Year

2023

Degree Name

Doctor of Philosophy

Department

School of Mechanical, Materials, Mechatronic and Biomedical Engineering

Abstract

The discovery of High-Entropy Alloys (HEAs) has been a significant development in the field of Materials Science. In 2004, Cantor introduced the concept of single solid solution alloys containing several elements in equal or near equal proportions. The concept was also introduced by Yeh and co-workers, who coined the term ‘HEA’. This challenged conventional thinking about how alloys could be designed and opened up new possibilities for creating materials with unique properties. In 2014, Yiping Lu and his team proposed the concept of dual-phase eutectic HEAs, which has enabled the development of improved HEAs with both high strength and high ductility. This approach involves creating a microstructure with two different phases that work together to enhance the overall performance of the alloy. Both of these concepts have sparked a significant amount of research interest and have led to major advancements in the field of HEAs. However, despite the promising properties of HEAs, there are still significant challenges in studying their mechanical and tribological properties, especially at high temperatures.

One of the challenges in studying HEAs is the lack of experimental data on their mechanical and tribological properties, particularly for high temperature applications in fields such as aerospace, automotive, power plants. Unlike conventional alloys such as steel or Ni-based alloys, the compositions of HEAs can be adjusted with multiple metal elements at equi- or near equiatomic ratios, which can significantly affect the microstructure and mechanical behaviour of the alloy. However, for nearly all HEAs, the evolution of wear, friction, and tribolayers composition during high-thermal sliding or rolling processes are still unknown. This lack of understanding can limit the application of HEAs in high-temperature environments, where the well-established tribological properties of the material are critical. Therefore, continued research on the thermal behaviour of HEAs is critical to unlock their full potential and promoting their widespread use in high-end applications.

FoR codes (2008)

0912 MATERIALS ENGINEERING, 0913 MECHANICAL ENGINEERING, 0915 INTERDISCIPLINARY ENGINEERING

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Unless otherwise indicated, the views expressed in this thesis are those of the author and do not necessarily represent the views of the University of Wollongong.