcoming of a threshold stress and show that this hypothesis gives a natural explanation to some of the most salient aspects of their mechanical behavior.

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“…At high temperatures the hard

phase deforms by dislocation climb [ 7 , 8 , 9 ], while the softer

channels are plastically deformed by a glide of the usual fcc

<110> {111} dislocations [ 10 ]. The high symmetry of the [001] tensile axis results in eight of the 12 available slip systems being equally active.…”

Section: Introductionmentioning

confidence: 99%

Dislocation Densities and Velocities within the γ Channels of an SX Superalloy during In Situ High-Temperature Creep Tests

Schenk

Tréhorel

Dirand³

et al. 2018

Materials

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The high-temperature creep behavior of a rafted [001] oriented AM1 Ni-based single crystal superalloy was investigated during in situ creep tests on synchrotrons. Experiments were performed at constant temperatures under variable applied stress in order to study the response (plastic strain, load transfer) to stress jumps. Using two different diffraction techniques in transmission (Laue) geometry, it was possible to measure the average lattice parameters of both the γ matrix and the γ′ rafts in the [100] direction at intervals shorter than 300 s. The absolute precision with both diffraction techniques of the constrained transverse mismatch (in the rafts’ plane) is about 10−5. After stress jumps, special attention is given to the evolution of plastic strain within the γ channels. The relaxation of the Von Mises stress at leveled applied stress shows evidence of dislocation multiplication within the γ channels. From the analysis, we showed an interaction between plastic stress and dislocation density of the γ phase.

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Core structure of a〈100〉 superdislocations in a single-crystal superalloy during high-temperature and low-stress creep

Cited by 18 publications

References 25 publications

Anisotropic Stress Rupture Properties of a 3rd-Generation Nickel-Based Single-Crystal Superalloy at 1100 °C/150 MPa

Anisotropic Stress Rupture Properties of a 3rd-Generation Nickel-Based Single-Crystal Superalloy at 1100 °C/150 MPa

High-Temperature Dislocation Climb in the γ′ Rafts of Single-Crystal Superalloys: The Hypothesis of a Control by Dislocation Entry into the Rafts

Dislocation Densities and Velocities within the γ Channels of an SX Superalloy during In Situ High-Temperature Creep Tests

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