High‐entropy boride–carbide ceramics by sequential boro/carbothermal synthesis. Issue 9 (1st May 2022)

• Record Type: Journal Article
• Authors: Smith, Steven M.; Feng, Lun; Fahrenholtz, William G.; Hilmas, Greg E.; Huang, Tieshu
• Is Part Of: Journal of the American Ceramic Society. Volume 105:Issue 9(2022)
• Page Start: 5543
• Page End: 5547
• Publication Date: 2022-05-01
• Subjects: borides -- carbides -- synthesis -- ultrahigh temperature ceramics; Ceramics -- Periodicals; 620.1405
• DOI: 10.1111/jace.18517
• Languages: English
• ISSNs: 0002-7820

Abstract

Abstract: A dual‐phase high‐entropy boride (HEB)/carbide (HEC) ceramic with a fine grain size was synthesized by a sequential boro/carbothermal process. In the first step, an Hf–Nb–Ta–Ti–Zr‐containing carbide was synthesized by a carbothermal reduction of oxides followed by the reaction of the carbide with B4 C and ZrH2 to convert part of the carbide to boride. The resulting composition was ∼29 vol% HEB with an average grain size of ∼1.1 μm. Solid solution formation occurred at the densification temperature of 1900°C resulting in a relative density higher than 99%. The Vickers hardness was 26.5 ± 1.4 GPa. This is the first report of synthesizing dual‐phase boride–carbide high‐entropy ceramics from carbothermally synthesized, HEC powders.