scholarly journals Tunable stacking fault energies by tailoring local chemical order in CrCoNi medium-entropy alloys

2018 ◽  
Vol 115 (36) ◽  
pp. 8919-8924 ◽  
Author(s):  
Jun Ding ◽  
Qin Yu ◽  
Mark Asta ◽  
Robert O. Ritchie
Keyword(s):  
Mechanical Behavior ◽  
Energy Difference ◽  
Stacking Fault ◽  
Face Centered Cubic ◽  
Structure Property ◽  
Chemical Order ◽  
High Entropy ◽  
Structure Property Relationships ◽  
The Face ◽  
Robust Processing

High-entropy alloys (HEAs) are an intriguing new class of metallic materials due to their unique mechanical behavior. Achieving a detailed understanding of structure–property relationships in these materials has been challenged by the compositional disorder that underlies their unique mechanical behavior. Accordingly, in this work, we employ first-principles calculations to investigate the nature of local chemical order and establish its relationship to the intrinsic and extrinsic stacking fault energy (SFE) in CrCoNi medium-entropy solid-solution alloys, whose combination of strength, ductility, and toughness properties approaches the best on record. We find that the average intrinsic and extrinsic SFE are both highly tunable, with values ranging from −43 to 30 mJ⋅m−2 and from −28 to 66 mJ⋅m−2, respectively, as the degree of local chemical order increases. The state of local ordering also strongly correlates with the energy difference between the face-centered cubic (fcc) and hexagonal close-packed (hcp) phases, which affects the occurrence of transformation-induced plasticity. This theoretical study demonstrates that chemical short-range order is thermodynamically favored in HEAs and can be tuned to affect the mechanical behavior of these alloys. It thus addresses the pressing need to establish robust processing–structure–property relationships to guide the science-based design of new HEAs with targeted mechanical behavior.

scholarly journals Formation and Anisotropic Mechanical Behavior of Stacking Fault Tetrahedron in Ni and CoCrFeNiMn High-Entropy Alloy

2022 ◽  
Vol 8 ◽  
Author(s):  
Sen Hu ◽  
Tao Fu ◽  
Qihao Liang ◽  
Shayuan Weng ◽  
Xiang Chen ◽  
...  
Keyword(s):  
Mechanical Behavior ◽  
Critical Stress ◽  
Three Dimensional ◽  
Stacking Faults ◽  
Stacking Fault ◽  
High Entropy Alloy ◽  
Face Centered Cubic ◽  
High Entropy ◽  
Stacking Fault Tetrahedron ◽  
Dynamics Simulations

Stacking fault tetrahedron (SFT) is a kind of detrimental three-dimensional defect in conventional face-centered cubic (FCC) structural metals; however, its formation and anisotropic mechanical behavior in a CoCrFeNiMn high-entropy alloy (HEA) remain unclear. In this work, we first performed molecular dynamics simulations to verify the applicability of the Silcox-Hirsch mechanism in the CoCrFeNiMn HEA. The mechanical responses of the SFT to shear stress in different directions and that of the pure Ni counterpart were simulated, and the evolutions of the atomic structures of the SFTs during shear were analyzed in detail. Our results revealed that the evolution of the SFT has different patterns, including the annihilation of stacking faults, the formation and expansion of new stacking faults, and insignificant changes in stacking faults. It was found that the effects of SFT on the elastic properties of Ni and HEA are negligible. However, the introduction of SFT would reduce the critical stress, while the critical stress of the CoCrFeNiMn HEA is much less sensitive to SFT than that of Ni.

Review of Hierarchical Multiscale Modeling to Describe the Mechanical Behavior of Amorphous Polymers

2009 ◽  
Vol 131 (4) ◽  
Author(s):  
J. L. Bouvard ◽  
D. K. Ward ◽  
D. Hossain ◽  
S. Nouranian ◽  
E. B. Marin ◽  
...  
Keyword(s):  
Mechanical Behavior ◽  
Multiscale Modeling ◽  
Coarse Graining ◽  
Amorphous Polymers ◽  
Multiscale Methods ◽  
Structure Property ◽  
Lightweight Materials ◽  
Structure Property Relationships ◽  
Modeling Strategy ◽  
Hierarchical Multiscale

Modern computational methods have proved invaluable for the design and analysis of structural components using lightweight materials. The challenge of optimizing lightweight materials in the design of industrial components relates to incorporating structure-property relationships within the computational strategy to incur robust designs. One effective methodology of incorporating structure-property relationships within a simulation-based design framework is to employ a hierarchical multiscale modeling strategy. This paper reviews techniques of multiscale modeling to predict the mechanical behavior of amorphous polymers. Hierarchical multiscale methods bridge nanoscale mechanisms to the macroscale/continuum by introducing a set of structure-property relationships. This review discusses the current state of the art and challenges for three distinct scales: quantum, atomistic/coarse graining, and continuum mechanics. For each scale, we review the modeling techniques and tools, as well as discuss important recent contributions. To help focus the review, we have mainly considered research devoted to amorphous polymers.

scholarly journals Generalized Stacking Fault Energy of Al-Doped CrMnFeCoNi High-Entropy Alloy

