Utilization of high entropy alloy characteristics in Er-Gd-Y-Al-Co high entropy bulk metallic glass
- Authors
- Kim, Jinyeon; Oh, Hyun Seok; Kim, Jinwoo; Ryu, Chae Woo; Lee, Geun Woo; Chang, Hye Jung; Park, Eun Soo
- Issue Date
- 2018-08-15
- Publisher
- PERGAMON-ELSEVIER SCIENCE LTD
- Citation
- ACTA MATERIALIA, v.155, pp.350 - 361
- Abstract
- In the present study, we carefully evaluate the role of high entropy alloy (HEA) characteristics on glass forming ability (GFA) and mechanical responses in a newly developed Er-Gd-Y-Al-Co high entropy bulk metallic glass (HE-BMG) by comparison with the Er-Al-Co and Er-Y-Al-Co bulk metallic glasses (BMGs). The addition of multiple rare-earth elements (REs) to Er-Al-Co BMG results in both higher fragility according to Adam-Gibbs theory and slower crystallization kinetics according to confusion principle. Based on these mutual competitions, the Er18Gd18Y20Al24Co20 HE-BMG can be successfully fabricated up to 5 mm in diameter for glass formation. In particular, the HE-BMG exhibits unexpected structural bias and more fragile manner via preferential covalent bonding of Co-Al and various RE-Al clusters, which leads to larger deviation from the typical BMGs' behavior in the relation between fragility and elastic properties. Furthermore, the HE-BMG effectively retards crystallization kinetics, which was confirmed by exceptionally sluggish nanocrystallization of multi-precipitates from metastable liquid and longer post-recalescence plateau duration in cooling curve of solidification from stable liquid. Indeed, the increased structural instability due to HEA characteristics (preferential short-range order and sluggish crystallization) in HE-BMGs reduces cut-off size of self-organized shear avalanches and increases the number of chaotic shear avalanches, which can distribute the applied strain more homogeneously, resulting in enhanced intrinsic ductility. Consequently, these results provide a guideline on how to design HE-BMGs with promising properties by utilizing HEA characteristics, and thus can give us a strategy for bridging BMG and HEA. (C) 2018 Acta Materialia Inc. Published by Elsevier Ltd. All rights reserved.
- Keywords
- FORMING ABILITY; AMORPHOUS METAL; NI; ZR; CRYSTALLIZATION; THERMODYNAMICS; FRAGILITY; BEHAVIOR; DESIGN; HF; FORMING ABILITY; AMORPHOUS METAL; NI; ZR; CRYSTALLIZATION; THERMODYNAMICS; FRAGILITY; BEHAVIOR; DESIGN; HF; High entropy bulk metallic glass; High entropy alloy characteristics; Structural bias; Sluggish crystallization; Intrinsic ductility
- ISSN
- 1359-6454
- URI
- https://pubs.kist.re.kr/handle/201004/121032
- DOI
- 10.1016/j.actamat.2018.06.024
- Appears in Collections:
- KIST Article > 2018
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