Nanoscale Origins of the Size Effect in the Compression Response of Single Crystal Ni-Base Superalloy Micro-Pillars

Ying, Siqi; Sui, Tan; Papadaki, Chrysanthi; Salvati, Enrico; Brandt, León Romano; Zhang, Hongjia; Korsunsky, Alexander M.

doi:10.3390/ma11040561

Cited by 8 publications

(3 citation statements)

References 29 publications

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“…Nanoindentation is an effective method to measure the mechanical properties of materials at the nanoscale, such as the elastic modulus, hardness and strain hardening effect. So far, this technology has been applied to obtain the mechanical properties of various materials including not only pure metals such as Al, Cu, Ag, Ni, and Fe [ 5 , 6 , 7 , 8 ]; but also alloys such as TiAl, U–Cu, Fe–Ni–C, Zr–Cu–Ag–Al and nickel superalloys [ 9 , 10 , 11 , 12 , 13 , 14 , 15 ].…”

Section: Introductionmentioning

confidence: 99%

Nanoindentation of γ-TiAl with Different Crystal Surfaces by Molecular Dynamics Simulations

Fan

Zhou

et al. 2019

Materials

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The periodicity and density of atomic arrangement vary with the crystal orientation, which results in different deformation mechanisms and mechanical properties of γ-TiAl. In this paper, the anisotropic characteristics for γ-TiAl with (100), ( 1 ¯ 10 ) and (111) surfaces during nanoindentation at 300 K have been investigated by molecular dynamics simulations. It is found that there is no obvious pop-in event in all load-depth curves when the initial plastic deformation of γ-TiAl samples occurs, because the dislocation nucleates before the first load-drop; while a peak appears in both the unloading curves of the ( 1 ¯ 10 ) and (111) samples due to the release of energy. Stacking faults, twin boundaries and vacancies are formed in all samples; however, interstitials are formed in the (100) sample, a stacking fault tetrahedron is formed in the (111) sample; and two prismatic dislocation loops with different activities are formed in the ( 1 ¯ 10 ) and (111) samples, respectively. It is also concluded that the values of the critical load, strain energy, hardness and elastic modulus for the (111) sample are the maximum, and for the (100) sample are the minimum. Furthermore, the orientation dependence of the elastic modulus is greater than the hardness and critical load.

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Section: Introductionmentioning

confidence: 99%

Nanoindentation of γ-TiAl with Different Crystal Surfaces by Molecular Dynamics Simulations

Fan

Zhou

et al. 2019

Materials

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“…For the last SCNBSs with penetrable phase boundary, the intrinsic microstructural size effect on mechanical behaviors has already been widely studied by experiments [34][35][36] and DDD simulations [37][38][39][40][41][42]. In addition, the synergetic action of both intrinsic and extrinsic size effects for SCNBSs has also been investigated by micropillar compression using experimental tests [43][44][45][46][47] and DDD simulations [48]. It is commonly found that the extrinsic size effect is negligible when the micropillar diameter is sufficiently larger than the internal microstructure length (i.e.…”

Section: Introductionmentioning

confidence: 99%

An efficient algorithm of dislocation-precipitate interactions for single crystal nickel-based superalloys within discrete dislocation dynamics and its application

Huang¹,

Huang²

2021

Modelling Simul. Mater. Sci. Eng.

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In this paper, the discrete dislocation dynamics (DDD) framework for single crystal nickel-based superalloys (SCNBSs) modeling is extended to simulate the superdislocation pairs shearing numerous precipitates more efficiently. An adaptive dislocation segment meshing scheme by specially treating the dislocation segments deposited on the γ/γ′ interfaces is also used to decrease the computational expense. In addition, the MPI parallel algorithm is also realized to increase the computational speed. Through this DDD framework, the size-related plastic response of SCNBSs microcrystal containing collections of precipitates is systematically investigated. Two types of SCNBSs microcrystal samples, one with intact precipitates and the other with partial precipitates truncated by free surfaces, are established for different sample sizes. The influence of the sample size, two types of boundary, and the coherency stress induced by lattice mismatch between the two phases are discussed. The results show that the influence of sample size on the yield strength and the dispersity of stress–strain curves are relatively weak when more than four precipitates across the cross section. And the effect of sample size on deformation mode and the dislocation density is still evident for all the considered sample sizes. For two types (intact and truncated precipitates) of SCNBSs microcrystal samples, the remarkable difference in their mechanical responses and dislocation evolution appears when there is only one precipitate across the cross section. In addition, the misfit stress can significantly change the dislocation distribution in different channels. However, it has less influence on the tensile stress–strain response for the considered tensile loading condition. Our results indicate that to properly characterize the global mechanical behavior of bulk SCNBSs by micro-test, the microcrystal sample should present more than sixteen whole precipitates across the cross section.

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“…It was found that the pore size increased with increasing withdrawal rate of the single crystal castings. Porosity determines the mechanical properties of SX castings made of nickel-based superalloy and it is an important evaluation criterion of their quality [25,26,27,28,29,30].…”

Section: Introductionmentioning

confidence: 99%

The Effect of Withdrawal Rate on Crystal Structure Perfection, Microstructure and Creep Resistance of Single Crystal Castings Made of CMSX-4 Nickel-Based Superalloy

et al. 2019

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This study focuses on the evaluation of the crystal structure perfection in the single crystal made of CMSX-4 nickel superalloy and its effect on creep resistance. Single crystal castings were manufactured by directional solidification process at the withdrawal rate of 1, 3, 5 and 7 mm/min. Light (LM) and electron (SEM, TEM) microscopy, X-ray diffraction and Mossbauer spectroscopy were used for evaluation of the microstructure and crystal structure perfection. Castings were also subjected to creep tests. The best creep resistance was obtained for the casting manufactured at the withdrawal rate of 3 mm/min, characterized by the highest crystal structure perfection compared to the other castings examined.

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Nanoscale Origins of the Size Effect in the Compression Response of Single Crystal Ni-Base Superalloy Micro-Pillars

Cited by 8 publications

References 29 publications

Nanoindentation of γ-TiAl with Different Crystal Surfaces by Molecular Dynamics Simulations

Nanoindentation of γ-TiAl with Different Crystal Surfaces by Molecular Dynamics Simulations

An efficient algorithm of dislocation-precipitate interactions for single crystal nickel-based superalloys within discrete dislocation dynamics and its application

The Effect of Withdrawal Rate on Crystal Structure Perfection, Microstructure and Creep Resistance of Single Crystal Castings Made of CMSX-4 Nickel-Based Superalloy

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