Effect of lattice misfit on the evolution of the dislocation structure in Ni-based single crystal superalloys during thermal exposure

Long, Haibo; Wei, Hua; Liu, Yinong; Mao, Shengcheng; Zhang, Jianxin; Xiang, Sisi; Chen, Yanhui; Gui, Weimin; Li, Qing; Zhang, Ze; Han, Xiao

doi:10.1016/j.actamat.2016.08.035

Cited by 92 publications

(19 citation statements)

References 29 publications

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“…We estimated the lattice misfit of the current alloys based on Svoboda's scheme [ 22 ] for calculating the stress created by two adjacent coherent phases in superalloys. [ 23 ] The lattice misfit δ is defined as δ = 2( ɑ γ − ɑ γ′ )/( ɑ γ + ɑ γ′ ), where ɑ γ and ɑ γ′ are the lattice parameters of the two adjacent FCC phases. For the alloy annealed at 600 °C for 240 h, the lattice misfit is around 0.37% and the associated lattice misfit stress is estimated to be around 375.9 MPa.…”

Section: Resultsmentioning

confidence: 99%

Beyond Solid Solution High‐Entropy Alloys: Tailoring Magnetic Properties via Spinodal Decomposition

Rao

Dutta

Körmann

et al. 2020

Adv Funct Materials

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Since its first emergence in 2004, the high‐entropy alloy (HEA) concept has aimed at stabilizing single‐ or dual‐phase multi‐element solid solutions through high mixing entropy. Here, this strategy is changed and renders such massive solid solutions metastable, to trigger spinodal decomposition for improving the alloys’ magnetic properties. The motivation for starting from a HEA for this approach is to provide the chemical degrees of freedom required to tailor spinodal behavior using multiple components. The key idea is to form Fe‐Co enriched regions which have an expanded volume (relative to unconstrained Fe‐Co), due to coherency constraints imposed by the surrounding HEA matrix. As demonstrated by theory and experiments, this leads to improved magnetic properties of the decomposed alloy relative to the original solid solution matrix. In a prototype magnetic FeCoNiMnCu HEA, it is shown that the modulated structures, achieved by spinodal decomposition, lead to an increase of the Curie temperature by 48% and a simultaneous increase of magnetization by 70% at ambient temperature as compared to the homogenized single‐phase reference alloy. The findings thus open a pathway for the development of advanced functional HEAs.

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Section: Resultsmentioning

confidence: 99%

Beyond Solid Solution High‐Entropy Alloys: Tailoring Magnetic Properties via Spinodal Decomposition

Rao

Dutta

Körmann

et al. 2020

Adv Funct Materials

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show abstract

“…On the other hand, some shearing dislocations could be observed in γ′ phase. The great lattice mismatch between γ and γ′ phase could cause the dislocation piling-up at the interface and hinder the dislocation shearing into the γ′ phase [25]. As a result, less amount of the dislocation in the γ′ phase could be observed, as shown in Fig.…”

Section: Tensile Behavior Of K416b Alloy At Room Temperature After Thermal Exposurementioning

confidence: 97%

Effect of Long-Term Thermal Exposures on Tensile Behaviors of K416B Nickel-Based Superalloy

Chen

Xie

Shu

et al. 2020

Acta Metall. Sin. (Engl. Lett.)

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The effect of long-term thermal exposure on the tensile behavior of a high W content nickel-based superalloy K416B was investigated. The microstructure and the deformation characteristics were observed by scanning electron microscopy and transmission electron microscopy, and the phase transformation of the alloy during long-term thermal exposure was analyzed by X-ray diffraction patterns and differential thermal analysis. Results showed that after thermal exposure at 1000 °C, the MC carbides in the K416B alloy decomposed into M 6 C. During tensile deformation, dislocations slipping in γ matrix crossed over the M 6 C by Orowan bowing mechanism. With the increase of thermal exposure time, the secondary M 6 C reduced greatly the yield strength of the alloy at room temperature. Meanwhile, the continuous distribution of the secondary M 6 C with great brittleness in the grain boundary could become the main source of crack, which might change the fracture characteristic of the alloy from trans-granular to intergranular.

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“…An equivalent volume of a cuboidal γ′ particle can be easily measured from its area through geometric projection. On the other hand, lots of interfacial dislocations can be thermally generated to relieve γ/γ′ constraint strain, especially for long-term aging [25,26]. In order to weaken the influence of massive interfacial dislocations on γ′ coarsening, the aging times in this study were selected to avoid producing abundant interfacial dislocations.…”

Section: Thermal Exposure Experimentsmentioning

confidence: 99%

Effect of Interactions Among Elements on Diffusion Process Associated with γ′ Coarsening in a Ni-Based Single-Crystal Superalloy

Wang

Liu

et al. 2020

Acta Metall. Sin. (Engl. Lett.)

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Coarsening of cuboidal γ′ precipitates and relevant diffusion process in Ni-based single-crystal superalloy CMSX-4 were investigated at 1000, 1020 and 1040 °C for specific times. The γ′ coarsening kinetics followed a cubic rate law with time and was presumably controlled by bulk diffusion of elements in γ matrix. The associated diffusion activation energy was experimentally determined to be about 300 kJ/mol when it is considered the temperature-dependent thermo-physical parameters in modified Lifshitz-Slyozov-Wagner theory. The influence of temperature on γ/γ′ microstructure is briefly discussed based on pseudo-binary [Ni]-[Al] phase diagram. Interactions among elements can effectively raise the local vacancy formation and vacancy-atom exchange barriers close to γ-and γ′-partitioning elements, respectively. Thus, it can significantly reduce the inter-coupling migrations of atoms during the macroscopic cross-diffusion process associated with γ′ coarsening of Nibased superalloys.

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Effect of lattice misfit on the evolution of the dislocation structure in Ni-based single crystal superalloys during thermal exposure

Cited by 92 publications

References 29 publications

Beyond Solid Solution High‐Entropy Alloys: Tailoring Magnetic Properties via Spinodal Decomposition

Beyond Solid Solution High‐Entropy Alloys: Tailoring Magnetic Properties via Spinodal Decomposition

Effect of Long-Term Thermal Exposures on Tensile Behaviors of K416B Nickel-Based Superalloy

Effect of Interactions Among Elements on Diffusion Process Associated with γ′ Coarsening in a Ni-Based Single-Crystal Superalloy

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