No abstract

No abstract

Secondary phases, either introduced by alloying or heat treatment, are commonly 31 present in most high-entropy alloys (HEAs). Understanding the formation of secondary 32 phases at high temperatures, and their effect on mechanical properties, is a critical issue 33 that is undertaken in the present study, using the Al x CoCrFeNi (x = 0.3, 0.5, and 0.7) as 34 a model alloy. The in-situ transmission-electron-microscopy (TEM) heating observation, 35 an atom-probe-tomography (APT) study for the reference starting materials (Al 0.3 and 36 Al 0.5 alloys), and thermodynamic calculations for all three alloys, are performed to 37 investigate (1) the aluminum effect on the secondary-phase fractions, (2) the 38 annealing-twinning formation in the face-centered-cubic (FCC) matrix, (3) the 39 strengthening effect of the secondary ordered body-centered-cubic (B2) phase, and (4) 40 the nucleation path of the secondary phase thoroughly. The present work will 41 substantially optimize the alloy design of HEAs and facilitate applications of HEAs to a 42 wide temperature range.

Obtaining strong interfacial affinity between filler and polymer is critical to the preparation of mixed matrix membranes (MMMs) with high separation efficiency. However, it is still a challenge for micron-sized metal organic frameworks (MOFs) to achieve excellent compatibility and defect-free interface with polymer matrix. Thin layer of ionic liquid (IL) was immobilized on micron-sized HKUST-1 to eliminate the interfacial nonselective voids in MMMs with minimized free ionic liquid (IL) in polymer matrix, and then the obtained IL decorated HKUST-1 was incorporated into 4,4'-(hexafluoroisopropylidene)diphthalic anhydride-2,3,5,6-tetramethyl-1,3-phenyldiamine (6FDA-Durene) to fabricate MMMs. Acting as a filler/polymer interfacial binder, the favorable MOF/IL and IL/polymer interaction can facilitate the enhancement of MOF/polymer affinity. Compared to MMM with only HKUST-1 incorporation, MMM with IL decorated HKUST-1 succeeded in restricting the formation of nonselective interfacial voids, leading to an increment in CO selectivity. The IL decoration method can be an effective approach to eliminate interfacial voids in MMMs, extending the filler selection to a wide range of large-sized fillers.