The effect of internal stress on thermal and mechanical properties of Ni–Nb–Zr thin film amorphous alloys

Abstract This study investigated the effect of initial internal stress on the thermal and mechanical properties of Ni–Nb–Zr thin film amorphous alloys (TFAAs) for MEMS devices. Samples with tensile and compressive stress and varying alloy compositions were prepared. Thermal properties were measured using differential scanning calorimetry and thermal mechanical analyzer, bulge and tensile tests assessed mechanical properties. Results showed that initial internal stress significantly influenced the β -relaxation temperature ( T β ), but not glass transition temperature ( T g ) or crystallization temperature ( T x ), which were dependent on alloy composition. The initial internal stress of TFAAs was almost relaxed by β -relaxation during heating. By contrast, the mechanical properties of as sputtered TFAA samples were affected significantly by the initial internal stress. However, annealing around T β diminished the initial internal stress effect. Therefore, precise control of internal stress and alloy composition is essential for optimizing the performance and reliability of Ni–Nb–Zr TFAAs in MEMS applications.