The microstructural and mechanical properties of an ultrafine-grained (UFG) Al-Zn alloy processed by high-pressure torsion (HPT) are investigated using depth-sensing indentations, focused ion beam, scanning electron microscopy and scanning transmission electron microscopy. Emphasis is placed on the microstructure and the effects of grain boundaries at room temperature. The experiments show the formation of Zn-rich layers at the Al/Al grain boundaries that enhance the role of grain boundary sliding leading to unique plastic behavior in this UFG material. The occurrence of significant grain boundary sliding at room temperature is demonstrated by deforming micro-pillars. Our results illustrate a potential for using UFG materials as advanced functional materials in electronic microdevices.

As-quenched and stress field annealed FINEMET ribbons were irradiated with 246 MeV energy Kr, 470 MeV energy Xe and 720 MeV energy Bi ions and investigated by 57 Fe Mössbauer spectroscopy and XRD methods. The change in relative areas of the 2nd and 5th lines in the Mössbauer spectra indicated significant changes in the magnetic anisotropy of both as-quenched and stress annealed FINEMET due to irradiation with swift heavy ions. Differences were observed between the effect of irradiations with various ions having different energy and fluence. The effect of irradiation on the magnetic orientation in FINEMET was explained in terms of radiation induced defects. The swift heavy ion irradiation can be applied to produce FINEMET ribbons with more favorable soft magnetic properties for technological applications.

When ultrafine-grained (UFG) samples are deformed plastically, it is necessary to consider the role of grain boundaries even at the micrometer scale in sample size. We report here the occurrence of intensive grain boundary sliding (GBS) at room temperature in micro-pillars of a UFG aluminum alloy having an unusually high strain rate sensitivity. A consequence of this GBS is that the intermittent flow with detrimental strain avalanches characterizing micro-sized conventional crystals is not present in UFG materials, thereby illustrating a potential for effectively applying these UFG materials in micro-devices.Recently, the size-scale effects in plastic deformation have been studied both experimentally [1][2][3] and theoretically [4,5] for several different materials. In the case of conventional crystalline materials, as with metals, it is well established that the decreasing sample size may significantly affect the fundamental mechanisms of plasticity: for example, in dislocation storage, multiplication, motion, pinning, etc. Therefore, although the plasticity of macroscopic samples appears as a smooth process, in the plastic deformation of microcrystals specific dislocation avalanches are formed leading to an uncontrolled deformation process including also the possibility of catastrophic failure. Accordingly, micrometer-sized samples of coarse-grained metals are not suitable for use in the fabrication of micro-devices.It is well established that bulk ultrafine-grained (UFG) materials may be achieved by using severe plastic deformation (SPD) techniques, [6,7] decreasing the grain sizes into the submicrometer and nanometer ranges. Typically, the materials produced by SPD exhibit tensile ductilities below 10% at ambient temperature due to exhaustion in their work hardening capacity. Furthermore, this low ductility is correlated with extremely low strain rate sensitivity (SRS) of~0.01-0.03 characterizing the mechanical behavior of these materials. [8] It was suggested that the mechanical properties of UFG metals may be improved if grain boundary sliding (GBS) is achieved at relatively low temperatures. [9][10][11] It was recently shown that SPD is capable of improving the room-temperature ductility of an Al-30 wt% Zn UFG alloy processed by high-pressure torsion (HPT) [11] since this UFG material became super-ductile with unusually high elongations up to >150% and an unusually high SRS of~0.22. In this work, we applied a focused ion beam (FIB), depth-sensing indentations and scanning electron microscopy (SEM) to reveal experimentally the basic deformation mechanism in this UFG alloy at the micrometer scale. We report here the plastic deformation of UFG micro-pillars, demonstrate the occurrence of intensive GBS at room temperature and note the potential for effectively applying these UFG materials in micro-devices.The experiments were conducted using an aluminum-based alloy containing 30 wt% Zn prepared from high-purity components by vacuum induction melting. Disks having diameter of 20 mm and thicknesses of 0.8 mm wer...

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Graphene was grown on a Ni (111) thin layer, used as a substrate. The Ni layer itself was grown on single crystal sapphire (0001). Carbon was deposited by chemical vapor deposition using a mixture of methane, argon and hydrogen at atmospheric pressure implementing a constant gas flow (4.8-5 l/min) varying both the gas composition and the deposition temperature