Hierarchical crack buffering triples ductility in eutectic herringbone high-entropy alloys

The mechanical behavior of a partially recrystallized fcc-CoCrFeNiTi0.2 high entropy alloys (HEA) is investigated. Temporal evolutions of the morphology, size, and volume fraction of the nanoscaled L12-(Ni,Co)3Ti precipitates at 800 °C with various aging time were quantitatively evaluated. The ultimate tensile strength can be greatly improved to ~1200 MPa, accompanied with a tensile elongation of ~20% after precipitation. The temporal exponents for the average size and number density of precipitates reasonably conform the predictions by the PV model. A composite model was proposed to describe the plastic strain of the current HEA. As a consequence, the tensile strength and tensile elongation are well predicted, which is in accord with the experimental results. The present experiment provides a theoretical reference for the strengthening of partially recrystallized single-phase HEAs in the future.

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Microstructure and Microsegregation in Directionally Solidified FeCoNiCrAl High Entropy Alloy

Advanced Materials Research ◽

10.4028/www.scientific.net/amr.189-193.3840 ◽

2011 ◽

Vol 189-193 ◽

pp. 3840-3843 ◽

Cited By ~ 5

Author(s):

Hong Bao Cui ◽

Hai Yan Wang ◽

Jin Yong Wang ◽

Heng Zhi Fu

Keyword(s):

Directional Solidification ◽

Electron Microprobe ◽

Solidification Rate ◽

High Entropy Alloy ◽

High Entropy Alloys ◽

Interface Morphology ◽

Directionally Solidified ◽

High Entropy ◽

Interdendritic Segregation ◽

Cast Condition

Directional solidification (DS) of FeCoNiCrAl high entropy alloy is carried out to investigate the microstructures and microsegregation under controlled solidification conditions. With an increasing solidification rate, the interface morphology grows in a planar, cellular and dendritic manner. The microstructures of the dendritic and interdendritic segregation areas are found to be spherical precipitates and basket-weave structures, respectively. With the help of an electron microprobe, microsegregation is determined in directionally solidified FeCoNiCrAl high entropy alloys. In contrast to the as-cast condition, directional solidification can refine microstructures of FeCoNiCrAl high entropy alloy dramatically and reduce microsegregation effectively.

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Effect of Copper Addition on the AlCoCrFeNi High Entropy Alloys Properties via the Electroless Plating and Powder Metallurgy Technique

Crystals ◽

10.3390/cryst11050540 ◽

2021 ◽

Vol 11 (5) ◽

pp. 540

Author(s):

Mohamed Ali Hassan ◽

Hossam M. Yehia ◽

Ahmed S. A. Mohamed ◽

Ahmed Essa El-Nikhaily ◽

Omayma A. Elkady

Keyword(s):

Compressive Strength ◽

Powder Metallurgy ◽

Atomic Radius ◽

The Other ◽

High Entropy Alloy ◽

Coating Process ◽

High Entropy Alloys ◽

Powder Metallurgy Technique ◽

Copper Metal ◽

High Entropy

To improve the AlCoCrFeNi high entropy alloys’ (HEAs’) toughness, it was coated with different amounts of Cu then fabricated by the powder metallurgy technique. Mechanical alloying of equiatomic AlCoCrFeNi HEAs for 25 h preceded the coating process. The established powder samples were sintered at different temperatures in a vacuum furnace. The HEAs samples sintered at 950˚C exhibit the highest relative density. The AlCoCrFeNi HEAs model sample was not successfully produced by the applied method due to the low melting point of aluminum. The Al element’s problem disappeared due to encapsulating it with a copper layer during the coating process. Because the atomic radius of the copper metal (0.1278 nm) is less than the atomic radius of the aluminum metal (0.1431 nm) and nearly equal to the rest of the other elements (Co, Cr, Fe, and Ni), the crystal size powder and fabricated samples decreased by increasing the content of the Cu wt%. On the other hand, the lattice strain increased. The microstructure revealed that the complete diffusion between the different elements to form high entropy alloy material was not achieved. A dramatic decrease in the produced samples’ hardness was observed where it decreased from 403 HV at 5 wt% Cu to 191 HV at 20 wt% Cu. On the contrary, the compressive strength increased from 400.034 MPa at 5 wt% Cu to 599.527 MPa at 15 wt% Cu with a 49.86% increment. This increment in the compressive strength may be due to precipitating the copper metal on the particles’ surface in the nano-size, reducing the dislocations’ motion, increasing the stiffness of produced materials. The formability and toughness of the fabricated materials improved by increasing the copper’s content. The thermal expansion has increased gradually by increasing the Cu wt%.

