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Micro-alloying of rare earth elements can improve the properties of Al alloys, but the mechanisms how they change the microstructures and therefore the properties of the alloys are still generally unclear. Using scanning electron microscopy and atomic-resolution transmission electron microscopy, here we have revealed the microstructural differences between two AlMgSi alloys with and without La-addition, and investigated the impacts of La-addition on specific microstructure-property relationships of the material. It is shown that La-addition has three significant effects on the microstructures and the properties of AlMgSi alloys. Firstly, La-addition changes the types of precipitates formed during aging. Most of β" precipitates formed in the peak-aged alloy with La-addition are polycrystalline β" precipitates. In the over-aging stage of this alloy, the dominant precipitates formed are the β"/U2, β"/β' and β'/U2 composite precipitates, rather than the expected β' precipitates. Secondly, La-addition induces the formation of numerous FCC AlSiLa intermetallics, which significantly refine the grain size and enhance the strength and the ductility of the alloy. Thirdly, La-addition may enhance the electrical conductivity of the age-hardened alloy by reducing the solute atoms in the Al-matrix. [Display omitted] • Microstructure changes of an AlMgSi alloy induced by La-addition are revealed. • Polycrystalline β" precipitates form in the peak-aged alloy with La-addition. • Multiphase composite precipitates form in the over-aged alloy with La-addition. • AlSiLa intermetallics improve the La-added alloy's strength and ductility. • Reduced solutes account for the La-added alloy's improved electrical conductivity. [ABSTRACT FROM AUTHOR]

The burgeoning advancement of electronic technology and wireless communications has opened up an unprecedented era of electromagnetic wave applications, but the accompanying issues of electromagnetic pollution are equally deserving of profound attention. In recent years, a variety of novel electromagnetic absorbers have been ingeniously designed and actively emerged, among which carbon-based materials have become one of the most promising alternatives for next-generation electromagnetic functional materials, owing to the low density, tunable electrical properties, high stability, and chemical tolerance. This article comprehensively reviews the current research status and frontier science of carbon-based absorbing materials serving in microwave frequency band, and discusses in detail the microwave absorption mechanisms of various carbon-based systems as well as the critical factors affecting microwave attenuation. Furthermore, strategies to optimize microwave absorption performance of carbon-based materials through component design, structural modification, morphology modulation, and composite approaches will be discussed, with particular emphasis on their intrinsic correlation with magnetic-dielectric loss characteristics. Finally, the urgent requirements for improving carbon-based absorbing materials and insights into future development are provided, covering from material design to performance optimization to device-based applications. This review endeavors to support valuable references for research on carbon-based microwave absorbing materials and to stimulate further innovative thinking. [Display omitted] [ABSTRACT FROM AUTHOR]