Dresden 2014 – wissenschaftliches Programm

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MM: Fachverband Metall- und Materialphysik

MM 6: Microstructure and Phase Transformations I - Martensitic phase transformations

MM 6.2: Vortrag

Montag, 31. März 2014, 10:30–10:45, IFW B

Composition-dependent atomic positions in Ti-Nb martensites — •Matthias Bönisch^1,2, Mariana Calin¹, Lars Giebeler^1,3, Arne Helth^1,3, Annett Gebert¹, Werner Skrotzki^1,2, and Jürgen Eckert^1,3 — ¹IFW Dresden, D-01069 Dresden, Germany — ²Technische Universität Dresden, Institute of Structural Physics, D-01069 Dresden, Germany — ³Technische Universität Dresden, Institute of Materials Science, D-01069 Dresden, Germany

In this work the influence of Nb addition on the structural characteristics of martensitic phases in the Ti-Nb system is studied in detail. The orthorhombic martensite alpha'' commonly observed in rapidly quenched beta-stabilized Ti-based alloys represents an intermediate structure between the hexagonal martensite alpha' found at low solute content and the bcc beta-phase present at high solute content. While the distortion of the orthorhombic unit cell by addition of beta-stabilizing atoms is well documented in literature, experimental data about the detailed atomic positions in dependence of chemical composition is missing. For this study we prepared a series of binary Ti-Nb alloys by casting techniques followed by homogenization treatment and water quenching. We used X-ray diffraction combined with Rietveld-based analyses to study the gradual structural changes of alpha' and alpha'' martensites effected by addition of Nb and determined their compositional boundaries. In case of orthorhombic alpha'' we found that besides the lattice parameters the locations of atoms on (002)alpha'' planes very sensitively respond to the amount of Nb present.