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A review on phase prediction in high entropy alloys

Proceedings of the Institution of Mechanical Engineers Part C Journal of Mechanical Engineering Science ◽

10.1177/09544062211008935 ◽

2021 ◽

pp. 095440622110089

Author(s):

Vinay Kumar Soni ◽

S Sanyal ◽

K Raja Rao ◽

Sudip K Sinha

Keyword(s):

Solid Solution ◽

Phase Formation ◽

Single Phase ◽

High Entropy Alloy ◽

High Entropy Alloys ◽

Modeling Tools ◽

High Entropy ◽

Recent Developments ◽

Phase Prediction ◽

The Stability

The formation of single phase solid solution in High Entropy Alloys (HEAs) is essential for the properties of the alloys therefore, numerous approach were proposed by many researchers to predict the stability of single phase solid solution in High Entropy Alloy. The present review examines some of the recent developments while using computational intelligence techniques such as parametric approach, CALPHAD, Machine Learning etc. for prediction of various phase formation in multicomponent high entropy alloys. A detail study of this data-driven approaches pertaining to the understanding of structural and phase formation behaviour of a new class of compositionally complex alloys is done in the present investigation. The advantages and drawbacks of the various computational are also discussed. Finally, this review aims at understanding several computational modeling tools complying the thermodynamic criteria for phase formation of novel HEAs which could possibly deliver superior mechanical properties keeping an aim at advanced engineering applications.

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Research on the nucleation and growth of high-entropy alloy

Materials Letters ◽

10.1016/j.matlet.2020.129206 ◽

2021 ◽

Vol 285 ◽

pp. 129206

Author(s):

M. Wang ◽

S. Guo ◽

X. Lin ◽

W.D. Huang

Keyword(s):

Nucleation And Growth ◽

High Entropy Alloy ◽

High Entropy

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Compression stress strengthening modelling of a ultrafine-grained equiatomic SPS CoCrFeNiNb high-entropy alloy

Proceedings of the Institution of Mechanical Engineers Part C Journal of Mechanical Engineering Science ◽

10.1177/0954406220943245 ◽

2020 ◽

pp. 095440622094324

Author(s):

Marcello Cabibbo ◽

Filip Průša ◽

Alexandra Šenková ◽

Andrea Školáková ◽

Vojtěch Kučera ◽

...

Keyword(s):

Powder Metallurgy ◽

Mechanical Alloying ◽

Oxide Phase ◽

High Entropy Alloy ◽

Induction Melting ◽

High Entropy Alloys ◽

High Entropy ◽

Plasma Sintering ◽

Transmission Electron ◽

Spark Plasma

High-entropy alloys are known to show exceptionally high mechanical properties, both compression and tensile strength, and unique physical properties, such as their phase stability. These quite unusual properties are primarily due to the microstructure generated by mechanical alloying processes, such as conventional induction arc melting, powder metallurgy, or mechanical alloying. In the present study, an equiatomic CoCrFeNiNb high-entropy alloy was prepared by a sequence of conventional induction melting, powder metallurgy, and compaction via spark plasma sintering. The high-entropy alloys showed uniform sub-micrometer grain microstructure consisted by a mixture of an fcc solid solution strengthened by a hcp Laves phase and a third intergranular oxide phase. The as-cast high-entropy alloys showed an ultimate compression strength (UCS) of ∼1400 MPa, which after sintering and compaction at 1273 K increased up to ∼2400 MPa. Extensive transmission electron microscopy quantitative analyses were carried out to model the UCS. A quite good agreement between the microstructure-strengthening model and the experimental UCS was found.

