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The effects of trace (0.05 at.%) Cd addition on the high-temperature (250 °C) age-hardening behavior, precipitate microstructure and room-temperature tensile properties of an Al-0.8Mg-0.8Si (wt.%) alloy were investigated. The results showed that the Cd addition not only accelerated the precipitation kinetics but also increased the peak hardness of Al–Mg–Si alloys. The quantitative analysis of the peak-aged precipitates based on (high-resolution) transmission electron microscopy images indicated that the Cd addition refined the size of needle-shaped precipitates and increased their number density. High-angle annular dark-field scanning transmission electron microscopy characterizations revealed that the Cd addition stimulated the heterogeneous nucleation of β" on the early formed nanosized Cd-rich precipitates and Cd-containing QP lattices, resulting in a much-refined precipitate microstructure. Furthermore, the Cd addition also enhanced the room-temperature tensile properties of the peak-aged alloy. The Cd-added alloy exhibited higher yield strength, ultimate tensile strength, and total elongation than the Cd-free alloy, which was due to the refined precipitate microstructure and narrowed precipitate-free zone along the grain boundaries. [Display omitted] • Effect of Cd on the age-hardening behavior of Al–Mg–Si alloys at 250 °C was investigated. • Cd greatly accelerated the precipitation kinetics and increased the peak hardness. • Cd significantly refined the precipitate microstructure by stimulating the heterogeneous nucleation of β". • Both strength and elongation of peak-aged alloys were improved by trace Cd addition. [ABSTRACT FROM AUTHOR]

The bendability of Al–Mg–Si alloy sheets is a key parameter for their application as skins of automotive body panels. In the present study, the influence of heating rate on the bendability of Al-0.6Mg-1.0Si (in wt%) alloy was investigated using optical microscopy (OM), scanning electron microscopy (SEM), and electron backscatter diffraction (EBSD). The bendability of Al–Mg–Si alloy was found to be significantly dependent on the heating rate of solution treatment. After bending, the rapidly heated specimen exhibited only slight surface undulation, while the slowly heated specimen showed severe surface necking and even micro-cracks. The severe surface necking was caused by intensive shear bands formed during bending, and the micro-cracks were the results of the interaction between the intensive shear bands and coarse second phase particles. Elongated coarse grains were more likely to produce intensive shear bands, and cube-oriented grains impeded the formation of shear bands. The schematics of recrystallization and bending processes for Al-0.6 Mg-1.0 Si alloy considering two different heating rates are proposed. • Heating rate during solution treatment affected the bendability of Al–Mg–Si alloys significantly. • Rapid heating resulted in a better bendability due to the formation of finer equiaxed grains and more cube oriented grains. • Severe surface necking occurred in slowly heated specimen after bending due to the formation of intensive shear bands. • A model was proposed to illustrate the variation of bendability for the samples with two different heating rates. [ABSTRACT FROM AUTHOR]

• Boron addition significantly improved the oxidation resistance of high-Nb-containing TiAl alloys at 900 °C. • The lamellar colony structure was refined effectively by boron addition. • The refinement of lamellar colony structure enhanced the spalling resistance of the oxide scale. • The generated oxide implants intensified the adhesion of the oxide scale. The influence of boron addition on oxidation behaviors of high-Nb-containing TiAl alloys was investigated using isothermal oxidation tests at 900 °C in air. The results indicated that boron addition refined the lamellar colony structure and significantly improved the high-temperature oxidation resistance. Fine lamellar colonies were conducive to reducing thermal stress during oxidation, which delayed the cracking of the oxide scale. Furthermore, the generated oxide implants intensified the adhesive strength between the oxide scale and substrate, further enhancing the oxide-scale spallation resistance. In summary, the superior adhesion of the oxide scale resulted in a better oxidation resistance of the boron-containing alloy. [ABSTRACT FROM AUTHOR]

Using a first-principles method in combination with thermodynamic models, we investigate the interaction between rhenium/osmium (Re/Os) and defects to explore the mechanism of radiation-induced Re/Os precipitation in tungsten (W). We demonstrate that radiation-induced defects play a key role in the solute precipitation in W, especially for self-interstitial atoms (SIAs). The presence of SIAs can significantly reduce the total nucleation free energy change of Re/Os, and thus facilitate the nucleation of Re/Os in W. Further, SIA is shown to be easily trapped by Re/Os once overcoming a low energy barrier, forming a W-Re/Os mixed dumbbell. Such W-Re/Os dumbbell forms a high stable Re/Os-Re/Os dumbbell structure with the substitutional Re/Os atoms, which can serve as a trapping centre for subsequent interstitial-Re/Os, leading to the growth of Re/Os-rich clusters. Consequently, an interstitial-mediated migration and aggregation mechanism for Re/Os precipitation in W has been proposed. Our results reveale that the alloying elements-defects interaction has significantly effect on their behaviors under irradiation, which should be considered in the design of W-based alloys for future fusion devices. [ABSTRACT FROM AUTHOR]

[Display omitted] • Bi-Pd single atom alloy (SAA) nanodendrites (NDs) with Bi atomically dispersed in Pd matrices have been synthesized. • The FEs of CO on Bi 6 Pd 94 -SAA NDs catalyst reach 90.5 % and 91.8 % in H-type and gas diffusion flow cells, respectively. • The Pd mass normalized current densities of CO are 173.7 mA/cm2 and 111.4 A/g Pd at only -0.48 vs. RHE in a gas diffusion flow cell. • DFT calculation indicate that single Bi atom doping decreases H affinity and increases the reaction barrier for H 2 evolution on Pd. • Bi doping also decreases the free energy for *COOH generation which is a key intermediate for CO production. Pd is a catalyst for electrochemical CO 2 reduction to CO but often disturbed by H 2 and formate formation at low overpotentials due to its strong affinity to H atoms. Herein, guided by density functional theory (DFT) calculations, Bi-Pd single atom alloy (SAA) nanodendrites (NDs) with Bi atomically dispersed in Pd matrices have been developed for efficient CO 2 reduction to CO. The Faradic efficiencies (FEs) of CO on the Bi 6 Pd 94 -SAA ND catalyst reach 90.5 % and 91.8 % in H-type and gas diffusion flow cells with overpotentials of only 290 and 200 mV, respectively, which are among the best of the reported Pd-based electrocatalysts. The greatly enhanced CO formation on the Bi 6 Pd 94 -SAA NDs can be attributed to the increased reaction barriers for H 2 formation due to a lower H coverage resulted from Bi doping, and the decreased free energy for *COOH generation which is a key intermediate for CO production. [ABSTRACT FROM AUTHOR]