Numéro |
J. Phys. IV France
Volume 112, October 2003
|
|
---|---|---|
Page(s) | 323 - 326 | |
DOI | https://doi.org/10.1051/jp4:2003893 |
J. Phys. IV France 112 (2003) 323
DOI: 10.1051/jp4:2003893
Martensitic transformation in nanostructured Fe-Ni alloys
Q. Meng, Y. Rong and T.Y. Hsu (Xu Zuyao)School of Materials Science and Engineering, Shanghai Jiao Tong University, Shanghai 200030, China
Abstract
In Fe-Ni thin films prepared by magnetron sputtering at room temperature, the bcc structure can exist stably in a larger range
of Ni-content than that in Fe-Ni equilibrium diagram. Furthermore, the experiment verified that the bcc structure forms directly
from collision of atoms during the sputtering process, rather than the product of fcc
bcc martensitic transformation. The starting temperature for bcc
fcc transformation in thin films is near to that of bulk Fe-Ni alloys. Theoretical calculations show that the nucleation barrier
of martensitic transformation and the critical size of the martensitic embryo increase with decreasing grain size within the
nanometer scale, implying that the martensitic transformation in nano-sized grains would be suppressed. Moreover, the autocatalytic
tendency of martensitic transformation is significantly weakened within a transformed grain or within its neighboring grain
due to the reduction of probability of martensite nucleation or the drop of the stress field at grain boundary produced by
martensitic transformation.
© EDP Sciences 2003