Tailoring thermally induced nano-quasicrystallization and deformation-assisted nanocrystallization for mechanical property improvement in Zr-Al-Ni-Cu-Pd bulk metallic glasses

The material design tailoring of a synergistic effect of an in-situ nano secondary phase formation and deformation-induced nanocrystallization for improving the mechanical strength and ductility, has been investigated in Zr₆₅Al_7.5Ni₁₀Cu_17.5-xPd_x bulk metallic glasses (BMGs). As-cast Zr₆₅Al_7.5Ni ₁₀Cu_17.5-xPd_x (x = 5-17.5) BMGs have significant ductility in compressive deformation, which is attributed to deformation-induced dynamic nanocrystallization. The 10at% Pd-containing BMG with a low volume fraction of the quasicrystalline (QC) phase of less than 6% exhibits increases in strength and Young's modulus, in addition to a remaining plasticity of ∼5%, compared with the monolithic glassy alloy. Such improvements in the mechanical properties originate from the combination of two effects of in-situ homogeneous nano-QC formation and deformation-induced inhomogeneous nanocrystallization. The present method should be regarded as a new technique for the production of BMGs with high strength and good ductility.