Plastic deformation by glassy structure control in Zr–Al–Ni–Cu-based BMGs

Zr65Al7.5Ni10Cu17.5−xPdx (x = 0–17.5) bulk metallic glasses (BMGs) were produced in various chamber atmospheres in Cu mold casting. The glassy structure with a larger amount of relaxation enthalpy can be obtained casting under the ambient Ar and He atmospheres, which originates from enhanced cooling effect. These unrelaxed BMGs exhibit an improvement of ductility in the compressive deformation. Especially, Pd-containing BMGs have a significant plasticity of approximately 6%, in which deformation-induced inhomogeneous nanocrystallization also occurs. The synergistic effect of unrelaxed glassy structure and deformation-induced nanostructure change is regarded as a new technique for the improvement of ductility in the BMGs.