Ni-Mn-Ga alloys close to the stoichiometric composition Ni2MnGa belong to the quite new family of ferromagnetic shape memory alloys. These alloys are characterized by the magnetic field induced strain (MFIS) based on the comparably easy motion of twin boundaries under a magnetic field. They are mostly chosen as a potential candidate for practical application especially promising for actuators and sensors because they are showing the largest MFIS so far. Depending on the chemical composition and heat treatment, at least three martensitic structures can be distinguished in the Ni-Mn-Ga system. However, the effect mentioned above only exists in two modulated structures. Since for the intended application of MFIS in technology polycrystalline materials seem to be more appropriate in contrast to single crystals, the specific polycrystalline aspects are considered. Factors important for decreasing the twinning stress and increasing the twinning strain of polycrystalline Ni-Mn-Ga alloys are texturing, adjusting the structure by annealing and training by thermomechanical treatments. To achieve pronounced MFIS in polycrystals, fabrication processes are needed to produce specific strong textures. The material texturing has been obtained by directional solidification and plastic deformation by hot rolling and hot extrusion as well as high pressure torsion (HPT). To examine the texture of coarse-grained Ni-Mn-Ga alloys (due to a solidification process or dynamic recrystallization), diffraction of synchrotron radiation and neutrons was applied. The texture results show that the texture of Ni-Mn-Ga subjected to directional solidification, hot rolling and hot extrusion is a fibre or weak biaxial texture. However, local synchrotron measurements reveal that the global fibre texture of the hot extruded sample is a ”cyclic” fibre texture, i.e. it is composed of components related to the radial direction rotating around the extrusion axis. This allows finding regions with a strong texture component. The texture after HPT is characterized by a strong cube with the cube favourably oriented. The initial microstructure of the Ni-Mn-Ga alloys is a typical self-accommodated microstructure of martensite. High resolution EBSD mappings show macro, micro twins and two types of microstructure. The twin plane is determined to be {110). In a typical martensitic transformation the high-temperature phase has a higher crystallographic symmetry than the low-temperature phase. Consequently, austenite may transform to several martensitic variants, the number of which depends on the change of symmetry during transformation. Generally, in a cubic-to-tetragonal transformation (5M case) three variants can form with the c-axis oriented close to the three main cubic axes of austenite. However, close examination of the high resolution EBSD mapping reveals that more than just three orientations, as expected from the Bain model, exist in Ni50Mn29Ga21. Each of three Bain variants may be split in some twin relations in different regions of the sample which differ from each other by about few degrees creating a much higher number of variants. The training process, as the last step in the preparation procedure of Ni-Mn-Ga alloys, consists of multi-axis compression finally leading to a single-variant state. Compression of polycrystalline samples leads to motion of those twin boundaries changing the volume fraction of particular martensitic variants in such a way that the shortest axis (c-axis) becomes preferentially aligned parallel to the compression axis. It allows reducing the twinning stress and maximizing the twinning strain. To understand the training process in more detail, the interaction of the twin variants with the neighbourhood of parent austenite grains was investigated.

Det finns tydliga rekommendationer för att värmeöverförande vinyl kan appliceras på polyester- eller bomullstextilier och hur lång tid med vilken temperatur man ska använda. Men det finns ingen information att hitta om hur resultatet blir om man applicerar vinylen på andra texturer än släta ytor eller värmekänsliga material. Syftet med denna studie är att undersöka vad som sker med det estetiska uttrycket och hur man kan applicera värmeöverförande vinyl på olika textila material med ett hållbart resultat. Undersökningen är uppdelad i två faser där första delen undersöker om det är möjligt att få vinylen att fästa på olika texturer och material. I detta experiment visar resultatet att det är möjligt och att rekommendationerna för vinylen bör vidgas men att det går diskutera vidare vad som är ett hållbart resultat. I den andra delen har jag tittat på de estetiska aspekterna där jag undersökt hur vinylens uttryck påverkats av textilens textur. Resultatet visar att vinylen påverkas av textilen, inte bara av dess textur utan även beroende på hur tunn eller tjock textilen är. Genom att välja olika typer av textiler kan man påverka vinylens uttryck, om den är tung/lätt, blank/matt eller slät/ojämn.

