Strong liquid behavior of Zr-Ti-Cu-Ni-Be bulk metallic glass forming alloys
- California Inst. of Tech., Pasadena, CA (United States). Keck Lab. of Engineering Materials
The viscosities of the Zr{sub 46.75}Ti{sub 8.25}Cu{sub 7.5}Niu{sub 10}Be{sub 27.5} and the Zr{sub 41.2}Ti{sub 13.8}Cu{sub 12.5}Ni{sub 10}Be{sub 22.5} bulk metallic glass forming liquids was determined from the melting point down to the glass transition in the entire temperature range of the supercooled liquid. The temperature dependence of the viscosity in the supercooled liquid obeys the Vogel-Fulcher-Tammann (VFT) relation. The fragility index D is about 20 for both alloys and the ratio between glass transition temperature and VFT temperature is found to be 1.5. A comparison with other glass forming systems shows that these bulk metallic glass formers are strong liquids comparable to sodium silicate glass. Furthermore, they are the strongest among metallic glass forming liquids. This behavior is a main contributing factor to the glass forming ability since it implicates a higher viscosity from the melting point down to the glass transition compared to other metallic liquids. Thus, the kinetics in the supercooled liquid is sluggish and yields a low critical cooling rate for glass formation. The relaxation behavior in the glass transition region of the alloys is consistent with their strong glassy nature as reflected by a stretching exponent that is close to 0.8. The microscopic origin of the strong liquid behavior of bulk metallic glass formers is discussed.
- Sponsoring Organization:
- USDOE, Washington, DC (United States); Alexander von Humboldt-Stiftung, Bonn (Germany)
- DOE Contract Number:
- FG03-86ER45242
- OSTI ID:
- 580912
- Report Number(s):
- CONF-961202--; ISBN 1-55899-359-2
- Country of Publication:
- United States
- Language:
- English
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