Thickness dependence of the martensitic transformation in textured Cu-Al-Ni thin films grown by sputtering on Si (001)

Abstract

We study the thickness influence on the martensitic transformation in Cu-Al-Ni thin films grown by sputtering on Si (001). Thin films with thicknesses between 0.1 μm and 2.25 mm were grown at 563 K. The analysis of the microstructure reveals a columnar growth with preferred orientation Cu-Al-Ni L21 (001)[100]//Si (001)[100]. The martensitic transformation is strongly suppressed for films thinner than 1.3mm, which can be related with an interfacial layer imposing restitutive forces. This is evidenced in the extended transformation / retransformation ranges and in the absence of hysteresis for 0.15 μm thick films.