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MM: Fachverband Metall- und Materialphysik

MM 30: Topical session: Interface-Controlled Microstructures: Mechanical Properties and Mechano-Chemical Coupling - Structure and Deformation II

MM 30.3: Vortrag

Dienstag, 21. März 2017, 12:15–12:30, BAR 205

Grain boundary strain accommodation mechanisms in ultrafine-grained Pd — •Yulia Ivanisenko¹, Nariman A. Enikeev², and Kejing Yang³ — ¹Institute of Nanotechnology, Karlsruhe Institute of Technology, 76021 Karlsruhe, Germany — ²Institute of Physics of Advanced Materials, Ufa State Aviation Technical University, 450000 Ufa, Russia — ³Robert Bosch GmbH, AE/EAI2, D71701 Schwieberdingen, Germany

The role of non-crystallographic deformation modes such as grain boundary sliding and rotation in plasticity of ultrafine-grained materials (UFG) is still a matter of discussion. In general, it is assumed that such strain accommodation is considerable at grain sizes in the range of a few tens of nanometers while for the larger grains dislocation-based mechanisms operate. In situ SEM compression test was performed on UFG Pd sample with a mean grain size of 135 nm and orientations of statistically sound sampling of grains were monitored. In order to separate the effects related with dislocation slip, the modeling of the evolution of grain orientations under compression using the methods of crystal plasticity simulation were performed. The analysis of the results shows that grain boundary sliding and non-crystallographic grain rotations contribute considerably to the plasticity of UFG materials. The grains tend to slide and to rotate in a group mode, which testifies to collective character of grain boundary deformation mechanisms in UFG Pd. It was proposed that such grain rotations provide a mechanism for the accommodation of the strain incompatibility between neighboring grains arising during straining.