Martensitic transformation in thin-film (TiPd)50(TiNi)50

We have produced thin films of(TiPd)(50)(TiNi)(50) shape-memory alloy (SMA) by de magnetron sputtering at an elevated temperature. 'As-grown' films were crystalline, requiring no post-deposition anneal. A SMA film, approximately 1.5 mu m thick, grown on a Si(100) cantilever, approximately 80 mu m thick, showed a martensitic transformation near room temperature. The martensitic transformation was observed by measuring cantilever damping, cantilever bending and X-ray diffraction (XRD) patterns, all as functions of temperature. The XRD patterns indicated that the film was purely austenite (B2 phase) at high temperatures and was a mixture of austenite and martensite at low temperatures. Damping measurements suggest that the low-temperature martensite is a mixture of B19 and B19' phases. The transformation was reversible and exhibited a temperature hysteresis of approximately 25 degrees.