Nanoscaled superelastic behavior of shape memory alloy/metallic glass multilayered films

The mechanical properties of multilayered films with alternate layers of shape memory alloy (SMA) and metallic glass (MG) were studied. Specifically, TiNi SMA and ZrCuAlNi MG were deposited alternately on the Si substrate using magnetron sputtering. The as-deposited multilayered film was amorphous. The annealing temperature was chosen judiciously to crystalize TiNi layer while ZrCuAlNi layer remained amorphous. The superelastic behavior of SMA/MG multilayered film was characterized using nanoindentation tests. The stress required to induce martensitic transformation of TiNi layer increased as the thickness of TiNi layer decreased. Also, the multilayered SMA/MG films were found to have the better deformation recovery after indentation unloading which could be due to the synergy effects of superelasticity from SMA layers and high elastic strain limit from MG layers.