Confined to ultrathin two-dimensional (2D) architectures, high-entropy alloys (HEAs) could leverage synergistic cocktail effects and entropy-stabilized phases to enable exceptional oxygen evolution reaction (OER) kinetics and stability via maximized specific surface areas and quantum confinement. However, synthesizing atomically precise 2D HEAs remains fundamentally challenging due to disparate metal nucleation kinetics. Herein, we demonstrate a facile low-temperature (80 ℃) ionic layer epitaxy synthesis of ultrathin 2D HEA FeCoNiMo. The OER catalytic activity exhibited a strong inverse correlation with the 2D HEA thickness, where atomic-scale dimensional reduction significantly enhanced electrocatalytic performance. Atomic-scale confinement to 1.1 nm thickness unlocks exceptional OER performance. This 1.1 nm 2D HEA FeCoNiMo revealed a record-low overpotential of 79 mV at 10 mA·cm^–2 and unprecedented stability (<10% activity decay after 1532 h operation). Especially, its benchmark mass activity (9725.2 A·g^–1) represented three orders of magnitude enhancement over IrO₂ (5.7 A·g^–1) at the same overpotential of 79 mV. Density functional theory (DFT) reveals that thickness reduction facilitates charge redistribution toward Fe active sites, optimizes the rate-determining step energy barrier, and strengthens adsorbate-catalyst interactions. This work provides fundamental insights into 2D confinement effects in HEAs and establishes a general strategy for designing highly efficient electrocatalysts for sustainable energy applications.

To investigate the influences of Cr₂AlC mass fraction and supersonic plasma spraying process on the microstructure and mechanical properties of Cr₂AlC reinforced 410 stainless steel composite coatings, the coatings containing different mass fractions of Cr₂AlC were prepared and investigated. The composite coating exhibited low porosity and high adhesion strength. The addition of Cr₂AlC significantly enhanced the hardness of the composite coatings through particle strengthening. However, when the mass fraction of Cr₂AlC was 20%, the aggregation of Cr₂AlC resulted in a strong decrease in the coating preparation efficiency, as well as a decline in adhesion strength. In the supersonic plasma spraying process, the Ar flow rate mainly influenced the flight velocity of the particles, while the H₂ flow rate and the current mainly affected the temperature of the plasma torch. Consequently, all of them influenced the melting degree of particles and the quality of the coating. The lowest porosity and the highest hardness and adhesion strength could be obtained when the Ar flow rate is 125 L/min, the H₂ flow rate is 25 L/min, and the current is 385 A.

In order to enhance the ablation-resistant performance of stainless-steel conductive rails, Mo coating, 410 stainless steel coating and 15 wt% Cr₂AlC particles reinforced 410 stainless steel composite coating were prepared and evaluated. Different from the weak interfacial strength caused by the dissimilar metals between Mo and steel rails, 410 stainless steel coating has better interfacial contact with steel rails. The introduction of Cr₂AlC into 410 stainless steels further strengthened the mechanical properties of coating by alloy strengthening effect and particle strengthening effect, as the decomposition of Cr₂AlC into nano CrC particles is accompanied with the diffusion of Al atoms into 410 stainless steels. It was found that the composite coating can still resist arc erosion at 150 A current, as a dense oxide film formed during the ablation process and the decomposition of Cr₂AlC contributed to the heat absorption.

As one novel reinforcement used in magnesium composite, nano-layered flaky ternary MAX particle exhibits interesting anisotropic ceramic and metal properties. In order to accurately simulate the mechanical properties and damage behavior of MAX particle reinforced magnesium composite, we developed one finite element (FE) model based on 2D and 3D microstructural observations of 10 vol.% Ti₂AlC-AZ91D composite. To improve the accuracy, matrix ductile damage, particle internal delamination deformation behaviors, and particle-matrix interfacial behaviors were respectively introduced into this model. The visual deformation processes of crack generation and propagation were carefully presented and discussed. The effects of interfacial strength and particle orientation on material properties were systematically investigated.

To understand the relationship between the process-microstructure-mechanical properties of the high-pressure die-casting (HPDC) AE44 magnesium alloy, 3D reconstruction and 2D characterization were carried out on the HPDC castings produced with different process parameters (low slow-shot speed, fast slow-shot speed, solidification pressure). Microstructural characterization revealed that the formation of shrinkage pores are closely related to ESCs, which were mainly controlled by the low slow-shot speed in shot sleeve (ESCs growth time) and fast slow-shot speed into the die cavity (distribution of ESCs). In addition, solidification pressure can significantly reduce the shrinkage porosity in the center by improving the feeding capacity of liquid metal. Tensile fracture revealed that the tearing ridge is mainly evolved from the slip band of ESCs. The quantity and distribution of ESCs determine the fracture mode of castings. The relationship between mechanical properties of castings and the morphology of ESCs and porosity is also statistically discussed.

3D reconstruction and 2D observation were conducted to characterize the microstructure of the castings produced through high pressure die casting with different parameters. Our results indicate that shrinkage pores generally co-existed with externally solidified crystals (ESCs). In specimen produced without fast slow shot speed, big net-shrinkage pores accompanied with ESCs were found in the center of the specimen. When the casting pressurization was introduced, the shrinkage pores gathered to the specimen center and became much less due to the optimization of melt feeding. Much more porosity was found near the gate rather than in the middle of the rod bar, especially gas pores. The filling process simulation reveals that the middle position of the bars was firstly filled and followed by the near gate position accompanied with one intense turbulent flow.