Evolution of the elastic modulus of Zr–Cu–Al BMGs during annealing treatment and crystallization: Role of Zr/Cu ratio

•We measured the Young's modulus and the internal friction vs temperature of BMG.•The softening rate of Young's modulus decreases with the increase of Zr.•The amplitude of the E relaxation increases with the Zr concentration.•The evolution of E during crystallization reveals two consecutive steps.

In this study, the Young's modulus (E) and the internal friction (Q− 1) of bulk metallic glasses ZrxCu(90 − x)Al10 for x = 45, 50, 55 and 60 were measured. Using a technique of resonant frequency and damping analysis, these parameters were measured in real time from room temperature up to 800 °C. Two kinds of thermal treatment were performed: i) below Tg over several days in order to analyze the annealing treatment; ii) above Tg with increasing temperature at a constant rate in order to characterize the crystallization process. The evolution of E is discussed and has revealed interesting information concerning the structure modification during thermal treatments. After the crystallization treatment, phase characterization measurements of the samples were performed using the X-ray diffraction technique. The crystallized phases and their influences on the evolution of the Young's modulus are discussed as a function of the Zr/Cu ratio.