In situ study of γ-TiAl lamellae formation in supersaturated α 2-Ti 3Al grains

Limei Cha*, Thomas Schmoelzer, Zaoli Zhang, Svea Mayer, Helmut Clemens, Peter Staron, Gerhard Dehm

*Corresponding author for this work

Research output: Contribution to journalArticlepeer-review

12 Scopus citations

Abstract

In situ heating transmission electron microscopy (TEM) was used to investigate the initial stage of γ-TiAl lamellae formation in an intermetallic Ti-45Al-7.5Nb alloy (in at.%). The material was heat treated and quenched in a non-equilibrium state to consist mainly of supersaturated, ordered α 2-Ti 3Al grains. Subsequently, specimens were annealed inside a TEM up to 750 °C. The in situ TEM study revealed that ultra-fine γ-TiAl laths precipitate in the α 2-matrix at ≈730 °C which exhibit the classical Blackburn orientation relationship, i.e. (0001)α 2//(111)γ and [$112̄0] α 2//<110]γ. The microstructural development observed in the in situ TEM experiment is compared to results from conventional ex situ TEM studies. In order to investigate the precipitation behavior of the γ-phase with a complementary method, in situ high energy X-ray diffraction experiments were performed which confirmed the finding that γ-laths start to precipitate at ≈730 °C from the supersaturated α 2- matrix.

Original languageEnglish
Pages (from-to)299-303
Number of pages5
JournalAdvanced Engineering Materials
Volume14
Issue number5
DOIs
StatePublished - May 2012
Externally publishedYes

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