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

TY - JOUR

T1 - In situ study of γ-TiAl lamellae formation in supersaturated α 2-Ti 3Al grains

AU - Cha, Limei

AU - Schmoelzer, Thomas

AU - Zhang, Zaoli

AU - Mayer, Svea

AU - Clemens, Helmut

AU - Staron, Peter

AU - Dehm, Gerhard

PY - 2012/5

Y1 - 2012/5

N2 - 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.

AB - 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.

UR - http://www.scopus.com/inward/record.url?scp=84860825672&partnerID=8YFLogxK

U2 - 10.1002/adem.201100272

DO - 10.1002/adem.201100272

M3 - 文章

AN - SCOPUS:84860825672

SN - 1438-1656

VL - 14

SP - 299

EP - 303

JO - Advanced Engineering Materials

JF - Advanced Engineering Materials

IS - 5

ER -