2021/12/15 by Sashank Shivakumar, Shivakumar, Sashank, Mingde Qin +9 · 1 citation
Earth and Planetary Sciences · Engineering · #FOS: Physical sciences #High Entropy Alloys Studies #High-pressure geophysics and materials #Intermetallics and Advanced Alloy Properties #Materials Science (cond-mat.mtrl-sci)
paper · pdf · doi:10.48550/arxiv.2112.07977
openalex publication_date 2021/12/15 · openalex created_date 2022/10/07 · openalex updated_date 2026/07/28
A new type of compositionally complex (medium- or high-entropy) M5Si3 silicides is synthesized. Both (V1/5Cr1/5Nb1/5Ta1/5W1/5)5Si3 and (Ti1/5Zr1/5Nb1/5Mo1/5Hf1/5)5Si3 form single-phase homogenous solid solutions. Notably, (V1/5Cr1/5Nb1/5Ta1/5W1/5)5Si3 forms the hexagonal gamma (D88) phase, while all its five constituent binary silicides, V5Si3, Cr5Si3, Nb5Si3, Ta5Si3, and W5Si3, are stable in the tetragonal alpha (D8l) or beta (D8m) phases. Annealing at 1600C demonstrates that this hexagonal gamma phase is stable. Comparison of the experimental and calculated X-ray diffraction patterns, Rietveld refinements, and analysis of aberration-corrected scanning transmission electron microscopy high-angle annular dark-field images suggest cation ordering, which reduces the configurational entropy. This work expands the field of high-entropy and compositional complex ceramics by not only discovering a new compositional complex silicide phase but also demonstrating the cation ordering and unusual phase stability. These compositionally complex silicides can be combined with refractory high-entropy alloys to make the high-entropy counterparts to the Nb-silicide and Mo-Si-B composites.