Tougher, lighter, and more formable and machinable metals for broader ranges of applications at higher temperatures are needed now more than ever. High-performance computing, high-resolution microscopy, and advanced spectroscopy methods, including neutrons and synchrotron x-rays, together with advances in metallurgy and metal mixology, reveal the potential of multicomponent advanced metals, such as multicomponent bulk metallic glasses and advanced high-entropy alloys. The development of new experimental approaches relates bulk properties and voxel-associated optimized properties throughout structures with high resolution. The correlations from in situ measurements greatly improve crystal plasticity-based models. This issue of MRS Bulletin overviews recent progress in the field, and this article highlights the importance of these new perspectives. The latest progress and directions in the science and technology for prospective high-temperature metals for structural applications are reported.

High-entropy alloys (HEAs) have been the focus of wide-ranging studies for their applications as next-generation structural materials. For high-temperature industrial applications, creep behavior of structural materials is critical. In addition to high-temperature tensile, compressive, and notched tests, elevated-temperature nanoindentation is a relatively new testing method for HEAs. With the high accuracy of depth-sensing technology and a stable temperature-controlling stage, elevated-temperature time-dependent mechanical behavior of HEAs can be investigated, especially at localized regions without the limitations of the standard specimen size used for traditional creep testing. Also, the creep response from each grain in polycrystalline samples with various crystalline orientations can be explored in detail. This article overviews current progress in studying creep behavior in HEAs via nanoindentation technology.

Magnesium alloys usually lack “operative deformation slip mechanisms” because of their hexagonal close-packed structure. Therefore, the mechanical behavior of magnesium alloys at different temperatures is dictated by other deformation mechanisms such as twinning, detwinning, secondary twinning, or dynamic recrystallization (DRX). Twinning and DRX can affect the development of grain size and orientation distribution, as well as the deformation behavior of magnesium alloys. The current understanding of the mechanisms and mechanics of these different deformation modes and their implementation in crystal plasticity-based modeling are highlighted in this article. Future directions in the development of constitutive models are also discussed.

A low-cost synthesis approach was developed for the fabrication of four symmetric meso-substituted water-soluble thiolated polyethylene glycol gold-coated superparamagnetic iron oxide nanoparticles–porphyrin (p-hydroxyphenyl [THPP], 3,5-dimethoxyphenyl [TdMPP], 3-pyridyl[T-3-PyP], and 1-methylpyridinium-3-yl[T3-Py+P4I−]) conjugates to achieve materials with enhanced absorption and therapeutic properties. After evaluation of their antibacterial inhibition characteristics against four nocosomial pathogens (Staphylococcus aureus, Escherichia coli, Pseudomonas aeruginosa, and Enterococcus faecalis), THPP and TdMPP conjugates showed some remarkable minimum inhibitory concentration values of 0.104 and 0.625 mg/mL against E. coli and E. faecalis, respectively, making these materials to be alternative agents for the inhibition of these pathogens in the environmental and clinical fields.

Multifunctional antifogging (AF) coatings consisting of alternating layers of positively charged ZrO2 nanoparticles (NPs) and negatively charged SiO2 NPs were rapidly fabricated via spray-spin-blow layer-by-layer electrostatic assembly followed by calcination. The resultant coatings of only three bilayers exhibited excellent AF, superhydrophilic, antireflective (AR), and self-cleaning (SC) properties, as well as high mechanical stability. These were demonstrated by various methods, e.g., transmission and scanning electron microscopy, X-ray diffraction, UV-Vis spectrometry, a contact angle test, a boiling test (constant 100 °C), a low-temperature test, and mechanical stability tests. ZrO2 and SiO2 NPs were synthesized and utilized as building blocks for fabricating the coatings. The resultant coatings exhibited excellent AF and SC properties due to the superhydrophilicity of the coating, showed excellent AR properties due to the quarter-wave coating with a low refractive index, and exhibited excellent superhydrophilic properties due to a rough microtextured surface. The simplicity of the fabrication process, easy availability of the nanomaterials, and excellent adhesion to substrates for the coating preparation might make the low-cost, nontoxic, and eco-friendly multifunctional coatings potentially useful in optical and display devices.

We report on enhanced mechanical, tribological, and surface-wettability characteristics of polymeric films dispersed with inorganic fullerene (IF)-type tungsten disulfide (WS2) nanoparticles derived through a two-step hydrothermal route. Imaging through transmission electron microscopy suggests the occurrence of polyhedral cage-like structures with a visibly nonspherical hollow ranging 55–75 nm. The mechanical stability of IF-type WS2 dispersed in polyvinyl alcohol (PVA) gets improved with increasing nano-inclusions, and upto 6 wt% loading. As compared with nanosheets, the IF-WS2 in PVA at the critical loading offers nearly 28.6, 33.6, and 42% respective improvements as regards, breaking stress, elongation at break, and toughness. Moreover, Stribeck curves in the mixed lubricating regime have revealed a nearly ∼80% reduction of coefficient of friction (COF) due to inclusion of IF-type WS2 in PVA. In the hydrodynamic region, the COF is drastically lowered from a typical value of 0.55 to 0.15 at the maximal sliding velocity with nanoparticle loading and despite the fact that the tribo feature gives a rising trend for a particular curve. Furthermore, exhibiting a progressive increase in water contact angle, a clear transition from the hydrophilic (∼64°) to hydrophobic (∼107°) surface of the nanocomposite films has been witnessed after inclusion of nano IF-WS2. An increased hydrophobicity and lowered surface adhesion and COF values along with marginal drop in surface energy are ensured in the investigated specimens. Investigation of responsive tribological and wetting–dewetting transition would find scope not only in coating and textile industry but also in smart miniaturized components.

Magnesium (Mg) alloys have received considerable attention as favorable orthopedic implant materials. However, their uncontrolled degradation in the physiological environment has led to premature implant failure. Thus, to address this problem, the present study was focused on developing protective monolayer coatings of fluorine-doped hydroxyapatite (FHA) and a bilayer coating of FHA and poly(lactic acid) (FHA–PLA) on AZ31 Mg. The synthesis involved microwave irradiation which helped in rapid synthesis of FHA coatings and spin coating for developing the PLA layer. Results revealed the formation of dense and defect-free FHA–PLA hybrid coatings. Importantly, they helped in significant reduction of galvanic–corrosion reactions of AZ31 in a physiological medium. The corrosion current density of FHA/PLA–coated samples was about two orders of magnitude lower than uncoated samples. Their lower weight losses further confirmed the coatings’ corrosion resistance. Combined, the as-synthesized FHA–PLA coatings can provide favorable corrosion protection to AZ31 Mg.