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Microstructural Evolution in MgAlLiZnCaY and MgAlLiZnCaCu Multicomponent High Entropy Alloys

Materials Science Forum ◽

10.4028/www.scientific.net/msf.928.183 ◽

2018 ◽

Vol 928 ◽

pp. 183-187 ◽

Cited By ~ 2

Author(s):

Khin Sandar Tun ◽

Manoj Gupta

Keyword(s):

Microstructural Evolution ◽

Microstructural Development ◽

High Entropy Alloy ◽

High Entropy Alloys ◽

Light Weight ◽

Aluminum Casting ◽

High Entropy ◽

Characterization Studies ◽

Melt Deposition ◽

Constituent Elements

In this research study, two light weight multi-component high entropy alloys (HEAs) consisting of six constituent elements were synthesized. The high entropy alloy having a chemical composition of Mg35Al33Li15Zn7Ca5Y5(atomic pct.) had a density of 2.25 g/cm3, while the high entropy alloy having a composition of Mg35Al33Li15Zn7Ca5Cu5(atomic pct.) had a density of 2.27 g/cm3. The strategy of non-equiatomic composition, high entropy of mixing coupled with low density was applied in designing the alloy systems. Disintegrated melt deposition (DMD) technique was used to synthesize the materials and characterization studies were performed on as-cast materials. The present study emphasizes on examining and understanding the microstructural development in the two light weight high entropy alloys. The formation and presence of phases and microstructural evolution were studied by interchanging yttrium and copper. Microstructural observations revealed presence of multiple phases in the developed alloys and the simplification of the microstructure when copper is used instead of yttrium. Microhardness results revealed a significant increase in hardness of of both the HEAs (3.8 – 4.2 times) when compared to AZ31 commercial magnesium alloy.Keywords: High Entropy Alloy, Magnesium, Aluminum, Casting, Microstructure

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Effect of Mo Addition on The Microstructure and Mechanical Properties of CoCuFeNi High Entropy Alloy

Metals ◽

10.3390/met10081017 ◽

2020 ◽

Vol 10 (8) ◽

pp. 1017

Author(s):

Yang Shao ◽

Huan Ma ◽

Yibing Wang

Keyword(s):

Mechanical Properties ◽

Solution Structure ◽

Tensile Tests ◽

Atomic Ratio ◽

Vacuum Arc ◽

High Entropy Alloy ◽

High Entropy Alloys ◽

High Entropy ◽

Microstructure And Mechanical Properties ◽

Mo Content

In order to reveal the effect of Mo addition on the microstructure and mechanical properties, (CoCuFeNi)100-xMox (x = 0, 10, 15, 19, and 25, x values in atomic ratio) high entropy alloys were prepared by vacuum arc-melting. The results showed that with Mo addition, the μ phase formed and serious separation occurred in the high entropy alloys. The content of μ phase increased with the increase in Mo content. The microstructure of the alloys changed from an initial single-phase face-center-cubic (FCC) solid solution structure (x = 0) to a hypoeutectic microstructure (x = 15), then to a full eutectic microstructure (x = 19), and finally to a hypereutectic microstructure (x = 25). Coherent interface between μ phase and FCC phase was observed. The (CoCuFeNi)81Mo19 alloy with fully eutectic microstructures exhibited the highest yield strength of 557 MPa and fracture strength of 767 MPa in tensile tests at room temperature. The fracture surface revealed that the formation of great amounts of the μ phase resulted in the loss of ductility of (CoCuFeNi)100-xMox alloys.

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Cooling Rate and Size Effect on the Microstructure and Mechanical Properties of AlCoCrFeNi High Entropy Alloy

Journal of Engineering Materials and Technology ◽

10.1115/1.3120387 ◽

2009 ◽

Vol 131 (3) ◽

Cited By ~ 64

Author(s):

F. J. Wang ◽

Y. Zhang ◽

G. L. Chen ◽

H. A. Davies

Keyword(s):

Solid Solution ◽

Atomic Ratio ◽

High Entropy Alloy ◽

High Entropy Alloys ◽

Body Centered Cubic ◽

Mechanical Behaviors ◽

High Entropy ◽

Intermediate Phases ◽

Different Diameters ◽

Very High

High entropy alloys are usually defined as the kind of alloys with at least five principle components, each component has the equi-atomic ratio or near equi-atomic ratio, and the high entropy alloys can have very high entropy of mixing, forming simple solid solution rather than many complex intermediate phases. In this paper, the size effects on the microstructure and mechanical behaviors of a high entropy alloy of AlCoCrFeNi was studied by preparing as-cast rod samples with different diameters. The alloy independent of cast diameter samples has the same phase of body centered cubic solid solution. With decreasing casting diameter, both the strength and the plasticity are increased slightly.

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