Recovery of less relaxed state in Zr-Al-Ni-Cu bulk metallic glass annealed above glass transition temperature

Abstract

The relaxation state of metallic glass is determined by the cooling rate at low temperatures in a supercooled liquid. Based on this result, we can control the relaxation state of Zr55Al10Ni5Cu30 bulk metallic glass by recovery annealing just above the glass transition temperature (Tg). We rejuvenate the relaxation state for approximately 50% in the enthalpy of relaxation at a cooling rate of 4.4 K/s after annealing, as compared with that of the as-cast state. Mechanical softening also occurred upon the rejuvenation. The results suggest another method of controlling the structure of metallic glasses to improve their properties.