Regensburg 2004 – wissenschaftliches Programm
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M: Metallphysik
M 8: Phasenumwandlungen I
M 8.3: Vortrag
Montag, 8. März 2004, 15:15–15:30, H4
In situ observation of nucleation processes in Ti-V during phase separation — •Ingo Ramsteiner, Andreas Schöps, Harald Reichert, and Helmut Dosch — Max-Planck-Institut für Metallforschung, Heisenbergstr. 3, 70569 Stuttgart
Ti and V form a disordered bcc solid solution at high temperatures, which phase separates into various structures at low temperatures. We performed time resolved in situ x-ray measurements on the phase separation process in Ti2V3, TiV and Ti3V2 single crystals. High energy x-rays (70-80 keV) allow to penetrate bulk samples of more than 1 mm thickness in transmission geometry. Using a fast 2D detector system we resolve the evolution of the diffuse scattering on an almost flat plane in reciprocal space within seconds. Upon cooling the sample from the high temperature equilibrium phase into the miscibility gap we observe the formation and evolution of Bragg reflections indicating the nucleation of precipitates. The corresponding positions in reciprocal space allow to determine the alignment of the nuclei with respect to the parent lattice. The experiments demonstrate, that a controlled variation of the thermal history leads to nucleation of different structures.