Thermal stability and crystallization kinetics of Cu-Zr-Al-Ag BMGs investigated with isothermal electrical resistance measurement

• Published in: Metals and materials international 2014, 20(4), , pp.669-676
• Main Authors: Wang, Li-Fang, Cui, Xiao, Zhang, Qi-Dong, Zu, Fang-Qiu
• Format: Article
• Language: English
• Subjects: Alloys; Atomic structure; Characterization and Evaluation of Materials; Chemistry and Materials Science; Copper; Crystal growth; Crystallization; Engineering Thermodynamics; Fluctuation; Heat and Mass Transfer; Machines; Magnetic Materials; Magnetism; Manufacturing; Materials Science; Metallic Materials; Nucleation; Processes; Solid Mechanics; Thermal stability; 재료공학
• ISSN: 1598-9623; 2005-4149
• DOI: 10.1007/s12540-014-4012-3

The thermal stability and crystallization kinetics of the Cu x Zr 84- x Al 8 Ag 8 ( x = 42, 40, 38, and 36) bulk metallic glasses (BMGs) were studied by measurement of isothermal electrical-resistance. As the composition becomes richer in Zr, the longer incubation time at the same relative annealing temperature, and the larger local activation energy needed to achieve the same crystallized volume-fraction, indicate improved thermal stability, which resists crystallization. The improved thermal stability is attributed to a denser atomic random-stacking structure and larger negative heat-of-mixing. During isothermal annealing processes, the four BMGs exhibited the same nucleation mechanism, which is a decreasing rate of nucleation over time. However, the crystal growth mechanisms of the four BMGs are different. The crystallization of the Cu 36 Zr 48 Al 8 Ag 8 and Cu 38 Zr 46 Al 8 Ag 8 BMGs is interface-controlled growth, contrasting with diffusion-controlled growth for the Cu 40 Zr 44 Al 8 Ag 8 and Cu 42 Zr 42 Al 8 Ag 8 alloys. The different growth modes may be caused by fluctuations in composition due to changes in the quantity and distribution of Cu-rich and Ag-rich regions.