High Entropy Alloys (HEAs) are new classes of structural metallic materials that show remarkable property combinations. Yet, often times interesting compositions are still found by trial and error. Here we show an “Effective Atomic Radii for Strength” (EARS) methodology, together with different semi-empirical and first-principle models, can be used to predict the extent of solid solution strengthening to discover and design new HEAs with unprecedented properties. We have designed a Cr45Ni27.5Co27.5 alloy with a yield strength over 50% greater with equivalent ductility than the strongest HEA (Cr33.3Ni33.3Co33.3) from the CrMnFeNiCo family reported to date. We show that values determined by the EARS methodology are more physically representative of multicomponent concentrated solid solutions. Our methodology permits high throughput, property-driven discovery and design of HEAs, enabling the development of future high-performance advanced materials for extreme environments.
Ruddlesden–Popper
(layered perovskite) phases are attracting
significant interest because of their unique potential for many applications
requiring mixed ionic and electronic conductivity. Here we report
a new, previously undiscovered layered perovskite of composition,
Ce
x
Sr2–x
MnO4 (x = 0.1, 0.2, and 0.3). Furthermore,
we demonstrate that this new system is suitable for solar thermochemical
hydrogen production (STCH). Synchrotron radiation X-ray diffraction
and transmission electron microscopy are performed to characterize
this new system. Density functional theory calculations of phase stability
and oxygen vacancy formation energy (1.76, 2.24, and 2.66 eV/O atom,
respectively with increasing Ce content) reinforce the potential of
this phase for STCH application. Experimental hydrogen production
results show that this materials system produces 2–3 times
more hydrogen than the benchmark STCH oxide ceria at a reduction temperature
of 1400 °C and an oxidation temperature of 1000 °C.
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