Thermal Stability and Crystallization Behavior of Zr-Al-Ni-Cu-Ag Metallic Glasses with Multicomponent Replacement

Abstract:

In order to improve the thermal stability and to obtain a large supercooled liquid region of metal glasses, the Zr_65-x(Al_0.21Ni_0.29Cu_0.04Ag_0.46)_35+x (x=0, 7.5, 15.0, 22.5) metallic glasses were investigated. The effects of component concentrations on the thermal stability, heat-induced precipitate phases, and mechanical properties were analyzed. Results show that with increasing the component concentrations, the peak position of the broad diffraction pattern shifts towards higher angles, indicating the occurrence of glass transition phenomenon. With increasing the glass transition temperature (T_g) and crystallization temperature (T_x), the liquidus temperature (T_l) is decreased, leading to decrease in the temperature difference (namely supercooled liquid region, ΔT_x) between T_x and T_g and resulting in the increase in reduced glass transition range (T_rg). Additionally, the nucleation activation energy (E_x) and the growth activation energy (E_p1) are increased with increasing the solute concentration. The primary crystal changes from the combination of tetragonal Zr₂Ni, Zr₂(Cu, Ag), ZrAg, and hexagonal Zr₅Al₃ phases into the single tetragonal ZrAg phase. The Vickers hardness is also increased with increasing the solute concentration. In this research, a novel metallic glass, Zr_65-x(Al_0.21Ni_0.29-Cu_0.04Ag_0.46)_35+x (x=7.5), is developed, which presents a large ΔT_x of 141 K, high thermal stability, and strong crystallization resistance. This research adopting the multicomponent replacement strategy is of great significance to improve the thermal stability of metallic glasses.