Ductility of bulk nanocrystalline composites and metallic glasses at room temperature

Mechanical properties of bulk Zr60Cu20Pd10Al10 nanocrystalline composite and Zr55Ni5Cu30Al10 metallic glass were measured by compression tests at room temperature. The Zr60Cu20Pd10Al10 as-quenched alloy obviously exhibits plastic strain while no distinct plastic deformation is recognized in the Zr55Ni5Cu30Al10 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 Zr55Ni5Cu30Al10 metallic glass, nanocrystals with main grain sizes of about 2 nm were embedded in the amorphous matrix of the bulk Zr60Cu20Pd10Al10 alloy which showed the maximum plastic strain. (C) 2000 American Institute of Physics. [S0003-6951(00)01027-5].