| Numéro |
J. Phys. Colloques
Volume 43, Numéro C4, Décembre 1982
ICOMAT-82International Conference on Martensitic Transformations |
|
|---|---|---|
| Page(s) | C4-597 - C4-601 | |
| DOI | https://doi.org/10.1051/jphyscol:1982494 | |
International Conference on Martensitic Transformations
J. Phys. Colloques 43 (1982) C4-597-C4-601
DOI: 10.1051/jphyscol:1982494
NEW NEUTRON SCATTERING MEASUREMENTS OF PREMARTENSITIC STATE OF Cu-Zn-Al
G. Guénin1, D. Rios Jara1, M. Morin1, L. Delaey2, 1, R. Pynn3 et P.F. Gobin11 Institut national des Sciences Appliquées de Lyon, L.A. 341, C.N.R.S., France
2 Katholieke Universiteit Leuven, Belgium
3 Institut Laue Langevin, Grenoble, France
Abstract
Some phonon dispersion curves have already been observed in β phase alloys which exhibit martensitic transformation (Au-Cu-Zn, Cu-Al-Ni, Cu-Zn-Al). The interesting feature is that the whole TA2 <110> branch is very low in energy. Furthermore an anomaly at q = 2/3 qBZ has been noticed which is possibly related to the low température 9R martensite. In the present work this branch was measured in β Cu-Zn-Al transforming in 2H and compared too the one of β Cu-Zn-Al transforming in 9R martensite. The anomaly at q = 2/3 qBZ is present in the two cases. The slope at q = 0 is higher for the β Cu-Zn-Al (2H) than for the β Cu-Zn-Al (9R) whereas the frequency at qBZ is smaller. On the β Cu-Zn-Al (9R) the phonons related to the possibly present ω-phase have been measured. The explored wave vector directions were <111> and <112>. The phonon dispersion surface shows a saddle point and no minimum at the location of ω phase in the reciprocal lattice. No "static" phase is detected, many possible locations in the reciprocal lattice have been explored. Fundamental differences are shown between the dynamical behaviour of b.c.c. alloys transforming into martensite and that of b.c.c. alloys transforming into ω-phase.