Isothermal nanocrystallization behavior of bulk metallic glass composites in supercooled liquid region

Abstract

Abstract Bulk metallic glass composites (BMGCs) reinforced by micro‐ (spherical size of about 10 μm) and nano‐sized (20–50 nm) Al 3 Zr crystals were synthesized by copper mold suction casting method. The isothermal crystallization of Cu 40 Zr 44 Ag 8 Al 8 BMGCs in the supercooled liquid region was studied by differential scanning calorimeter (DSC), X‐ray diffractometer (XRD), scanning electron microscopy (SEM), and transmission electron microscopy (TEM). The mechanisms for nucleation and growth of the crystalline phases precipitated in two‐stage crystallization process and the effect of the isothermal treatment on the in situ crystalline phases were discussed. Results show that the BMGCs experience a primary crystallization process. Nano‐sized Al 3 Zr and Cu 10 Zr 7 phases precipitate from the amorphous matrix successively. Furthermore, isothermal annealing has no effect on the pre‐existing particles in the as‐cast sample, which creates a new method to synthesize BMGCs strengthened by duplex crystalline phases with a large size difference. And the reinforced phase could also be dominated with intention if the as‐cast BMGCs preparation and isothermal treatment process can be controlled more accurately.