Viscous flow of Cu55Zr30Ti10Co5 bulk metallic glass in glass-transition and semi-solid regions

2013 ◽  
Vol 68 (3-4) ◽  
pp. 219-222 ◽  
Author(s):  
S.V. Ketov ◽  
A. Inoue ◽  
H. Kato ◽  
D.V. Louzguine-Luzgin
Keyword(s):  
Glass Transition ◽  
Metallic Glass ◽  
Viscous Flow ◽  
Bulk Metallic Glass ◽  
Semi Solid

scholarly journals Effects of Annealing on Enthalpy Recovery and Nanomechanical Behaviors of a La-Based Bulk Metallic Glass

Metals ◽  
2021 ◽  
Vol 11 (4) ◽  
pp. 579
Author(s):  
Ting Shi ◽  
Lanping Huang ◽  
Song Li
Keyword(s):  
Glass Transition ◽  
Transition Temperature ◽  
Glass Transition Temperature ◽  
Metallic Glass ◽  
Bulk Metallic Glass ◽  
Structural Relaxation ◽  
Supercooled Liquid ◽  
Supercooled Liquid Region ◽  
Liquid Region ◽  
Nanoindentation Measurement

Structural relaxation and nanomechanical behaviors of La65Al14Ni5Co5Cu9.2Ag1.8 bulk metallic glass (BMG) with a low glass transition temperature during annealing have been investigated by calorimetry and nanoindentation measurement. The enthalpy release of this metallic glass is deduced by annealing near glass transition. When annealed below glass transition temperature for 5 min, the recovered enthalpy increases with annealing temperature and reaches the maximum value at 403 K. After annealed in supercooled liquid region, the recovered enthalpy obviously decreases. For a given annealing at 393 K, the relaxation behaviors of La-based BMG can be well described by the Kohlrausch-Williams-Watts (KWW) function. The hardness, Young’s modulus, and serrated flow are sensitive to structural relaxation of this metallic glass, which can be well explained by the theory of solid-like region and liquid-like region. The decrease of ductility and the enhancement of homogeneity can be ascribed to the transformation from liquid-like region into solid-like region and the reduction of the shear transition zone (STZ).

Strong Liquid Behavior of Zr-Ti-Cu-Ni-Be Bulk Metallic Glass Forming Alloys

1996 ◽  
Vol 455 ◽  
Author(s):  
Ralf Busch ◽  
Andreas Masuhr ◽  
Eric Bakke ◽  
William L. Johnson
Keyword(s):  
Glass Transition ◽  
Melting Point ◽  
Metallic Glass ◽  
Bulk Metallic Glass ◽  
Supercooled Liquid ◽  
Glass Transition Region ◽  
Glass Forming ◽  
Liquid Behavior ◽  
Metallic Liquids ◽  
Microscopic Origin

ABSTRACTThe viscosities of the Zr46.75Ti8.25Cu7.5Ni10Be27.5 and the Zr41.2Ti13.8Cu12.5Ni10Be22.5 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.

Effect of Heat Treatment on the Properties of (Fe0.6Co0.4)71Si5Nb4B20 Bulk Metallic Glass

2021 ◽  
Vol 875 ◽  
pp. 70-75
Author(s):  
Syed Zameer Abbas ◽  
Rashid Ali ◽  
Syed Muttahir Shah ◽  
Owais Jan ◽  
Munim Awan
Keyword(s):  
Glass Transition ◽  
Metallic Glass ◽  
Bulk Metallic Glass ◽  
Cast Alloy ◽  
Amorphous Structure ◽  
Indentation Hardness ◽  
Alloy Sample ◽  
Scanning Calorimetry ◽  
Heat Treated Sample ◽  
Heat Treated

Bulk metallic glasses (BMGs) are an important class of materials with unique set of properties. A bulk metallic glass with composition of (Fe0.6Co0.4)71Nb4Si5B20 was cast in the form of a 1 mm thick strip in a water cooled copper mold. The BMG produced was characterized for structure, thermal and mechanical properties. The X-ray diffraction performed on the as cast alloy has shown completely amorphous structure. The glass transition and crystallization peak temperatures obtained through differential scanning calorimetry scan were 542 °C and 588.4 °C, respectively. Some cast amorphous alloy sample was annealed below glass transition (450 °C for 30 mi93nutes) and others above glass transition (580 °C for 5 minutes) temperatures. Nano- indentation hardness of 13.3 GPa was obtained for as cast alloy while a hardness values of 12.8 and 15.84 GPa were measured for heat treated alloys at temperature of 450 °C and 580 °C, respectively. Increase in hardness was attributed to formation of crystals in an amorphous matrix whereas decrease in hardness was due to relaxation of quenching residual stresses. The maximum value of elastic modulus obtained through indentation was 255 GPa for 580 °C heat treated sample.

Thermal cycling effect on the kinetics of glass transition and crystallization of a Zr-based bulk metallic glass

2020 ◽  
Vol 142 (1) ◽  
pp. 63-73 ◽  
Author(s):  
Pan Gong ◽  
Fangwei Li ◽  
Geng Yin ◽  
Lei Deng ◽  
Xinyun Wang ◽  
...  
Keyword(s):  
Glass Transition ◽  
Metallic Glass ◽  
Thermal Cycling ◽  
Bulk Metallic Glass ◽  
Kinetics Of

Machinability of BMG

2012 ◽  
Vol 521 ◽  
pp. 225-253
Author(s):  
Mustafa Bakkal
Keyword(s):  
High Temperature ◽  
Metallic Glass ◽  
Viscous Flow ◽  
Bulk Metallic Glass ◽  
Light Emission ◽  
Cutting Speed ◽  
Good Surface ◽  
High Cutting Speed ◽  
Exothermic Chemical Reaction ◽  
Good Surface Roughness

This chapter covers the series of machinability evaluation test result and discussions of Zr52.5Ti5Cu17.9Ni14.6Al10bulk metallic glass (BMG). These tests are lathe turning, drilling, milling and preliminary level grinding tests. In the continuous machining methods such as turning, drilling and grinding of BMG, above a threshold cutting speed, the low thermal conductivity of BMG leads to chip temperatures high enough to cause the chip oxidation and associated light emission. The high temperature produced by this exothermic chemical reaction causes crystallization within the chips. Chips morphology suggests that increasing amounts of viscous flow control the chip-removal process. Moreover, viscous flow and crystallization can occur during the machining of the bulk metallic glass, even under the high temperature gradient and strain rate. High cutting speed significantly reduced the forces for BMG machining due to thermal softening. However, in intermittent cutting process which is milling, there is no high temperature problem, special burr formations the rollover and the top burr were observed along the slot and achieved good surface roughness, Ra= 0.113 μm, using conventional WC-Co cutting tool. In each method, tests repeated for the conventional materials for comparison purpose. This study concludes the precision machining of BMG is possible with the selection of feasible tools and process parameters for each method.

Steady-state tensile viscous flow forming of bulk metallic glass

2012 ◽  
Vol 536 ◽  
pp. S109-S112
Author(s):  
E. Soinila ◽  
S. Bossuyt ◽  
H. Hänninen
Keyword(s):  
Steady State ◽  
Metallic Glass ◽  
Viscous Flow ◽  
Bulk Metallic Glass ◽  
Flow Forming
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