Regensburg 2004 – wissenschaftliches Programm
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M: Metallphysik
M 15: Phasenumwandlungen III
M 15.2: Vortrag
Dienstag, 9. März 2004, 12:00–12:15, H16
Phase transition of Ni12at.%Al by plastic deformation — •Peter Drechsler1 and Ferdinand Haider2 — 1Abteilung für Funktionswerkstoffe der Medizin und Zahnheilkunde, Universität Würzburg, Pleicherwall 2, 97070 Würzburg — 2Lehrstuhl für Experimentalphysik I, Universität Augsburg, Universitätsstraße 1, 86159 Augsburg
The cyclic behavior of the stress response of polycrystalline Ni12at.%Al under lcf loading at mean plastic strain rates between 10−3 1/s and 10−1 1/s and temperatures between 298 K and 773 K shows after the inital hardening caused by the nucleation of psb either further hardening or saturation and softening. The behavior of the flow stress can be related to the particle size of the γ′-precipitates as tem investigation revealed. Depending on strain rate and temperature one can distinguish two ranges in which the average radius of the precipitates shrinks or grows. This effekt can be simulated by means of a model, that includes the shrinking of the precipitates by dislocation cutting as well as the deformation induced accelerated diffusion for the growth of the particles. The calculated values for the diffusion coefficient agree with values of Militizer et al. for the deformation induced vacancy production. The model predicts the values of the radii of the precipitates qualitatively and quantitatively. The tem investigation and the model clearly show the two ranges of shrinking and growth. The average particle grows with increasing temperature and decreasing strain rate.