Growth of TiNiHf shape memory alloy thin films by laser ablation of composite targets

Ti1yxNiHfx shape memory alloy thin films with Hf content up to 13.33 at.% were fabricated using a KrF excimer laser ablation system with different composite targets in high vacuum for the first time. As-deposited amorphous Ti36.63Ni50.04Hf13.33 thin film was annealed for crystallization. The phase transformation behaviors of the thin film were characterized by differential scanning calorimetry. Both the heating and cooling curves exhibited double endotherms and exotherms indicating the presence of R-phase during the phase transformation. The forward martensitic transformation temperature is 318C, which is consistent with the co-existence of high-temperature parent phase austenite.and the low-temperature phase martensite.at room temperature. The lower transition temperatures of the thin film compared with that of bulk material with the same composition was attributed to the refined grain size and the Ni content, which was slightly above 50 at%. The fabrication of TiNiHf shape memory alloy thin films by pulsed laser deposition will contribute to the successful development of microactuators. q1998 Elsevier Science B.V.