High-entropy alloys (HEAs) with multiple principal elements open up a practically infinite space for designing novel materials. Probing this huge material universe requires the use of combinatorial and high-throughput synthesis and processing methods. Here, we present and discuss four different combinatorial experimental methods that have been used to accelerate the development of novel HEAs, namely, rapid alloy prototyping, diffusion-multiples, laser additive manufacturing, and combinatorial co-deposition of thin-film materials libraries. While the first three approaches are bulk methods which allow for downstream processing and microstructure adaptation, the latter technique is a thin-film method capable of efficiently synthesizing wider ranges of composition and using high-throughput measurement techniques to characterize their structure and properties. Additional coupling of these high-throughput experimental methodologies with theoretical guidance regarding specific target features such as phase (meta)stability allows for effective screening of novel HEAs with beneficial property profiles.

The development of electrocatalysts with high activity and low cost has attracted growing attentions in recent years. Herein, we reported the Mn-doped CoP nanosheet arrays on flexible activated carbon cloth (Mn–CoP/CC) for the effective oxygen evolution reaction (OER) at low overpotential and high current density. Due to the novel 3D nanostructures of the carbon cloth and doping effect of the Mn element, the Mn doped CoP/CC electrode delivered the best overpotential of 317 mV for water splitting with the current density of 10 mA/cm2, a Tafel slope of ∼65.1 mV/dec, and excellent stability over 16 h in 1.0 mol/L KOH, which is superior or comparable to the most of the reported cobalt-based catalysts. Thus outstanding electrocatalytic performance originates from the Mn doping effect, which resulted in increased surface area and fast charge-transfer. It is believed that these findings would help us to develop high effective and stable electrocatalysts for water splitting.

Monosized spherical Cu–20% Sn (wt%) alloy particles with diameter ranging from 70.6 to 334.0 μm were prepared by the pulsated orifice ejection method (termed “POEM”). Fully dense without pores and bulk inclusions, the cross-sectional micrographs of the spherical alloy particles indicate an even distribution of Cu and Sn. These spherical Cu–Sn alloy particles exhibit a good spherical shape and a narrow size distribution, suggesting that the liquid Cu–Sn alloy can completely break the balance between the surface tension and the liquid static pressure in the crucible micropores and accurately control the volume of the droplets. Furthermore, the cooling rate of spherical Cu–20% Sn alloy particles is estimated by a Newton’s cooling model. The cooling rate of the Cu–20% Sn alloy particle decreases gradually with the particle diameter increasing. Smaller particles have higher cooling rates and when the particle diameter is less than 70 μm, the cooling rate of particles can reach more than 3.3 × 104 K/s. The secondary dendrite arm spacing has strong dependence on particle diameter which increases gradually with the increase of particle diameter. The results demonstrate that POEM is an effective route for fabrication of high-quality monosized Cu–20% Sn alloy particles.

Temperature-dependent (173–373 K) hyperpolarized 129Xe nuclear magnetic resonance (129Xe NMR) analyses along with transmission electron microscopy and N2 adsorption measurements have been applied to understand pore structure and interconnectivity of bare and grafted mesoporous silicon sponge (MSS) materials. The Xe NMR chemical shift data indicate the existence of micropores inside the larger mesopore channels and the effects of grafting on the pore surfaces. The grafted layer estimated at 2 nm in thickness blocks the micropores on the surfaces of mesoporous channels. Partitioning of Xe between the micropores and the mesopores in the MSS materials is temperature-dependent, with Xe principally occupying the micropores at lower temperatures. In addition, the temperature-dependent Xe peak shift of MSS materials verifies the increased uniformity and interconnectivity of mesopores after surface grafting. The results from this study provide useful information for design and development of novel materials.

Given the global water challenges, solar-driven steam generation has become a renewed topic recently as an energy-efficient way for clean water production. Here, a hybrid plasmonic structure consisting of a top layer of TiN nanoparticles (NPs) and a bottom layer of mesoporous anodized alumina membrane (AAM) was rationally designed and fabricated. The top TiN NPs with broadband light absorption acted as a plasmonic heating layer, which converted the absorbed light to heat efficiently for interfacial water heating. The AAM acted as the mechanical support layer, guaranteeing the heat isolation and continuous water replenishment. With optimized thickness of the TiN top layer, a solar steam generation efficiency of 87.7% was achieved in this study. This efficiency is comparable or even higher than prior studies. The current work proves the capability of the TiN NPs as an alternative photothermal material.

The design and the processing of a new class of titanium boride (TiB)-based bulk cermets containing a metallic phase (β-Ti phase) for toughening is presented. The general approach is rapid reaction and densification, using starting powders of Ti, TiB2, Fe, and Mo, by electric-field-activated sintering. The cermets consist of two-phase microstructures in which the boride phase formed as a networked structure of TiB whiskers that were created in situ upon the reaction between the powders. Hardness, flexural strength, and fracture toughness measurements of these materials revealed that they possess an interesting set of properties up to: hardness values of 1090 kg/mm2, flexural strength values of 953 MPa, and fracture toughness values of 18 MPa m1/2. A remarkable finding is that although the metallic phase fractured by microscopic cleavage, the cermets showed good fracture toughness values. The present study not only illustrates the process details and microstructure leading to these properties but also provides a broad powder metallurgical approach to design and synthesize cermets that may yield further improved properties.

