| Numéro |
J. Phys. IV France
Volume 112, October 2003
|
|
|---|---|---|
| Page(s) | 685 - 688 | |
| DOI | https://doi.org/10.1051/jp4:2003975 | |
J. Phys. IV France 112 (2003) 685
DOI: 10.1051/jp4:2003975
Stability of B2-type structure and martensitic transformation in Ti-Ni shape memory alloys
T. Fukuda1, T. Sakamoto1, T. Terai1, T. Kakeshita1 and K. Kishio21 Department of Materials Science and Engineering, Graduate School of Engineering, Osaka University, 2-1 Yamada-oka, Suita, Osaka 565-0871, Japan
2 Department of Applied Chemistry, Graduate School of Engineering, University of Tokyo, 7-3-1 Hongo, Bunkyo-ku, Tokyo 113-8666, Japan
Abstract
We have investigated electrical resistivity and magnetic susceptibility in a series of
Fe alloys, and observed their microstructure by electron microscopy, in order to know the phase stability of the B2-type structure.
Following results were obtained: (i) The B2-R transformation temperature decreases as the iron content increases, and disappears
in alloys with
. (ii) The alloy with
x=8 shows a negative temperature coefficient in electrical resistivity and an inflection point in the temperature dependence
of magnetic susceptibility curve, and these anomalies are suppressed as iron content increases and disappear completely in
alloys with
. (iii) The electron diffraction of the alloy with
x=8 shows 1/3
<110
> diffuse scattering, and its intensity increases as temperature decreases. Furthermore, the dark field image obtained from
the diffuse scattering show domain-like structure with its size smaller than 10mm. The results of (ii) and (iii) are related
to the instability of the B2-type structure in Ti-Ni based alloys. As for such origin, the Fermi-surface-nesting of the B2-type
structure with a vector
![$q=1/3[110]2\pi/a$](/articles/jp4/abs/2003/11/jp4pr10p685/img5.gif){kind=small}
is considered.
© EDP Sciences 2003