| 61. |
- Huang, Shuo, et al.
(författare)
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Plastic deformation transition in FeCrCoNiAlx high-entropy alloys
- 2019
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Ingår i: Materials Research Letters. - : Taylor & Francis. - 2166-3831. ; 7:11, s. 439-445
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Tidskriftsartikel (refereegranskat)abstract
- The competition between plastic deformation mechanisms in FeCrCoNiAlx high-entropy alloys is explored as a function of temperature by first-principle theory. Investigating the generalized stacking fault energy, we identify a strong interplay between the magnetic and chemical effects. At cryogenic conditions (ferromagnetic state), full-slip is accompanied by martensitic transformation, whereas increasing temperature towards room-temperature (paramagnetic state) changes the deformation mechanism to full-slip plus twinning. Alloying with Al reduces the susceptibility for stacking fault formation in the ferromagnetic state and promotes twinning in the paramagnetic state. The present advance in magneto-plasticity reveals new opportunities for tailoring the mechanical response in high-entropy alloys. IMPACT STATEMENT: Magnetic state critically affects the γ-surface of FeCrCoNiAlx and is responsible for the emergence of the exceptional metastable twinning phenomena at room temperature.
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| 62. |
- Huang, Shuo, et al.
(författare)
-
Strengthening Induced by MagnetoChemical Transition in Al-Doped Fe-Cr-Co-Ni High-Entropy Alloys
- 2018
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Ingår i: Physical Review Applied. - : American Physical Society. - 2331-7019. ; 10:6
-
Tidskriftsartikel (refereegranskat)abstract
- Alloys with adjustable mechanical performance are of fundamental interest in material designs. Here, we investigate the magnetic- and chemical-ordering behavior of the ferromagnetic Fe-Cr-Co-Ni-Al-x (1 <= x <= 2.5) high-entropy alloys with the help of first-principle alloy theory. The lattice constants and the single- and polycrystalline elastic parameters for partially ordered and random structures are considered. In contrast to the trend found for the completely disordered phase, we demonstrate that ordering driven primarily by Al results in an enhanced Young's modulus, especially at high-Al concentrations, which is in line with the observed increase of the hardness for systems with a body-centered-cubic underlying lattice. The results suggest that outstanding strength and ductility can be realized by proper control of the ordering level in single- and multiphase high-entropy alloys.
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| 63. |
- Huang, Shuo, et al.
(författare)
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Temperature dependent stacking fault energy of FeCrCoNiMn high entropy alloy
- 2015
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Ingår i: Scripta Materialia. - : Elsevier BV. - 1359-6462 .- 1872-8456. ; 108, s. 44-47
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Tidskriftsartikel (refereegranskat)abstract
- The stacking fault energy (SFE) of paramagnetic FeCrCoNiMn high entropy alloy is investigated as a function of temperature via ab initio calculations. We divide the SFE into three major contributions: chemical, magnetic and strain parts. Structural energies, local magnetic moments and elastic moduli are used to estimate the effect of temperature on each term. The present results explain the recently reported twinning observed below room-temperature and predict the occurrence of the hexagonal phase at cryogenic conditions.
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| 64. |
- Huang, Shuo, et al.
(författare)
-
Thermal expansion in FeCrCoNiGa high-entropy alloy from theory and experiment
- 2017
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Ingår i: Applied Physics Letters. - : AMER INST PHYSICS. - 0003-6951 .- 1077-3118. ; 110:24
-
Tidskriftsartikel (refereegranskat)abstract
- First-principle alloy theory and key experimental techniques are applied to determine the thermal expansion of FeCrCoNiGa high-entropy alloy. The magnetic transition, observed at 649 K, is accompanied by a significant increase in the thermal expansion coefficient. The phase stability is analyzed as a function of temperature via the calculated free energies accounting for the structural, magnetic, electronic, vibrational and configurational contributions. The single-and polycrystal elastic modulus for the ferro-and paramagnetic states of the face-centered and body-centered cubic phases are presented. By combining the measured and theoretically predicted temperature-dependent lattice parameters, we reveal the structural and magnetic origin of the observed anomalous thermal expansion behavior. Published by AIP Publishing.
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| 65. |
- Huang, Shuo, et al.
(författare)
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Thermo-elastic behavior of hexagonal Sc-Ti-Zr-Hf high-entropy alloys
- 2022
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Ingår i: Journal of Physics D. - : IOP Publishing. - 0022-3727 .- 1361-6463. ; 55:23
-
Tidskriftsartikel (refereegranskat)abstract
- Recent advances in tuning the long-standing strength-ductility tradeoff have drawn attention to high-entropy alloys (HEAs), and the appearance of hexagonal close-packed (hcp) structures has been emphasized. However, few studies have explored the elastic moduli of hcp HEAs, which is of prime importance for improved understanding of the outstanding mechanical properties. In this work, we focus on a set of equiatomic rare-earth-free HEAs with hcp structures, i.e. ScTiZr, ScTiHf, ScZrHf, TiZrHf, and ScTiZrHf, and their thermo-elastic properties are studied using quantum mechanical first-principles methods. It is found that, for all considered HEAs, the hexagonal axial ratio shows a weak dependence on the temperature effect, and the thermal expansion coefficient remains almost unchanged above room temperature. From the calculated temperature-dependent single-crystal elastic constants, we analyzed the mechanical stability, elastic anisotropy, and derived polycrystalline moduli. Results indicate that the present HEAs exhibit rather high elastic isotropy and large elastic softening resistance. The ab initio predicted Young's modulus, shear modulus, and specific modulus do not obey the rule of mixture, which indicates that there exists a strong intrinsic hardening effect in all of the considered HEAs. The calculated results are in good agreement with the available experimental measurements.