WE43 magnesium foils (thickness ≤ 200 μm) were successfully produced via hot rolling. The initially extruded material was heat treated at 450 °C for 2 h to achieve a more homogenous microstructure. Afterwards the sheets were hot rolled at 480 °C in two to five rolling passes to achieve a thickness less than 200 μm and finally heat treated (T5 and T6 heat treatment). Microstructural und texture evolution after foil rolling and the final heat treatment were investigated and the resulting mechanical properties were also evaluated. Therefore, the samples were quenched directly after foil rolling and the final heat treatment. The foil rolling led depending on the number of the rolling passes either to a deformation microstructure (two and three passes) or globular grains (four and five passes).

WE43 magnesium foils (thickness ≤ 200 μm) were successfully produced via hot rolling. The initially extruded material was heat treated at 450 °C for 2 h to achieve a more homogenous microstructure. Afterwards the sheets were hot rolled at 480 °C in two to five rolling passes to achieve a thickness less than 200 μm and finally heat treated (T5 and T6 heat treatment). Microstructural und texture evolution after foil rolling and the final heat treatment were investigated and the resulting mechanical properties were also evaluated. Therefore, the samples were quenched directly after foil rolling and the final heat treatment. The foil rolling led depending on the number of the rolling passes either to a deformation microstructure (two and three passes) or globular grains (four and five passes).

No description available.

Energy dissipation, fuel consumption, real-estate property prices and health issues are some of the aspects related to the tyre/pavement interaction and its functional properties of rolling resistance and noise. The first two aspects are affected by the tyre/road interaction as energy is dissipated mostly by hysteretic losses as the tyre is subjected to dynamic deformations when contacting the pavement surface. The other effect of this contact system that is analysed in this thesis is noise. Excessive noise exposure leads to a decrease in real-estate property values and even health issues such as increased blood pressure, sleep disturbance, cognitive impairment in children, among others. To mitigate such issues, a good understanding of the underlying causes is crucial and therefore a holistic approach was used to analyse the contact interaction in a more comprehensive way, encompassing the pavement, tyre, environmental and contact media (contaminations). Both noise and rolling resistance were analysed after subjecting the contact system to controlled interventions in one variable while maintaining the other variables constant and then comparing to a reference condition. In the first part of the investigative work, different tyres were tested while maintaining the pavement, environment and contact media constant, allowing an evaluation of the impact of winter tyres on noise and rolling resistance. In the second part, an intervention in the pavement was applied while maintaining the other variables constant. allowing an evaluation of the impact of surface grinding on noise and rolling resistance. The first part quantified how noisier studded tyres are in comparison to non-studded tyres, yet no substantial difference in rolling resistance was found. The second part revealed the potential of the horizontal grinding to reduce noise and rolling resistance, having a limitation, on the duration of such effects, especially for Swedish roads where studded tyres are used. / Energiförluster, bränsleförbrukning, fastighetspriser och hälsoproblem är några av de effekter som följer av däckens interaktion med vägytan och som relaterar till de funktionella egenskaperna för rullmotstånd och buller. De första två effekterna uppkommer av väg- och däckinteraktionen eftersom energi förbrukas mestadels genom hysteresförluster när däcken utsätts för dynamiska deformationer vid kontakt med vägytan. Den andra effekten av däck/vägkontakten som analyseras i avhandlingen är buller. Alltför hög bullerexponering intill boendemiljöer leder