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Trace elements such as boron (B) and zirconium (Zr) can increase creep resistance in nickel-based superalloys. This study investigates the change of microstructures on the grain boundary (GB) in phase-controlled nickel-based superalloys through the addition of trace elements. The basis alloy without B and Zr has distributed micrometer-sized (Nb, Ti)C and Cr23C6 carbides at the GBs. Zr is detected alongside Nb and Ti within certain (Nb, Ti)C carbides and its addition increases the fraction of (Nb, Ti)C or (Nb, Ti, Zr)C carbides. B affects the formation of precipitates constructed by nanometer-sized precipitates, which are Cr23C6 carbides, Cr23(C, B)6 boro-carbides, and Cr-rich borides, surrounded by γ' phases. This film structure, which includes nanometer-sized precipitates surrounded by γ' phases, forms more continuously with the addition of B and Zr. It is constructed with precipitates of (Nb, Ti)C carbides and Cr23(C, B)6 boro-carbides surrounded by γ' phases. Numerous nanometer-sized precipitates (i.e., (Nb, Ti)C and Cr23(C, B)6) are distributed alternately within the film structure. The effect of the addition of B and Zr is such that nucleation sites of each precipitate are formed simultaneously and alternately along the GBs. The experimental results were discussed by correlating them with the predicted fraction of stable phases depending on the temperatures of these alloys, using the JMatPro program. [ABSTRACT FROM AUTHOR]

Recently, Al‐batteries (AlBs) have become promising candidates for post‐lithium batteries, with [EMImCl] : AlCl3 (1 : 1.5) as the most commonly used electrolyte. However, progress in the development of AlBs is currently hindered by the lack of understanding of its solid‐electrolyte interface. Monitoring the structure of this interface under operational conditions by complementary spectroscopy could help to identify and overcome bottlenecks of the system. Reflection anisotropy spectroscopy (RAS), an optical in situ technique, provides access to physical and chemical properties of electrochemical interfaces on an atomistic level. Herein, we report the first example of RAS as an in situ characterization technique for non‐aqueous battery systems, investigating an Al(110)‐based model system. During chemical pre‐treatment in [EMImCl] : AlCl3, the Al(110) surface passivation film is modified. The oxide film is partially etched while an inhomogeneous passivation layer forms, increasing the surface roughness. Upon electrochemical cycling, applied potential‐dependent oscillations of the anisotropy are observed and demonstrate the applicability of RAS to monitor phenomena such as plating/stripping and surface passivation in real‐time. [ABSTRACT FROM AUTHOR]

A proton exchange membrane (PEM) is a crucial component for the effective and stable operation of energy conversion and storage devices, such as fuel cells, water electrolyzers, and redox flow batteries. However, perfluorinated sulfonic acid (PFSA) membranes—the most widely used PEM—have ultimate limitations of low proton selectivity to other active species because of their wide and randomly connected proton channels. Many attempts have been made to enhance the ion selectivity through morphology control, but it is still necessary to achieve significant improvement to overcome the permeability–selectivity trade-off. In this study, we demonstrate an ultrathin (∼30 nm) PFSA membrane with highly ordered hydrophilic domains. The well-controlled nanostructures are generated from the pre-aligned PFSA ionomers on the aqueous substrate, and further morphology development in the size and orientation of domains, and crystallinity, is finely adjusted via thermal annealing. Through this bottom-up morphology control, the ultrathin membrane has highly aligned ion channels with 55% crystallinity, resulting in about 800 times higher proton selectivity and 2 orders of magnitude lower areal resistance compared to 25 μm-thick PFSA membranes (Nafion 211). Furthermore, when the ultrathin membrane is applied to a vanadium redox flow battery (VRFB), the cell shows higher energy efficiency (∼76%) than a cell with a commercial Nafion membrane at the current density of 200 mA cm−2. [ABSTRACT FROM AUTHOR]

Flow-based microfluidic biochips (FMBs) have been rapidly commercialized and deployed in recent years for biological computing, clinical diagnostics, and point-of-care-tests (POCTs). However, outsourcing FMBs makes them susceptible to material-level attacks by malicious actors for illegitimate monetary gain. The attacks involve deliberate material degradation of an FMB's polydimethylsiloxane (PDMS) components by either doping with reactive solvents or altering the PDMS curing ratio during fabrication. Such attacks are stealthy enough to evade detection and deteriorate the FMB's function. Furthermore, material-level attacks can become prevalent in attacks based on intellectual property (IP) theft, such as counterfeiting, overbuilding, etc., which involve unscrupulous third-party manufacturers. To address this problem, we present a dynamic material-level watermarking scheme for PDMS-based FMBs with microvalves using a perylene-labeled fluorescent dye. The dyed microvalves show a unique excimer intensity peak under 405 nm laser excitation. Moreover, when pneumatically actuated, the peak shows a predetermined downward shift in intensity as a function of mechanical strain. We validated this protection scheme experimentally using fluorescence microscopy, which showed a high correlation (R2 = 0.971) between the normalized excimer intensity change and the maximum principal strain of the actuated microvalves. To detect curing ratio-based attacks, we adapted machine learning (ML) models, which were trained on the force-displacement data obtained from a mechanical punch test method. Our ML models achieved more than 99% accuracy in detecting curing ratio anomalies. These countermeasures can be used to proactively safeguard FMBs against material-level attacks in the era of global pandemics and diagnostics based on POCTs. [ABSTRACT FROM AUTHOR]