The magnetic sensors based on soft magnetic effects of amorphous fibers are one of the highlights in scientific research in recent years. The amorphous fibers not only have excellent mechanical properties but also have unique magnetic properties, such as high permeability. As a result, sensors made of this kind of material can show the characteristics of sensitivity and durability. The processing and their advantages and disadvantages are mainly introduced in the chapter, and the properties reported in recent years are also summed up, including mechanical behavior, magnetic properties and shape-memory effects.
Part of the book: Magnetic Sensors
Entropic Alloys for Cryogenic Applications
The entropic alloys can be categorized into four types of alloys, e.g., high-entropy alloys, medium-entropy alloys, low-entropy alloys, and pure metals. The high-entropy alloys are a new kind of materials where the mixing entropy plays an important role in the phase formation. Because of the unique structures, the entropic alloys exhibit many outstanding properties, which even break the performance limits of traditional materials, including the excellent low-temperature properties. The mechanical properties of the entropic alloys serving at low temperature are mainly introduced in this chapter, including strength, plasticity, fracture behaviors, and impact resistance, and the reasons for these behaviors reported in recent years are also summed up.
Part of the book: Stainless Steels and Alloys
Light-Weight and Flexible High-Entropy Alloys
The lightweight and flexible materials can improve people’s quality of daily life; in addition, the materials can be widely used in aerospace, automotive, consumer electronics, etc. Recently, high-entropy alloys had become hot issues in materials science with many excellent properties; therefore, we can combine the design ideas of high-entropy alloys with lightweight materials and flexible materials, taking into account the advantages of two types of materials, and promoting the development and progress of new materials. In the chapter, we will elaborate on the relationship between the microstructure and properties of lightweight high-entropy alloys and the design ideas of high-entropy alloys with flexible materials that were investigated in recent years. Furthermore, as the microstructure and mechanical properties of the alloys exhibit the nonlinear behaviors with entropy on high-entropy alloys, we would like to define the lightweight high-entropy alloy as the density is lower than 6 g/cm3, the mix-entropy of these alloys is higher than 1R (here, R is gas constant), and the number of components is four or more. Finally, it is expected to broaden the research field of high-entropy alloys and provide some new directions for the development of new materials.
Part of the book: Engineering Steels and High Entropy-Alloys
Design and High-Throughput Screening of High Entropy Alloys
A balanced parameter was proposed to design the high entropy alloys (HEAs), which defined by average melting temperature Tm times entropy of mixing ΔSm over enthalpy of mixing ΔHm, Ω=TmΔSm/ΔHm, if Ω is larger than 1.1, we can predict that the entropy is high enough to overcome the enthalpy, and solid solution is likely to form rather than the intermetallic ordered phases. The composition can be further refined by using high-throughput screening by preparing the compositional gradient films. Multiple targets co-sputtering is usually used to prepare the films, and physical masking can separate the samples independently, chemical masking can also applied if possible. One example is the self-sharpening screening by using nanoindentations, the serration behaviors may related to the self-sharpening compositions.
Part of the book: Advances in High-Entropy Alloys
Breaking the Property Trade-Offs by Using Entropic Conceptions
Entropic conception has been used as an effective strategy for developing materials to break the property recordings of current materials, for example, breaking the trade-off between the high-strength and low-ductility structural alloys. The performance of materials usually under a complex circumstance, a balance of multiple properties, for example, combined the high-strength, high ductility, high conductivity, high corrosion resistance, high irradiation resistance, etc., the strategy of high-entropy-alloy (HEA) will provide a materials design and development technology to realize the goal. Magnetic materials usually exhibit excellent magnetic properties but weak mechanical properties and corrosion resistance. The reported unique behaviors of HEAs, for example, self-healing effects may be the mechanism for the high irradiation resistance of the HEAs, and self-sharpening behaviors of the tungsten-based HEAs main closely be related to the serration behaviors.
Part of the book: High Entropy Materials
Simulation and Calculation for Predicting Structures and Properties of High-Entropy Alloys View all chapters
High-entropy alloys (HEAs) have attracted the attention of scholars due to their outstanding properties such as excellent fracture, and irradiation resistance for various applications. However, the complex composition space hinders the exploration of new HEAs. The traditional experimental trial-and-error method has a long periodicity and is difficult to understand the complexity of the structural characteristics of HEAs. With the rise of the “Materials Genome Initiative”, simulation methods play an important role in accelerating the development of new materials and speeding up the design process of new HEAs. In this chapter, some of the multi-scale simulation methods, such as density functional theory (DFT) calculations and molecular dynamics (MD) methods, used in designing HEAs and predicting their properties are reviewed. The advantages and limitations of these methods are discussed, and the role of computational simulation methods in guiding experiments is illustrated. This study aims to promote the rapid development of computational simulation methods in HEAs.
Part of the book: High Entropy Materials