till minskning av fastighetspriser och även till hälsoproblem såsom ökat blodtryck, sömnstörning, kognitiv försämring hos barn, med mera. För att mildra sådana problem, är det avgörande att ha en god förståelse av de bakomliggande orsakerna, och därför används här ett helhetsgrepp för att genomföra en mer omfattande analys av interaktionen. Analysen inkluderar egenskaper hos vägytan, däcken, omgivande miljö samt kontaktmedier (förorenande skikt).. Både buller och rullmotstånd har analyserats efter att på ett kontrollerat sätt ha varierat en viss variabel medan de andra variablerna hållits konstanta, och sedan jämföra resultaten med referensförhållandet. I den första delen av denna undersökning provades flera olika däck medan vägytan, miljö- och kontaktmedier hölls konstanta. Detta möjliggjorde en utvärdering av effekterna av olika vinterdäck på rullmotstånd och buller. I den andra delen beskrivs effekter av en förändring av vägytan, utförd genom att slipa bort topparna i vägtexturen, medan de andra variablerna hålls konstanta.. Den första delen kvantifierar bullerökningen vid användning av dubbdäck i jämförelse med odubbade vinterdäck. Några betydande skillnader i rullmotstånd hittades däremot inte mellan de två däckgrupperna. Den andra delen av texten visar på potentialen av horisontell slipning för att minska buller och rullmotstånd, dock är varaktigheten begränsad; särskilt för svenska vägar där dubbdäck används. / <p>QC 20180212</p>

In this study polycrystalline NiAl has been subjected to torsion deformation. Torsion has been used because of its characteristics. By this deformation mode high shear strains (gamma = 18 in this study) can be imposed on the sample. The deformation conditions are well-defined because of the local deformation mode, which is simple shear. Due to the monoclinic sample symmetry one half of the pole figure is needed in order to obtain the complete texture information, which is more than is needed e.g. by extrusion or rolling. Therefore, texture analysis might be more sensitive with respect to texture components. Furthermore, torsion deformation is characterized by being inhomogeneous in terms of the amount of shear strain and shear strain rate along the sample radius. The shear strain gradient makes the analysis of different stages of deformation on the same sample (i.e. under the same deformation conditions) possible. Another characteristic being special for torsion is that samples change their length, although no axial stress is applied. This effect is known as Swift effect and will be analyzed in detail. The deformation, microstructure and texture development subject to the shear strain are studied by different techniques (Electron Back-Scatter and High Energy Synchrotron Radiation). Beside the development of microstructure and texture with shear strain, the effect of an initial texture as well as the deformation temperature on the development of texture and microstructure constitute an important part of this study. Therefore, samples with three different initial textures were deformed in the temperature range T = 700K – 1300K. The development of the microstructure is characterized by two different regimes depending on the deformation temperature T. For T up to 1000K, continuous dynamic recrystallization (CDRX) takes place. This mechanism leads to the deformation-induced dislocations forming low angle grain boundaries (LAGBs) or being incorporated into them and the successive transformation of these boundaries into high angle grain boundaries (HAGBs) by a further increase of their misorientation. The predictions of this model were compared with the experimental results. The shear stress – shear strain curves are characterized by a peak at low strains, which is followed by softening and a steady state at high strains. This condition is fulfilled for a number of samples, but especially &amp;lt;111&amp;gt; oriented samples do not show a softening stage at low temperatures. Grain refinement takes place for all samples and the average grain size decreases with temperature. The predicted LAGB decrease is in best agreement with the experiments at the lowest temperatures (T = 700K and 