Dresden 2017 – wissenschaftliches Programm
MM 52.2: Vortrag
Mittwoch, 22. März 2017, 17:15–17:30, IFW B
The applicability of grain boundary engineering on ultrafine grained Cu-Ni alloys — •Friederike Emeis, Martin Peterlechner, Harald Rösner, Sergiy V. Divinski, and Gerhard Wilde — Institute of Materials Physics, Westfälische Wilhelms-Universität Münster, D-48149
Grain boundary engineering (GBE) is a concept used to design a thermal stable microstructure by the introduction of special grain boundaries (Σ3-, Σ9-GBs) and their conjunctions. Due to the poor thermal stability of severely deformed materials, GBE is of interest to design an ultrafine grained and thermally stable microstructure with retained enhanced properties. In the present investigation, GBE is applied to severely deformed Cu-Ni alloys (including the pure end-members). Copper and nickel are completely miscible in the liquid and the solid state and thus the stacking fault energy (SFE) of the solid solutions also varies strongly and systematically for the different alloy compositions. The SFE is related to the tendency to undergo twinning (Σ3-GB). The annealing-induced microstructure evolution of the severely deformed Cu-Ni alloys is analyzed. Most of the concepts describing the microstructural behavior are only valid for pure materials. For the alloys, the concurrent effects from SFE and solid solution need to be considered. The data on the development of the GB structure and grain size lead to the conclusion that not only a small SFE but a second mechanism is important to prevent grain growth and to achieve a high fraction of suitable GBs. For Cu50Ni50 and Cu65Ni35 the microstructure was optimized.