High pressure torsion induced structural transformations in Ti- and Zr-based amorphous alloys

Open School-Conference of NIS Countries Ultrafine Grained and Nanostructured Materials

Gunderov, D.V.^1,3 ; Boltynjuk, E.V.^2 ; Ubyivovk, E.V.^2 ; Churakova, A.A.^1,3 ; Abrosimova, G.E.^4 ; Sitdikov, V.D.^1 ; Kilmametov, A.R.^5 ; Valiev, R.Z.^1,2

Ufa State Aviation Technical University, 12 K. Marx str., Ufa

450008, Russia^1

Saint Petersburg State University, 28 Universitetskiy pr., Saint Petersburg

198504, Russia^2

Institute of Molecule and Crystal Physics - Subdivision, Ufa Federal Research Centre, Russian Academy of Sciences, Prospekt Oktyabrya 151, Ufa

450075, Russia^3

Institute of Solid State Physics, Russian Academy of Sciences, 2 Academician Ossipyan str., Chernogolovka, Moscow District

142432, Russia^4

Karlsruhe Institute of Technology (KIT), Institute of Nanotechnology, Hermann-von-Helmholtz-Platz 1, Eggenstein-Leopoldshafen

76344, Germany^5

关键词: Amorphous matrices;    Amorphous nanoclusters;    Bulk metallic glass;    Coordination sphere;    High pressure torsions;    Strain induced;    Structural transformation;    Zr-based amorphous alloys;   

Others  :  https://iopscience.iop.org/article/10.1088/1757-899X/447/1/012052/pdf
DOI  :  10.1088/1757-899X/447/1/012052

来源: IOP

【 摘 要 】

The melt-spun (MS) Ti50Ni25Cu25 alloy and the Zr62Cu22Al10Fe5Dy1 bulk metallic glass (BMG) were subjected to high pressure torsion (HPT). X-ray diffraction (XRD) measurements show a shift of the first diffraction halo to a low angle after HPT processing, which corresponds to an increase in the values of the radius of the first coordination sphere and the free volume. Direct density measurements confirmed an increase in free volume values. A special TEM procedure was used for a detailed study of the microstructure of both amorphous alloys after HPT processing. The study revealed the formation of a large density of shear bands (SBs) in both alloys. Nanocrystals are formed directly in shear bands as a result of strain-induced nanocrystallization. Amorphous nanoclusters with a size of 20 nm are formed in an amorphous matrix surrounding the SBs in the HPT-processed MS alloy Ti50Ni25Cu25. The formation of nanoclusters was not observed in BMG Zr62Cu22Al10Fe5Dy1 after HPT processing.