800K). Deviations from the model can be explained by the temperature dependence of the grain boundary mobility. For temperatures T &amp;gt; 1000K, discontinuous dynamic recrystallization (DDRX) occurs, by which new grains form by nucleation and subsequent growth. The texture is characterized by two components, {100}&amp;lt;100&amp;gt; (cube, C) and {110}&amp;lt;100&amp;gt; (Goss, G). The intensity of G increases with temperature, while that of C decreases independent of the initial orientation. Both components have their maximum deviated about the 1 axis. The deviation is larger for grains containing the C component and decreases with temperature. Grains containing the G component have the smaller deviation, which decreases with temperature and strain. Texture simulations based on the full constraint Taylor model under the assumption of {110}&amp;lt;100&amp;gt; and {110}&amp;lt;110&amp;gt; slip were done with the experimental &amp;lt;110&amp;gt; and &amp;lt;111&amp;gt; fibres as well as a theoretical &amp;lt;100&amp;gt; fibre and a {100}&amp;lt;100&amp;gt; single orientation (ideal as well as rotated about the torsion axis). The G component is predicted by the simulations and is therefore a deformation texture. However the C component does not appear in the simulation. It therefore must originate by different mechanisms. For the non-&amp;lt;100&amp;gt; oriented samples, possibly nucleation is responsible for the formation of C oriented nuclei. Simulations with single orientations lead to the conclusion, that the ideal C orientation rotates about the 1 axis, while other C orientations, which are rotated about the torsion axis, increasingly converge towards the G component with strain. A single G orientation on the other hand is stable against such a rotation and is therefore the most likely steady state texture. Based on these results it is proposed, that ideally C oriented nuclei rotate until an orientation is reached into which they grow. These new grains are further rotated up to a critical angle, at which a part of them disappears either by adjacent grains or new C oriented nuclei. The recrystallization texture for T &amp;gt; 1000K is most likely the C component as well. Torsional creep of NiAl is characterized by a stress exponent, which depends on temperature and an activation energy, which is stress dependent. A model incorporating both dependencies is proposed and applied to the creep data. It is shown that these equations are able to describe the experimental findings. Thus creep of NiAl based on this model is dominated by non-diffusional processes such as cross slip of &amp;lt;100&amp;gt; screw dislocations for T  1000K. For T &amp;gt; 1000K the stress exponent and the activation energy are in a region, which according to previous reports is rather dominated by dislocation-climb controlled creep. The Swift effect, due to which samples change their axial dimension during torsion without applied axial stress, is observed for NiAl. It is strongly related to the texture development and in the case of NiAl the C component is identified as being responsible for shortening, whereas the G component leads to lengthening as long as it is not aligned with the shear system. Both tendencies can be explained based on the active slip systems. Simulations fail to predict the experimental observation, because the C component is not present. HESR and EBSD were compared with respect to local texture measurements. It was concluded depending on the average grain size HESR has an advantage in terms of grain statistics. For DDRX samples however, both methods are limited. Local texture inhomogeneities can be better detected using EBSD, whereas for an overall local texture information HESR is better suited.

