Bin Chen

Fe/Cr substitution in α-Al₁₂(Fe,Cr)₃Si₂-type intermetallic particles was investigated using first-principles calculations combined with the Debye–Grüneisen model over 0–850 K at zero external pressure. To examine Fe/Cr mixing within the α framework, 238-atom hP238 cells were modeled at x_Cr = 0, 0.239, 0.500, 0.739, and 1.000. At 0 K, static mixing enthalpy was negative at x_Cr = 0.239 and 0.500 but became slightly positive at the highest sampled intermediate Cr fraction, x_Cr = 0.739. The x_Cr = 1.000 model served only as a hypothetical hP238 endpoint. At a homogenization temperature of 813 K, configurational entropy favored Fe/Cr mixing, while the vibrational contribution was positive and partly offset this effect. The resulting mixing free energies were −11.0 and −6.0 meV/atom for x_Cr = 0.239 and 0.500, respectively, and +7.6 meV/atom for x_Cr = 0.739. The results show that low-to-intermediate Cr substitution, including near-equiatomic Fe/Cr occupancy, is thermodynamically favorable within the α framework, whereas the sampled Cr-rich intermediate composition is unfavorable relative to the two modeled hP238 end members.

This study investigated the interface characteristics and properties of hot roll bonded 2205 stainless steel/AH36 shipbuilding steel clad plate (2205/AH36 CP). The microstructure, element diffusion, and mechanical properties at the interface were characterised using SEM/EBSD, TEM, EDS analysis and in-situ nano-indentation tests. Results indicate a well-bonded interface with no microcracks or pores, confirming metallurgical bonding. The interface exhibited a transition zone with element diffusion, leading to the formation of a decarburising layer in AH36 and a carburising layer in 2205 steel. Nano-indentation tests revealed a hardness peak at the interface due to the formation of M23C6 phase. TEM observations confirmed the gradual transitional characteristic of the interface microstructure. Tensile tests in conjunction with digital image correlation (DIC) analysis demonstrated the ductility of the clad plate and the uniform distribution of strain, with no detected interface cracking.

This review systematically synthesizes the research progress on θ-series precipitates. It traces the historical evolution of θ-series precipitate research, from the accidental discovery of age hardening in Duralumin to the atomic-scale insights enabled by advanced electron microscopy and computational methods. The precipitation sequence (supersaturated solid solution → GP zones → θ″ → θ′ → θ), transformation mechanisms, and interfacial characteristics of θ′/Al are comprehensively analyzed, with special attention to ongoing controversies such as the structure of GP zones and the pathways of θ″ → θ′ transition. Furthermore, the review discusses how alloying elements regulate θ′ stability through interfacial segregation, vacancy interactions, and co-precipitation effects. Critical unresolved challenges are highlighted, including the kinetic limitations of θ′ coarsening and the need for mechanistic studies on multi-element microalloying. This synthesis aims to provide a foundation for future research toward designing high-performance age-hardenable aluminum alloys.

In this study, the β' phase in Mg‐Gd‐Y‐Ag alloy is characterized at the atomic scale using a Cs‐corrected high‐angle annular dark‐field scanning transmission electron microscopy (HAADF‐STEM). Meanwhile, the influence of Ag doping with different concentrations on the precipitation of β“‐phase configurations is investigated. The calculation of formation enthalpy indicates that an appropriate amount of Ag doping can optimize the atomic arrangement, reduce the nucleation barrier, and thus promote nucleation. The results of the adhesion and interfacial energy show that Ag doping changed the atomic bonding, structural order within the material, and it makes the system unstable. In terms of β” nucleation, the interfacial energy directly affects the nucleation potential barrier. A low interfacial energy is favorable for β' nucleation. Ag doping increases the interfacial energy, thereby raising the nucleation potential barrier and inhibiting β' nucleation. Moreover, the higher the Ag concentration, the more pronounced the inhibitory effect. The electronic structure properties show that within a specific energy range, the electrons in the 4d orbitals of Ag will transfer to the 5f orbitals of Gd. This electron transfer enhances the atomic bonding within the crystal, forms a more stable electronic structure, and further improves the stability of the crystal.