Microstructure, mechanical properties, corrosion, and wear behavior of high-entropy alloy AlCoCrFeNix (x>0) and medium-entropy alloy (x=0)

  • Author / Creator
    Sim, Rui Ken
  • As one of the early studied high-entropy alloys, AlCoCrFeNi drew considerable attention due to its attractive mechanical properties. Efforts were made to improve this material by alloying with additional elements or modifying the ratio of its elements for improved properties. On the other hand, medium-entropy alloys with fewer elements can also have superior performance with less complication. In this study, we investigated the microstructures and properties of as-cast AlCoCrFeNix alloys (x = 0-2), focusing on the microstructural evolution and the corresponding mechanical properties and resistance to wear, corrosion, and corrosive wear. In particular, the Ni-free four-element medium-entropy alloy, AlCoCrFe, was examined and compared with its five-element high-entropy companion, AlCoCrFeNi. It was observed that the medium-entropy alloy was harder and had a higher resistance to wear and corrosion than the five-element alloy. Detailed microstructural analyses demonstrated that the medium-entropy alloy AlCoCrFe had a spinodal-decomposed nanostructure, which grew into a two-phase microstructure with phase transformation in the five-element high-entropy alloy. With increasing Ni content, one of the phases changed from a disordered BCC structure to a softer and more ductile FCC structure, further lowering the strength of the high-entropy alloy and its resistance to wear. The medium-entropy alloy showed certain advantages with superior properties while having less complicated microstructure features.

  • Subjects / Keywords
  • Graduation date
    Fall 2022
  • Type of Item
  • Degree
    Master of Science
  • DOI
  • License
    This thesis is made available by the University of Alberta Library with permission of the copyright owner solely for non-commercial purposes. This thesis, or any portion thereof, may not otherwise be copied or reproduced without the written consent of the copyright owner, except to the extent permitted by Canadian copyright law.