Heat treatment processes play a pivotal role in optimizing the microstructure and mechanical properties of Mg-Li alloys, thereby enhancing their performance and expanding their potential applications in structural and lightweight engineering fields. In this study, the influence of solution and aging treatments on the microstructure, phase transformation, and microhardness of friction-stir-processed (FSPed) LAZ931 Mg-Li alloy was investigated to obtain the optimal solution treatment temperature and time. An optimal solution treatment at 460 °C for 0.5 h under an Ar gas atmosphere facilitated complete α-phase dissolution with subsequent aging at 125 °C, triggering precipitation-mediated hardening. An X-ray diffraction (XRD) analysis identified a new MgLi₂Al phase in the stirring zone (SZ) in addition to the α, β, and AlLi phases. Aging kinetics at 125 °C showed that SZ hardness increased to 110.5 HV after solution treatment, which was 5.3% higher than the base metal (BM). After 3 h of aging, microhardness peaked at 86.5 HV before decreasing due to the decomposition of the metastable MgLi₂Al phase into the stable AlLi phase. The microhardness stabilized at around 78 HV, which was 16.2% higher than that of the original SZ. These experimental results provide a fundamental understanding of property structure for meeting the growing demand for lightweight materials and improving material properties.

Adsorbed molecules can modulate the behavior of magnesium (Mg) and Mg alloy in biomedical applications. The interaction regularity and mechanism of biomolecules (such as amino acids, dipeptides, and tripeptide) on a Mg(0001) surface, the influence of dipole correction, and the effects of alloying elements and electronic structure were investigated in this study using first-principles calculations. Specifically, the adsorption energy (E_ads) of functional groups (-NH₂, -COOH and -CN₃H₄), amino acids (arginine (Arg), glycine (Gly), and aspartic acid (Asp)), dipeptides (arginine–glycine (Arg-Gly), glycine–aspartic acid (Gly-Asp), and arginine–aspartic acid (Arg-Asp)), and arginine–glycine–aspartic acid (RGD) tripeptide were systematically calculated. Dipole correction slightly enhanced the interaction between molecules and Mg surfaces, but the E_ads trend remained unchanged. The addition of alloying elements improved the interaction of molecules and Mg-based alloy surfaces. This study will be of fundamental importance in understanding the interaction regularity of molecules on Mg and Mg-based alloy surfaces and provide possibilities for surface modification design of biomedical materials.

Elucidating the interfacial interaction mechanisms between biomolecules and metal surfaces is crucial for designing functionalized biomedical materials. This study employs first-principles calculations based on density functional theory (DFT) to investigate the adsorption behaviors of arginine (Arg), glutamic acid (Glu), aspartic acid (Asp), and valine (Val) on magnesium (Mg) and Mg alloy surfaces. The adsorption behaviors of four kinds of amino acids on Mg and Mg alloy surfaces were analyzed through optimized adsorption configurations, adsorption energies (E_ads), bond lengths, projected densities of states (PDOSs), and differential charge densities. The calculated results of E_ads followed the order of Arg > Glu > Asp > Val, driven by functional group spatial configurations and electron transfer efficiency. Alloying elements facilitated charge redistribution on the Mg and Mg alloy surfaces, enhancing the interaction between amino acids and the alloy surfaces. Notably, the guanidino group of Arg exhibited exceptional adsorption stability and multi-dentate bonding, increasing electron donation to the Mg(0001) surface, achieving the highest E_ads (−1.67 eV). This work provides insights into the structure–activity relationships between amino acids and Mg and Mg alloy surfaces, offering a foundation for designing biomolecule-derived functional coatings and strategies for improving the biocompatibility of Mg and Mg alloy implants.

Glycine (Gly), as one of the fundamental components of biomolecules, plays a crucial role in functional biomolecular coatings. The presence of structural defects and hydroxyl-containing functional groups in magnesium (Mg) materials, which are commonly used as biomedical materials, significantly affects their biocompatibility and corrosion resistance performance. This study computationally investigates the influence of vacancy defects and hydroxyl groups on the adsorption behavior of Gly on Mg(0001) surfaces. All potential adsorption configurations are considered through first-principles calculations. The findings indicate that stronger chemisorption occurs when Gly is positioned at the edge of the groove, where the surface has a vacancy defect concentration of 1/3. Among the four adsorption locations, the fcc-hollow site is determined to be the most favorable adsorption site for hydroxyl. The adsorption energy of Gly on the Mg(0001) surface containing the hydroxyl (−1.11 eV) is 0.05 eV more than that of on the Mg(0001) surface (−1.16 eV). The adsorption energies, electronic properties, charge transfer, and stable configurations are calculated to evaluate the interaction mechanism between Gly and defective surfaces. Calculated results provide a comprehensive understanding of the interaction mechanism of biomolecules on defective Mg surfaces and also indicate the directions for future experimental research.

Functional Arg-Gly-Asp (RGD) tripeptide has a tremendous potential in clinical applications to accelerate the endothelialization of Magnesium (Mg) alloy vascular stent surface. The interaction mechanism of RGD on different surfaces of Mg and Mg alloy is important for promoting the development of Mg alloy vascular stent, yet still unclear. In the present work, first-principles calculation within density functional theory (DFT) was performed to investigate the interaction mechanism. The electron redistribution, effect of alloying elements and changes in the density of states of the adsorption systems were studied. The results revealed that RGD interacted with different surfaces of Mg (0001), Mg(11$\overline{2}$0) and Mg(10$\overline{1}$1) through ligand covalent bond; the pronounced localization of electrons of Mg(11$\overline{2}$0) and Mg(10$\overline{1}$1) surfaces promoted the adsorption of RGD tripeptide compared with that on the Mg(0001) surface; Zn/Y/Nd alloying elements improved the adsorption of RGD. Calculated results could provide insight for the interaction mechanism of biomolecule on the Mg and Mg-based alloy surfaces, and point out some directions for the future experimental efforts.

Steel-fiber-reinforced concrete (SFRC), as a composite engineering material, exhibits excellent physical and mechanical properties, making it widely applied in civil engineering, construction, water conservancy, transportation, and port industries. To date, significant progress has been made in the research of plain and single-hook (3D) steel-fiber-reinforced concrete both domestically and internationally. With advancements in technology, multi-end hooked 4D and 5D steel fibers have emerged, offering more end hooks and a higher tensile strength. These fibers possess a stronger anchorage capacity with the matrix, and SFRC with multi-end hooked fibers exhibits superior tensile and flexural properties. However, research on multi-end hooked (4D and 5D) steel-fiber-reinforced concrete is still in its early stages, particularly regarding the axial tensile stress–crack width constitutive relationship. The accuracy and rationality of this constitutive relationship directly affect the reliability and precision of structural design. Therefore, in this study, a novel σ-w constitutive relationship model for steel-fiber-reinforced concrete and an axial tensile stress–crack width testing method for SFRC are proposed, based on 16 sets of uniaxial tensile tests. This model considers the comprehensive effects of the concrete matrix, fiber bridging, fiber volume fraction, fiber shape factor (effects of the number of hooked ends), aspect ratio, and crack width.