The Effect of Scandium Ternary Intergrain Precipitates in Al-Containing High-Entropy Alloys.

We investigate the effect of alloying with scandium on microstructure, high-temperature phase stability, electron transport, and mechanical properties of the AlCoCrFeNi, AlCoCrCuFeNi, and AlCoCrCuFeNi high-entropy alloys. Out of the three model alloys, AlCoCrFeNi adopts a disordered CsCl structure type. Both of the six-component alloys contain a mixture of body-centered cubic () and face centered cubic () phases.

An Alternative Route to Pentavalent Postperovskite.

Two different high-pressure and -temperature synthetic routes have been used to produce only the second-known pentavalent CaIrO3-type oxide. Postperovskite NaOsO3 has been prepared from GdFeO3-type perovskite NaOsO3 at 16 GPa and 1135 K. Furthermore, it has also been synthesized at the considerably lower pressure of 6 GPa and 1100 K from a precursor of hexavalent Na2OsO4 and nominally pentavalent KSbO3-like phases.