Effect of Ag content on thermal stability and crystallization behavior of Zr–Cu–Ni–Al–Ag bulk metallic glass

Abstract

Thermal stability and crystallization behavior of Zr70−xCu12.5Ni10Al7.5Agx (x=0–16) bulk metallic glasses (BMGs) have been investigated. It is revealed that glass transition temperature (Tg), crystallization temperature (Tx) shift towards higher temperature with the increase of Ag content. The supercooled liquid region ΔTx increases from 72K for the Ag-free BMG to 110K for the BMG with x=16. Two or three stages of crystallization process with primary precipitation of icosahedral phase (I-phase) occurs in the BMGs with x=0–10. However, single stage of crystallization mode with the formation of Zr2Cu and/or Zr2Ni crystalline phase takes place in the BMGs with x=12–16. The formation of I-phase involves inward diffusion of Zr and outward diffusion of Cu and Ni. Partial substitution of Zr with Ag stabilizes the supercooled liquid by suppressing the redistribution of constitutional elements to form I-phase or crystalline phase, leading to the enhancement of thermal stability of Zr-based BMGs.