A new strategy to design eutectic high-entropy alloys using mixing enthalpy

2017 ◽  
Vol 91 ◽  
pp. 124-128 ◽  
Author(s):  
Yiping Lu ◽  
Hui Jiang ◽  
Sheng Guo ◽  
Tongmin Wang ◽  
Zhiqiang Cao ◽  
...  
Keyword(s):  
Mixing Enthalpy ◽  
High Entropy Alloys ◽  
High Entropy ◽  
New Strategy

scholarly journals A new strategy to design eutectic high-entropy alloys using simple mixture method

2018 ◽  
Vol 142 ◽  
pp. 101-105 ◽  
Author(s):  
Hui Jiang ◽  
Kaiming Han ◽  
Xiaoxia Gao ◽  
Yiping Lu ◽  
Zhiqiang Cao ◽  
...  
Keyword(s):  
High Entropy Alloys ◽  
High Entropy ◽  
New Strategy

Microstructural Evolution and Hardness of CoxCrCuFeNi High-Entropy Alloys

2014 ◽  
Vol 789 ◽  
pp. 79-83 ◽  
Author(s):  
Xing Yan Gao ◽  
Ning Liu ◽  
Yun Xue Jin ◽  
Zhi Xuan Zhu
Keyword(s):  
Supersaturated Solid Solution ◽  
Xrd Analysis ◽  
Mixing Enthalpy ◽  
High Entropy Alloys ◽  
Micro Hardness ◽  
Hardness Testing ◽  
Cooling Process ◽  
High Entropy ◽  
Interdendritic Phase ◽  
Microstructure Characteristic

The effects of Co contents on the microstructure characteristic and phase structure of CoxCrCuFeNi high-entropy alloys were investigated by SEM, EDS and XRD. The microstructures consisted of dendrites and many nanoprecipitations in the interdendritic. Increase Co contents,the size of nanoprecipitated phase in the interdendritic firstly increased and then decreased slightly. According to XRD analysis, two simple FCC phases, dendrite phase and Cu-rich interdendritic phase were found. As a result of slow diffusion, supersaturated solid solution was formed during solidification and then nanophase was precipitated during the following cooling process. The results of EDS revealed that Fe、Co and Cr were rich in dendrites, while Cu was rich at the interdendritic. For element Ni, which was rich in dendrites when x≤1.0, but was almost the normal value in dendrites for x>1.0. The reason for segregation was related to the positive mixing enthalpy between elements. The contents of Co had little impact on the hardness of CoxCrCuFeNi high-entropy alloys according to micro-hardness testing.

scholarly journals Necessary Thermodynamics Factors to Obtain Simple Solid Solutions in High-Entropy Alloys from the Al-Ti-Co-Ni-Fe System

2017 ◽  
Vol 62 (4) ◽  
pp. 2141-2145 ◽  
Author(s):  
K. Górecki ◽  
P. Bała ◽  
T. Kozieł ◽  
G. Cios
Keyword(s):  
Crystal Structure ◽  
Electron Concentration ◽  
Valence Electron ◽  
Intermetallic Phases ◽  
Mixing Enthalpy ◽  
Valence Electron Concentration ◽  
High Entropy Alloys ◽  
High Entropy ◽  
Mixing Entropy ◽  
Design And Synthesis

AbstractIn this paper findings regarding the design and synthesis of High-Entropy Alloys based on mixing enthalpy, mixing entropy,δparameter, Ω parameter and valence electron concentration are presented. Four alloys were synthesised with different predicted crystalline structures. Results of the microstructure and crystal structure studies are presented. It was shown that predicted structures as well as complex intermetallic phases exist in the material. The validity of valence electron concentration as well as additional parameters such as mixing enthalpy, mixing entropy and others necessary to obtain only the solid solution in High-Entropy Alloys were examined.

Effects of mixing enthalpy and cooling rate on phase formation of AlxCoCrCuFeNi high-entropy alloys

Materialia ◽  
2019 ◽  
Vol 6 ◽  
pp. 100292 ◽  
Author(s):  
X.D. Xu ◽  
S. Guo ◽  
T.G. Nieh ◽  
C.T. Liu ◽  
A. Hirata ◽  
...  
Keyword(s):  
Cooling Rate ◽  
Phase Formation ◽  
Mixing Enthalpy ◽  
High Entropy Alloys ◽  
High Entropy

Synthesis and Characterization of Novel High Entropy Alloys

2020 ◽  
Vol 978 ◽  
pp. 167-173
Author(s):  
Anil Kumar ◽  
B. Vinith ◽  
Aditya Kumar Choudhary ◽  
Manoj Kumar Chopkar
Keyword(s):  
Mechanical Alloying ◽  
Synthesis And Characterization ◽  
Mixing Enthalpy ◽  
Valence Electron Concentration ◽  
High Entropy Alloys ◽  
Face Centered Cubic ◽  
High Entropy ◽  
Cubic Structure ◽  
Face Centered

