Ti–Cu–Ni shape memory bulk metallic glass composites

Abstract New Ti–Cu–Ni shape memory bulk metallic glass composites were obtained by carefully controlling the cooling rate upon quenching. This allows for the formation of a metastable microstructure consisting mainly of ductile, spherical martensitic Ti(Ni,Cu) precipitates embedded in an amorphous matrix also containing a small volume fraction of TiCu and Ti2Cu precipitates. These composites exhibit large ductility and high strength combined with a strong work-hardening behaviour. A deformation mechanism is proposed with the help of experimental observations and finite-element simulation. The simulation results demonstrate that stress concentrations occur around the precipitates, which promotes a heterogeneous stress distribution and the formation of multiple shear bands. Additionally, different transformation temperatures were observed for martensitic precipitates depending on whether they are completely or partially embedded in the amorphous matrix.