Microstructural, thermomechanical and tribological behavior of refractory high-entropy AlxCr0.25Nb0.5Ta0.5Ti1.5 (x = 0.5, 1) alloys

Abbas Saeed Hakeem*, Akeem Yusuf Adesina*, Abdul Samad Mohammed*, Mirza Murtuza Ali Baig, Muhammad Ali Ehsan, Ahmed Al Ghanim, Nasirudeen Ogunlakin, Syed Ali Abbas, Turki Nabieh Mohammad Baroud

*Corresponding author for this work

Research output: Contribution to journalArticlepeer-review

1 Scopus citations


Refractory high-entropy alloys (RHEAs) with varying Al composition AlxCr0.25Nb0.5Ta0.5Ti1.5 (x = 0.5, 1) possessing a single body-centered cubic phase were prepared by arc melting followed by casting in a copper mold. The developed RHEAs were subjected to mechanical, thermal and tribological evaluation. The RHEAs demonstrated a homogeneous equiaxed microstructure within which fine dendritic structures grew depending on the Al content in the alloy. The density, hardness, and coefficient of thermal expansion decreased with increased Al content from x = 0.5 to x = 1. Furthermore, it was found that the coefficient of friction increased from 0.7 to 0.8 while the specific wear rate increased by about 87% when the Al content increased from x = 0.5 to x = 1. This was attributed to the microstructural changes, crystal size difference, and reduced density resulting in a reduction in the hardness of the alloy with increasing Al content from x = 0.5 to x = 1. Abrasive wear through ploughing coupled with severe plastic deformation was found to be the dominating wear mechanism, as revealed by the field emission scanning electron microscopy and energy-dispersive X−ray spectroscopy analysis.

Original languageEnglish
Pages (from-to)2394-2406
Number of pages13
JournalJournal of Materials Research and Technology
StatePublished - 1 Sep 2023

Bibliographical note

Funding Information:
The authors would like to acknowledge the support from IRC-HES and DROC, King Fahd University of Petroleum and Minerals, Dhahran 31261, Saudi Arabia. The authors are thankful to Dr. Saad Sheikh and Dr. Sheng Guo (Chalmers University of Technology, Sweden), who provided as-cast samples, and Dr. Saad Sheikh, Dr. Hideyuki Murakami (National Institute for Materials Science, Japan), for carrying out the microstructural analysis (EBSD).

Publisher Copyright:
© 2023 The Authors


  • Coefficient of friction
  • Coefficient of thermal expansion
  • Refractory high-entropy alloy
  • Structure
  • Wear resistance

ASJC Scopus subject areas

  • Ceramics and Composites
  • Biomaterials
  • Surfaces, Coatings and Films
  • Metals and Alloys


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