The effects of Ni or Nb additions on the relaxation behavior of Zr<inf>55</inf>Cu<inf>35</inf>Al<inf>10</inf> metallic glass

Abstract

Many questions raised in the field of metallic glasses (MGs) are inherently attributed to β relaxation. Therefore, this study investigated the behavior of β relaxation in the Zr55Cu35Al10 MG by differential scanning calorimetry (DSC) under different heating rates. Minor additions of Ni and Nb into the base alloy and pre-annealing process were also carried out to highlight the features of β relaxation in the thermal curves. The results showed that the pre-annealing process led to the appearance of an endothermic peak under the glass transition temperature (Tg), which is a sign of reversible β relaxation in the glassy structure. Moreover, the peak position of the endothermic event was at 0.78 Tg, 0.83 Tg, and 0.87 Tg for Zr55Cu35Al10, (Zr55Cu35Al10)98Ni2, and (Zr55Cu35Al10)98Nb2, respectively, which indicated the crucial role of minor addition on the evolution of β relaxation. In addition, the pre-annealing process from 3 h to 48 h demonstrated that the endothermic peaks in the minor-added samples tended to shift to higher temperatures. Furthermore, structural characterization of MGs revealed various types of short-range and medium-range orders in the Ni- and Nb-added alloys, leading to a different relaxation behavior in the glassy structure.