| 1. |
- Lu, Yiping, et al.
(author)
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Promising properties and future trend of eutectic high entropy alloys
- 2020
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In: Scripta Materialia. - : Elsevier BV. - 1359-6462. ; 187, s. 202-209
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Journal article (peer-reviewed)abstract
- Eutectic high-entropy alloys (EHEAs), as a sub-group of high-entropy alloys (HEAs), are becoming a new research hotspot in the metallic materials community because of their excellent castability, fine and uniform microstructures even in the as-cast state, high strength, and good ductility. Some of the EHEAs have shown promising potentials for industrial applications. Here, the history, interesting solidification microstructure and mechanical properties, and the design strategy of EHEAs are reviewed, and their future prospects are outlined.
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| 2. |
- Qin, Gang, et al.
(author)
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A novel face-centered-cubic high-entropy alloy strengthened by nanoscale precipitates
- 2019
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In: Scripta Materialia. - : PERGAMON-ELSEVIER SCIENCE LTD. - 1359-6462 .- 1872-8456. ; 172, s. 51-55
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Journal article (peer-reviewed)abstract
- A new single-phase face-centered-cubic (FCC) Co9Cr7Cu36Mn25Ni23 [atomic percent, similar hereinafter] high-entropy alloy (HEA) was prepared by arc melting. A uniform distribution of nanometer-sized precipitates was achieved. The tensile yield strength, ultimate tensile strength, and elongation were 401 MPa, 700 MPa, and 36%, respectively. The energy-dispersive spectrometer results showed that the nano-precipitates were rich in Co and Cr elements. Moreover, the crystal-forming behavior and the nanoscale-precipitates-forming mechanism were revealed. Acta Materialia Inc. Published by Elsevier Ltd. All rights reserved.
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| 3. |
- Qin, Gang, et al.
(author)
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An as-cast high-entropy alloy with remarkable mechanical properties strengthened by nanometer precipitates
- 2020
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In: Nanoscale. - : ROYAL SOC CHEMISTRY. - 2040-3364 .- 2040-3372. ; 12:6, s. 3965-3976
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Journal article (peer-reviewed)abstract
- High-entropy alloys (HEAs) with good ductility and high strength are usually prepared by a combination of forging and heat-treatment processes. In comparison, the as-cast HEAs typically do not reach strengths similar to those of HEAs produced by the forging and heat-treatment processes. Here we report a novel equiatomic-ratio CoCrCuMnNi HEA prepared by vacuum arc melting. We observe that this HEA has excellent mechanical properties, i.e., a yield strength of 458 MPa, and an ultimate tensile strength of 742 MPa with an elongation of 40%. Many nanometer precipitates (5-50 nm in size) and domains (5-10 nm in size) are found in the inter-dendrite and dendrite zones of the produced HEA, which is the key factor for its excellent mechanical properties. The enthalpy of mixing between Cu and Mn, Cr, Co, or Ni is higher than those of mixing between any two of Cr, Co, Ni and Mn, which leads to the separation of Cu from the CoCrCuMnNi HEA. Furthermore, we reveal the nanoscale-precipitate-phase-forming mechanism in the proposed HEA.
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| 4. |
- Shen, Yong-Feng, et al.
(author)
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Deformation mechanisms of a 20Mn TWIP steel investigated by in situ neutron diffraction and TEM
- 2013
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In: Acta Materialia. - : Elsevier. - 1359-6454 .- 1873-2453. ; 61:16, s. 6093-6106
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Journal article (peer-reviewed)abstract
- The deformation mechanisms and associated microstructure changes during tensile loading of an annealed twinning-induced plasticity steel with chemical composition Fe-20Mn-3Si-3Al-0.045C (wt.%) were systematically investigated using in situ time-of-flight neutron diffraction in combination with post mortem transmission electron microscopy (TEM). The initial microstructure of the investigated alloy consists of equiaxed gamma grains with the initial alpha'-phase of similar to 7% in volume. In addition to dislocation slip, twinning and two types of martensitic transformations from the austenite to alpha'- and epsilon-martensites were observed as the main deformation modes during the tensile deformation. In situ neutron diffraction provides a powerful tool for establishing the deformation mode map for elucidating the role of different deformation modes in different strain regions. The critical stress is 520 MPa for the martensitic transformation from austenite to alpha'-martensite, whereas a higher stress (>600 MPa) is required for actuating the deformation twin and/or the martensitic transformation from austenite to epsilon-martensite. Both epsilon- and alpha'-martensites act as hard phases, whereas mechanical twinning contributes to both the strength and the ductility of the studied steel. TEM observations confirmed that the twinning process was facilitated by the parent grains oriented with < 1 1 1 > or < 1 1 0 > parallel to the loading direction. The nucleation and growth of twins are attributed to the pole and self-generation formation mechanisms, as well as the stair-rod cross-slip mechanism.
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