Berlin 2018 – scientific programme

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MM: Fachverband Metall- und Materialphysik

MM 22: Microstructure and Phase Transformations

MM 22.4: Talk

Tuesday, March 13, 2018, 11:00–11:15, TC 010

High-pressure torsion induced phase transformations in Cu- and Ti-based alloys — •Askar Kilmametov¹, Yulia Ivanisenko¹, Boris Straumal^1,2, Andrey Mazilkin^1,2, Mario Kriegel³, Olga Fabrichnaya³, David Rafaja³, and Horst Hahn¹ — ¹Karlsruhe Institute of Technology (KIT), Institute of Nanotechnology, Karlsruhe, Germany — ²Institute of Solid State Physics, Russian Academy of Sciences, Chernogolovka, Russia — ³TU Bergakademie Freiberg, Institute of Materials Science, Freiberg, Germany

Severe plastic deformation not only leads to grain refinement but also accelerates mass-transfer and drives phase transformations in Cu-based alloys. Dynamic equilibrium between decomposition of (supersaturated) solid solution and dissolution of precipitates during high pressure torsion (HPT) of diluted Cu-based alloys has been studied. The precipitation of second phase particles from a solid solution and their dissolution take place simultaneously and compete with each other. The formation of high-pressure ω-phase has been studied in Ti-based alloys. A defect-rich ω-phase forms after HPT and persists in the samples also after the pressure release. The amount of retained ω-phase after HPT depends on the alloying element concentration. Based on the XRD and TEM observations, the crystallography and mechanisms of α to ω and β to ω phases transformations (which can be diffusionless as well as controlled by mass transfer) are discussed.