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The birth of high-entropy alloys: What is driving this metal revolution?
High entropy alloys (HEAs) are an emerging class of alloys, mainly composed of five or more elements mixed in relatively equal proportions. Traditional metal alloys are usually made up of just one or two main components, with small amounts of other elements added to enhance their properties. The concept of high entropy alloy was first proposed by Taiwanese scientist Ye Jinwei in 1995. This breakthrough led the materials science community to re-examine the design and application potential of alloys.
In the formation of high-entropy alloys, each element in the recipe has a subtle influence on the final result, reflecting how their interactions change the properties of the alloy.
High-entropy alloys have potentially superior properties compared to conventional alloys, including higher strength-to-weight ratios, improved fracture resistance, and corrosion resistance. Although HEAs have been studied since the 1980s, the real breakthrough came in the 2010s, when interest in this material increased significantly.
The development history of HEAs
Research on high entropy alloys began in 1981 and 1996, but it was not until 1995 that Ye Jinwei achieved his first success in actual alloy synthesis. Since then, research on HEAs has gradually gained popularity around the world, especially in 2004 when Ye and his team successfully designed a high-entropy alloy that can withstand extremely high temperatures and pressures. Potential applications of this type of alloy include racing cars, spacecraft, submarines, nuclear reactors and other high-tech fields.
The concept of high entropy alloy is not only a theoretical breakthrough, but also opens up new possibilities for many practical applications and gives us a new understanding of the properties of metal materials.
Core Effects of HEAs
The properties of high entropy alloys can be summarized into four core effects: high entropy effect, severe lattice distortion, slow diffusion and cocktail effect. These effects are special manifestations of HEAs in their microstructure and properties.
High Entropy Effect
The high entropy effect is one of the most important features in HEAs because it promotes the formation of solid solutions and simplifies the microstructure. Traditionally, multicomponent alloys are expected to form complex structures due to the various interactions between elements, but in fact the effect of high entropy enhances the stability of the solid solution, which is closely related to the second law of thermodynamics.
Severe lattice distortionDue to the multi-principal element solid solutions in HEAs, the concept of traditional lattice structure needs to be reconsidered. Each of these atoms is surrounded by different atoms, which leads to an increase in lattice strain and stress, with profound effects on the mechanical, thermal and electronic properties of the material.
Slowly spread
The special structure of HEAs leads to a slow diffusion rate, which greatly improves the thermal stability and structural integrity of the material. The complex atomic interactions during the diffusion process hinder the rapid movement of atoms, thereby enhancing the durability of the material.
Cocktail Effect
The cocktail effect emphasizes the enhancing effect of at least five main elements on the alloy properties. The properties of these alloys derive from the interactive cooperation of multiple components, further promoting the search and design of new materials.
New ideas for alloy design
Traditional alloy design usually improves performance by adding a small proportion of elements based on a main element, but in the design of HEAs, researchers need to explore the balance between multiple elements. According to preliminary studies, successful HEAs often need to contain some secondary phases to strengthen the material. However, the formation of single-phase materials remains an important approach to deepen the understanding of the basic mechanisms of HEAs.
Future Outlook
With the deepening of research, the understanding of HEAs will become more comprehensive, and their application areas will continue to expand. Whether high-entropy alloys can play a key role in future scientific and technological innovation and bring more convenience, efficiency and sustainability to human society has become an area that scientists continue to explore.
The question raised by this metal revolution is: How will high entropy alloys change our fundamental understanding of materials and their applications?
