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Dissimilar joints of AA6061 and Ti6Al4V alloys were obtained via friction stir welding using W-Re pin tools. The intermetallic compounds (IMCs) and the deformation of Ti matrix were depicted from the interfaces as probe length increased, which could be attributed to the promotion of interfacial pressure and temperature. TiAl3 was formed at all the Al/Ti interfaces in this study, and TiAl formed in the joint welded by 3.3 mm probe following TiAl3 for lower activation energy. Due to the increase of free energy caused by the solid dissolution of Ti in Al matrix, TiAl3 nanoparticles precipitated in the diffusion layer, which could be depicted at the Al side of the interface with an overall Ti concentration ranging from 3 to 5 (At. %). It is indicated that the amount of IMCs increased in the joints with increasing probe length. The mechanical properties of the joints were significantly affected by the interfacial microstructure. The shear strength and elongation reached the maximums of 147.5 MPa and 4.1% respectively using the pin tool with 3.1 mm probe. Cleavage fracture gradually dominated the fracture of the joints as the probe length increased, which could be attributed to the formation of intermetallic compounds.

To investigate the relationship between cluster correlation index and nanoclusters during rapid solidification, a molecular dynamics (MD) simulation study has been performed for FexNi(100−x)(40 ≤ x ≤ 80) amorphous alloys. Six kinds of common amorphous clusters with great similarity are explored by the newly developed Largest Standard Cluster Analysis (LSCA). The spatial distribution of clusters is analyzed by the correlation index, which is divided into strongly correlated clusters and weakly correlated clusters, and the effects of two different correlation clusters on the formation of nanoclusters are quantitatively researched. The results reveal that the Z14 correlation index of own connection is the strongest and increases with the increase of Fe content, while the correlation index between A13 and D-A13 is the weakest and it is not obvious with the increase of Fe content. In addition, Fe-rich alloys are more likely to congregate to form large-sized nanoclusters with high packing density due to the strong correlation index.

We report a facile approach to prepare a superior magnetic adsorbent towards Hg2+ ions by decoration of defective MoS2 (d-MoS2) nanosheets with Fe3O4 nanoparticles. The adsorption performance of the resulted d-MoS2/Fe3O4 nanohybrids towards Hg2+ ions was studied as a function of solution pH, contact time, and Hg2+ ions concentration. The d-MoS2/Fe3O4 nanohybrids simultaneously showed high adsorption capacity, outstanding selectivity, rapid adsorption rate, and excellent magnetic separation capability for the removal of Hg2+ ions. Their adsorption capacities at the residual concentration of Hg2+ ions 1 μg/L (drinking water regulation limit) and 2 μg/L (wastewater regulation limit) are 0.05 mg/g and 0.11 mg/g, respectively. With initial Hg2+ ions concentration of 10 mg/L, the residual concentration of Hg2+ ions decreased to as low as 1.7 μg/L after adsorption for only 20 min. The adsorption process can be well fitted by the pseudo-second-order kinetic model and Langmuir isotherm model, respectively. The maximum adsorption capacity of d-MoS2/Fe3O4 nanohybrids can reach 425.5 mg/g, which is much higher than other reported magnetic adsorbents. Moreover, the Hg2+ ions adsorbed d-MoS2/Fe3O4 nanohybrids could be well regenerated in acid solution without obvious decline of removal efficiency.

The composition and morphology of the Fe-bearing phase play a significant role in the mechanical properties of aluminum (Al) alloy sheets. In this work, we have studied the formation of Fe-bearing phases in an Al-0.53Mg-0.69Si-0.14Fe (wt%) alloy under the twin-roll casting (TRC) and the direct chill casting (DC) processes, respectively. We found that the π-AlFeMgSi phase was formed in the as-cast TRC sample, while the β-AlFeSi phase was formed in the as-cast DC sample. The differences in the formation of Fe-bearing phases are attributed to the promotion of the peritectic reaction to form the π-AlFeMgSi phase via the TRC process. Furthermore, after homogenization treatment at 550 °C and 2 h, the π-AlFeMgSi phase in the as-cast TRC sample completely decomposed into the fine β-AlFeSi phase, while it was insufficient to dissolve the β-AlFeSi phase in the as-cast DC sample. This is owing to the lower dissolution temperature of the π-AlFeMgSi phase compared to the β-AlFeSi phase. The decomposition of the π-AlFeMgSi phase expands the solid solubility and promotes the aging precipitation, resulting in higher yield strength of the TRC sample than that of the DC sample during the peak-aging treatment. Our work provides new insight into the development of high-performance AA6xxx series alloys based on the TRC process.

Two dimensional (2D) layered MoS2 nanosheets are gaining increasing attention due to their attractive properties associated with myriads potential applications. However, large-scale production of high-quality MoS2 nanosheets in a simple manner remains a big challenge. Herein, we present a facile approach for scalable production of defect-free MoS2 nanosheets by direct ultrasonication exfoliation of bulk MoS2 crystals in ethanol in the presence of pyrene. Our findings indicate that the pyrene can not only serve as an exfoliating agent to significantly accelerate the exfoliation process but also endow the resulted MoS2 nanosheets with excellent solution dispersibility and stability. The obtained MoS2 nanosheets are highly crystalline and exhibit superior electrical properties as compared with the bulk MoS2. In addition, the MoS2 nanosheets can also be employed as nanofillers to enhance the mechanical properties of polymers. Moreover, this method can also be extended to exfoliation of other 2D layered transition metal dichalcogenide as demonstrated by the exfoliation of bulk WS2 crystals in this study. This work thus brings more opportunities for the investigation and applications of 2D layered inorganic nanosheets.