High-entropy alloys (HEAs), for short, are alloys formed from five or more equal or approximately equal amounts of metals. Since high-entropy alloys may have many desirable properties, they have received considerable attention in materials science and engineering. Previous alloys may have only one or two major metal components. For example, iron is used as the base and some trace elements are added to enhance its properties, so the result is an iron-based alloy. In the past, the more metals are added to the alloy, the more brittle the material will be. However, unlike conventional alloys, high-entropy alloys have multiple metals but are not brittle. High entropy alloy breaks through the traditional material design concept, is a new alloy design concept, in mechanical properties, corrosion resistance, wear resistance, magnetic properties, radiation resistance and other aspects of excellent performance, or become the next generation of alloy benchmark.
High Entropy Alloys
High-entropy alloys (HEA), abbreviated as HEA, are alloys formed from five or more metals in equal or approximately equal amounts. High-entropy alloys have received considerable attention in materials science and engineering because of the many desirable properties they may have.
In the past, alloys may have had only one or two main metal components. For example, iron would be used as the base, and trace elements would be added to enhance the properties, resulting in an iron-based alloy.
In the past, if more metals are added to an alloy, it will make the material brittle, but unlike previous alloys, high entropy alloys have multiple metals but will not be brittle, which is a new kind of material.
High-entropy alloy breaks through the traditional concept of material design, is a new alloy design concept, in mechanical properties, corrosion resistance, wear resistance, magnetic properties, anti-irradiation and other aspects of excellent performance, or become the next generation of alloy benchmark.
The high entropy effect is the hallmark concept of HEA. Comparing the ideal entropy of formation with the enthalpy of pure metal (selected enthalpies of formation of IM compounds), it is known that in near equimolar alloys with 5 or more elements, it is more favorable to form SS phases rather than IM compounds.
At this point, only the entropy and enthalpy are analyzed for the conventional SS and IM phases without considering special combinations. The entropy values are also considered only for the generation entropy. Although vibrations, electrons and magnetism also affect the entropy value, the main factor is still the structure of the alloy.
The first "cocktail" effect is a phrase used by Prof. S. Ranganathan. The original intention was "a pleasant, pleasant mixture".
Later, it meant a synergistic mixture where the end result was unpredictable and greater than the sum of the parts. The phrase describes three different classes of alloys; bulk metallic glasses, superelastic and superplastic metals, and HEAs. The "cocktail" effect characterizes the structural and functional properties of amorphous bulk metallic glasses.
Severe lattice distortions are caused by the different atomic sizes in the high entropy phases. The displacement of each lattice position depends on the atoms occupying that position and the type of atoms in the local environment. These distortions are much more severe than in conventional alloys. The uncertainty of these variable atomic positions leads to a higher enthalpy of formation of the alloy.
Although physically this can reduce the intensity of the X-ray diffraction peaks, increase the hardness, reduce the electrical conductivity and decrease the temperature dependence of the alloy.
However, there is still a lack of systematic experiments to quantitatively describe what the values of these properties change. For example, shear modulus mismatches between constituent atoms may also contribute to hardening; changes in local bonding may also alter electrical conductivity, thermal conductivity, and associated electronic structure.
The first "cocktail" effect is a phrase used by Prof. S. Ranganathan. The original intention was "a pleasant, pleasant mixture". Later, it meant a synergistic mixture where the end result was unpredictable and greater than the sum of the parts.
The phrase describes three different classes of alloys; bulk metallic glasses, superelastic and superplastic metals, and HEAs. The "cocktail" effect characterizes the structural and functional properties of amorphous bulk metallic glasses.
Unlike other "core effects", the "cocktail" effect is not hypothesised and does not need to be proved. The "cocktail effect" refers to special material properties, often resulting from unexpected synergies.
Other materials can be described in this way, including physical properties such as near-zero coefficient of thermal expansion or catalytic response; functional properties such as thermoelectric response or photovoltaic conversion; ultra-high strength; good fracture toughness; and structural properties such as fatigue resistance or ductility.
The nature of the material is dependent on the material composition, microstructure, electronic structure and other features." The "cocktail" effect reveals the multielemental composition and special microstructure of MPEAs, which in turn produces unexpected nonlinear results.
The excellent comprehensive performance of high entropy alloy makes its wide range of application. High entropy alloys have excellent soft magnetic properties, and in mechanical properties, processing performance is better than the existing conventional soft magnetic materials; high entropy alloys have excellent high temperature stability, high temperature oxidation resistance, and can be applied in extreme environments; high entropy alloys have high hardness, high strength characteristics, and can be used as a coating for hard cutting tools; in addition to this, high entropy alloys can be used as light and heat conversion materials, lightweight alloy materials, mould materials, and so on.
High entropy alloys are also widely used in many fields such as motors, transformers, machine tools, consumer electronics, engine blades, jet aircraft engines, nuclear fusion and so on. High-entropy alloys have a strong amorphous formation ability, and certain high-entropy alloys can form amorphous phases in the as-cast organisation.
In contrast, to obtain amorphous organisation in conventional alloys, a great cooling rate is required to retain the organisation with irregular distribution of liquid atoms to room temperature. The study of amorphous metals has emerged only in recent years, due to the absence of dislocations in the structure, with high strength, hardness, plasticity, toughness, corrosion resistance and special magnetic properties, etc., and the application is also extremely wide, the preparation of amorphous high-entropy alloys will undoubtedly further expand the application areas of high-entropy alloys.
There is a wide variety of high-entropy alloys whose microstructures and properties are of high research value, with high-entropy effects being the main factor regulating their microstructure and structure. The present focus of attention in this field has evolved to seven alloy families, each comprising 6-7 elements, and has resulted in more than 408 new alloys.
These 408 alloys contain 648 different microstructures. It is found that the number of alloying elements and processing conditions have a significant effect on their microstructures. High-entropy alloys with different structures present different structural properties and functional characteristics. The unique structure and wide range of alloy types of high-entropy alloys provide the basis for their structural and functional applications.
High-entropy alloy is a brand new alloy field, which jumps out of the design framework of traditional alloys, and is a special alloy system with many excellent properties. Adjustment of its composition can further optimise its performance, and thus it has an extremely broad prospect for scientific research and industrial application.
At present, we can produce the following high entropy alloy ingots and bars by vacuum suspension melting, vacuum arc melting and vacuum induction melting, and process them into specific shapes according to customers' requirements, if you need, you can look for the following table and contact us for the corresponding information.
High entropy alloy has high hardness and high strength characteristics
High entropy alloy has excellent high temperature stability and high temperature oxidation resistance;
Superior to existing conventional soft magnetic materials in terms of mechanical properties and processing properties;
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