The development of efficient hydrogen storage materials is crucial for advancing hydrogen-based energy systems. In this study, we prepared a highly innovative palladium-phosphide-modified P-doped graphene hydrogen storage material with a three-dimensional configuration (3D Pd₃P_0.95/P-rGO) using a hydrothermal method followed by calcination. This 3D network hindering the stacking of graphene sheets provided channels for hydrogen diffusion to improve the hydrogen adsorption kinetics. Importantly, the construction of the three-dimensional palladium-phosphide-modified P-doped graphene hydrogen storage material improved the hydrogen absorption kinetics and mass transfer process. Furthermore, while acknowledging the limitations of primitive graphene as a medium in hydrogen storage, this study addressed the need for improved graphene-based materials and highlighted the significance of our research in exploring three-dimensional configurations. The hydrogen absorption rate of the material increased obviously in the first 2 h compared with two-dimensional sheets of Pd₃P/P-rGO. Meanwhile, the corresponding 3D Pd₃P_0.95/P-rGO-500 sample, which was calcinated at 500 °C, achieved the optimal hydrogen storage capacity of 3.79 wt% at 298 K/4 MPa. According to molecular dynamics, the structure was thermodynamically stable, and the calculated adsorption energy of a single H₂ molecule was −0.59 eV/H₂, which was in the ideal range of hydrogen ad/desorption. These findings pave the way for the development of efficient hydrogen storage systems and advance the progress of hydrogen-based energy technologies.

Ni/Pd co-modified graphene hydrogen storage materials were successfully prepared by a solvothermal method using NiCl₂·6H₂O and Pd(OAc)₂ and reduced graphene oxide (rGO). By adjusting the hydrothermal temperature, Pd–Ni is successfully alloyed, and the size of the obtained nanoparticles is uniform. The electronic structure of Pd was changed by alloying, and the center of the D-band moved down, which promoted the adsorption of hydrogen. The NiPd-rGO-180 sample, in which 180 represents the solvothermal temperature in centigrade (°C), has the highest hydrogen storage capacity of 2.65 wt% at a moderate condition (RT/4MPa). The excellent hydrogen storage performance benefits from the synergistic hydrogen spillover effect of Pd–Ni bimetal. The calculated hydrogen adsorption energies of Ni₂Pd₂-rGO are within the ideal range (−0.20 to −0.60 eV) of hydrogen ads/desorption; however, the introduction of substrate defects and the cluster orientation alter the hydrogen adsorption energy. This work provides an effective reference for the design and optimization of carbon-based hydrogen storage materials.

The pre-sintered preform (PSP) is an advanced technology for repairing the Ni-based superalloy blade in a turbine. In general, boron is added to the Ni-based superalloys in small quantities (1.0 wt.%) on the microstructure evolution and mechanical properties in Ni-based superalloys for the PSP application is rarely studied. The variety, composition and evolution of the precipitates during solution heat treatment in the alloy with high B content were determined by EBSD, EPMA and SEM. The results indicate that Cr, W and Mo-rich M₅B₃ type borides precipitate from the matrix and its area fraction reaches up to about 8%. The area fraction of boride decreases with the prolonging of solution time and the increase of temperature higher than 1120 °C. The borides nearly disappear after solution treatment at 1160 °C for 2 h. The redissolution of boride and eutectic results in the formation of B-rich area with low incipient melting (about 1189 °C). It can bond metallurgically with the blade under the melting point of the blade, which decreases the precipitation of harmful phases of the blade after PSP repairing. The microhardness within the grain in the PSP work-blank first decreases (lower than 1160 °C) and then increases (higher than 1185 °C) with the increase of solution heat treatment temperature due to the dissolving and precipitation of borides. The tensile strength of the combination of PSP work-blank and Mar-M247 matrix at room temperature after solution treatment is related to the area fraction of boride, incipient melting and the cohesion between PSP work-blank and Mar-M247 matrix.

Effects of the stress ratio on the very high cycle fatigue behaviors of 9%Cr turbine steel have been investigated at 630 °C. The experimental results show that the S–N curve has a continuous downward trend and has no fatigue limit with the increasing in the cycles at 630 °C. Meanwhile, according to the analysis of microstructure, there are two failure modes that were observed at different stress ratios (R = −1 and 0.1), including surface crack failure and internal crack failure, respectively. Besides, the theoretical threshold value of the crack growth is compared with the calculated value of the fracture surface. To decrease the difference between the threshold value of internal crack initiation and the corresponding theoretical value, a new model for the crack growth threshold of the interior-induced fracture at different stress ratios is proposed and discussed.

Gd₂Zr₂O₇ (GZO)-based compounds are currently one of the most promising materials for thermal barrier coatings (TBCs), in which some dopants are introduced. The dopants induce change in GZO lattice and improve the properties, however, the underlying mechanisms related to solid solution modes of the dopant remain insufficiently understood. In this study, first-principles calculations was employed to investigate the solid solution mechanism of Yb and Sc co-doping in GZO. The results showed that both substitutional and interstitial doping coexist in the GZO lattice. At a Yb doping content of 12.5 at.%, a substitutional solid solution formed in the GZO lattice, and further introduction of Sc into the lattice, Sc atom occupied interstitial sites at concentrations below 5.88 at.%. The calculation results indicate that 11.76 at.% Yb and 5.88 at.% Sc co-doped GZO (GYbSc) exhibited the lowest thermal conductivity, the highest coefficient of thermal expansion (CTE), and relatively high toughness. Experimental results demonstrated that GYbSc exhibits high toughness (2.09 MPa·m^1/2). At 1200 °C, the coefficient of thermal expansion of GYbSc increased by 5% compared to GZO, and its thermal conductivity decreased by 37%, with values of 11.059 × 10^-6 K^-1 and 0.935 W·m^-1·K^-1, respectively. GYbSc also displayed outstanding CMAS corrosion resistance. This work not only explore a promising TBC material, but also provides a new perspective for clarifying the mechanisms for the improved properties of doped compounds and developing novel TBC materials.

After solutionizing and aging at 980°C for various durations, the compressive deformation behaviour and mechanisms of the directionally solidified nickel-based superalloy CM247LC are investigated at room temperature. Experimental results show that the yield strength decreases gradually from 991 ± 1.2–672 ± 7.5 MPa with increasing the γ′ precipitate size from 145 ± 2–604 ± 19 nm. Transmission electron microscope observations on the slightly deformed specimens reveal that, in contrast to previous researches, plastic deformation of all the specimens is controlled by strongly coupled dislocations cutting through γ′ precipitates. Based on these experimental results, the relationship between the yield strength and precipitate size is discussed.