Meet the editor

Jiro Kitagawa received a BS in Physics from Kyoto University, Japan, in 1993, and an MS and Ph.D. in Physics from the University of Tokyo, Japan, in 1995 and 1998, respectively. At the University of Tokyo, Dr. Kitagawa carried out materials research on rare-earth intermetallic compounds. In 2002 he joined Hiroshima University, Japan, as a research associate studying terahertz technologies. From 2012 to 2014 he was an assistant

professor at Fukuoka Institute of Technology, Japan. He became a full professor there in 2015. His research interests include materials research on magnetic and superconducting materials. His current projects are on magnetism and superconductivity in high-entropy alloys.

Contents

**Section 1**

**Section 2**

**Section 3**

Superconductivity in HEA-Type Compounds *by Yoshikazu Mizuguchi and Aichi Yamashita*

Why Al-B4C Metal Matrix Composites? A Review

Materials Research on High-Entropy Alloy Superconductors *by Jiro Kitagawa, Naoki Ishizu and Shusuke Hamamoto*

*by Mohamed F. Ibrahim, Hany R. Ammar, Agnes M. Samuel, Mahmoud S. Soliman, Victor Songmene and Fawzy H. Samuel*

*by Mohamed Gamal Mahmoud, Yasser Zedan, Agnes-Marie Samuel,* 

Recent Advances of High Entropy Alloys: High Entropy Superalloys

Applications of Rare Earth Metals in Al-Si Cast Alloys

*Victor Songmene, Herebert W. Doty and Fawzy H. Samuel*

*by Modupeola Dada, Patricia Popoola, Ntombizodwa Mathe, Samson Adeosun, Sisa Pityana, Olufemi Aramide, Nicholus Malatji,* 

Design and High-Throughput Screening of High Entropy Alloys

*Thabo Lengopeng and Afolabi Ayodeji*

*by Yaqi Wu and Yong Zhang*

**Preface XI**

High-Entropy Alloy Superconductors **1**

**Chapter 1 3**

**Chapter 2 21**

High-Entropy Alloy Composites **37**

**Chapter 3 39**

**Chapter 4 65**

**Chapter 5 95**

Design of High-Entropy Alloys **113**

**Chapter 6 115**

## Contents


## **Chapter 7 131** Design and Development of High Entropy Alloys Using Artificial Intelligence *by Shailesh Kumar Singh and Vivek K. Singh*

Preface

High-entropy alloys (HEAs) are a new class of materials defined by crystals in which more than five elements, each with an atomic fraction between 5% and 35%, randomly occupy one crystallographic site. The concept of HEAs initially developed in single-site crystal structures such as face-centered cubic (fcc), body-centered cubic (bcc), and hexagonal-closed packing (hcp). However, the concept is now adopted in many multi-site alloys (multi-site HEAs). Due to the severe lattice distortion effect, many fcc or bcc HEAs show superior mechanical properties. The superior mechanical properties result from the cocktail effect, which means an enhancement of property beyond the simple mixture of constituent elements. The cocktail effect is also observed in a multi-site HEA; for example, outstanding thermal stability or enhancement of magnetic frustration in a high-entropy alloyed oxide. Due to the massive elemental combination of the HEA system, there are unlimited possibilities of finding new phenomena in the materials research on HEAs. The synthesis of a new single-phase or multiphase bulk sample is crucial work. In addition, fabrications of thin-film and nanocrystalline samples of well-known HEAs are important works. It is widely accepted that first-principle calculations, machine learning, and calculation of phase diagram (CALPHAD) are

This book covers some very interesting topics concerning the mechanical, physical, and chemical properties of new HEAs, including high strength, high ductility, good thermal stability, superconductivity, exotic magnetism, and so on. It also examines potential applications of HEAs, such as coating against corrosion, biomaterials, catalysts, shape memory alloys, magnetic refrigeration materials, and more. This book provides the reader with a comprehensive overview of the frontier of materials research and the exotic properties (mechanical, physical, chemical, etc.) and exciting

The book consists of three sections. Section 1 focuses on HEA superconductors. Chapter 1 summarizes the frontier studies of multi-site HEA superconductors. The chapter focuses on HEA-type compounds with the NaCl-type, the CuAl2-type, high-Tc cuprates, and BiS2-based layered structures. In the three-dimensional structures with the NaCl-type and the CuAl2-type, the improvement of superconducting properties by introducing the HEA state is not clearly observed, whereas some interesting properties are found. However, high-Tc cuprates and BiS2-based layered HEA superconductors, characterized by two-dimensional crystal structures, exhibit improved superconducting properties due to high-entropy effects. The HEA effects depend on structural dimensionality. Chapter 2 describes the materials

Section 2 is devoted to HEA composites. Chapter 3 examines an Al-B4C metal matrix composite (MMC), which is useful for shielding material for nuclear reactors. In this chapter, the authors introduce the microstructures of Al-B4C MMC samples. Furthermore, they examine the mechanical properties of samples and present the results from the viewpoint of microstructures. Chapter 4 reviews papers concerning the effect of mischmetal, La or Ce, and La+Ce additions on Al-Si

powerful methods for screening new compounds.

research on fcc and Mn5Si3-type HEA superconductors.

applications of HEAs.
