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HfO2 coatings with a thickness of approximately 8 μm were prepared on the refractory metals Mo surface by using chemical vapor deposition(CVD), and the reaction process of CVD HfO2 was thermodynamically analyzed by HSC Chemistry.The microscopic morphology, self-oriented growth and nanomechanical properties of HfO2 coatings were analyzed, and the bonding force of the coatings with the substrate and thermal shock resistance were tested. The results show that the HfO2 coating is well bonded to the substrate, and no macroscopic flaking occurs on the surface of the coating after 100 cycles of thermal shock from 25 ℃ to 2000 ℃; the adhesion of the coating is about 23 N as determined by the scratch test; the average emissivity of the surface of the coating is 0.48 in the band of 2.5-5 μm, which improves the average emissivity of Mo in the band by nearly 5 times.

Machine learning(ML) assisted high-entropy alloys(HEA) design is dedicated to solving the problem of long period and high cost of designing by traditional trial and error experimental methods. The classic AlCoCrCuFeNi HEA was taken as the research object. The phase structure prediction model and hardness prediction model were established respectively. The support vector machine(SVM) models have the best training performance in both tasks. The best phase classification accuracy is 0.944, and the root mean square error(RMSE) of the hardness regression model is 56.065HV. The two ML models are further connected in series. Based on the upper and lower limits of the data set, the high-throughput prediction and selection of phases and hardness of AlCoCrCuFeNi HEA are carried out simultaneously, thus realizing the efficient composition design of the new alloy. The experimental results show that the five new alloys are in accord with the predicted results, and the RMSE is 12.58HV. It shows that the ML models can predict the phase and hardness of HEA efficiently and accurately.

BaTiO3 has advantages of high permittivity, low dielectric loss, low cost and environment friendly. However, due to the nonlinear dielectric behavior occurred around the phase transition temperature of BaTiO3 ceramic, its availability in the field of temperature-stable capacitor is limited. To modify the dielectric-temperature properties of BaTiO3, a series of BaTi1-xCexO3 (x=0-0.20) ceramics was synthesized by solid-state reaction method. Ce dopant was introduced into the B-site (Ti-site) of BaTiO3. The effects of Ce dopant on the phase evolution, defect state, microstructure and dielectric properties were investigated. The modifying mechanism was also discussed with the help of first-principles calculation method. In all ceramic samples, it is revealed that Ce element completely enters the B-site of BaTiO3 in the form of Ce4+ ion. With the increase of Ce doping concentration, the room temperature structure of BaTi1-xCexO3 ceramics transforms from tetragonal/pseudo-cubic structure into orthorhombic/tetragonal structure, then into pseudo-cubic structure. Owing to the radius difference between Ce4+ and Ti4+ ions, Ce doping will lead to the rising of lattice parameters, accompanied by the appearance of local distortion and the decrease of long-range ferroelectric order, the variation of band structure, density of states and charge density configuration, as well as the generation of Ba and Ti vacancies. Compared with pure BaTiO3 ceramic, the average grain size of Ce-doped ceramics decreases first and then increases with the increase of Ce content, while the relative density of ceramics increases gradually. The peak dielectric constant of BaTi1-xCexO3 ceramic increases first and then decreases as the Ce concentration increasing. The corresponding temperature is slowly reduced from 122 ℃ to 112 ℃ in the x value range of 0-0.08, then rapidly declines to -3 ℃ in the x value range of 0.08-0.20. BaTi1-xCexO3 ceramics with x≥0.06 have the dielectric behavior of diffused phase transition (DPT). And the x=0.20 ceramic exhibits the typical characteristic of relaxor ferroelectric, with the room temperature dielectric constant of 3258.38, and the |Δεr/εr25 ℃|≤22% temperature range of -60-87 ℃, which matches the requirement of EIA X5S standard. Therefore, it can be concluded that B-site Ce doping will effectively enhance the permittivity stability of BaTiO3 in a variable temperature environment. This will provide some new ideas to develop dielectric materials with stable dielectric properties in wide temperature range.

Owing to the feature of ultrahigh power density, the dielectric capacitors play an increasingly important role in the field of industrial production, basic scientific research, aerospace, and military industry in recent years. However, the relatively low energy storage density of the dielectric capacitors generally leads to their big sizes, which is difficult to meet the miniaturization requirements of future devices. Polymer-ceramic nanocomposites can combine high permittivity of the ceramic fillers and the excellent breakdown strength of the polymer matrix, thus achieving excellent energy storage performance. At present, developing the polymer-ceramic nanocomposites with high energy storage density is the key to realize the miniaturization goal of dielectric capacitors in the future. The current research progress of polymer-ceramic nanocomposites for energy storage capacitor applications from three perspectives was systematically summarized, including regulation of the nanofillers, optimization of the interfaces, and design of the multilayer composite structure. Notably, the influences of the dimension, size, species, hierarchical structure of the nanofillers, interface optimization methods such as surface modification and core-shell structure construction, as well as multilayer structure design such as sandwich structure and gradient structure on the permittivity, breakdown strength and the energy storage density of the nanocomposites were introduced in detail. Meanwhile, the structure-activity relationships between the microstructure of nanocomposites and their energy storage properties were further analyzed and discussed. Finally, based on the challenges and shortcomings of the current research, the important development directions of this field in the future were proposed, including selecting the new 2D nanofillers, enhancing the energy storage efficiency, employing multimode combined optimization strategy, and constructing the corresponding dielectric capacitors.