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| 66. |
- Jafari, Fahimeh, et al.
(författare)
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Optimal Selection of Function Implementation in a Hierarchical Configware Synthesis Method for a Coarse Grain Reconfigurable Architecture
- 2011
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Ingår i: Proceedings. ; , s. 73-80
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Konferensbidrag (refereegranskat)abstract
- We have proposed a Dynamically Reconfigurable Resource Array (DRRA), which is a Coarse Grain Reconfigurable Architecture (CGRA). In this paper, we propose a hierarchical method for compiling DSP applications in Simulink into DRRA. In this method, each function in DRRA library can be implemented in different architecture styles and also each architectural style can be implemented in varying degrees of parallelism. Since selecting an appropriate implementation for functions of an application is very effective in performance and cost of architecture, we also formulate an optimization problem that considers implementations of functions as decision variables in order to minimize total energy consumed in the architecture under performance and cost constraints. A realistic case study exhibits up to 89% reduction of total energy consumption. It is worth mentioning that by using the proposed hierarchically compilation method, the design space is reduced dramatically while keeping the solution optimized in term of energy consumption. Hence, the optimization algorithm has low run-time complexity, enabling quick exploration of large design spaces.
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| 67. |
- Jorstad, S.G., et al.
(författare)
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The Event Horizon Telescope Image of the Quasar NRAO 530
- 2023
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Ingår i: Astrophysical Journal. - : American Astronomical Society. - 1538-4357 .- 0004-637X. ; 943:2
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Tidskriftsartikel (refereegranskat)abstract
- We report on the observations of the quasar NRAO 530 with the Event Horizon Telescope (EHT) on 2017 April 5-7, when NRAO 530 was used as a calibrator for the EHT observations of Sagittarius A*. At z = 0.902, this is the most distant object imaged by the EHT so far. We reconstruct the first images of the source at 230 GHz, at an unprecedented angular resolution of similar to 20 mu as, both in total intensity and in linear polarization (LP). We do not detect source variability, allowing us to represent the whole data set with static images. The images reveal a bright feature located on the southern end of the jet, which we associate with the core. The feature is linearly polarized, with a fractional polarization of similar to 5%-8%, and it has a substructure consisting of two components. Their observed brightness temperature suggests that the energy density of the jet is dominated by the magnetic field. The jet extends over 60 mu as along a position angle similar to -28 degrees. It includes two features with orthogonal directions of polarization (electric vector position angle), parallel and perpendicular to the jet axis, consistent with a helical structure of the magnetic field in the jet. The outermost feature has a particularly high degree of LP, suggestive of a nearly uniform magnetic field. Future EHT observations will probe the variability of the jet structure on microarcsecond scales, while simultaneous multiwavelength monitoring will provide insight into the high-energy emission origin.
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| 68. |
- Li, Shuo, et al.
(författare)
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A code generation method for system-level synthesis on ASIC, FPGA and manycore CGRA
- 2013
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Ingår i: MES '13 Proceedings of the First International Workshop on Many-core Embedded Systems. - New York, NY, USA : ACM. - 9781450320634 ; , s. 25-32
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Konferensbidrag (refereegranskat)abstract
- This paper presents a code generation method that translates an intermediate Register-Transfer Level (RTL) model of a system into its corresponding VHDL code for ASIC and FPGAs and MATLAB functions for manycores CGRAs. The intermediate representation consists of Function Implementation (FIMPs) and the glue logic. FIMPs are VHDL design units for the ASIC and FPGA implementation styles and MATLAB function templates for the CGRA implementation style, while the glue logic is a compact data structure storing Global Interconnect and Control (GLIC) information. The automatically generated implementation codes increase the resource usage by 1.5% on the average while reducing total design effort by two orders of magnitudes.
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| 69. |
- Li, Shuo, et al.
(författare)
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A code reuse method for many-core coarse-grained reconfigurable architecture function library development
- 2011
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Ingår i: 2011 International Symposium on Integrated Circuits, ISIC 2011. ; , s. 512-515
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Konferensbidrag (refereegranskat)abstract
- In this paper 1, a code reuse method is proposed to enhance the efficiency of the function library development of many core coarse-grained reconfigurable architecture. The method focuses on developing and using the precompiled ReCon-figurable Functions (RCFs) in the function library. By applying this method on the RCF development, functions are objectified like classes in any objective-oriented programming language. Using a function is to instantiate a selected RCF. Similar functions can be instantiated from the same RCF. Thus, the total number of RCFs to be compiled is reduced and the global programming efficiency is increased and the labor requirement for application development is reduced.
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| 70. |
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