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Investigation of the ordering and atomic site occupancies of Nb‐doped TiAl/Ti 3 Al intermetallics
Author(s) -
AlKassab Tala'at,
Yuan Yong,
Kluthe Christian,
Boll Torben,
Liu ZhiGuo
Publication year - 2007
Publication title -
surface and interface analysis
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.52
H-Index - 90
eISSN - 1096-9918
pISSN - 0142-2421
DOI - 10.1002/sia.2530
Subject(s) - materials science , intermetallic , transmission electron microscopy , alloy , phase (matter) , lamellar structure , crystallography , microstructure , atom probe , titanium alloy , titanium , field ion microscope , doping , atom (system on chip) , metallurgy , ion , chemistry , nanotechnology , optoelectronics , organic chemistry , computer science , embedded system
Titanium–aluminum alloys comprising mainly the TiAl‐phase and a small amount of the Ti 3 Al‐phase are promising candidates for application as high‐temperature materials. Alloying addition of Nb improves clearly the mechanical strength and the oxidation resistance of these alloys. A dual‐phase TiAl/Ti 3 Al alloy with additions of 5 at.%Nb was investigated in this study by means of field‐ion microscopy (FIM), tomographic atom probe (TAP) and transmission electron microscopy (TEM). It has been found that the structure of the two phases and the lamellar structure of the alloy were not seriously changed by the addition of 5 at.% Nb. The structural anisotropy of the TiAl phase along [100] and [001] directions, as revealed by FIM, was analyzed. FIM observations and atom probe analyses showed that Nb atoms in TiAl phase preferentially occupy Ti atomic sites. Preliminary reconstruction of the atomic stacking sequence perpendicular to [001] direction of the γ‐TiAl phase from the TAP measurements was demonstrated and is discussed. Copyright © 2007 John Wiley & Sons, Ltd.