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Joo Hyun Park Sang-Beom Lee Henri R. Gaye 《Metallurgical and Materials Transactions B》2008,39(6):853-861
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S. Hata T. Nakano N. Kuwano M. Itakura S. Matsumura Y. Umakoshi 《Metallurgical and Materials Transactions A》2008,39(7):1610-1617
The ordering mechanism of long-period superstructures (LPSs) in Al-rich TiAl alloys has been investigated by high-resolution
transmission electron microscopy (HRTEM). The LPSs are classified in terms of arrangements of base clusters with different
shapes and compositions formed in Ti-rich (002) layers of L10-TiAl matrix: square Ti4Al, fat rhombus Ti3Al, and lean rhombus Ti2Al type clusters. The HRTEM observations revealed that antiphase boundaries of long-range-ordered LPS domains and short-range-ordered
microdomains are constructed by various space-filling arrangements of the base clusters. Such a microscopic property characterized
by the base clusters and their arrangements is markedly analogous to that of the
* special-point ordering alloys such as Ni-Mo.
This article is based on a presentation given in the symposium entitled “Materials Behavior: Far from Equilibrium” as part
of the Golden Jubilee Celebration of Bhabha Atomic Research Centre, which occurred December 15–16, 2006 in Mumbai, India.
相似文献
S. Hata (Associate Professor)Email: |
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J.V. Bernier J.-S. Park A.L. Pilchak M.G. Glavicic M.P. Miller 《Metallurgical and Materials Transactions A》2008,39(13):3120-3133
This article presents a quantitative strain analysis (QSA) study aimed at determining the distribution of stress states within
a loaded Ti-6Al-4V specimen. Synchrotron X-rays were used to test a sample that was loaded to a uniaxial stress of 540 MPa
in situ in the A2 experimental station at the Cornell High Energy Synchrotron Source (CHESS). Lattice-strain pole figures (SPFs)
were measured and used to construct a lattice strain distribution function (LSDF) over the fundamental region of orientation
space for each phase. A high-fidelity geometric model of the experiment was used to drastically improve the signal-to-noise
ratio in the data. The three-dimensional stress states at every possible orientation of each α (hcp) and β (bcc) crystal within the aggregate were calculated using the LSDF and the single-crystal moduli. The stress components varied
by 300 to 500 MPa over the orientation space; it was also found that, in general, the crystal stress states were not uniaxial.
The maximum shear stress resolved on the basal and prismatic slip systems of all orientations within the α phase,
was calculated to illustrate the utility of this approach for better identifying “hard” and “soft” orientations within the
loaded aggregate. Orientations with low values of which are potential microcrack initiation sites during dwell fatigue conditions, are considered hard and were subsequently
illustrated on an electron backscatter diffraction (EBSD) map.
This article is based on a presentation given in the symposium entitled “Neutron and X-Ray Studies for Probing Materials Behavior”
which occurred during the TMS Spring meeting in New Orleans, LA, March 9–13, 2008, under the auspices of the National Science
Foundation, TMS, the TMS Structural Materials Division, and the TMS Advanced Characterization, Testing, and Simulation Committee.
相似文献
M.P. Miller (Professor)Email: |
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