Structures in textured Cu-Al-Ni shape memory thin films grown by sputtering

C. ESPINOZA TORRES; A. M. CONDÓ; N. HABERKORN; E. ZELAYA; D. SCHRYVERS; J. GUIMPEL,; F. C. LOVEY.

MATERIALS CHARACTERIZATION

ELSEVIER SCIENCE INC

Lugar: Amsterdam; Año: 2014 vol. 96 p. 256 - 262

1044-5803

The structure and texture formation in Cu-Al-Ni thin films of different thicknesses (1 um to 5 um) grown by DC magnetron sputtering without any intentional heating of the substrate is reported. The as-grown films present grains with an average size of 20 nm. The films with thickness of 1 um have a single metastable phase with an hexagonal structure and are textured with planes (0002) parallel to the plane of the films. It was observed that thicker films present phase coexistence between metastable hexagonal and BCC structures with a gradual increment of the BCC phase fraction. The films with thickness of 5 um are textured with planes (0002) and in the hexagonal structure, whereas in the BCC structure the films are textured with {110}BCC planes parallel to the plane of the films. This fact can be associated with self-heating of the substrate during the growth of the films and with the relative stability of the metastable phases. Free standing films annealed in a second step (1123 K for 1 hour) present austenitic B phase with L21 structure and sub-micrometric grains textured with {220}L21 planes parallel to the plane of the films. The martensitic transformation temperature was determined from the analysis of resistance againsttemperature measurements.