Ductility of bulk nanocrystalline composites and metallic glasses at room temperature

Mechanical properties of bulk ${\mathrm{Zr}}_{\mathrm{60}}{\mathrm{Cu}}_{\mathrm{20}}{\mathrm{Pd}}_{\mathrm{10}}{\mathrm{Al}}_{\mathrm{10}}$ nanocrystalline composite and ${\mathrm{Zr}}_{\mathrm{55}}{\mathrm{Ni}}_{\mathrm{5}}{\mathrm{Cu}}_{\mathrm{30}}{\mathrm{Al}}_{\mathrm{10}}$ metallic glass were measured by compression tests at room temperature. The ${\mathrm{Zr}}_{\mathrm{60}}{\mathrm{Cu}}_{\mathrm{20}}{\mathrm{Pd}}_{\mathrm{10}}{\mathrm{Al}}_{\mathrm{10}}$ as-quenched alloy obviously exhibits plastic strain while no distinct plastic deformation is recognized in the ${\mathrm{Zr}}_{\mathrm{55}}{\mathrm{Ni}}_{\mathrm{5}}{\mathrm{Cu}}_{\mathrm{30}}{\mathrm{Al}}_{\mathrm{10}}$ metallic glass. Moreover, the plastic strain increased by increasing the volume fraction of nanocrystals and achieved maximum value in the early stage of the nanocrystallization. High-resolution electron microscopy showed that, different from the microstructure of ${\mathrm{Zr}}_{\mathrm{55}}{\mathrm{Ni}}_{\mathrm{5}}{\mathrm{Cu}}_{\mathrm{30}}{\mathrm{Al}}_{\mathrm{10}}$ metallic glass, nanocrystals with main grain sizes of about 2 nm were embedded in the amorphous matrix of the bulk ${\mathrm{Zr}}_{\mathrm{60}}{\mathrm{Cu}}_{\mathrm{20}}{\mathrm{Pd}}_{\mathrm{10}}{\mathrm{Al}}_{\mathrm{10}}$ alloy which showed the maximum plastic strain.