COHERENT SUBNANOMETRIC PLATE PRECIPITATES FORMED DURING CRYSTALLIZATION OF AS-SPUTTERED TI-NI FILMS

It is shown by high resolution electron microscopy that coherent plate precipitates with 0.5-1 run thickness are formed in Ti-rich Ti-Ni thi n films when heat treated directly from the sputter-deposited amorphou s slate near the crystallization temperature. The precipitates are Ti- rich and formed on {100} planes of the B2 matrix phase with perfect co herency. The crystal structure of the precipitate is a body centered t etragonal with the c-axis normal to the habit plane. Owing to the exis tence of these coherent subnanometric precipitates, the parent phase i s greatly strengthened, resulting in very excellent shape memory prope rties such as 6% recoverable shape memory strain at the stress level o f 300 MPa without any appreciable plastic deformation.