Manufacturing of Textured Bulk Fe-SmCo5_{5} Magnets by Severe Plastic Deformation

Exchange-coupling between soft- and hard-magnetic phases plays an important role in the engineering of novel magnetic materials. To achieve exchange coupling, a two-phase microstructure is necessary. This interface effect is further enhanced if both phase dimensions are reduced to the nanometer scale. At the same time, it is challenging to obtain large sample dimensions. In this study, powder blends and ball-milled powder blends of Fe-SmCo$_{5}$ are consolidated and are deformed by high-pressure torsion (HPT), as this technique allows us to produce bulk magnetic materials of reasonable sizes. Additionally, the effect of severe deformation by ball-milling and severe plastic deformation by HPT on exchange coupling in Fe-SmCo$_{5}$ composites is investigated. Due to the applied shear deformation, it is possible to obtain a texture in both phases, resulting in an anisotropic magnetic behavior and an improved magnetic performance.Comment: 12 pages, 6 figures, 1 tabl

Search for dark matter produced in association with bottom or top quarks in √s = 13 TeV pp collisions with the ATLAS detector

A search for weakly interacting massive particle dark matter produced in association with bottom or top quarks is presented. Final states containing third-generation quarks and miss- ing transverse momentum are considered. The analysis uses 36.1 fb−1 of proton–proton collision data recorded by the ATLAS experiment at √s = 13 TeV in 2015 and 2016. No significant excess of events above the estimated backgrounds is observed. The results are in- terpreted in the framework of simplified models of spin-0 dark-matter mediators. For colour- neutral spin-0 mediators produced in association with top quarks and decaying into a pair of dark-matter particles, mediator masses below 50 GeV are excluded assuming a dark-matter candidate mass of 1 GeV and unitary couplings. For scalar and pseudoscalar mediators produced in association with bottom quarks, the search sets limits on the production cross- section of 300 times the predicted rate for mediators with masses between 10 and 50 GeV and assuming a dark-matter mass of 1 GeV and unitary coupling. Constraints on colour- charged scalar simplified models are also presented. Assuming a dark-matter particle mass of 35 GeV, mediator particles with mass below 1.1 TeV are excluded for couplings yielding a dark-matter relic density consistent with measurements

Influence of Gradient Residual Stress and Tip Shape on Stress Fields Inside Indented TiN Hard Coating

Nanoindentation of treated surfaces, thin films, and coatings is often used as a simple method to measure their hardness and stiffness. These quantities are technologically highly relevant and allow to qualitatively compare different material and surface treatments but fail to capture the entire extent of the highly complex mechanical interaction between indenter tip and the tested surface. Many studies have addressed this question by analytical or numerical modeling, but they must rely on verification by recalculating indentation curves or ex situ microscopy of surface deformation postexperiment. Herein, results from in situ measurements of the multiaxial stress distributions forming beneath an indenter tip while the tested sample is still under load are presented. A 9 μm-thick TiN hard coating is tested in 1) as-deposited state and 2) shot-peened by Al2O3 particles, using two diamond wedges as indenter tips, with 60° and 143° opening angle, respectively. The results reveal a strong influence of the tip shape on the deformation behavior and the main stress component developing inside the sample while under load. In addition, a crack-closing effect can be attributed to the exponentially declining near-surface compressive residual stress gradient that is present in the shot-peened sample

Gradient residual strain and stress distributions in a high pressure torsion deformed iron disk revealed by high energy X-ray diffraction

High energy X-ray diffraction is used to investigate for the first time the distribution of residual X-ray elastic stresses inside a high pressure torsion (HPT) deformed iron disk with a diameter and thickness of ~ 30 and ~ 8 mm, respectively. In the experiment, a dedicated conical slit system restricts the diffraction gauge volume in three dimensions to ~ 0.45 mm³, which is then used to scan the bulk sample cross-section in a non-invasive manner. Pronounced residuals stress gradients with maximal tensile stresses of ~ 200 MPa are observed along radial and tangential directions and are correlated to the deformation gradient arising from HPT

An investigation on shear banding and crystallographic texture of Ag–Cu alloys deformed by high-pressure torsion

Ag–Cu alloys of two different initial microstructures—a cast eutectic alloy (AgCu-E) and an equivolume Ag–Cu powder mixture (AgCu-P)—were deformed by high-pressure torsion. The codeformation of Ag and Cu grains led to uniform refinement and a nanolamellar microstructure for both alloys. However, the lamellar structure in AgCu-P alloys was broken at intermediate shear strains (γ > 150) by extensive shear banding. On the other hand, no shear banding was observed for AgCu-E alloy at similar microstructural refinement. At higher strains deformation induced intermixing of Ag and Cu atoms was observed. Further, three-dimensional diffraction analysis of AgCu-E alloy showed that in contrast to conventional single phase alloys, the Ag and Cu phases develop similar crystallographic texture

