EFFECT OF NANO-CRYSTALLIZATION ON THE MECHANICAL PROPERTIES OF THE (Zr_(53)Cu_(30)Ni_9Al_8)_(99.5)Si_(0.5) BULK METALLIC GLASS

摘要

The (Zr_(53)Cu_(30)Ni_9A_(l8))_(99.5)Si_(0.5) bulk metallic glass (BMG) rods, 3 mm in diameter, with different crystallization fraction for compression test were prepared by isothermal annealing the as-cast BMG rods at the temperature in the middle of supercooled temperature region for different time period in vacuum, respectively. The result of compression test revealed that the fracture strength of these samples increases with the crystallization ratio at the beginning, then decreases rapidly at 40 vol.% crystallization fraction. In addition, the best mechanical performance with 1970MPa yield strength and 3% plastic strain occurs at the sample with 30 vol.% nanocrystalline phase (with an average size about 50 nm). This was suggested these homogeneous distributed nanocrystals which embedded in the matrix may act as obstacles to branch the primary shear band into multiple shear band and result in improving the ductility.