Experiment and simulation of hot embossing of a bulk metallic glass with low pressure and temperature

The thermoplastic forming process of a bulk metallic glass (BMG) is simulated using commercial software DEFORM 3D and verified by hot-embossing experiment in this study. The fabrication process of micro-electro-mechanical systems (MEMS) includes a photoresist reflow technique, and Nickle-Cobalt (Ni-Co) electroplating to fabricate a first mold. Then, this mold is applied to hot emboss on an Mg-Cu-Y amorphous alloy to form a secondary mold. The thermal properties of the BMG material such as the glass transition temperature (T _g ) and the onset temperature (T_onset ) for the viscous flow are investigated using a differential scanning calorimetry (DSC) and a thermomechanical analyzer (TMA). The T_g of BMG is around 413 K (140°C). The hot-embossing temperature is set at 423 K (150°C). The supercooled liquid region ΔT between the T_g and the crystallization temperature (T_x) is the working temperature for the microforming study. This embossing process shows that the thermoplastic forming ability of the BMG material is better than polymethylmethacrylate (PMMA) which requires high hot-embossing pressure and temperature. BMG is not only a good material for the hot-embossing process to fabricate micro-structure directly, but also a fast-forming material for mold (or die) fabrication.