Numerical investigation of the mechanical behaviour of shape memory bulk metallic glass composites

Bulk metallic glasses are a new type of advanced materials. They are characterized by their topologically disordered atomic structures. The lack of long-range translational symmetry in the atomic arrangement in bulk metallic glasses contributes to a range of unique and outstanding mechanical properties. For example, the yield strength of metallic glasses can be as large as twice that of corresponding crystalline alloys. However, the major issue to hinder metallic glasses application is the apparent brittleness. Unlike crystalline alloys, metallic glasses show abrupt failure with zero macroscopic plasticity. Various methods are being investigated in material engineering to improve the plasticity of bulk metallic glasses. The most recent progress is to develop shape memory bulk metallic glass composites, a combination of metallic glass and shape memory alloy. The large stress-induced transformation strain in shape memory alloy leads to the increase in the plasticity of the new composite material. The stress-strain behaviour of shape memory bulk metallic glass composites was investigated in this paper by using the finite element method. A unit cell model, which includes shape memory alloy phase and metallic glass phase, under uniaxial tension were numerically simulated. The effects of phase volume fraction, transformation stress and strain on the stress-strain behaviour of this new composite material were examined in this research.