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The primary radiation damage in pure V and TiVTa concentrated solid-solution alloy (CSA) was studied using a molecular dynamics method. We have performed displacement cascade simulations to explore the generation and evolution behavior of irradiation defects. The results demonstrate that the defect accumulation and agglomeration in TiVTa CSA are significantly suppressed compared to pure V. The peak value of Frenkel pairs during cascade collisions in TiVTa CSA is much higher than that in pure V due to the lower formation energy of point defects. Meanwhile, the longer lifetime of the thermal spike relaxation and slow energy dissipation capability of TiVTa CSA can facilitate the recombination of point defects. The defect agglomeration rate in TiVTa CSA is much lower due to the lower binding energy of interstitial clusters and reduced interstitial diffusivity. Furthermore, the occurrence probability of dislocation loops in TiVTa CSA is lower than that in pure V. The reduction in primary radiation damage may enhance the radiation resistance of TiVTa CSA, and the improved radiation tolerance is primarily attributed to the relaxation stage and long-term defect evolution rather than the ballistic stage. These results can provide fundamental insights into irradiation-induced defects evolution in refractory CSAs. [ABSTRACT FROM AUTHOR]

Studying the interaction between solar flares and sunspot groups (SGs) is crucial for understanding and predicting solar activity. We examined the distribution, correlation, and flaring rates in the northern and southern hemispheres to reveal the relationship between different classes of soft X-ray (SXR) flares and different magnetic classifications of SGs. We discovered a significant north–south asymmetry in SXR flares and SG distribution over Solar Cycles (SC) 21–25. In the rising phase of SC24, the northern hemisphere's activity is significantly excessive. In the declining phase of SC24, the southern hemisphere's activity becomes significantly excessive. The total numbers of various SXR flares and SGs vary between the northern and southern hemispheres over the solar cycle. B-class flares are negatively correlated with all SGs at maximum but positively correlated at minimum. C-class flares correlate best with α and β SGs. M-class flares correlate best with β γ δ and β SGs. X-class flares correlate highest with β γ δ SGs. The flaring rate of each flare class is lowest for α SGs and highest for β γ δ SGs. The flaring rates are higher in the southern hemisphere than in the northern hemisphere. Our results demonstrate that solar flares originate from different sources of solar active regions; the high-energy flares tend to be caused by more complex magnetic fields. [ABSTRACT FROM AUTHOR]

ZnGeP _2 single crystals weakly doped by manganese (Mn) were grown by vertical gradient freezing method from polycrystalline batch which was synthesized by the modified two temperature vapor phase transport method. Energy Disperse Spectroscopy (EDS), X-ray diffraction (XRD), X-ray photoelectron spectroscopy (XPS) and Fourier Transform Infrared Spectrometry (FTIR) were employed to characterize the doping single crystals. The un-doped and Mn doped single crystals show the same color. XRD results manifest that the obtained Mn doped ZnGeP _2 has tetragonal structure with slight lattice distortion and has no segregation. The EDS results indicate a good stoichiometry of ZnGeP _2 weakly doped with Mn. From the XPS results, the doped single crystal with no impurity phases were successfully obtained by the vertical gradient freezing method. FTIR spectra show a slight decrease in infrared transmittance of Mn doped single crystals.

In this study, AgGaSe _2 single crystal was successful grown by vertical gradient freezing method. Meanwhile, the precipitates on AgGaSe _2 single crystal were investigated by x-ray photoelectron spectroscopy (XPS). This technique was recommended as a practicable method to study the precipitates while they are difficult to be detected by other measurements owing to their components and fairly low content. In addition, Energy Disperse Spectroscopy (EDS) and x-ray diffraction (XRD) were employed to characterize the quality of the as-grown AgGaSe _2 single crystal. The EDS results indicate a slight deviation from stoichiometric ratio along growth defects. The XRD results manifest that AgGaSe _2 crystal has single phase and high purity. The XPS results indicate that precipitates exist on as-grown AgGaSe _2 single crystal mainly in the form of Ga _2 Se _3 . Ga _2 O _3 and Ag _2 O were detected by XPS on the polished surface of the as-grown crystal wafer which was regarded as an oxide layer. The study on precipitates may provide important reference for growth process improvement and post-treatment to obtain high quality AgGaSe _2 single crystal.

Irradiation-induced defects frequently impede the slip of dislocations, resulting in a sharp decline in the performance of nuclear reactor structural materials, particularly core structural materials. In the present work, molecular dynamics method is used to investigate the interactions between edge dislocations and three typical irradiation-induced defects (void, Frank loop, and stacking fault tetrahedron) with the sizes of 3 nm, 5 nm, and 7 nm at different temperatures in Fe–10Ni–20Cr alloy. The critical resolved shear stresses (CRSSs) are compared among different defect types after interacting with edge dislocations. The results show that the CRSS decreases with temperature increasing and defect size decreasing for each defect type during the interaction with edge dislocations, except for the case of 3-nm Frank loops at 900 K. According to a comparison, the CRSS in Frank loop is significantly higher than that of others of the same size, which is due to the occurrence of unfaulting and formation of superjog or stacking-fault complex during the interaction. The atomic evolution of irradiation-induced defects after interacting with dislocations can provide a novel insight into the design of new structural materials. [ABSTRACT FROM AUTHOR]

Electrochemical polishing (ECP) offers incomparable advantages and great potential in metal polishing by surface errors correction. This paper systematically investigates the ultimate roughness and surface errors correction ability of ECP over different spatial frequency ranges. This paper further explores the law of ECP influencing errors at different frequency ranges, proposes and clarifies the concept of critical spatial frequency, and studies the law of polishing parameters affecting critical spatial frequency by using spatial frequency spectrum analysis. The surface roughness evolution and ultimate roughness of ECP were investigated using the surface error filtering method based on the critical spatial frequency. The ultimate roughness of ECP was determined by two different strategies, (i) stepwise polishing and (ii) one-step polishing. In addition, the stepwise polishing was also investigated for any possible inconsistency with one-step polishing on the final surface roughness. As ECP progressed, the optimization speed of surface roughness gradually decreased, and the surface roughness eventually reached a stable limiting value. Further analysis revealed that crystal corrosion is mainly responsible for inhibiting surface roughness optimization. [ABSTRACT FROM AUTHOR]