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The precipitation mechanism of the Q phase in Al-Mg-Si-Cu alloys has long been the subject of ambiguity and debate since its metastable phase (Q′) has the same crystal structure and similar lattice parameters as its equilibrium counterparts. In the present work, the evolution of the Q′ (Q) phase during aging is studied by combination of quantitative atomic-resolution scanning transmission electron microscopy and atom probe tomography. It was found that the transformation from the Q′ to the Q phase involves changes of the occupancy of Al atoms in atomic columns of the Q′ (Q) phase. The Al atoms incorporated in the Cu, Si and Mg columns are gradually released into the Al matrix, while mixing between Cu and Si atoms occurs in the Si columns. This transformation process is mainly attributed to the low lattice misfit of the equilibrium Q phase. Besides, the formation of various compositions of the Q phase is due to the different occupancy in the atomic columns of the Q phase. The occupancy changes in the columns of the Q phase are kinetically controlled and are strongly influenced by the alloy composition and aging temperature. [ABSTRACT FROM AUTHOR]

Anatase–mordenite nanocomposite was synthesized in situ and characterized by X-ray diffraction analysis, Brunauer–Emmett–Teller measurements, infrared (IR) spectroscopy, electron diffraction measurements, energy-dispersive X-ray spectroscopy, X-ray photoelectron spectroscopy, and scanning and transmission electron microscopy. It was found that X-ray-amorphous anatase located in the zeolite micropores resulted in a decrease in the specific surface of anatase–mordenite compared to the initial mordenite. Anatase-containing nanoparticles in anatase–mordenite showed round shape and formed nano-associates and conglomerates. The water content in the zeolite cavities in anatase–mordenite was lower compared to mordenite. Anatase–mordenite nanocomposite exhibited higher photocatalytic activity in the model decomposition reaction of methyl orange under ultraviolet (UV) radiation and higher adsorption capacity for extraction of P(V) and As(V) ions from aqueous environment in the dark compared to the initial mordenite or anatase due to an increase in the content of active OH-groups on the nanocomposite surface compared to mordenite and an increase in the specific surface compared to anatase. [ABSTRACT FROM AUTHOR]