Modification of atomic mobility in a Ti-based bulk metallic glass by plastic deformation or thermal annealing

• Published in: Intermetallics Vol. 28; pp. 128 - 137
• Main Authors: Qiao, J.C., Pelletier, J.M., Kou, H.C., Zhou, X.
• Format: Journal Article
• Language: English
• Published: Elsevier Ltd 01.09.2012; Elsevier
• Subjects: Amorphous materials; Atomic mobilities; B. Glasses, metallic; B. Internal friction; Cold rolling; Crystal defects; Crystallization; D. Microstructure; E. Mechanical properties, theory; Engineering Sciences; Materials; Metallic glasses; Plastic deformation; Viscoelasticity; D. Microstructure; B. Internal friction; B. Glasses, metallic; E. Mechanical properties, theory; As-cast; Point defects; Visco-elastic; Atoms; Mechanical properties; Transition regions; Amorphous state; Plastic deformation; Thermal-annealing; E. Mechanical; Bulk metallic glass; metallic; Glass transition; Zirconium; Atomic mobility; Structural relaxation; Glasses; Mechanical response; Low temperatures; Driving frequencies; Metallic glass
• ISSN: 0966-9795; 1879-0216
• DOI: 10.1016/j.intermet.2012.04.004

Evolution of atomic mobility in a Ti40Zr25Ni8Cu9Be18 bulk metallic glass was studied by dynamic mechanical analysis (DMA) in different states: as-cast, after structural relaxation, after crystallization and after deformation (cold-rolled). Characteristics of Ti40Zr25Ni8Cu9Be18 bulk metallic glass are similar to that observed in other based bulk metallic glasses in the amorphous state: at low temperature, the material is mainly elastic and the mechanical response is independent of driving frequency, while on the other hand, the visco-elastic component becomes very large in the glass transition region. Structural relaxation and crystallization induce a decrease in the visco-elastic component, suggesting that atomic mobility is reduced. In contrast, atomic mobility is increased by a plastic deformation (i.e. cold-rolling). The higher is the cold-rolling ratio, the higher is the visco-elastic component. The experimental results were analyzed in the framework of quasi-point defects theory, which is based on the existence of defects in amorphous materials (polymer, bulk metallic glasses and other non-crystalline solids). [Display omitted] ► Atomic mobility in Ti40Zr25Ni8Cu9Be18 bulk metallic glass have been investigated by dynamic mechanical analysis. ► The atomic mobility can be evaluated through the value of the loss factor. ► Structural relaxation and crystallization induce a decrease of the loss factor. ► Cold-rolling increases the concentration of defects and therefore enhances the atomic mobility. ► The higher is the cold-rolling ratio, the higher is the loss factor.