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With the goal of lightweight and strong microwave absorption, polyaniline/aminopropyltriethoxysilane/silicon carbide (PANI/APTES/SiC) nano-composites with hierarchical architecture were fabricated through a facile in situ polymerization method. Herein, the SiC powders were modified with APTES in advance to achieve a more uniform envelope by PANI. The composites with different thicknesses of PANI layer and adjustable dielectric properties can be obtained by altering the PANI ratio. For the optimized sample, the minimum value of reflection loss is − 51.34 dB at 13.92 GHz with a thickness of 1.9 mm and the effective attenuation bandwidth is in a broad range from 12.19 to 17.45 GHz (bandwidth of 5.26 GHz). The outstanding absorption properties are closely related to the suitable impedance matching and the multiple loss mechanisms. [ABSTRACT FROM AUTHOR]

Heat treatable Al-Zn-Mg alloys can be strengthened by the precipitation of second phase particles. In this article, four Al-Zn-Mg-based alloys with different Cu contents have been prepared. The effects of Cu content on the aging behaviors of the whole precipitation process of the prepared Al-Zn-Mg alloys have been investigated using hardness tests, transmission electron microscope, selected election diffraction patterns, and their simulations. It has been shown that a certain amount of Cu promotes a rapid hardening response at the early stage of aging and the nucleation of both GP-II zones and the η′ precipitates. However, the addition of Cu above 3 wt% in alloys would decrease the accelerating effect of the transition from the GP-II zone to the η′ precipitates. The η precursor has been observed in Cu-containing alloys and it can retard the transition to the stable phase. [ABSTRACT FROM AUTHOR]

Heat treatable Al-Zn-Mg alloys can be strengthened by the precipitation of second phase particles. In this paper, Al-6.57%Zn-2.83%Mg and Al-6.57%Zn-2.83%Mg-3.92%Cu alloys (in wt%) in T7 state (140 °C for 96 h) have been prepared. The effects of Cu and Al on the concentration and structure of equilibrium η (MgZn) phase have been investigated by high resolution transmission electron microscopy, aberration-corrected scanning transmission electron microscopy, selected election diffraction pattern simulations, and first-principles calculations. The effects of Cu and Al substitution on the diffraction characteristics of the η phase and the general rule of Cu and Al substitution in the η phase have been discussed. [ABSTRACT FROM AUTHOR]