Dresden 2014 – wissenschaftliches Programm
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MM: Fachverband Metall- und Materialphysik
MM 34: Poster Session
MM 34.2: Poster
Dienstag, 1. April 2014, 18:00–20:00, P4
Grain boundary enthalpy changes by mechanical deformation of nanocrystalline alloys — •Michael Deckarm1, Jonathan Schäfer2, Patric Gruber3, Karsten Albe2, and Rainer Birringer1 — 1Universität des Saarlandes, FR 7.2 Experimentalphysik, 66123 Saarbrücken — 2Technische Universität Darmstadt, Fachbereich Material- und Geowissenschaften, Fachgebiet Materialmodellierung, 64281 Darmstadt — 3Karlsruher Institut für Technologie, Institut für Angewandte Materialien, 76344 Eggenstein-Leopoldshafen
In as-prepared nanocrystalline (nc) alloys, grain boundaries (gb) are usually in unknown local non-equilibrium configurations, reflecting the preparation history. However, a thermally activated recovery process below the onset temperature of grain growth permits a local equilibration of the gb and thus providing a well defined reference state.
Starting from this reference state we deformed nc (alloy) samples by uni-axial compression and investigated the change of gb enthalpy as a function of plastic strain by calorimetry.
The experimental findings are in large parts in excellent agreement with the results of a hybrid MD/MC simulation method for the same material.
Surprisingly, annealing leads to significantly increased yield stresses and narrowing of the microplastic regime in uniaxial compression tests. Obviously, the configurational state of the gb seems to significantly influence the overall mechanical behaviour of nc metals at the low end of the nanoscale.