A low-temperature synthesis method for Mn3O4/graphene is described in this research. Adjusting the reaction time and temperature allows control over the phase and morphology of the synthesized manganese oxide, and therefore the microwave absorbing properties. X-ray diffraction, Raman spectroscopy, transmission electron microscopy, and vector network analysis are used to characterize the phase, morphology, and electromagnetic properties. The results reveal that long reaction time can increase the particle size and high temperature can destroy the initial structure of graphene both of which have negative impact on the microwave absorbing properties. The Mn3O4–graphene composite synthesized in 140 °C for 4 h shows a maximum reflection loss (RL) reaching −20 dB at 14.4 GHz with absorber thickness of 2 mm, as well as an effective absorption bandwidth of more than 5 dB corresponding to RL below −10 dB.

In the present work, the TiB2-reinforced AA6061 composites were successfully in situ synthesized by laser surface alloying using a mixture of Ti and AlB2 powders. The microstructure evolution and properties of the composites were systematically studied. The results showed that TiB2 particles displayed a homogeneous distribution in the aluminum matrix with controllable contents and morphologies. By adjusting the molar ratio of alloying powders, phase constitution of the composites was varied. Thermodynamic calculation was used to analyze the phase selection during the solidification. It was found that the morphology of TiB2 particles was converted from hexagonal plate into rod-like structure with an increase of Ti contents. Transmission electron microscopy results illustrated that the in situ synthesized TiB2 particles exhibited a well-bonded interface with the Al matrix. Properties characterization revealed a significant enhancement in microhardness and abrasion resistance compared with the aluminum substrate attributed to the presence of the TiB2 reinforcements. The strengthening and wear mechanism were also discussed.

(1 − x)Ba(Mg1/3Ta2/3)O3–xBa(Co1/3Nb2/3)O3 (BMT–BCN, x = 0.0, 0.20, 0.25, 0.30, 0.40) ceramics were prepared using the traditional solid-state reaction method. X-ray diffraction patterns have shown that the intensities of (001) and (100) super-lattices decrease with the increase in the BCN content. Seven main Raman vibrational modes are observed, assigned, and illustrated, in particular. Raman shifts of Eg(O) modes and the FWHM values of F2g(O)/A1g(O) modes have close relationship with the dielectric properties. The calculated values by the four-parameter semiquantum model based on IR reflectivity match well with the measured data (@3.8 GHz), which means that most of dielectric contribution to the system may be ascribed to the absorption of structural phononic oscillations at the infrared region, and the contribution from the scattering of the defective phonons is small. The contributions of each vibrational mode on the dielectric responses were investigated in detail, indicating that the low-frequency modes (A2u(1) and Eu(1)) have a decisive role to the dielectric properties.

Graphitic carbon nitride (g-C3N4) is considered as a promising heterogeneous catalyst for photocatalytic H2 evolution from water under visible light illustration, and its photocatalytic performance could be controlled through its texture and optical/electronic properties. Herein, we present a facile one-step heating method for the synthesis of B/P/F doped g-C3N4 photocatalysts (BCN, PCN, and FCN). The prepared photocatalysts were characterized by XRD, SEM, UV-vis absorption, FTIR, BET, XPS, PL, and photocurrent measurement. The results show that the B/P/F doping increased the interplanar stacking distance of g-C3N4, enlarged the optical absorption range, and improved the photocatalytic activity of H2 evolution. FCN exhibits the highest photocatalytic activity, followed by BCN, and PCN that has the lowest performance. This work studies the doping effects of the nonmetal elements on the photocatalytic activities, the electronic structures as well as the band gaps of g-C3N4, to provide a feasible modification pathway to design and synthesize highly efficient photocatalysts.

The atomic structure, electronic structure, and physical properties of (TiZrNbCu)1−xNix (x ≤ 0.5) metallic glasses (MGs) were studied in both the high-entropy (0 < x < 0.35) and the higher Ni concentration range (x ≥ 0.35). Atomic structure studies performed with X-ray diffraction and synchrotron powder diffraction provided average atomic volumes, structure factors, radial distribution functions, coordination numbers, and packing densities. Electronic structure studies performed using photoemission spectroscopy and low-temperature specific heat provided information about the electronic density of states within the valence band and at the Fermi level and also about interatomic bonding and atomic vibrations [from the Debye temperature and the boson peak (BP)]. Variations of both atomic structure and electronic structure with x showed a clear change for x ≥ 0.35, which corresponds to a valence electron number ≥7.4. All physical properties, namely, thermal stability parameters, Debye temperatures, BPs, magnetic, elastic, and electronic transport properties, change their concentration-dependence for x ≥ 0.35. The results are compared with those for binary and ternary MGs of the same elements.

Ti–Al alloys are established as promising candidates for aerospace applications due to their lightweight, good elevated temperature strength, and decent corrosion resistance. In this study, a Ti–51Al (at.%) alloy is fabricated by spray deposition. The effects of temperature and strain rate on the deformation behavior of the spray-deposited Ti–Al alloy are investigated. The microstructural evolution of the Ti–Al alloy with different deformation temperatures is discussed in detail. A strain-dependent constitutive equation was proposed to predict the flow stresses at the elevated temperatures for the spray-deposited Ti–Al alloy. The microstructure of the as-deposited Ti–51Al alloy exhibits a α2/γ lamellar-structure with average size 25 ± 2 μm, due to the high cooling rate observed during solidification. The lamellar structure is embedded on a γ matrix. The amount of the α2/γ lamellar-structure reduces gradually with increasing the hot deformation temperature. After hot isostatic pressing at 1523 K, the microstructure is mainly comprised of the γ matrix.