scholarly journals Laser-Ignited Self-Propagating Sintering of AlCrFeNiSi High-Entropy Alloys: An Improved Technique for Preparing High-Entropy Alloys

Metals ◽  
2019 ◽  
Vol 9 (4) ◽  
pp. 438 ◽  
Author(s):  
Ya-Jun An ◽  
Li Zhu ◽  
Si-Han Jin ◽  
Jing-Jing Lu ◽  
Xian-Yang Liu
Keyword(s):  
Low Cost ◽  
Raw Material ◽  
High Entropy Alloy ◽  
High Entropy Alloys ◽  
High Entropy ◽  
Effective Components ◽  
Alloy Compound ◽  
Si Content ◽  
Chromite Powder ◽  
Improved Technique

AlCrFeNiSi system porous high-entropy alloy material is manufactured by laser ignition and self-propagating sintering of natural chromite powder, which provides the idea of breaking the traditional synthesis procedure of high-entropy alloy compound material. The raw material powder obtained by ball milling is compacted into cylindrical compacts, and the self-propagating reaction comes from the ignition caused by the laser on the surface of compacts, the high-entropy alloy composite of chrome iron powder synthesized by laser sintering, is obtained as well. The raw material is prepared from Al, Cr, Fe, Ni and Si elements with similar effective components of natural chromite powder. The selected chromite powder is energy-saving and environment-friendly, so the preparation of high-entropy alloy by the low-cost short-process can be made for processing for pre-theoretical reserve and process design. The effect of Si content on microstructure and properties of AlCrFeNiSi high-entropy alloy is investigated.

Preparation of CoCrFeNiCuMnSix High Entropy Alloys and their Microstructure and Properties

2013 ◽  
Vol 750-752 ◽  
pp. 615-618 ◽  
Author(s):  
Li Sheng Zhang
Keyword(s):  
Phase Structure ◽  
Optical Microscope ◽  
Vacuum Arc ◽  
High Entropy Alloy ◽  
High Entropy Alloys ◽  
Dendrite Morphology ◽  
High Entropy ◽  
Bcc Structure ◽  
Si Content ◽  
Cast Microstructure

According to the design concept of multi-element high-entropy alloys, seven kinds of elements (Cr, Mn, Fe, Co, Ni, Cu and Si) were selected in this work to design a series of CoCrFeNiCuMnSix high entropy alloys. Metal power was melted by vacuum arc furnace. Cast microstructure and phase structure of the high entropy alloy were Characterized by optical microscope (OM), scanning electron microscopy (SEM), X-ray diffraction (XRD). And then, hardness, wear resistance and corrosion resistance were tested. Phase structure of cast microstructure, the morphology of the microstructure and mechanical properties of the CoCrFeNiCuMnSix high entropy alloys were researched systematic in the condition of different content Si. The results show that the crystal structure is simple BCC structure. With the increasing Si content, the alloy cast structure changes from dendrite morphology to cellular morphology. It was Si content that plays an important role in increasing significantly the hardness of the alloy. The hardness of the maximum value reaches to HV985.

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

Crystals ◽  
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%.

A review on phase prediction in high entropy alloys

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.

Low-cost high entropy alloy (HEA) for high-efficiency oxygen evolution reaction (OER)

Nano Research ◽  
2021 ◽  
Author(s):  
Lalita Sharma ◽  
Nirmal Kumar Katiyar ◽  
Arko Parui ◽  
Rakesh Das ◽  
Ritesh Kumar ◽  
...  
Keyword(s):  
Oxygen Evolution ◽  
Oxygen Evolution Reaction ◽  
High Efficiency ◽  
Low Cost ◽  
High Entropy Alloy ◽  
High Entropy

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

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.

Microstructural Evolution in MgAlLiZnCaY and MgAlLiZnCaCu Multicomponent High Entropy Alloys

2018 ◽  
Vol 928 ◽  
pp. 183-187 ◽  
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

On the prediction of low-cost high entropy alloys using new thermodynamic multi-objective criteria

2018 ◽  
Vol 161 ◽  
pp. 73-82 ◽  
Author(s):  
A.E. Gheribi ◽  
A.D. Pelton ◽  
E. Bélisle ◽  
S. Le Digabel ◽  
J.-P. Harvey
Keyword(s):  
Low Cost ◽  
High Entropy Alloys ◽  
High Entropy ◽  
Multi Objective

scholarly journals Effect of Heat Treatment and Titanium Addition on the Microstructure and Mechanical Properties of Cast Fe31Mn28 Ni15Al24.5Tix High-Entropy Alloys

2019 ◽  
Vol 2019 ◽  
pp. 1-10 ◽  
Author(s):  
Shimaa El-Hadad ◽  
Mervat Ibrahim ◽  
Mohamed Mourad
Keyword(s):  
Mechanical Properties ◽  
Heat Treatment ◽  
Treatment Time ◽  
Low Cost ◽  
High Hardness ◽  
Lamellar Spacing ◽  
High Entropy Alloys ◽  
Titanium Addition ◽  
High Entropy ◽  
Ti Content

High-entropy alloys (HEAs) are multiprincipal element alloys with controllable properties. Studying the mechanical properties of these alloys and relating them to their microstructures is of interest. In the current investigation, Fe31Mn28 Ni15Al24.5Tix high-entropy alloys with Ti content (0–3 wt.%) were prepared by casting in an induction furnace. Different heat treatments were applied, and the microstructure and hardness of the cast samples were studied. It was observed that addition of up to 3.0 wt.% Ti significantly increases the hardness of the alloy from 300 to 500 (Hv) by the combined effect of solid solution strengthening and via decreasing lamellar spacing. Heat treatment at 900°C for 10 h enhanced the hardness at lower Ti percentages (0.0–0.8 wt.%) by decreasing the lamellar spacing, while no change was observed at higher Ti content. It was also observed that extending the treatment time to 20 h affected negatively the hardness of the alloy. Concluding, HEAs can achieve high hardness using low-cost principle elements with minor alloying additives compared to the other traditional alloys.

scholarly journals Prediction of Strength and Ductility in Partially Recrystallized CoCrFeNiTi0.2 High-Entropy Alloy

Entropy ◽  
2019 ◽  
Vol 21 (4) ◽  
pp. 389 ◽  
Author(s):  
Hanwen Zhang ◽  
Peizhi Liu ◽  
Jinxiong Hou ◽  
Junwei Qiao ◽  
Yucheng Wu
Keyword(s):  
Tensile Strength ◽  
Single Phase ◽  
Volume Fraction ◽  
Tensile Elongation ◽  
High Entropy Alloy ◽  
High Entropy Alloys ◽  
Number Density ◽  
High Entropy ◽  
Average Size ◽  
Strength And Ductility

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.

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

Metals ◽  
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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