High entropy alloys (HEAs) generally exhibit either high resistance to deformation or high toughness due to the presence of body-centered or face-centered cubic structure, respectively. To overcome these limitations, new high entropy alloys have been developed in the present study. This investigation aims to synthesis and characterization of novel CoCrFeNi3Si, CoCrFe2Ni2Si, and Co2CrFeNi2Si high entropy alloys. The mechanical alloying route is used to synthesize these alloys. Grinding was carried out to 20h and X-ray diffraction (XRD) analysis was done at different time intervals of grinding. The face-centered cubic structure along with the intermetallic compound of Ni-Si was observed after 20h of grinding. Furthermore, a pseudo binary strategy based on the valence electron concentration and mixing enthalpy is also employed to design the high entropy alloys considered in the present study. Carefully analysis of the XRD pattern indicates that from 5 to 20h of mechanical alloying there is a decrement in the initial peaks of elements observed.

scholarly journals Liquid Phase Separation in High-Entropy Alloys—A Review

Entropy ◽  
2018 ◽  
Vol 20 (11) ◽  
pp. 890 ◽  
Author(s):  
Nicholas Derimow ◽  
Reza Abbaschian
Keyword(s):  
Phase Separation ◽  
Liquid Phase ◽  
Liquid Phase Separation ◽  
Miscibility Gap ◽  
Mixing Enthalpy ◽  
High Entropy Alloys ◽  
High Entropy ◽  
Entropy Of Mixing ◽  
Miscibility Gaps ◽  
Alloy Systems

It has been 14 years since the discovery of the high-entropy alloys (HEAs), an idea of alloying which has reinvigorated materials scientists to explore unconventional alloy compositions and multicomponent alloy systems. Many authors have referred to these alloys as multi-principal element alloys (MPEAs) or complex concentrated alloys (CCAs) in order to place less restrictions on what constitutes an HEA. Regardless of classification, the research is rooted in the exploration of structure-properties and processing relations in these multicomponent alloys with the aim to surpass the physical properties of conventional materials. More recent studies show that some of these alloys undergo liquid phase separation, a phenomenon largely dictated by low entropy of mixing and positive mixing enthalpy. Studies posit that positive mixing enthalpy of the binary and ternary components contribute substantially to the formation of liquid miscibility gaps. The objective of this review is to bring forth and summarize the findings of the experiments which detail liquid phase separation (LPS) in HEAs, MPEAs, and CCAs and to draw parallels between HEAs and the conventional alloy systems which undergo liquid-liquid separation. Positive mixing enthalpy if not compensated by the entropy of mixing will lead to liquid phase separation. It appears that Co, Ni, and Ti promote miscibility in HEAs/CCAs/MPEAs while Cr, V, and Nb will raise the miscibility gap temperature and increase LPS. Moreover, addition of appropriate amounts of Ni to CoCrCu eliminates immiscibility, such as in cases of dendritically solidifying CoCrCuNi, CoCrCuFeNi, and CoCrCuMnNi.

scholarly journals Development of Precipitation-Strengthened Al0.8NbTiVM (M = Co, Ni) Light-Weight Refractory High-Entropy Alloys

Materials ◽  
2021 ◽  
Vol 14 (8) ◽  
pp. 2085
Author(s):  
Kangjin Lee ◽  
Yunjong Jung ◽  
Junhee Han ◽  
Sung Hwan Hong ◽  
Ki Buem Kim ◽  
...  
Keyword(s):  
Mechanical Properties ◽  
Yield Strength ◽  
Single Phase ◽  
Elevated Temperatures ◽  
Critical Role ◽  
Mixing Enthalpy ◽  
Homogeneous Distribution ◽  
High Entropy Alloys ◽  
Light Weight ◽  
High Entropy

Single-phase solid-solution refractory high-entropy alloys (RHEAs) have been receiving significant attention due to their excellent mechanical properties and phase stability at elevated temperatures. Recently, many studies have been reported regarding the precipitation-enhanced alloy design strategy to further improve the mechanical properties of RHEAs at elevated temperatures. In this study, we attempted to develop precipitation-hardened light-weight RHEAs via addition of Ni or Co into Al0.8NbTiV HEA. The added elements were selected due to their smaller atomic radius and larger mixing enthalpy, which is known to stimulate the formation of precipitates. The addition of the Ni or Co leads to the formation of the sigma precipitates with homogeneous distribution. The formation and homogeneous distribution of sigma particles plays a critical role in improvement of yield strength. Furthermore, the Al0.8NbTiVM0.2 (M = Co, Ni) HEAs show excellent specific yield strength compared to single-phase AlNbTiV and NbTiVZr RHEA alloys and conventional Ni-based superalloy (Inconel 718) at elevated temperatures.

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