Publication:
Microstructural characterization of TI-44AL-11NB in the chill-cast and directionally solidified configurations

Loading...
Thumbnail Image
Authors
Halladay, Timothy R.
Subjects
Gamma-Titanium-Aluminum Alloys
Niobium
Intermetallics
Microstructure
Scanning Electron Microscopy
Transmission Electron Microscopy
Advisors
Fox, Alan G.
Menon, Sarath
Date of Issue
1998-12-01
Date
Publisher
Monterey, California. Naval Postgraduate School
Language
en_US
Abstract
The microstructural evolution in chill-cast and directionally solidified Ti-44Al-11Nb (at.%) was studied by x-ray diffraction (XRD), scanning electron microscopy (SEM), and transmission electron microscopy (TEM) methods. From this data, the microstructural distribution and formation sequences of various phases like Al3Ti, TiAl, and Ti3Al were established. The elemental and phase distributions were determined by TEM with energy dispersive x-ray spectroscopy (EDX) and spectrum imaging. Both casting techniques produced the same phases, (Al3Ti, TiAl, and Ti3Al with some Nb in solid solution), but the microstructural distribution was markedly different. The chill-casting technique resulted in a coarser microstructure, with large gamma crystals and duplex regions of either (gamma + alpha2) or (gamma + Al3Ti) interspersed throughout the alloy. The directional solidification technique resulted in a much more uniform microstructure with fine lamellar grains in a dendritic macrostructure. Both casting techniques showed enrichment of niobium in interdendritic regions
Type
Thesis
Description
Series/Report No
Department
Mechanical Engineering
Other Units
Identifiers
NPS Report Number
Sponsors
Funder
Format
ix, 75 p.;28 cm.
Citation
Distribution Statement
Approved for public release; distribution is unlimited.
Rights
This publication is a work of the U.S. Government as defined in Title 17, United States Code, Section 101. Copyright protection is not available for this work in the United States.
Collections