No abstract

No abstract

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.

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.

The concept of high entropy alloy (HEA) opens a vast unexplored composition range for alloy design. As a well-studied system, Al-Co-Cr-Fe-Ni has attracted tremendous amount of attention to develop new-generation low-density structural materials for automobile and aerospace applications. In spite of intensive investigations in the past few years, the phase stability within this HEA system is still poorly understood and needs to be clarified, which poses obstacles to the discovery of promising Al-Co-Cr-Fe-Ni HEAs. In the present work, the CALPHAD approach is employed to understand the phase stability and explore the phase transformation within the Al-Co-Cr-Fe-Ni system. The phase-stability mapping coupled with density contours is then constructed within the composition-temperature space, which provides useful guidelines for the design of low-density Al-Co-Cr-Fe-Ni HEAs with desirable properties. (I) Introduction Over the last decade, the concept of high entropy alloy (HEA) [1] has attracted worldwide attention for the design of novel metallic materials. HEAs contain multi-principal components (5) in equal or near-equal atomic ratios and form a simple solid-solution structure, such as bcc, fcc, or hcp. This concept has revolutionized the traditional alloy design that is usually based on one or, at most two key elements, and opens a vast unexplored composition range for promising alloy design. As one of the model HEA systems, the Al-Co-Cr-Fe-Ni HEAs have been extensively investigated in the literature [2-21]. The microstructural evolution, mechanical properties, magnetic and electrical properties, as well as oxidation resistance and anti-irradiation resistance [22] on a vast range of elemental compositions and temperatures had been reported. Despite intensive investigations, a vast

The mechanical behavior of a single phase (fcc) Al0.3CoCrFeNi high-entropy alloy (HEA) was studied in the low and high strain-rate regimes. The combination of multiple strengthening mechanisms such as solid solution hardening, forest dislocation hardening, as well as mechanical twinning leads to a high work hardening rate, which is significantly larger than that for Al and is retained in the dynamic regime. The resistance to shear localization was studied by dynamically-loading hat-shaped specimens to induce forced shear localization. However, no adiabatic shear band could be observed. It is therefore proposed that the excellent strain hardening ability gives rise to remarkable resistance to shear localization, which makes this material an excellent candidate for penetration protection applications such as armors.

High propylene/propane separation membranes containing grape-branched MOFs/CNTs as filler with improved MOF dispersion and filler/polymer interface.

No abstract