Investment analysis of a broiler further processing plant

Az elmúlt évtizedek alatt az összes húsféleség közül a baromfihús-termelése nőtt a legerőteljesebben. A lakosság életszínvonalának emelkedésének hatására egyre növekszik a kereslet a kényelmi, magasabban feldolgozott termékek iránt. A magyar baromfiágazat, ezen belül is a vágócsirke vertikum legfőbb problémái a tartósan alacsony jövedelmezőség, valamint az objektív versenyhátrányok megléte a nemzetközi konkurenciával szemben. A versenyhátrány okozója az elégtelen termékfejlesztés és innováció a feldolgozó szférában, valamint az, hogy a feldolgozóknál a magas hozzáadott értékű termékek alacsony részarányt képviselnek a termék-szortimenten belül.Dolgozatom középpontjában egy magyarországi vágócsirke vertikumban működő integráció továbbfeldolgozó üzem létesítő beruházása áll. Feltételezésem értelmében az integráció jövedelmezősége hosszútávon javul, ha a cégcsoport alkalmazkodik a változó piaci igényekhez, és növeli az általa előállított késztermékek feldolgozottsági fokát. Célkitűzésem ezen üzemlétesítő beruházás, illetve, az ezt megtestesítő műszaki fejlesztés indokoltságának és életképességének vizsgálata.MSc/MAVállalkozásfejlesztésK

Phase Decomposition of a Single-Phase AlTiVNb High-Entropy Alloy after Severe Plastic Deformation and Annealing

An equiatomic AlTiVNb high-entropy alloy is deformed by high pressure torsion inducing a nanocrystalline microstructure. The samples then are subjected to isochronal heat treatments between 300$^{\circ}$C and 1000$^{\circ}$C. The hardness increase from $\approx$ 7.4 GPa for the as- processed state to 10.4 GPa for an annealing temperature of 700$^{\circ}$C, while for higher temperatures the hardness starts to decrease. Furthermore, the reduced modulus increases after annealing treatments as well. It will be shownthat the unusual annealing response can be related to the formation of intermetallic phases creating a multi-phase nanocomposite material during annealing. The results give new insights into the thermodynamic stability of this alloy, which are also relevant for coarser-grained microstructures

Combining hardness measurements of a heat-treated crankshaft bearing with cross-sectional residual stress and retained austenite distributions measured by HEXRD

Surface hardening is commonly used to modify mechanical properties of crankshaft bearings. In this work, residual stress and hardness distributions across the crankshaft bearings cross-sections are evaluated using synchrotron high-energy X-ray diffraction and hardness testing. It is shown that the measured hardening depth correlates with a point of sudden sharp reversal of the stress gradient from compressive to tensile. This point is linked to the microstructure and does not shift with subsequent tempering or trimming of the sample. The superimposed data is used to interpret the evolution of stresses during the quenching and tempering cycle and gain understanding of the hardening process for such complex geometries. Within the hardened zone retained austenite is found to increase with depth to over 15 %, which is attributed to reduced quenching effects as the material is further away from the surface. All measured properties agree in the determined hardening depth of 3.5 mm to 4.5 mm, which in turn fits well with optical evaluation of metallographic microsections

Indentation response of a superlattice thin film revealed by in-situ scanning X-ray nanodiffraction

Nanocrystalline materials such as thin films, and in particular, multilayers with a periodicity in the nanometer range, i.e. superlattice films, possess properties that cannot be found in their coarse-grained bulk counterparts. Mechanical characterization of such structures is therefore of high interest, but also very challenging, due to the small length scales involved and has therefore most often been performed ex-situ using electron microscopy. In this work, however, we report on the first in-situ micromechanical analysis of a CrN-AlN superlattice thin film cross-section. The sample was deposited using reactive magnetron sputtering and sublayer thicknesses were chosen so as to stabilize AlN in its cubic crystal structure. Using a synchrotron X-ray nanoprobe, maps of internal stresses and morphological changes were tracked by means of wide-angle X-ray diffraction and simultaneous small-angle X-ray scattering, while the sample was loaded to various degrees with a wedged diamond tip. The results reveal a high compressive strength of about 13 GPa, while through-thickness cracks form, following tensile stresses >1.4 GPa and thereby provide a relaxation mechanism. Layer rotation up to several degrees and significant layer compression up to 7% were also found, but along with the internal stress response, their nature is mostly elastic, meaning that in the post-loading state only a fraction of the effects observed under load remains