Abstract:
Generally bulk metallic glasses (BMGs) posses very less ductility and toughness at room temperature. Over
the recent past years to improve up on these properties in many alloy system BMG composites have been
developed. It was also reported that Cu47.5Zr47.5Al5 BMG composite shows a very high strength together
with an extensive work hardening-like behavior of large ductility around 18%. In this study, the influence
of superheat on microstructure and the resulting mechanical properties in Cu47.5Zr47.5Al5 bulk metallic
glass-matrix composite alloy has been studied. The Cu47.5Zr47.5Al5 melt solidifies into a composite microstructure consisting of crystalline precipitates embedded in an amorphous matrix. The crystalline phase
consists of B2 CuZr (cubic primitive with CsCl structure) with a small amount of monoclinic CuZr
martensitic structure embedded in an amorphous matrix. The volume fraction of crystalline phases varies
with melting current as well as position along the length of the as-cast rod, depending on the local cooling
condition. The volume fraction and the distribution of the crystalline precipitates are heterogeneous in the
amorphous matrix. Room temperature uniaxial compression tests revealed high yield strength ranging
from 796 to 1900 MPa depending upon the volume fraction of the crystalline phases present. The presence
of the dendritic B2 CuZr significantly improved the ductility. The BMG composites show a pronounced
plastic strain up to 14% for the higher volume fraction of crystalline phase.
