A Comparative Study of Thermal Oxidization Resistance of a High-Entropy Metal Boride and a High-Entropy Metal Carbide
Year: 2026
Type: article
Abstract: We present a systematic study of thermal oxidation resistance of transition metal borides and carbides up to 1300 °C in a dry air environment. A High-Entropy Metal Boride (HEMB), of composition (Hf0.2, Mo0.2, Nb0.2, Ta0.2, Zr0.2)B2, and a similar High-Entropy Metal Carbide (HEMC) (Hf, Mo, Nb, Ta, Zr)C5 were synthesized from precursor mixtures, under 30 MPa of pressure at a temperature of 1800 °C using a Spark Plasma Sintering Device. The synthesized phases were confirmed via X-ray Diffraction analysis, which showed a pure hexagonal AlB2-type structure for HEMB and a face-centered cubic (FCC) structure for HEMC, with lattice parameters, a = 3.10 Å and c = 3.37 Å for HEMB and a = 4.524 Å for HEMC. Oxidation resistance was evaluated using a simultaneous thermogravimetric analysis and differential scanning calorimetry (TGA/DSC) stage in which HEMB and HEMC were heated up to 1300 °C at a rate of 2 °C/min in a dry air environment. Scanning electron microscopy (SEM) was used to analyze the resulting oxidized material. Our study demonstrates that HEMB shows better thermal oxidation resistance as compared to a similar metal composition HEMC at high temperatures.
Source: Materials
DOI: 10.3390/ma19132720
Authors: Seth Iwan, Yogesh K. Vohra
Institution: University of Alabama at Birmingham
Language: English
Subfield: Ceramics and Composites
Field: Materials Science
Domain: Physical Sciences
Open Access status: gold
Estimated APC paid: $3,137
Awards: G2197881191, THERE IS A CRITICAL NEED FOR STRUCTURAL MATERIALS IN VARIOUS HYPERSONIC PLATFORMS ESPECIALLY IN SHARP WING LEADING EDGES AND NOSE CONES THAT CAN WITHSTAND EXTREME STRESSES, ABLATION, AND HIGH TEMPERATURES EXCEEDING 2300 K IN AN OXIDIZING ENVIRONMENT. WE ARE PROPOSING TWO DIFFERENT PATHWAYS FOR HIGH-PRESSURE HIGH-TEMPERATURE (HPHT) SYNTHESIS OF NOVEL MATERIALS WHICH WILL HAVE HARDNESS IN THE 10-30 GPA RANGE (ABLATION RESISTANCE) AND AT THE SAME TIME CAN WITHSTAND HIGH TEMPERATURES OF 2300 K WITHOUT ANY THERMAL DEGRADATION. THE HPHT SYNTHESIS, THERMAL STABILITY, AND SHEAR STRENGTH MEASUREMENTS WILL BE CARRIED OUT AT THE HIGH-PRESSURE COLLABORATIVE ACCESS TEAM (HPCAT) FACILITY, ADVANCED PHOTON SOURCE. WE WILL EMPLOY LARGE-VOLUME PRESS WITH INSITU ENERGY-DISPERSIVE X-RAY DIFFRACTION AS WELL AS RADIAL X-RAY DIFFRACTION TECHNIQUE IN A DIAMOND ANVIL CELL. THE FIRST PATHWAY WOULD BE HIGH-ENTROPY MATERIALS CONTAINING A MIXTURE OF FIVE OR MORE ELEMENTAL SPECIES THAT REPRESENT A PARADIGM SHIFT IN MATERIALS SCIENCE WHERE A VARIETY OF OXIDES, CARBIDES, AND BORIDES CAN BE SYNTHESIZED WITH SUPERIOR PHYSICAL AND MECHANICAL PROPERTIES THAN ARE ACCESSIBLE FROM THE CONSTITUENT MATERIALS. IN THE FIRST PATHWAY, WE WILL FOCUS ON HPHT SYNTHESIS AND THERMAL EQUATION OF STATE MEASUREMENTS ON HIGH-ENTROPY TRANSITION METAL BORIDES LIKE (HF0.2, MO0.2, TA0.2, NB0.2, TI0.2)B2 THAT HAS EXCELLENT THERMAL OXIDATION RESISTANCE. THE SECOND PATHWAY WOULD BE ULTRAHARD BORON-RICH COMPOUNDS BASED ON B12 ICOSAHEDRON LIKE B50C2 THAT HAVE BEEN RECENTLY SYNTHESIZED BY CHEMICAL VAPOR DEPOSITION AND YET TO BE REPRODUCED IN BULK-FORM BY HPHT TECHNIQUES. THE MATERIALS THAT ARE VALIDATED UNDER EXTREME CONDITIONS WILL BE INCORPORATED IN TO COMPOSITES FOR APPLICATIONS IN VARIOUS HYPERSONIC PLATFORMS. UNDER PRIOR NNSA SUPPORT, WE HAVE DEMONSTRATED OUR CAPABILITY IN THIS AREA BY SUCCESSFUL HPHT SYNTHESIS AND THERMAL EQUATION OF STATE MEASUREMENTS OF HIGH ENTROPY MATERIALS. UAB GRADUATE STUDENTS HAVE REGULARLY INTERNED AT NNSA LABORATORIES INCLUDING SANDIA NATIONAL LABS AND LOS ALAMOS NATIONAL LAB. UNDER PRIOR NNSA SUPPORT, SIX PHD GRADUATES UNDER PI MENTORSHIP HAVE JOINED NNSA COMPLEX AND ARE HAVING SUCCESSFUL CAREERS AND PROGRESSING TO LEADERSHIP POSITIONS. WE PLAN TO CONTINUE THIS SUCCESSFUL ACTIVITY IN WORKFORCE DEVELOPMENT AND EXTEND INTERNSHIPS OF GRADUATE STUDENTS AND POSTDOCTORAL SCHOLARS TO ALL DOE/NNSA LABORATORIES.
OpenAlex ID: W7165865073