Berlin 2005 – wissenschaftliches Programm
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M: Metallphysik
M 32: Poster TU B (Symposium Tomographic Methods in Materials Research M-32.32-55)
M 32.47: Poster
Montag, 7. März 2005, 14:30–16:30, Poster TU B
Study of semi-solid casting and processing with X-ray phase-sensit ive tomography — •S. Zabler1, A. Haibel2, A. Rack2, A. Rueda1, H. Riesemeier3, G. Weidemann3, J. Goebbels3, and J. Banhart1,2 — 1Institut für Werkstoffe (TU), 10623 Berlin — 2Hahn-Meitner-Institut Berlin, Abteilung SF3, 14109 Berlin — 3Bundesanstalt für Materialforschung und -prüfung, 12205 B erlin
Alloys with a globular microstructure are the feedstock for industr ial components processed in the semi-solid state which requires thi xotropic behaviour of the melt. The fundamental link between alloy micros tructure and thixotropic breakdown, occuring when shear stress is a pplied, was first reported for Sn-Pb15 (Spencer 1972). During the past th ree decades thixo-processing has been established for a wide range of all oys but structural analysis remained however limited to metallography (2D images) and rheology (global measurement of viscosity as a function of s hear rate, temperature and shear time). Non-destructive three-dimensional structure analysis was first performed at the ESRF in 2000. It initiated a new rush for the investigation and modelling of the semi-solid casting process. In a first approach we use alloys with higher absorption contra st than common Al-Si in order to characterize the three-dimensional image s of dendritic and globular structures. Then we show recent e xperiments from the tomography setup of BAMline at the synchrotron BESSYII. The setup provides high spatial resolution using X rays with a partial spatial coherence thus allowing 3D phase-sensitive imag ing of neighbouring elements that are undistinguishable to absorption to mography.