Superplastic Deformation of Supercooled Liquid in Zr-Based Bulk Glassy Alloys Containing Nano-Quasicrystalline Particles

Abstract

The tensile deformation behavior of the supercooled liquid in the bulk glassy Zr₆₅Al_7.5Ni₁₀Cu_12.5Ag₅ and Zr₆₅Al_7.5Ni₁₀Cu_12.5Pd₅ alloys was investigated in comparison with the glassy Zr₆₅Al_7.5Ni₁₀Cu_17.5 alloy. An icosahedral phase precipitates as the primary precipitation phase from the supercooled liquid in the Ag- or Pd-containing alloy. The deformation behaviors of both the alloys were similar to that of the Zr₆₅Al_7.5Ni₁₀Cu_17.5 alloy at relatively high strain rates of about 1×10⁻² s⁻¹. While the largest elongation of the Zr₆₅Al_7.5Ni₁₀Cu_17.5 alloy, 270%, was obtained at 3×10⁻³ s⁻¹, those of the alloys containing Ag or Pd were about 400% at 1×10⁻³ s⁻¹. Apparent strain hardening due to the growth of the icosahedral particles was observed during the deformation of both the alloys at lower strain rates. The plastic deformation of the supercooled liquid continues even after the precipitation of the icosahedral particles, while the deformation of the Zr₆₅Al_7.5Ni₁₀Cu_17.5 alloy is inhibited by the onset of crystallization.