The late Variscan rapid extrusion of ultra-high pressure metamorphic rocks into a preexisting nappe stack is the striking feature of the Erzgebirge, N-Bohemian Massif. Complex deformation increments, the large scatter of orientation and geometry of the finite strain ellipsoid as well as partly inverted metamorphic and age profiles are controversially discussed. Structural analysis and geothermobarometry show that deeply buried continental crust emplaced under transpression with horizontal σ1 (NNW-SSE) and σ3 stress axes. Thereby, west-directed lateral escape of isothermally exhumed high-pressure units led to the formation of an exhumation channel. The pervasive fabric of quartz-feldspar rocks formed between 400–650 °C. Based on Ar-Ar geochronology, the deformation in the exhumation channel is framed between 340 and 335 Ma. This preliminary results allow a modern texture analysis of natural shear zones, i.e. electron back scattering and neutron diffraction of quartz from shear zones of the exhumation channel. Because of an extensive and complex dataset, the crystallographic orientation of quartz is statistically analysed. I applied multidimensional scaling of the error between orientation density functions to visualize quartz textures together with additional microstructural features. I show that the temporal coexistence of two crystallographic orientation endmembers is the exclusive result of varying strain rates and differential stress. This thesis combines for the first time crystallographic textures of the Erzgebirge with modern plate tectonic concepts of the European Variscan orogeny.:Table of contents PREFACE Channel exhumation models in collisional Orogens Texture evolution of quartz in orogenic shear zones The structure of the thesis PART 1: THE EXHUMATION CHANNEL OF THE ERZGEBIRGE: GEOLOGICAL CONSTRAINS 1 Introduction 2 Geological Setting 2.1 The Variscan orogeny 2.2 The Saxo-Thuringian Zone as part of the European Variscides 2.3 Tectonics – constraints for an exhumation channel (<340 Ma) 3 Methods and Data processing 3.1 Field work, sample collection and selection 3.2 Geochemistry 3.3 MLA 3.4 EMP analyses and pressure-temperature estimations 3.5 Ar-Ar dating 3.6 Ar-Ar data handling and statistical treatment 4 Results 4.1 Geochemistry and Mineral Content of the Channel Rocks 4.2 Tectonics of the exhumation channel 4.2.1 Mica schists – roof of the channel 4.2.2 Paragneisses and Orthogneiss (type 1) 4.2.3 Orthogneiss (mgn) 4.2.4 Orthogneiss (type 2) – footwall of the channel 4.3 Petrology and Mineral chemistry 4.3.1 Garnet 4.3.2 Plagioclase 4.3.3 White mica 4.3.4 Biotite 4.4 Geothermobarometry 4.5 40Ar/39Ar – geochronology 4.5.1 Step heating 4.5.2 Single grain fusion 4.5.3 Ar-Ar and mineral chemistry 4.5.4 Ar-Ar and structural geology 5 The tectonometamorphic evolution of the exhumation channel 5.1 Local change in finite strain ellipsoid orientation 5.2 Evidence for advective heat transfer during exhumation 5.3 Position of the gneiss complex Reitzenhain-Catherine 5.4 Do Ar-Ar ages of the Erzgebirge represent cooling or recrystallization? 6 The channel model 6.1 Pre-channel stage – subduction 6.2 Channel stage – lateral extrusion 6.3 Post-channel stage – extensional doming 7 The Constrains for Texture analyses in a channel-type exhumation shear zone PART 2: QUARTZ TEXTURE AND MICROSTRUCTURAL EVOLUTION IN A CHANNEL-TYPE EXHUMATION SHEAR ZONE 1 Introduction 2 State of the Art 2.1 Dynamic recrystallization mechanism in quartz. 2.2 Texture evolution from natural and experimental deformed quartz 2.3 Quartz c-axis and textures in the Erzgebirge 3 Sample description 3.1 Mineral content 3.2 Quartz microstructures 3.2.1 Type 1 – Predominance of GBM 3.2.2 Type 2 – GBM overprints SGR 3.2.3 Type 3 – Equal ratio of GBM and SGR 3.2.4 Type 4 – Predominance of SGR 4 Methods 4.1 Time of Flight data processing and analysis 4.2 EBSD data processing and analysis 4.3 Multidimensional scaling 5 Results 5.1 Pole figure geometry 5.2 Multidimensional scaling 5.3 Texture properties and recrystallization 5.4 Grain and sample properties 5.5 Intragranular misorientation 5.6 Subgrain misorientation axes, slip systems and Schmid factor 6 Discussion 6.1 The dependence of quartz content and distribution and the particular CPO 6.2 The context between grain sizes, shape preferred orientation (SPO) and crystal preferred orientation (CPO) 6.3 Active slip systems during ductile quartz deformation 6.4 Recrystallization mechanism and texture 7 Conclusions GENERAL CONCLUSIONS REFERENCES APPENDIX A Isochemistry during metamorphism B Confidentiality of the PT estimations C Discrepancy of WPA and WMA D Appendix Figures E Appendix Tables

