Time-dependent mechanical behavior of phase-separated ZrCuTiTa thin films under nanoindentation

A series of Ta-modified amorphous ZrCuTi thin films were produced by magnetron sputter deposition techniques. Microstructural examination using transmission electron microscopy indicated that the Ta addition induced phase separation and resulted in two-phase glass structures. The composition and morphology (such as density, size, and volume fraction) of the second-phase structure were characterized. The mechanical properties, including modulus and hardness, were measured using a nanoindentation method and compared with the predictions from theoretical models. Nanoindentation creep experiments were also conducted to evaluate the viscoelastic response of the two-phase glasses. The characteristic relaxation time was found to be a function of the glass transition temperature. Its physical significance was discussed.