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Herein, we report the successful synthesis of single crystalline boron nanotubes in a Cu alloy via a novel and simple direct melt reaction process. The boron nanotubes are perfect single crystals with a β-rhombohedral structure, whose size can be controlled and changed. The combined experimental and dynamic simulation results lead to the conclusion that the boron nanotubes in the Cu alloy can be considered as a crystal skeleton, closely related to the liquid structure and solidification characteristics of the Cu–B alloy, which is significantly affected by the cooling rate and boron concentration. In addition, the stable morphology of the boron nanotubes, which minimizes the energy content, is not a round tube but a parallelogram. Thus, boron tubes with large size range scale can be prepared in Cu alloys. [ABSTRACT FROM AUTHOR]

In this work, boron spheres were successfully prepared in Cu alloy by a simple direct melt reaction method. Spherical boron can form in the Cu-B alloy cooled at a high cooling rate, and boron spheres can be obtained by the acid corrosion of metal Cu. The size of boron spheres extracted from Cu alloy can be controlled and changed from about 3 nm to several hundreds of nanometers. The boron spheres consist of loose disorder center and irregular layers outside. The aggregation of two boron spheres should follow twinning mechanism. [ABSTRACT FROM AUTHOR]

In this work, the influences of alloying elements like Cu and Fe on the microstructures and tensile properties (at 350 °C) of network AlN p reinforce Al composites have been studied. After alloying element introduction, Cu atoms tend to segregate on the AlN p /Al interface, while Fe atoms not. Meanwhile, the α–Al grains show a 〈111〉 Al fiber texture in the AlN p reinforced Al composites with Cu addition and a {110} Al 〈111〉 Al texture in the AlN p reinforced Al composites containing Fe, which are different from the random α–Al orientations in the AlN p /Al composites without element addition. The tensile properties of AlN p /Al composites containing alloying elements at 350 °C are affected by the preferred orientations of α–Al grains and the changes of dislocation density. The elongation of the composites containing Cu increased remarkably from 3.5% to 14% with just little tensile strength sacrifice at 350 °C. Nevertheless, after Fe incorporation, the tensile strength is increased to 140 MPa, coupled with the elongation of 7% at 350 °C. [ABSTRACT FROM AUTHOR]

The structural and compositional evolution of precipitates in Al-Mg-Si-Cu alloys were systematically investigated by atomic resolution high-angle annular dark-field scanning transmission electron microscopy and atom probe tomography. In under-aged alloys, most of precipitates have a disordered structure, with a substructure of β″ (LDC) and Cu sub-unit cluster or C unit cell. After aging to peak strength, disordered precipitates including β″, QP1 and QP2 phases are formed. The disordered QP1 and QP2 phases, which contain the unit cells of Q′ and C phases, respectively, are the precursor phases of Q′ phase in these alloys. The β″ phase can transform into the disordered QP1 phase by incorporating Cu atoms, forming Cu sub-unit clusters and QP lattice. When the alloy is over-aged, the ordering and transformation of QP1 to Q′ occurs by the formation of Cu sub-unit clusters, the ordering of QP lattice, and the ordering of QC lattice. In contrast, the transformation of the disordered QP2 phase are rather sluggish. After sufficient aging, Q′, C and disordered QP2 transform into the Q phase. During the evolution of the precipitates in these alloys, a continuous incorporation of Mg, Si and Cu atoms and release of Al atoms occur. These findings provide new insights in understanding precipitation in Al-Mg-Si-Cu alloys. [ABSTRACT FROM AUTHOR]