The research work in this thesis has been devoted to understand the formation mechanism of single-crystalline and textured polycrystalline nanoparticles and nanoflakes of SmCo5 and Nd2Fe14B prepared by surfactant-assisted (SA) ball milling and to study their microstructural and magnetic properties. The nanoparticles and nanoflakes are promising candidates to be used as hard magnetic phase for the fabrication of high-energy-density exchange-coupled nanocomposite magnets. The influence of a range of different surfactants, solvents and milling parameters on the characteristics of ball-milled powder has been systematically investigated. Small fraction (~10 wt.%) of SmCo5 nanoparticles of average diameter 15 nm along with textured polycrystalline nanoflakes of average diameter 1 µm and average thickness of 100 nm were obtained after SA – ball milling of SmCo5 powder. Isolated single-crystalline particles (200-500 nm) and textured polycrystalline flakes (0.2-1.0 µm) of Nd2Fe14B have been prepared in bulk amount (tens of grams), after SA – ball milling of dynamic-hydrogen-disproportionation-desorption-recombination (d-HDDR) processed Nd2Fe14B powder. These single-crystalline Nd2Fe14B particles are promising for their microstructure for the fabrication of exchange-coupled nanocomposite permanent magnets. The SmCo5 and Nd2Fe14B flakes and particles were well aligned in magnetic field: the former showed [001] out-of-plane orientation while the latter showed [001] in-plane orientation. A maximum degree of texture values of 93 % and 88 % have been obtained for the magnetically-oriented SmCo5 flakes and Nd2Fe14B single-crystalline particles, respectively. SA – ball milling resulted in an increase of coercivity of SmCo5 particles from 0.45 T for un-milled powder to a maximum value of 2.3 T after 1 h of milling, further milling resulted in a decrease of the coercivity. The coercivity of SA – ball-milled Nd2Fe14B particles decreased drastically from 1.4 T for un-milled d-HDDR powder to 0.44 T after 0.5 h of milling, isolated single-crystalline particles (200-500 nm size) obtained after 4 h of SA – ball milling showed a coercivity of 0.34 T. The drastic decrease in coercivity of ball-milled Nd2Fe14B particles is attributed to the morphological change because the demagnetization in Nd2Fe14B magnets is governed by nucleation mechanism. A remarkable enhancement in coercivity from 0.26 T to 0.70 T for ethanol-milled sample and from 0.51 T to 0.71 T for oleic-acid-milled samples has been obtained after an optimum heat-treatment at 400 0C. An increase of α-Fe and Nd2O3 phase contents and a sharp change of lattice parameter c of Nd2Fe14B was observed when heat-treating above 400 0C. The change in lattice parameter at higher temperature is thought to be due to partial substitution of carbon atoms present in the surfactant or solvent, for boron atoms. / Das Ziel dieser Arbeit ist es, den Mechanismus der Herstellung von einkristallinen und texturierten polykristallinen Nanopartikeln und Nanoflakes aus SmCo5 und Nd2Fe14B durch Tensid-gestütztes Kugelmahlen zu verstehen. Des Weiteren soll deren Gefüge und magnetische Eigenschaften untersucht werden. Die Nanopartikel sind vielversprechende Kandidaten zur Verwendung als hartmagnetische Phase in hochentwickelten, austauschgekoppelten Nanokomposit-Magneten. Der Einfluß der Art der verwendeten Tensid, Lösungsmittel sowie Mahlparameter auf die Eigenschaften der kugelgemahlenen Pulver wurde systematisch untersucht. Ein kleiner Anteil (~10 m.