The elemental segregation behaviors and interactions between point defects and symmetrical tilt grain boundaries (GBs) in TiVTa concentrated solid–solution alloys (CSAs) have been studied through hybrid Monte Carlo/molecular dynamics (MC/MD) simulations. A pure V model, a random TiVTa CSA with randomly distributed elements, and an equilibrated TiVTa CSA with Ti segregation were constructed to investigate the influence of chemical disorder and local elemental segregation on defect–GB interactions. For defect–GB interactions, GBs interact more strongly with interstitials than with vacancies. Compared with the pure V, the vacancy absorption length scale of GBs is greater, whereas the interstitial absorption length scale of GBs is shorter in TiVTa CSAs due to the chemical fluctuation and local lattice distortion. This means a higher recombination efficiency of point defects in TiVTa CSAs. The elemental (Ti) segregation in TiVTa CSAs can further enhance the sink strength of GBs towards interstitials, while simultaneously reducing their sink strength towards vacancies. Consequently, the preference effects of GBs towards interstitials and vacancies are amplified in the equilibrated CSA due to local ordering, thereby reducing efficient defect annihilation around GBs. These results provide fundamental insights into the irradiation defect dynamics of CSAs with body-centered cubic (bcc) structure.

Molecular dynamics simulations were carried out to study the effect of chemical short-range order (CSRO) on the primary radiation damage in TiVTaNb high-entropy alloys (HEAs). We have performed displacement cascade simulations to explore the CSRO effect on the generation and evolution behaviors of irradiation defects. The results demonstrate that CSRO can suppress the formation of Frenkel pairs in TiVTaNb HEAs, with the suppression effect becoming more pronounced as the degree of CSRO increases. CSRO can change the types of interstitial defects generated during cascade collisions. Specifically, as the degree of CSRO increases, the proportion of Ti-related interstitials shows a marked enhancement, primarily evidenced by a significant rise in Ti-Ti dumbbells accompanied by a corresponding decrease in Ti-V dumbbells. CSRO exhibits negligible influence on defect clustering and the nucleation and evolution of dislocation loops. Regardless of CSRO conditions, TiVTaNb HEAs preserve exceptional radiation tolerance throughout the cascade damage process, suggesting that the intrinsic properties of this multi-principal element system dominate its radiation response. These findings provide fundamental insights into the CSRO effect on defect formation and evolution behaviors in HEAs, which may provide new design strategies for high-entropy alloys.

Long-term creep testing is expensive and time-consuming, which makes a reliable creep curve prediction essential for the design and safety assessment of high-temperature components. This paper presents a data-driven approach using a backpropagation neural network (BPNN) to interpolate the full creep curve from a limited set of experimental data. Creep tests were conducted on TP321H stainless steel at 550 °C under five stress levels (160–200 MPa) for up to 8000 h. A three-hidden-layer BPNN was trained on only four stress levels (160, 170, 190, and 200 MPa) and subsequently applied to predict the complete creep curve in the held-out 180 MPa condition. Its predictive performance was compared with the classical θ-projection method. The BPNN prediction agrees closely with the experimental curve, with $R^2$ = 0.990 and RMSE = 0.0547%, compared with 0.770 and 0.1443% for the θ-projection method. These results indicate that, for the present material and test conditions, a BPNN trained on four creep curves can accurately interpolate the creep curve at 180 MPa without constitutive assumptions.

The tensile and low-cycle fatigue properties of a Fe-Ni-based GH1059 superalloy were investigated at room temperature (RT, about 25 °C) in air and at 550 °C in high vacuum. The tensile curve at 550 °C indicated that dynamic strain aging in the material at high temperature. The fatigue life and stress-strain behavior were analyzed, and fatigue parameters were obtained. The fatigue life decreased with increasing temperature. The cyclic deformation behaviors were composed of three stages at RT: cyclic hardening, gradual cyclic softening, and final rapid rupture. The cyclic deformation behaviors at 550 °C were different: the second stage of specimen at 0.4% strain amplitude was cyclic hardening and the second stage of specimen at 0.9% strain amplitude was stress saturation. The difference is because of dynamic strain aging at high temperature. Based on the fatigue data, the changes of friction stress were analyzed, and the results reflected microstructural evolution associated with fatigue behavior. The microstructural evolution during fatigue process was observed using a scanning electron microscope and a transmission electron microscope. The changes in dislocation densities accounted for the effects of temperature and strain amplitude on the fatigue behavior of GH1059.