The article describes the effect of friction stir processing (FSP) on the superplastic behaviour of the Al–4.5 Mg alloy containing Sc and Zr. The results yielded by the FSPed sheet were compared with the superplastic behaviour of the same alloy produced conventionally by cold rolling. The measurements of the superplasticty included the flow stresses and the maximum elongations of the alloy at initial strain rates ranging from 1×10−3 s−1 to 1 s−1, and at testing temperatures from 350 °C to 500 °C. The inclusion of the FSP step considerably enhanced the superplastic behaviour of the alloy in comparison with its rolled counterparts, which was reflected in higher elongations at higher strain rates and lower forming temperatures.
COBISS.SI-ID: 1315679
Metal grinding is a one of the manufacturing technologies that is greatly connected to particles emission. Particles generated during the grinding process are dangerous in terms of its potential penetration deeply into the lungs of an operator. The level of risk for human respiratory system is related to nature, shape and size of the particles, and for this reason it is important to have a quality characterization of emitted particles. This paper focuses on particles characterization on the bases of image analysis from scanning electron microscopy (SEM). The research was conducted during the process of grinding of steel EN 90MnV8, using personal sampler. Results of image analysis, consisted of Feret’s diameter and circularity, showed quite a wide range of sizes and significant deviation of particles from regular shape.
COBISS.SI-ID: 1314911
Fe-Pd nanowires were synthesised in anodic alumina templates by applying both potentiostatic and pulsed electrodeposition regimes. When using potentiostatic deposition, only fragmented nanowires were obtained; however, the use of pulse deposition was shown to be effective for producing solid nanowires. In order to achieve this, different on-times for the deposition and off-times between the pulses in an electrolyte with a constant concentration of Fe(III) and Pd(II) ions at pH 9 were employed. Homogeneous nanowires with the composition Fe55 +/- 5Pd45 +/- 5, lengths of 2.5 mu m and diameters of 200 nm were synthesised under the following pulsed conditions E-on = -1.4 V, t(on) = 2 s and E-off = -0.1 V, t(off) = 10 s for 5000 cycles. The as-deposited nanowires had a fcc crystal structure and were magnetically soft (H-C approximate to 5 kA/m) with the easy axis of magnetization perpendicular to the long axes of the nanowires, mainly due to the dipolar coupling within the template. In order to promote the ordering into the L1(0) phase, annealing in the temperature range 400-700 degrees C for 1-9 h in Ar + 7% H-2 was performed. The highest coercivity of 122 kA/m was achieved by annealing at 600 degrees C for 5 h.
COBISS.SI-ID: 27644199
The objective of this study was to investigate the structural properties of a cold-rolled platinum foil used to manufacture multi-electrode spiral nerve cuffs. Methods: To attain this objective, 0.03-mm-thick cold-rolled platinum foil strips with 99.99 wt% purity were used. The resistivity measurements were made using a 4-point probe technique in which the strips were subjected to dynamic annealing in an argon atmosphere. The stored energy of platinum was recorded in an argon atmosphere using differential scanning calorimetry (DSC). Finally, the microstructure of the strips was investigated by optical microscopy. Results: In the resistivity measurements, a small change is observed at ~280°C. This change could be explained as the partial recovery elicited by the decrease of dislocation density. Above 500°C, a significant decrease in resistivity was recorded, and the decrease reached a maximum at ~750°C. These results are consistent with the recrystallization trend detected in DSC, namely the DSC measurement detected very weak heat release during recrystallization, which was actually accumulated during the cold-working. This exothermal peak occurred in the temperature range 380-800°C.
COBISS.SI-ID: 31529177
Intercrystally distributed nonmetallic inclusions greatly increase weld susceptibility to hot cracking. Oxide and sulphide inclusions are the result of contaminated base material or its highly oxidised surfaces and they can be a consequence of metallurgical reactions between welding slag and remelted base material, while carbide inclusions can occur due to the mixing of high-carbon base and low-carbon filler material. All welding surfaces must thus be cleaned before welding and the least possible mixture of base with filler material must be enusured during welding.
COBISS.SI-ID: 1314655