As one kind of advanced high temperature structural and functional materials, it is necessary for fiber reinforced silicon carbide matrix composites (SiC CMCs) in the field of thermal management (TM) to combine the efficient heat transfer and high temperature heat resistance. Common fibers reinforced SiC CMCs, such as carbon fibers reinforced SiC CMCs (Cf/SiC or Cf/C-SiC), silicon carbide based fiber reinforced SiC CMCs (SiCf/SiC), etc., have a low degree of graphitization of the reinforcing fiber and are difficult to form an effective heat transport network. The latest research progress on the preparation and properties of fiber reinforced SiC CMCs with highly thermal conductivity was reviewed in this paper. The heat transport ability of fiber reinforced SiC CMCs can be improved by introducing highly thermal conductive phase, optimizing interfacial structure, making silicon carbide crystal coarse-grained, and designing preform structure. Moreover, the development of the fiber reinforced SiC CMCs with highly thermal conductivities was prospected, that is, comprehensively considering the factors that affect the performance of SiC CMCs, flexibly using the structure-activity relationship between the microstructure and properties of the composites, in order to prepare fiber reinforced SiC CMCs with stable size, excellent properties.

One of the key problems restricting the commercial application of controllable nuclear fusion reactors is plasma facing materials (PFMs). As the most promising PFMs, there are still many problems in the applications of tungsten and tungsten alloys. Due to their high strength at elevated temperatures, high melting point and good irradiation resistance, refractory multi-principal-element alloys are expected to meet the needs of PFMs. In the present study, (TiVTa)95X5(X=Cr, Zr, W) was designed and manufactured by using arc-melting. The effects of the addition of Cr, Zr and W on the microstructure and phase stability at 900 ℃ of TiVTa-based alloys were investigated by XRD, SEM and EDS. The results show that as-cast TiVTa-based alloys are simple solid solutions with BCC structure. After homogenization treatment at 1200 ℃, phase decomposition occurs in the (TiVTa)95Cr5 alloy, and a small amount of second phase C15_Laves appears in the matrix. At 900 ℃, TiVTa-based alloys are all decomposed into a BCC main phase and a C15_Laves second phase which mainly distributed along the grain boundaries, and the volume fraction of the second phase in TiVTa and (TiVTa)95W5 alloys is small whereas the addition of Cr and Zr intensifies the phase decomposition. After phase structure and elemental analysis, the lattice constant and elemental composition of the precipitated C15_Laves phases in (TiVTa)95X5(X=Cr, Zr, W) alloys are inconsistent with the possible Laves phase in the binary alloy system, and the difference is mainly attributed to the elemental composition of the Laves phase.

Ti-Zr-Ta refractory alloy has excellent mechanical properties and impact-initiated energy release characteristics, and shows good application prospects in the field of energetic structural materials. At present, Ti-Zr-Ta alloy is mainly prepared by melting process. However, its components are all refractory metals, so it is difficult to fabricate large parts with uniform structure by melting and casting. Based on this, the Ti-Zr-Ta refractory alloy powder was prepared by hydrogenation-dehydrogenation, and then sintered by vacuum hot-pressing process. On this basis, the microstructure, mechanical properties and shock-induced energy release characteristics of the sintered Ti-Zr-Ta alloy were studied. The results show that the average particle size of Ti-Zr-Ta alloy powder prepared by hydrogenation-dehydrogenation is 9.4 μm, and it is composed of three phases of BCC1, BCC2 and HCP. The density of Ti-Zr-Ta alloy sintered at 1300 ℃ is 7.34 g/cm3, which roughly achieves full densification, and the alloy is mainly composed of two phases of BCC1 and BCC2. The quasi-static compressive strength and fracture deformation are 1637 MPa and 6.4%, respectively, showing brittle fracture characteristics. In the ballistic gun experiment, the peak overpressure generated by 5.6 g of as-sintered Ti-Zr-Ta alloy breaking through the target plate at a speed of 1493 m/s in the 27 L closed target box reaches 0.195 MPa, showing excellent impact energy release characteristics, and the energy release is mainly derived from the oxidation reaction of small fragments generated by high-speed impact of alloy projectiles.

W-Zr alloy has the advantages of high density, high strength and high reaction potential, which can not only exert the excellent penetration ability of tungsten-based alloy, but also provide additional damage by using the oxidation reaction of zirconium. W-Zr alloys have shown great application potential in reactive fragment, armor-piercing projectiles, and small caliber projectiles, and have attracted attention both domestically and internationally. The preparation methods, mechanical properties, and reaction characteristics of W-Zr alloy reactive structural materials were summarized in this paper, especially focusing on the penetration ability and energy release characteristics. On the basis, it was proposed that the future development of W-Zr alloys should focus on the regulation of combustion characteristics of W and the improvement of plasticity. Additionally, there is still a lack of systematic research on the synergistic mechanism between the microstructure, mechanical properties, dynamic fracture, and reaction energy release of W-Zr alloys, which requires further improvement through a combination of experimental research and simulation calculations.

In this article, we proposed a novel but simple multilayer resin film infusion-compressive molding (MLRFI-CM) manufacturing process that can harness the resin shear flow to architect hierarchical carbon fiber reinforced polymer (CFRP) composites with tunable 1D nanocarbons orientation. Via this novel process, we demonstrated that the orientation of two typical 1D nanocarbons, namely, the carbon nanotubes (CNTs) and carbon nanofibers (CNFs), can be successfully tuned via altering the infusion time and that the tuning strategy is especially effective toward CNTs. Further, the structure-performance relationships between the electrical conductivity/interlaminar shear strength (ILSS) and filler through-thickness orientation of the hierarchical CFRP composites is explored and compared. In the best case, with only 0.3 wt% of CNTs, the ILSS of CFRP composites revealed an increase of 19.7%, and the through-thickness conductivity demonstrated an increase of 38%.