%) von SmCo5 Nanopartikeln mit mittlerem Durchmesser von 15 nm zusammen mit texturierten polykristallinen Plättchen mit mittlerem Durchmesser von 1 µm und mittlerer Dicke von 100 nm wurden nach Tensid-gestütztes Kugelmahlen erzeugt. Alleinstehende einkristalline Partikel (200-500 nm) und texturierte polykristalline Plättchen (0,2-1,0 µm) aus Nd2Fe14B wurden in größeren Mengen (einige 10 g) hergestellt. Das verwendete Ausgangspulver wurde hierbei durch dynamisches-Hydrierung-Disproportionierung-Desorption-Rekombination (d-HDDR) hergestellt und anschließend Tensid-gestütztes Kugelmahlen. Die genannten einkristallinen Nd2Fe14B Partikel sind ebenfalls vielversprechend als hartmagnetischer Bestandteil von austauschgekoppelten Nanokomposit-Magneten. Die SmCo5- und Nd2Fe14B-Plättchen und -Partikel wurden alle in einem Magnetfeld ausgerichtet: erstere zeigten aus der Ebende herauszeigende und letztere in der Ebene liegende [001]-Orientierung. Ein maximaler Texturgrad von 93% wurde für im Magnetfeld ausgerichtete SmCo5 flakes bzw. 88% für einkristalline Nd2Fe14B Partikel erzielt. Tensid-gestütztes Kugelmahlen führte zu einem Anstieg der Koerzitivfeldstärke von SmCo5 Partikeln von 0,45 T für ungemahlenes Pulver auf 2,3 T nach einer Mahldauer von 1 h. Weiteres Mahlen führte zu einem Abfall der Koerzitivfeldstärke. Die Koerzitivfeldstärke von Tensid-gestütztes Kugelmahlen Nd2Fe14B Partikeln verringerte sich stark von 1,4 T von ungemahlenem d-HDDR Pulver auf 0,44 T nach 0,5 h Mahlen. Freistehende einkristalline Partikel (200-500 nm groß), welche nach 4 h Tensid-gestütztes Kugelmahlen erhalten wurden, zeigten eine Koerzitivfeldstärke von 0,34 T. Der starke Abfall der Koerzitivfeldstärke von gemahlenen Nd2Fe14B Partikeln wird die morphologischen Veränderungen zurückgeführt, da die Ummagnetisierung nukleationsgesteuert ist. Ein bemerkenswerter Anstieg der Koerzitivfeldstärke von 0,26 T auf 0,70 T wurde für eine in Ethanol gemahlene Probe verzeichnet, sowie ein Anstieg von 0,51 auf 0,71 T für eine Probe, welche mit einer Zugabe von Oleinsäure gemahlen wurde. Beide Proben wurden einer optimierten Wärmebehandlung bei 400°C unterzogen. Bei höheren Temperaturen wurde für Nd2Fe14B ein Anstieg der Menge an α-Fe und Nd2O3 gefunden und eine sprungartige Veränderung des Gitterparameters c der Nd2Fe14B Phase. Die Veränderung des Gitterparameters wird auf die partielle Substitution von Kohlenstoffatomen des Tensid oder Lösungsmittels gegen Boratome zurückgeführt.

In this study polycrystalline NiAl has been subjected to torsion deformation. Torsion has been used because of its characteristics. By this deformation mode high shear strains (gamma = 18 in this study) can be imposed on the sample. The deformation conditions are well-defined because of the local deformation mode, which is simple shear. Due to the monoclinic sample symmetry one half of the pole figure is needed in order to obtain the complete texture information, which is more than is needed e.g. by extrusion or rolling. Therefore, texture analysis might be more sensitive with respect to texture components. Furthermore, torsion deformation is characterized by being inhomogeneous in terms of the amount of shear strain and shear strain rate along the sample radius. The shear strain gradient makes the analysis of different stages of deformation on the same sample (i.e. under the same deformation conditions) possible. Another characteristic being special for torsion is that samples change their length, although no axial stress is applied. This effect is known as Swift effect and will be analyzed in detail. The deformation, microstructure and texture development subject to the shear strain are studied by different techniques (Electron Back-Scatter and High Energy Synchrotron Radiation). Beside the development of microstructure and texture with shear strain, the effect of an initial texture as well as the deformation temperature on the development of texture and microstructure constitute an important part of this study. Therefore, samples with three different initial textures were deformed in the temperature range T = 700K – 1300K. The development of the microstructure is characterized by two different regimes depending on the deformation temperature T. For T up to 1000K, continuous dynamic recrystallization (CDRX) takes place. This mechanism leads to the deformation-induced dislocations forming low angle grain boundaries (LAGBs) or being incorporated into them and the successive transformation of these boundaries into high angle grain boundaries (HAGBs) by a further increase of their misorientation. The predictions of this model were compared with the experimental results. The shear stress – shear strain curves are characterized by a peak at low strains, which