The 9–12% Cr ferritic–martensitic heat-resistant steel is the main candidate structural material for the Lead-cooled Faster Reactor. The lower Gibbs free energy change of Si oxide can promote the formation of a stable oxide layer, which can improve the corrosion resistance of the material. Therefore, it is of great significance to study the effect of silicon (Si) on the corrosion resistance of T91 steel in lead–bismuth eutectic (LBE). The corrosion resistance of T91 steel with Si contents of 0.5 wt.%, 1.3 wt.%, and 2.0 wt.%, both in dynamic and static LBE at 550 °C, was investigated. The microstructure was analyzed by X-ray diffraction (XRD), scanning electron microscope (SEM) and transmission electron microscope (TEM), while the oxide films were characterized by electron probe microanalysis (EPMA). Results show that the addition of Si is conducive to improving the corrosion resistance of T91 steel in LBE. T91 steel with high Si content has a thinner and more stable oxide film. The change of Si content can change the contact angle between the steel and LBE, and the contact angle is the largest when the Si content is 1.3 wt.%. The Si-rich oxide layer is usually located in the inner oxide layer, which promotes the formation of a Cr oxide layer located in the internal oxidation zone (IOZ). Si will not enter the precipitated phase, but only change the ferrite content. The oxidation model of T91 steel containing Si in LBE was also proposed.

The hot deformation behavior of the GY200 Ni-based alloys with different tungsten (W) content were investigated by means of hot compression tests, microscopic observations, and processing maps at temperatures between 950 °C and 1200 °C, strain rate between 0.01 s⁻¹ and 10 s⁻¹ with strain of 0.9. The hyperbolic-sine type constitutive equations were established between peaks tress and deformation conditions through Z parameters, and for alloys with higher W content results in higher activation energy and complete recrystallization temperature. The hot-working maps were exploited based on the experimental data. The hot-working maps showed that the instability zone extended with increasing W content. The stable domain of alloys are located in the temperature range between 1025 °C and 1200 °C and strain rate range between 0.01 s⁻¹ and 1 s⁻¹, dominated by the dynamic recrystallization (DRX) microstructural evolution, suited for hot deformation. The cracking on the surface of the sample compressed at 950 °C was resulted from the tensile stress, while the fracture of the sample compressed at 1200 °C was triggered by the melting of grain boundaries.

The mechanism of the clustering in Al-Mg-Si-Cu alloys has been a long-standing controversial issue. Here, for the first time, the mechanism of the clustering in the alloy was investigated by a Kinetic Monte Carlo (KMC) approach. In addition, reversion aging (RA) was carried out to evaluate the simulation results. The results showed that many small-size clusters formed rapidly in the early stages of aging. With the prolongation of aging time, the clusters merged and grew. The small clusters formed at the beginning of aging in Al-Mg-Si-Cu alloy were caused by initial vacancies (quenching vacancies). The merging and decomposition of the clusters were mainly caused by the capturing of vacancies, and the clusters had a probability to decompose before reaching a stable size. After repeated merging and decomposition, the clusters reach stability. During RA, the complex interaction between the cluster merging and decomposition leaded to the partial irregular change of the hardness reduction and activation energy.

The high-temperature performance of 10CrNi2Mo3Cu2V steel is critically governed by the distribution of Cu-rich phases. This study systematically investigated the evolution of solute redistribution, Cu-rich phase precipitation, microstructural transformations, and mechanical properties in 10CrNi2Mo3Cu2V alloy under varying aging temperatures. Advanced characterization techniques, including atom probe tomography (APT) and transmission electron microscopy (TEM), were employed to analyze microstructural features and phase formation in both as-built and heat-treated specimens. The key findings reveal that copper atom segregation initiates at a tempering temperature of 350 °C. Upon increasing the temperature to 450 °C, extensive precipitation of nanoscale copper clusters is observed. Temperatures exceeding 450 °C trigger the formation of ε-Cu phases, which undergo subsequent coarsening. Notably, these copper clusters and Cu-rich precipitates act as dislocation pinning sites, promoting crack nucleation and propagation, thereby markedly degrading the alloy’s impact energy absorption capacity. The critical diameter for Orowan mechanism-governed strengthening by Cu-rich phases is determined to be ~6 nm, while the average diameter of matrix-penetrating Cu-rich particles is approximately 1.46 nm. Quantitative analysis demonstrated that the combined contributions of the Orowan bypass mechanism and particle-cutting mechanism yield a strength enhancement of ~219 MPa, which exhibits excellent agreement with experimentally measured strength increments. These results provide critical insights into the interplay between microstructural evolution and mechanical degradation in precipitation-strengthened steels under thermal exposure.