Room-temperature mechanical properties of a high-entropy diboride

Alec C. Murchie, Jeremy L. Watts, William G. Fahrenholtz, Gregory E. Hilmas

Research output: Contribution to journalArticlepeer-review

30 Scopus citations

Abstract

The mechanical properties of a (Hf,Mo,Nb,Ta,W,Zr)B2 high-entropy ceramic were measured at room temperature. A two-step synthesis process was utilized to produce the (Hf,Mo,Nb,Ta,W,Zr)B2 ceramics. The process consisted of a boro/carbothermal reduction reaction followed by solid solution formation and densification through spark plasma sintering. Nominally, phase pure (Hf,Mo,Nb,Ta,W,Zr)B2 was sintered to near full density (8.98 g/cm3) at 2000°C. The mean grain size was 6 ± 2 µm with a maximum grain size of 17 µm. Flexural strength was 528 ± 53 MPa, Young's modulus was 520 ± 12 GPa, fracture toughness was 3.9 ± 1.2 MPa·m1/2, and hardness (HV0.2) was 33.1 ± 1.1 GPa. A Griffith-type analysis determined the strength limiting flaw to be the largest grains in the microstructure. This is one of the first reports of a variety of mechanical properties of a six-component high-entropy diboride.

Original languageEnglish
Pages (from-to)2293-2299
Number of pages7
JournalInternational Journal of Applied Ceramic Technology
Volume19
Issue number4
DOIs
StatePublished - Jul 1 2022
Externally publishedYes

Funding

The authors would like to thank the Missouri S&T Advanced Characterization Laboratory for assistance with specimen characterization. Funding for the project was provided by GE Research under the project ‘‘Chemical Compatibility of Refractory High Entropy Alloys with Ultra‐High Temperature Ceramics.” The authors would like to thank program manager Andrew Detor for his support on this work.

Keywords

  • borides
  • ceramic engineering
  • mechanical properties

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