Papers by Author: R. Tamm

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Authors: Kurt Helming, R. Tamm, B. Fels
Authors: R. Hühne, B. Fels, R. Tamm, C.G. Oertel, Werner Skrotzki
Authors: R. Tamm, M. Lemke, C.G. Oertel, Werner Skrotzki
Authors: Werner Skrotzki, R. Tamm, C.G. Oertel
Authors: Werner Skrotzki, R. Tamm, Heinz Günter Brokmeier, Michael Oehring, Fritz Appel, Helmut Clemens
Authors: Werner Skrotzki, R. Tamm, Burghardt Klöden, C.G. Oertel, L. Wcislak, E. Rybacki
Authors: I. Hünsche, C.G. Oertel, R. Tamm, Werner Skrotzki, W. Knabl
Abstract: Recrystallization is an important tool to adjust the grain size and texture of polycrystalline materials in order to optimize their properties. In the present work recrystallization and the related changes of texture have been studied on rolled molybdenum sheets as a function of temperature and time. The microstructure was investigated by orientation contrast in a scanning electron microscope. The kinetics of recrystallization displayed in a JMAK plot yields Avrami coefficients decreasing with temperature from 2.5 to 1.1. The activation energy amounts to 5 eV, which agrees well with the volume self-diffusion coefficient. The textures of the sheet surface and central layer were measured by X-ray diffraction. The rolling texture in the centre of the sheets is characterized by a strong a-fibre with the rotated cube component {100}<110> dominating. Besides that, there exists a weak g-fibre. In contrast, the surface layer is characterized by a weak cube component. During recrystallization changes in texture are insignificant. With long annealing times all texture components tend to degrade. Conclusions regarding the deep-drawability are drawn.
Authors: Werner Skrotzki, K. Kegler, R. Tamm, C.G. Oertel
Abstract: Cast iron aluminides of three compositions were strongly deformed by hot extrusion and subsequently annealed. The texture development and kinetics of recrystallization were determined by local and global texture measurements. The deformation texture of Fe-10Al (A2 structure) is a <110>-fibre, Fe-35Al and Fe-50Al (B2 structure) show a <100>-<110> double fibre texture with <110> dominating Fe-35Al. The texture change with composition is due to a change in slip system. The deformed samples are partially dynamically recrystallized. The recrystallization components are aligned along the symmetry line <100>- <110> and towards <114> for Fe-10Al. For the other alloys the recrystallization texture is <111> with a tendency to <112>. The texture components do not change during static recrystallization. In general, the recrystallization texture is quite weak. The microstructure is very inhomogeneous ranging from deformed, strongly recovered to recrystallized areas. Beside primary recrystallization abnormal grain growth takes place. The heterogeneity of recrystallization makes it difficult to quantify the kinetics of recrystallization. The results are discussed with respect to the order of the alloys.
Authors: R. Tamm, A. Singh, V. Neu, K. Subba Rao, Werner Skrotzki, C.G. Oertel, S. Leinert, S. Fähler, Ludwig Schultz, B. Holzapfel
Abstract: Hard magnetic Sm-Co thin films were prepared on Cr buffered MgO(001) single crystals by pulsed laser deposition. The texture of the films as well as the magnetic properties were measured for films deposited at different temperatures. Sm-Co is a system with high uniaxial magnetic anisotropy, where the c-axis is the axis of easy magnetization. Thin films of this material, with high coercivity and remanence, are of increasing interest for application in magnetic miniature devices. To explore the potential of this permanent magnetic material, a strong texture with a wellaligned c-axis is required. Analysis of several pole figures shows that mainly two types of orientations develop which grow epitaxially on Cr. For one orientation, the c-axis lies n the sample surface parallel to Cr(110). The c-axis of the second orientiation is tilted by 60° out of the surface plane.
Authors: Werner Skrotzki, R. Tamm, R. Klemm, E. Thiele, C. Holste, H. Baum
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