The loading rate effect on the brittle-ductile transition temperatures of tungsten single crystals at the micro-scale was investigated by microcantilevers with a (100)[001] crack system. Specimens with a length to width to height of 15 µm / 4 µm / 6 µm were fabricated by focused ion beam milling. At low temperatures (-90 to -25 °C) the samples failed by brittle cleavage fracture, irrespective of the applied loading rate at a fracture toughness of 3.2 MPa•m 1/2 . With increasing temperatures up to 500 °C and depending on the applied loading rate, the fracture toughness increased and significant crack tip plasticity and dislocation-controlled microcleavage were observed by means of high resolution electron backscatter diffraction measurements performed after testing. With respect to macroscopic specimens, a shift of the brittle-ductile transition to lower temperatures and a significantly lower activation energy of the brittle-ductile transition of 0.36 eV were found. We explain this by the increase in flow stresses due to sample size effects.

The effect of the addition of magnesium (up to 10 wt%, expressed as MgO) on the phase composition, the microstructure and the mechanical properties of hydroxyapatite-based ceramics (HA) was studied by X-ray powder diffraction, infrared spectroscopy, scanning electron microscopy, and mechanical testing. Doping with magnesium did not change the crystal lattice of HA but, due to an isomorphous substitution of Mg 2+ for Ca 2+ , it caused a decrease in the average grain size, an increase of microporosity, a removal of the texture, and the formation of a weak intergranular boundary. The transcrystallite fracture pattern of pure HAwas changed to a predominantly intercrystallite one. This resulted in a decrease in density (down to 2.93 g cm -3), in microhardness (down to 400 MPa), in compressive strength (down to 190 MPa) and in improved plastic properties of the material (increasing the fracture toughness K 1C up to 2.7 MPa m 1/2 , close to that of the bone). It is interesting that the K 1C increase could be only observed for a small concentration of additives (up to 1 wt%), i.e. close to the Mg concentration in natural bone mineral.

Focused electron beam induced deposition (FEBID) is a flexible direct-write method to obtain defined structures with a high lateral resolution. In order to use this technique in application fields such as plasmonics, suitable precursors which allow the deposition of desired materials have to be identified. Well known for its plasmonic properties, silver represents an interesting candidate for FEBID. For this purpose the carboxylate complex silver(I) pentafluoropropionate (AgO2CC2F5) was used for the first time in FEBID and resulted in deposits with high silver content of up to 76 atom %. As verified by TEM investigations, the deposited material is composed of pure silver crystallites in a carbon matrix. It showed good electrical properties and a strong Raman signal enhancement. Interestingly, silver crystal growth presents a strong dependency on electron dose and precursor refreshment.

Focused electron beam-induced deposition using the heteroleptic complex (η 3 -C 3 H 5 )Ru(CO) 3 Br as a precursor resulted in deposition of material with Ru content of 23 at. %. Transmission electron microscopy images indicated a nanogranular structure of pure Ru nanocrystals, embedded into a matrix containing carbon, oxygen, and bromine. The deposits were purified by annealing in a reactive 98% N 2 /2% H 2 atmosphere at 300 °C, resulting in a reduction of contaminants and an increase of the Ru content to 83 at. %. Although a significant volume loss of 79% was found, the shrinkage was observed mostly for vertical thickness (around 75%). The lateral dimensions decreased much less significantly (around 9%). Deposition results, in conjunction with previous gasphase and condensed-phase surface studies on the electron-induced reactions of (η 3 -C 3 H 5 )Ru(CO) 3 Br, provide insights into the behavior of allyl, carbonyl, and bromide ligands under identical electron beam irradiation.

This paper studied the formation mechanism of white layer of a next generation nickel-based superalloy formed under severe plastic deformation induced by a mechanical material removal process.A graded microstructure of the white layer in the nickel-based superalloy has been revealed for the first time, which is composed of (i) a "dynamic recrystallisation" layer formed by nanocrystalline (~200 nm) grains at the vicinity of the surface and (ii) a "dynamic recovery" layer with subgrain microstructures extending further into the subsurface. The mechanism of surface grain refinement was identified based on the results obtained via crystallographic and chemical analysis, as well as in-situ micro-mechanics experiments in the scanning electron microscope. It is found that in the top surface layer not only grain refinement but also the ' phase dissolution occurs, changing drastically from the bulk material. Furthermore, it is shown how the high plastic strain and cutting temperature along the subsurface causes grain refinement in the white layer and grain elongation in the subsurface. The ' precipitates in the recrystallisation layer are dissolved during the machining process, while the ultrahigh cooling rate suppresses the further precipitation of this phase, resulting in the supersaturation of  grains or minimized ' precipitates in the top surface layer. Hence, the grain refinement does not result in an increase of mechanical stiffness but a deterioration of mechanical properties due to the dissolution of the strengthening phase ', which leads to a lower strength and increased ductility.Machining is generally treated as a cold-working process. However, according to our findings hotworking with dynamic recrystallisation and recovery, as well as phase evolution, occurs in the white layer of nickel-based superalloys.