Amorphous solid

Transmission electron microscopy

Electron backscatter diffraction

High entropy alloys

Metallurgy

Materials science

Chromatography

Carbide

Ceramic

Nano-

Grain boundary

Ball mill

Nanotechnology

Selected area diffraction

Microstructure

Spark plasma sintering

Composite material

Analytical Chemistry (journal)

Crystallography

Chemistry

Scanning electron microscope

Journal of the European Ceramic Society

A High Entropy (Hf-Ta-Zr-Nb)C Ultra-High Temperature Ceramic (UHTC) was fabricated by ball milling and Spark Plasma Sintering (SPS) with a density of 99%. The microstructure characteristics were investigated using X-ray diffraction (XRD), scanning electron microscopy (SEM) in combination with electron back scattered diffraction (EBSD) and transmission electron microscopy (TEM). Atomic structure and local chemical disorder was determined by means of scanning transmission electron microscopy (STEM) in conjunction with energy dispersive X-ray spectroscopy (EDS). According to the results, high purity, dense and homogeneous high entropy carbide with Fm-3 m crystal structure was successfully produced. The grain size ranged from approximately 5 μm to 25 μm with average grain size of 12 μm. Chemical analyses proved that all grains had the same chemical composition at the micro as well as on the nano/atomic level without any detectable segregation. The approximately 1.5 nm thin amorphous grain boundary phase contained impurities that came from the starting powders and the ball milling process.

Microstructure of (Hf-Ta-Zr-Nb)C high-entropy carbide at micro and nano/atomic level