Deformation and crystallization of Zr-based amorphous alloys in homogeneous flow regime

Abstract

The purpose of this study is to experimentally investigate the interaction of inelastic deformation and microstructural changes of two Zr-based bulk metallic glasses (BMGs): Zr 41.25 Ti 13.75 Cu 12.5 Ni 10 Be 22.5 (commercially designated as Vitreloy 1 or Vit1) and Zr 46.75 Ti 8.25 Cu 7.5 Ni 10 Be 27.5 (Vitreloy 4, Vit4). High-temperature uniaxial compression tests were performed on the two Zr alloys at various strain rates, followed by structural characterization using differential scanning calorimetry (DSC) and transmission electron microscopy (TEM). Two distinct modes of mechanically induced atomic disordering in the two alloys were observed, with Vit1 featuring clear phase separation and crystallization after deformation as observed with TEM, while Vit4 showing only structural relaxation with no crystallization. The influence of the structural changes on the mechanical behaviors of the two materials was further investigated by jump-in-strain-rate tests, and flow softening was observed in Vit4. A free volume theory was applied to explain the deformation behaviors, and the activation volumes were calculated for both alloys.

Atomic probe tomography and creep deformation studies of highly dynamic metallic systems: copper-zirconium based metallic glass alloys and tin-based alloy

“…Tao et. al reported a similar trend in Zr-based amorphous alloys system of which T g decreased with decreasing strain rate [51].…”

“…Bulk amorphous samples were produced via conventional solidification techniques at cooling rates as low as 1-100 K/s [47][48][49][50]. Vitreloys and related family of Zr-based and Zr-Cu-based alloys have attracted recent interests [51][52][53][54][55][56] due to their high resistance against crystallization as well as low critical cooling rates which opened up many new possibilities such as direct casting and thermoplastic forming.…”