Orientación preferencial de granos y microestructura de láminas delgadas de aleaciones de Cu-Al-Ni.

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

Congreso; 10th Inter-American Congress of Electron Microscopy 2009; 2009

The preferential grain orientation and microstructure of CuAlNi shape memory alloy thin films was determined by transmission electron microscopy and X-ray diffraction. The shape memory effect in shape memory alloys is due to the martensitic transformation, in which a change in the crystalline structure takes place without diffusion. Films with a thickness of 5,3 ¦Ìm were grown by means of DC Magnetron Sputtering at room temperature on a substrate of Si(100). The target was prepared of Cu-26.9at%Al-5.5at%Ni. After grown, the films were removed from the substrate and encapsulated in quartz tubes under Ar atmosphere. They were annealed at 1023K during 3600s and quenched in water at room temperature. After a thermal treatment the martensitic transformation was measured by electrical resistometry. Transmission electron microscopy samples were electro-polished with double jet and also prepared using the focus ion beam technique in collaboration with the research group of the Institut f¨¹r Werkstoffe, RUB, Germany. Before the heat treatment [001] hexagonal (2H), [111]BCC and related martensitic orientations were the preferential orientations normal to the surface of the films. After the heat treatment, mainly the [110]B2 normal to the surface and related martensitic orientations were observed. This difference can be rationalized considering the crystallography of the martensitic transformation where the [110] B2 orientation is obtained from the [001] hexagonal orientation.