is followed by softening and a steady state at high strains. This condition is fulfilled for a number of samples, but especially &amp;lt;111&amp;gt; oriented samples do not show a softening stage at low temperatures. Grain refinement takes place for all samples and the average grain size decreases with temperature. The predicted LAGB decrease is in best agreement with the experiments at the lowest temperatures (T = 700K and 800K). Deviations from the model can be explained by the temperature dependence of the grain boundary mobility. For temperatures T &amp;gt; 1000K, discontinuous dynamic recrystallization (DDRX) occurs, by which new grains form by nucleation and subsequent growth. The texture is characterized by two components, {100}&amp;lt;100&amp;gt; (cube, C) and {110}&amp;lt;100&amp;gt; (Goss, G). The intensity of G increases with temperature, while that of C decreases independent of the initial orientation. Both components have their maximum deviated about the 1 axis. The deviation is larger for grains containing the C component and decreases with temperature. Grains containing the G component have the smaller deviation, which decreases with temperature and strain. Texture simulations based on the full constraint Taylor model under the assumption of {110}&amp;lt;100&amp;gt; and {110}&amp;lt;110&amp;gt; slip were done with the experimental &amp;lt;110&amp;gt; and &amp;lt;111&amp;gt; fibres as well as a theoretical &amp;lt;100&amp;gt; fibre and a {100}&amp;lt;100&amp;gt; single orientation (ideal as well as rotated about the torsion axis). The G component is predicted by the simulations and is therefore a deformation texture. However the C component does not appear in the simulation. It therefore must originate by different mechanisms. For the non-&amp;lt;100&amp;gt; oriented samples, possibly nucleation is responsible for the formation of C oriented nuclei. Simulations with single orientations lead to the conclusion, that the ideal C orientation rotates about the 1 axis, while other C orientations, which are rotated about the torsion axis, increasingly converge towards the G component with strain. A single G orientation on the other hand is stable against such a rotation and is therefore the most likely steady state texture. Based on these results it is proposed, that ideally C oriented nuclei rotate until an orientation is reached into which they grow. These new grains are further rotated up to a critical angle, at which a part of them disappears either by adjacent grains or new C oriented nuclei. The recrystallization texture for T &amp;gt; 1000K is most likely the C component as well. Torsional creep of NiAl is characterized by a stress exponent, which depends on temperature and an activation energy, which is stress dependent. A model incorporating both dependencies is proposed and applied to the creep data. It is shown that these equations are able to describe the experimental findings. Thus creep of NiAl based on this model is dominated by non-diffusional processes such as cross slip of &amp;lt;100&amp;gt; screw dislocations for T  1000K. For T &amp;gt; 1000K the stress exponent and the activation energy are in a region, which according to previous reports is rather dominated by dislocation-climb controlled creep. The Swift effect, due to which samples change their axial dimension during torsion without applied axial stress, is observed for NiAl. It is strongly related to the texture development and in the case of NiAl the C component is identified as being responsible for shortening, whereas the G component leads to lengthening as long as it is not aligned with the shear system. Both tendencies can be explained based on the active slip systems. Simulations fail to predict the experimental observation, because the C component is not present. HESR and EBSD were compared with respect to local texture measurements. It was concluded depending on the average grain size HESR has an advantage in terms of grain statistics. For DDRX samples however, both methods are limited. Local texture inhomogeneities can be better detected using EBSD, whereas for an overall local texture information HESR is better suited.