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.

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

Microstructure of Rapidly Solidified Melt-Spun Ribbon in AlCoCrFeNi2.1 Eutectic High-Entropy Alloys

2016 ◽  
Vol 879 ◽  
pp. 1350-1354 ◽  
Author(s):  
Takeshi Nagase ◽  
Mamoru Takemura ◽  
Mitsuaki Matsumuro
Keyword(s):  
Grain Boundary ◽  
Rapid Solidification ◽  
Crystalline Structure ◽  
Xrd Analysis ◽  
Solidification Structure ◽  
High Entropy Alloys ◽  
High Entropy ◽  
Melt Spun ◽  
Melt Spun Ribbons ◽  
Rapidly Solidified

The microstructure of rapidly solidified melt-spun ribbon in AlCoCrFeNi2.1 eutectic high entropy alloys (EHEAs) was investigated for clarifying the effect of rapid solidification on the constituent phases and microstructure of specimens formed through solidification. XRD analysis indicates that the melt-spun ribbons were composed of a mixture of fcc and bcc phases. The rapidly solidified melt-spun ribbon shows a fine poly-crystalline structure with fcc matrix phase and crystalline precipitates in the grain boundary, indicating that the solidification structure in the melt-spun ribbon was significantly different from that obtained by conventional casting processes.

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.

Effect of Al Content on Microstructure and Properties of AlxMoNbTiV RCCA’s Alloys

2018 ◽  
Vol 941 ◽  
pp. 1111-1116 ◽  
Author(s):  
Antoine Lacour-Gogny-Goubert ◽  
Zhao Zhao-Huvelin ◽  
Agnès Bachelier-Locq ◽  
Ivan Guillot ◽  
Anne Denquin
Keyword(s):  
Room Temperature ◽  
High Entropy Alloys ◽  
Compression Tests ◽  
Micro Hardness ◽  
High Entropy ◽  
Al Content ◽  
Arc Melting ◽  
Bcc Structure ◽  
The Stability ◽  
Cast Microstructure

The objective of this study is the evaluation of high entropy alloys for aeroengines applications up to 1000°C. AlxNbMoTiV alloys with 10 and 20 at.% Al have been produced by arc melting. As-cast microstructure and phase transformations during heat treatments have been investigated through SEM, DRX and TEM, revealing the possibility of homogenization at 1400°C and the stability of the BCC structure at 1000°C and 800°C for both alloys. Mechanical properties have been evaluated through micro-hardness and compression tests up to 800°C. It appears that, although both alloys show a similar microstructure and hardness evolution with heat treatment, the Alloy containing 10 at.% of Al show a higher yield strength at room temperature and 800°C, related to the brittle character of the alloy containing 20 at.% of Al.

scholarly journals Polymorphic Transformation and Magnetic Properties of Rapidly Solidified Fe26.7Co26.7Ni26.7Si8.9B11.0 High-Entropy Alloys

Materials ◽  
2019 ◽  
Vol 12 (4) ◽  
pp. 590 ◽  
Author(s):  
Zequn Zhang ◽  
Kaikai Song ◽  
Ran Li ◽  
Qisen Xue ◽  
Shuang Wu ◽  
...  
Keyword(s):  
Magnetic Properties ◽  
Amorphous Alloys ◽  
Polymorphic Transformation ◽  
Supersaturated Solid Solution ◽  
High Entropy Alloys ◽  
High Entropy ◽  
Magnetic Performance ◽  
Increasing Temperature ◽  
Rapidly Solidified ◽  
Bcc Phase

In this work, the microstructural evolution and magnetic performance of the melt-spun amorphous and amorphous-crystalline Fe26.7Co26.7Ni26.7Si8.9B11.0 high-entropy alloys (HEAs) during crystallization were investigated, respectively. Upon heating fully amorphous ribbons, a metastable BCC supersaturated solid solution together with a little Ni31Si12 crystals first precipitated and then the (Fe,Co)2B crystals formed until the full crystallization was achieved. With further increasing temperature after full crystallization, a polymorphic transformation from a metastable BCC phase to two types of FCC solid solutions occurred. For the amorphous-crystalline HEAs, the dominant crystallization products were the metastable FCC but not BCC crystals. During crystallization, the primary metastable FCC crystals first transform into the metastable BCC crystals and then the newly-generated BCC phase transforms into two types of FCC phases with further increasing temperature. This temperature dependence of the gradual polymorphic transformation results in the change of magnetic properties of the present high-entropy amorphous alloys.

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.

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