Dresden 2003 – wissenschaftliches Programm

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M: Metallphysik

M 19: Symposium: Phasenumwandlungen in Schmelzen VIII

M 19.3: Vortrag

Dienstag, 25. März 2003, 17:00–17:15, IFW A

Structural and mechanical characterization of Zr-based bulk metallic glass matrix composites containing dendritic bcc phase precipitates — •Uta Kuehn, Juergen Eckert, Norbert Mattern, Nicolle Radtke, and Ludwig Schultz — IFW Dresden, P.O. Box 270016, D-01171 Dresden

The microstructure of multicomponent ZrNbCuNiAl alloys with a glassy or a nanocrystalline matrix and ductile bcc precipitates has been studied by means of X-ray diffraction, optical microscopy, scanning and transmission electron microscopy. These alloys exhibit significantly improved mechanical behaviour compared to the monolithic glass, because the in-situ glass-matrix composite undergoes work hardening and plastic deformation prior to failure. Calculated changes in composition and cooling rate lead to different volume fractions and dendrite sizes of the bcc phase and hence to different values of yield strength, elastic and plastic strain. The higher the volume fraction of the ductile dendritic bcc phase, the higher the plastic strain and the lower the yield strength. The glassy or nanocrystalline structure of the matrix influences mainly the elastic strain limit of such composites. Nevertheless, surprisingly also a nanocrystalline matrix leads to high elastic strain values. Illustrated by the presented compositions and different cooling rates we show the possibility of obtaining tailored mechanical properties for such composite materials.