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J. Phys. IV France
Volume 07, Numéro C5, November 1997
IVth European Symposium on Martensitic Transformations
Page(s) C5-221 - C5-226
IVth European Symposium on Martensitic Transformations

J. Phys. IV France 07 (1997) C5-221-C5-226

DOI: 10.1051/jp4:1997534

Coherent Subnanometric Plate Precipitates Formed during Crystallization of As-Sputtered Ti-Ni films

K. Ogawa1, T. Kikuchi1, S. Kajiwara1, T. Matsunaga2 and S. Miyazaki2

1  National Research Institute for Metals, 1-2-1 Sengen, Tsukuba 305, Japan
2  Institute of Material Sciences, Tsukuba University, Tennoudai, Tsukuba 305, Japan

It is shown by high resolution electron microscopy that coherent plate precipitates with 0.5-1 nm thickness are formed in Ti-rich Ti-Ni thin films when heat treated directly from the sputter-deposited amorphous state near the crystallization temperature. The precipitates are Ti-rich and formed on {100} planes of the B2 matrix phase with perfect coherency. The crystal structure of the precipitate is a body centered tetragonal with the c-axis normal to the habit plane. Owing to the existence of these coherent subnanometric precipitates, the parent phase is greatly strengthened, resulting in very excellent shape memory properties such as 6 % recoverable shape memory strain at the stress level of 300 MPa without any appreciable plastic deformation.

© EDP Sciences 1997