Berlin 2005 – wissenschaftliches Programm
Bereiche | Tage | Auswahl | Suche | Downloads | Hilfe
M: Metallphysik
M 3: Flüssige und amorphe Metalle II
M 3.2: Vortrag
Freitag, 4. März 2005, 11:45–12:00, TU H111
Mechanical properties of slowly cooled Zr-based composites containing dendritic bcc phase precipitates — •Nicolle Radtke1, Jürgen Eckert1,2, Uta Kühn1, and Ludwig Schultz1 — 1IFW Dresden, Institut für Metallische Werkstoffe, Postfach 270016, 01171 Dresden — 2TU Darmstadt, Institut für Physikalische Metallkunde, Petersenstr. 23, 64287 Darmstadt
We report about the microstructure, thermal stability and the mechanical properties of slowly cooled Zr-Nb-Cu-Ni-Al alloys with ductile bcc phase precipitates embedded in a glassy or a nanocrystalline matrix. The samples were prepared in form of rods by injection casting into a copper mould. The phase formation and the microstructure of the composite material are investigated by X-ray diffraction, EDX-analysis, scanning and transmission electron microscopy. The thermal stability was examined by differential scanning calorimetry and the mechanical behaviour was investigated by compression tests under quasistatic loading at room temperature and at higher temperatures. The formation of bcc phase dendrites and a glassy or a nanocrystalline matrix is strongly governed by the alloy composition and the actual cooling rate during solidification. Besides, changes in composition and cooling rate lead to different volume fraction and size of the bcc phase precipitates and, hence, to different values of yield strength, elastic and plastic strain. The formation of a nanocrystalline matrix depends on the melting temperature of the alloy and, hence, the cooling rate. Surprisingly, these sample exhibits higher yield strength and plastic strain than the samples containing an amorphous matrix.