Preface

It gives us immense pleasure to have this opportunity of editing this book on "Engineering Steels and High Entropy-Alloys". With the advancement of new materials, there is no doubt today that "Engineered Steels and High Entropy-Alloys" (HEAs) are the friendliest group of structural and instrumental materials that meet the needs of almost all industries. Besides, these are the materials that will be popular forever as they can be completely recycled. According to the World Steel Association, there are over 3,500 different grades of steel, each with unique physical, chemical, and environmental properties. It is well known that steel is composed of Fe and C, although it is the amount of C, as well as the extent of impurities and/or alloying elements that contribute to the properties of each steel grade. Indeed, the use of various technological methods allows us to purposefully change the microstructure, phase composition, and functional properties of steel products. Moreover, employing surface engineering methods, it is possible to create coatings that possess the properties of new materials.

Engineering steels are typically wrought steels engineered for mechanical, specialized, and allied technological applications requiring critical and often stringent levels of strength, ductility, toughness, and fatigue resistance. In special cases, steel may be required to exist at extremely high/low temperatures, corrosive, or harsh environments. Applications of these engineered high strength steel grades, often called Ultra High Strength Steels, are gripping current production of car bodies all around the world owing to their unique characteristics that not only allow lightweight but stronger parts than conventional steel counterparts. The composition, manufacturing route, and heat treatment procedures are carefully chosen to meet the customers' needs.

In recent times, the traditional alloy design approach has been shifted towards multi-component alloys known as HEA, thanks to the works of Prof. Brian Cantor, Prof. Jien-Wei Yeh, and Prof. S. Ranganathan. The traditional alloys such as steel, bronze, superalloys, etc. consist of one principal element with other elemental additions to enhance their microstructural and mechanical performance. In contrast, HEAs contains multiple principal elements in equimolar/near equimolar fractions to have a high configurational entropy that results in solid solution phases. The high entropy approach includes not only alloys but also ceramics and is regarded as a novel alloy design approach for various alloys including steels, superalloys, coatings, and ceramics, which possess excellent mechanical, thermal, and chemical stability, excellent creep resistance, oxidation/corrosion, and tribological and magnetic properties.

This breakthrough in HEA came after almost a century of research and development that resulted in a highly mature alloy design approach. It is expected that HEAs can satisfactorily replace traditional materials and design in advanced engineering applications. The ongoing research results in high entropy materials are very exciting covering a wide range of possibilities in areas such as jet engines, nuclear and power plants, marine structures, hard and thermal barrier coatings, and tools design.

**II**

**Section 3**

Science and Technology of High Entropy Materials **123**

**Chapter 7 125**

**Chapter 8 139**

**Chapter 9 157**

Novel Applications of High Entropy Alloys **179**

**Chapter 10 181**

**Chapter 11 199**

**Chapter 12 223**

Advances in Surface Engineering **237**

**Chapter 13 239**

**Chapter 14 255**

Light-Weight and Flexible High-Entropy Alloys

AlCrFeCoNi System for Military Applications

*by Sajid Ali Alvi, Hanzhu Zhang and Farid Akhtar*

High Entropy Alloys for Medical Applications

*by Victor Geanta, Ionelia Voiculescu, Petrica Vizureanu* 

Multicomponent Alloys for Biomedical Applications *by Lucien Reclaru, Lavinia Cosmina Ardelean, Alexandru Florian Grecu and Catalin Adrian Miu*

*by Anas Ahmad Siddiqui and Avanish Kumar Dubey*

Building and Architecture Paints and Coatings *by Valentina Loganina and Yerkebulan Mazhitov*

High-Entropy Alloys for Micro- and Nanojoining Applications

*by Victor Geanta and Ionelia Voiculescu*

Characterization and Testing of High-Entropy Alloys from

*by Yasong Li and Yong Zhang*

High-Entropy Ceramics

*and Andrei Victor Sandu*

*by Ashutosh Sharma*

Laser Surface Treatment

**Section 5**

**Section 4**

We have a great honor to thank all the co-editors, contributing authors, co-authors, and publication staff from IntechOpen for their efforts in preparing this book. We hope that the new experimental methodology given in the book will be the foundation for the development of new materials and technologies in materials science. This book will be useful to researchers, scientists, engineers, graduate and undergraduate level students across multi-disciplines. We hope that readers enjoy this book and that it will serve as an aid to create new exciting materials with unique properties.