Nanomaterials ◽  
2019 ◽  
Vol 10 (1) ◽  
pp. 59 ◽  
Author(s):  
Xun Sun ◽  
Hualei Zhang ◽  
Wei Li ◽  
Xiangdong Ding ◽  
Yunzhi Wang ◽  
...  
Keyword(s):  
Interfacial Energy ◽  
Stacking Fault ◽  
Stacking Fault Energy ◽  
High Entropy Alloy ◽  
High Entropy Alloys ◽  
Face Centered Cubic ◽  
High Entropy ◽  
Al Content ◽  
Generalized Stacking Fault ◽  
Generalized Stacking Fault Energy

Using first-principles methods, we investigate the effect of Al on the generalized stacking fault energy of face-centered cubic (fcc) CrMnFeCoNi high-entropy alloy as a function of temperature. Upon Al addition or temperature increase, the intrinsic and extrinsic stacking fault energies increase, whereas the unstable stacking fault and unstable twinning fault energies decrease monotonously. The thermodynamic expression for the intrinsic stacking fault energy in combination with the theoretical Gibbs energy difference between the hexagonal close packed (hcp) and fcc lattices allows one to determine the so-called hcp-fcc interfacial energy. The results show that the interfacial energy is small and only weakly dependent on temperature and Al content. Two parameters are adopted to measure the nano-twinning ability of the present high-entropy alloys (HEAs). Both measures indicate that the twinability decreases with increasing temperature or Al content. The present study provides systematic theoretical plasticity parameters for modeling and designing high entropy alloys with specific mechanical properties.

Stacking fault energy of face-centered-cubic high entropy alloys

2018 ◽  
Vol 93 ◽  
pp. 269-273 ◽  
Author(s):  
S.F. Liu ◽  
Y. Wu ◽  
H.T. Wang ◽  
J.Y. He ◽  
J.B. Liu ◽  
...  
Keyword(s):  
Stacking Fault ◽  
Stacking Fault Energy ◽  
High Entropy Alloys ◽  
Face Centered Cubic ◽  
High Entropy ◽  
Face Centered

scholarly journals Atomic Simulations of Grain Structures and Deformation Behaviors in Nanocrystalline CoCrFeNiMn High-Entropy Alloy

Materials ◽  
2019 ◽  
Vol 12 (7) ◽  
pp. 1010 ◽  
Author(s):  
Junling Hou ◽  
Qiang Li ◽  
Chuanbao Wu ◽  
Limei Zheng
Keyword(s):  
Plastic Deformation ◽  
Grain Size ◽  
Shape Change ◽  
High Entropy Alloy ◽  
Face Centered Cubic ◽  
Common Neighbor ◽  
High Entropy ◽  
Average Grain Size ◽  
The Face ◽  
Deformation Behaviors

Using the molecular dynamics method, the melting character, mechanical properties, microstructures, and strain deformation mechanisms of nanocrystalline CoCrFeNiMn high-entropy alloy are systematically investigated in the present work. The simulation results suggest that the melting point in CoCrFeNiMn high-entropy alloy decreases with the grain size, decreasing from 3.6 to 2.0 nm. The grain size has a significant effect on shear and Young’s modulus compared to bulk modulus. The stress-strain simulation demonstrates that the ultimate tensile strength decreases with the decrease of the grain size, while the plastic deformation increases with the decrease in grain size. While the average grain size decreases to 2.0 nm, the amorphization induced by small grain size reduces plastic deformation. The common neighbor analysis shows that the face-centered cubic (FCC) composition of CoCrFeNiMn decreases gradually with decreasing grain size. For the sample with a grain size of 2.0 nm, the FCC composition is about 19% at a strain of 20%, accompanied by severe amorphization. The inverse Hall-Petch effect is observed for nanocrystalline CoCrFeNiMn high-entropy alloy in the present simulations. The atomic snapshot of CoCrFeNiMn with a grain size of 2.0 nm under the uniaxial strain confirms that the grain shape change, stacking fault formation, and amorphization are important mechanisms of plastic deformation in nanocrystalline high-entropy CoCrFeNiMn.

Embedded atom calculations of unstable stacking fault energies and surface energies in intermetallics

1997 ◽  
Vol 12 (1) ◽  
pp. 93-99 ◽  
Author(s):  
D. Farkas ◽  
S. J. Zhou ◽  
C. Vailhé ◽  
B. Mutasa ◽  
J. Panova
Keyword(s):  
Antiphase Boundary ◽  
Stacking Fault ◽  
Interatomic Potentials ◽  
Face Centered Cubic ◽  
Surface Energies ◽  
Embedded Atom ◽  
Fcc Lattice ◽  
The Face ◽  
Face Centered ◽  
Stacking Fault Energies

We performed embedded atom method calculations of surface energies and unstable stacking fault energies for a series of intermetallics for which interatomic potentials of the embedded atom type have recently been developed. These results were analyzed and applied to the prediction of relative ductility of these materials using the various current theories. Series of alloys with the B2 ordered structure were studied, and the results were compared to those in pure body-centered cubic (bcc) Fe. Ordered compounds with L12 and L10 structures based on the face-centered cubic (fcc) lattice were also studied. It was found that there is a correlation between the values of the antiphase boundary (APB) energies in B2 alloys and their unstable stacking fault energies. Materials with higher APB energies tend to have higher unstable stacking fault energies, leading to an increased tendency to brittle fracture.

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