Analysis of the thermomechanical behavior of Ti–Ni shape memory alloy thin films by bulging and nanoindentation procedures

TiNi shape memory alloy (SMA) thin films are deposited by r.f. magnetron sputtering. In order to characterize their mechanical behavior, bulging and nanoindentation tests are performed. These two tests are made at complementary length scales (from 10 to 1000 nm for nanoindentation and from 1000 nm to macroscopic scale for bulging) and the obtained results are consistent. Bulging leads to the reorientation of the platelets of a martensitic film. Nanoindentation induces martensitic transformation in an austenitic film, and a reorientation or the creation of a new phase from a martensitic one.