Molecular Dynamics Study On Freezing Process Of TiAl Thin Films

MEMS(Micro Electro-Mechanical Systems) has been widely used in many science and engineering activity areas such as data storage, display, automotive applications, wireless communications, environmental monitoring, medical and biochemistry and so on. Bimorph structures have many applications in various MEMS. The bimorph structures can be actuated in different mechanisms, either thermal, electrostatic, piezoelectric, or in other ways. TiAl alloy films can be used to replace pure Al film for the fabrication of bimorph actuators due to theirs large elastic modulus, hardness, temperature stability and small density.Microstructural changes of molten TiAl films with40A width are investigated by using molecular dynamics simulations within the framework of embedded atom method(EAM) during quenching and continuous cooling processes, and the mocrostructural changes of molten TiAl films respectively with20A、40A、60A and80A are also simulated during quenching. Atomic local structures in these films are analyzed on the atom average energy, pair distribution functions, and pair analysis technique. On quenching, the local structure changes in the TiAl films are involved in three stages, whereas these changes in two stages on continuously cooling. The film thickness has effect on the structural changes within the low quenched temperature regions on quenching, where HCP and icosahedron structures are presented differences.