Structural and phase transformations in thin film Ti-aluminides and Ti/Al multilayers

Conference · Tue Dec 31 04:00:00 EST 1996

OSTI ID:490758

Banerjee, R; Swaminathan, S; Wheeler, R; Fraser, H L ^[1]

---

1. Ohio State Univ., Columbus, OH (United States). Dept. of Materials Science and Engineering

Multilayered Ti/Al thin films (with nominally equal layer thickness of Ti and Al) have been sputter deposited on oxidized silicon substrates at room temperature. Transmission electron microscopy (TEM) and high resolution electron microscopy have been used to characterize the structure of these multilayers as a function of the layer thickness. Ti changes from an hcp to an fcc and back to an hcp structure on reduction of the layer thickness. Al too changed from an fcc to an hcp structure at a layer thickness of 2.5 nm. The observed structural transitions have been explained on the basis of the Redfield-Zangwill model. Subsequently Ti-aluminide thin films were deposited using a {gamma}-TiAl target. These films were found to be amorphous in the as-deposited condition with crystallites of {alpha}-Ti(Al) embedded in the amorphous matrix. On annealing under a protective Ar atmosphere at a temperature of 550 C, the Ti-aluminide film crystallized into a nanocrystalline two phase microstructure consisting of {gamma}-TiAl and {alpha}{sub 2}-Ti{sub 3}Al. The crystallization of the aluminide film has been investigated in detail by in-situ annealing experiments on a hot stage in the TEM. The results of this investigation have been discussed in this paper.

• OSTI ID: 490758
• Report Number(s): CONF-960401--; ISBN 1-55899-337-1
• Country of Publication: United States
• Language: English

Related Subjects

36 MATERIALS SCIENCE
ALUMINIUM ALLOYS
ANNEALING
CRYSTALLIZATION
DATA
INTERMETALLIC COMPOUNDS
PHASE STUDIES
PHASE TRANSFORMATIONS
THIN FILMS
TITANIUM ALLOYS