The effect of Sc-microalloying and Y₂O₃ nano-particles on the microstructure and mechanical properties of as-cast Al-5.5Si alloy is studied by means of optical microscopy, transmission electron microscopy, hardness test and tensile test. The influence of annealing treatment on the microstructure and properties of the Al-Si alloys is also investigated as well. The results show that the addition of Sc and Y₂O₃ nano-particles could significantly improve the mechanical property of the Al-Si alloy. The ultimate tensile strength and yield strength of Al-Si-Sc/Y₂O₃ alloy are improved by around 45 and 71%, respectively, when compared to that of the Al-Si alloy. The effect of the nanosized particles (precipitated and added) on strengthening and deformation of Al-Si alloy is analyzed and discussed in detail. The results of annealing treatment indicate that the change in mechanical property of the Al-Si-Sc alloy during annealing treatment is mainly associated with the precipitation of the secondary Si phase. Graphical Abstract

The effect of warm rolling temperature on microstructure and texture of microcarbon dual-phase (DP) steel was investigated through scanning electron microscopy (SEM), electron backscatter diffraction (EBSD), and transmission electron microscopy (TEM). The results showed that with the increase of rolling temperature, the density and thickness of the deformation band first increased and then decreased. Ferrite and fine martensite were observed in the annealed sheet, and the ferrite had a much more homogeneous distribution in the sample rolled at 450 °C. During warm rolling, the ferrite developed a dominant γ-fiber and a weak α-texture. During the annealing of the rolled sheet, the intensity of the γ-fiber was increased and a weak {001} texture developed in the sample rolled at room temperature. An increase in the rolling temperature generated an initial decrease and subsequent increase in the strength of the unfavorable {001} texture in the annealed sheet. In addition, the strength reached a maximum at 550 °C due to an increase in the dissolved carbon in the matrix, which was result of carbide dissolution. By contrast, the intensity of the γ-fiber remained relatively higher and was deemed the weaker {001} component in the annealed sheet rolled at 450 °C. Therefore, a larger texture factor (f_γ-fiber/f_{(α-fiber+λ-fiber)}) can be produced under this process.

The semi-conductive properties of passive films formed on Cu-Ni alloy and Cu-Ni-La alloy were investigated in 0.1 M NaOH solution, by employing electrochemical impedance spectroscopy (EIS), Mott–Schottky analysis and point defect model (PDM). Results indicate that both the passive films formed on Cu-Ni alloy and Cu-Ni-La alloy display p-type semi-conductive characteristics with cation vacancies in order of magnitude of 1020 cm3. Compared with Cu-Ni alloy, La addition could significantly improve the corrosion resistance, due to a superior barrier passive film formed Cu-Ni-La alloy with a bigger film resistance (Rf), increased passive film thickness (Lss) in conjunction with decreased diffusion coefficient (D0).

To study the nucleation and recrystallization behavior of deformation bands, shear bands and grain boundaries during the recrystallization process, a heat treatment test was carried out on Cr-Ti-B low-carbon steel after warm rolling and cold rolling. The results show that recrystallization occurs preferentially in shear bands and grain boundaries. The γ deformation texture can be enhanced and the Goss texture can be weakened during the warm rolling and subsequent cold rolling process. Recrystallization of the deformation bands was observed, but the nucleation time of recrystallization in the deformation band is much slower than that in the shear band and grain boundary.