A precipitate-free AlCoFeNi eutectic high-entropy alloy with strong strain hardening

Published on Oct 30, 2021in Journal of Materials Science & Technology6.155
· DOI :10.1016/J.JMST.2021.03.005
Peijian Shi2
Estimated H-index: 2
Yat Li93
Estimated H-index: 93
+ 14 AuthorsYunbo Zhong20
Estimated H-index: 20
Abstract Over recent years, eutectic high-entropy alloys (EHEAs) have intrigued substantial research enthusiasms due to their good castability as well as balanced strength–ductility synergy. In this study, a bulk cast Al19.25Co18.86Fe18.36Ni43.53 EHEA is developed with fine in-situ lamellar eutectics. The eutectics comprise alternating ordered face-centered-cubic (L12) and ordered body-centered-cubic (B2) phases with semi-coherent interfaces. The resulting microstructure resembles that of most reported as-cast EHEAs, but the B2 lamellae are devoid of nano-precipitates because of the Cr-element removal in current tailored eutectic composition. Surprisingly, the B2 lamellae still feature much higher deformation resistance than the L12 lamellae, so that less lattice defects are detected in the B2 lamellae until the fracture. More interestingly, in the L12 lamellae we identify a dynamic microstructure refinement that correlates to extraordinary strain hardening in tension. The precipitate-free EHEA consequently shows excellent tensile ductility of ∼10 % and high ultimate strength up to ∼956 MPa.
#1Zhufeng He (NU: Northeastern University)H-Index: 2
#2Jia Nan (MOE: Chinese Ministry of Education)H-Index: 2
Last. C.T. Liu (CityU: City University of Hong Kong)H-Index: 106
view all 11 authors...
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#1Ting Xiong (CAS: Chinese Academy of Sciences)H-Index: 6
#2Wenfan Yang (CAS: Chinese Academy of Sciences)H-Index: 3
Last. Xiuliang Ma (CAS: Chinese Academy of Sciences)H-Index: 38
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Abstract Recently, the eutectic high-entropy alloy (EHEA), AlCoCrFeNi2.1, can reach a good balance of strength and ductility. The dual-phase alloy exhibits a eutectic lamellar microstructure with large numbers of interfaces. However, the role of the interfaces in plastic deformation have not been revealed deeply. In the present work, the orientation relationship (OR) of the interfaces has been clarified as the Kurdjumov-Sachs (KS) interfaces presenting 111 B 2 | | 110 F C C and 110 B 2 | | 111 F...
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Last. Peter K. LiawH-Index: 94
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Abstract In this study, a new Al0.9CoFeNi2 eutectic high entropy alloy (EHEA) was designed, and the microstructures as well as the deformation behavior were investigated. The bulk cast Al0.9CoFeNi2 EHEA exhibited an order face-centered cubic FCC (L12) and an order body-centered cubic (B2) dual-phase lamellar eutectic microstructure. The volume fractions of FCC (L12) and B2 phases are measured to be 60 % and 40 %, respectively. The combination of the soft and ductile FCC (L12) phase together with...
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Heterostructured materials are an emerging class of materials with superior performances that are unattainable by their conventional homogeneous counterparts. They consist of heterogeneous zones wi...
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#1Peijian Shi (SHU: Shanghai University)H-Index: 2
#2Yunbo Zhong (SHU: Shanghai University)H-Index: 20
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Abstract High strength of materials usually comes with low ductility due to the lost or short-lived strain hardening. Here, we uncover a sequentially-activated multistage strain hardening (SMSH) that allows for sustained and effective strain-hardening capability in strong ultrafine-grained eutectic high-entropy alloy (EHEA). Consequently, exceptional ductility is realized in an ultrafine-grained EHEA, accompanied with high ultimate strength. We demonstrate that the SMSH is derived from a coordin...
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#1Qi Zhang (Monash University, Clayton campus)H-Index: 12
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The fatigue performance of high strength aluminum alloys used in planes, trains, trucks and automobiles is notoriously poor. Engineers must design around this important limitation to use Al alloys for light-weighting of transportation structures. An alternative concept for microstructure design for improved fatigue strength is demonstrated in this work. Microstructures are designed to exploit the mechanical energy imparted during the initial cycles of fatigue to dynamically heal the inherent wea...
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Abstract Conventional Laves phase is extremely brittle at room temperature. However, through a systematic study, we showed that the quinary Co-Cr-Fe-Ni-Nb Laves phase in a eutectic high entropy alloy (EHEA) can be plastically deformed at room temperature when its size is refined below 200 nm. Based on our current results, we propose a general micromechanical model that not only explains the suppression of cracks in the high entropy Laves phase but also enables the extraction of its fracture toug...
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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 ...
31 CitationsSource
#1Gao Bo (Nanjing University of Science and Technology)H-Index: 8
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Ultrastrong materials can notably help with improving the energy efficiency of transportation vehicles by reducing their weight. Grain refinement by severe plastic deformation is, so far, the most effective approach to produce bulk strong nanostructured metals, but its scaling up for industrial production has been a challenge. Here, we report an ultrastrong (2.15 GPa) low-carbon nanosteel processed by heterostructure and interstitial mediated warm rolling. The nanosteel consists of thin (~17.8 n...
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#1Ting Xiong (CAS: Chinese Academy of Sciences)H-Index: 6
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Abstract High-entropy alloys (HEAs) have displayed numerous unique features, however, high strength and high ductility are still the urgently desired mechanical property. The current study reports an outstanding combination of high strength and excellent ductility achieved in a eutectic high-entropy alloy (EHEA) AlCoCrFeNi2.1. The great achievement relays on a dual-phase heterogeneous structure strengthened with nano-precipitates. The heterogeneous structure provides the alloy a good combination...
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