Influence of annealing on the elastic properties and microstructure of Cu58.1Zr35.9Al6 bulk metallic glass

The present paper aims to study the crystallization behavior and the elastic properties of Cu58.1Zr35.9Al6 bulk metallic glass using ultrasonic pulse focusing method. It is found that the changes of the elastic properties and microstructure can be classified into three stages corresponding to different temperature regions. Below the glass transition temperature Tg, no structural change was observed by X-ray diffraction, and annealing only induced structural relaxation. After annealing at the super-cooled liquid region, the new phase Cu10Zr7 formed, meanwhile, some anomalous acoustic and elastic behaviors occurred near Tg (490). Above the onset crystallization temperature Tx, the elastic properties increased further with the elevated temperature and Cu8Zr3 phase was also observed besides Cu10Zr7 phase. The annealing has a significant effect on the elastic property and microstructure of Cu58.1Zr35.9Al6 bulk metallic glass, which is closely related to the annihilation of quenched-in free volume and the improvement of the atom order degree.