Regensburg 2000 – scientific programme

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M: Metallphysik

M 10: Nanokristalle

M 10.5: Talk

Wednesday, March 29, 2000, 15:30–15:45, H6

On the Applicability of a Grain/interphase Boundary Sliding Controlled Superplastic Flow Model for the Deformation of Nanocrystalline Materials — •Subramshu Bhattacharya, Ulrich Betz, and Horst Hahn — Darmstadt University of Technology, Materials Science Department, Petersenstrasse 23, D-64287 Darmstadt

It is well known that superplastic deformation in conventional microcrystalline metals and alloys at temperatures above half the melting point is best explained when Grain/interphase Boundary Sliding (GBS) controls the rate of flow. Recently, a detailed model for GBS controlled superplastic deformation was presented in which the physics of the sliding process was considered. In this study, the high temperature deformation behaviour of some nanocrystalline materials have been analysed for the numerical validation of the model. Additionally, it was decided to apply this model to the low temperature deformation behaviour of a dense nanocrystalline ceramic, 5 mol. % yttria stabilised tetragonal zirconia. The dense sintered specimens were tested under tension and compression at different temperatures (around and below half the melting

point) and stress/strain rate levels for their deformation behaviour. It is shown that the model for GBS controlled flow is capable of describing the low temperature deformation behaviour in the nanocrystalline 5 mol. % yttria stabilised tetragonal zirconia ceramic.