Shear thinning of the bulk metallic glass forming alloy Zr41.2 Ti13.8 Cu12.5 Ni10.0 Be22.5 close to the liquidus temperature.

2003 ◽  
Vol 806 ◽  
Author(s):  
Tyler Shaw ◽  
Christopher Way ◽  
Ralf Busch
Keyword(s):  
Metallic Glass ◽  
Bulk Metallic Glass ◽  
Power Law ◽  
Liquidus Temperature ◽  
Flow Behavior ◽  
Shear Thinning ◽  
Shear Rates ◽  
Glass Forming ◽  
Power Law Index ◽  
Type Response

ABSTRACTThe viscous properties of the multi component Zr41.2 Ti13.8 Cu12.5 Ni10.0 Be22.5 bulk metallic glass forming alloy was studied above the liquidus temperature. A shear thinning behavior for the molten alloy has been discovered. The shear thinning behavior can be characterized as a power law fluid with a power-law index of -0.5. Additionally, at low shear rates and temperatures near the liquidus temperature a visco-elastic type response in the flow behavior is observed.

Computational Modeling of Enhanced Laminar Flow Heat Transfer in Viscoplastic Fluids in Corrugated-Plate Channels

2002 ◽  
Author(s):  
Hossam M. Metwally ◽  
Raj M. Manglik
Keyword(s):  
Heat Transfer ◽  
Yield Stress ◽  
Power Law ◽  
Flow Behavior ◽  
Shear Thinning ◽  
Bingham Plastic ◽  
Wide Range ◽  
Order Of Magnitude ◽  
Colburn Factor ◽  
Power Law Index

The enhanced heat transfer in laminar viscoplastic, shear thinning, Herschel-Bulkley fluid flows in sinusoidal corrugated-plate channels is investigated. With uniform-temperature plate walls, periodically developed flows are considered for a wide range of flow rates (10 ≤ Reg ≤ 700) and pseudoplastic flow behavior indices (n = 0.54, 0.8, and 1.0; the latter representing a Bingham plastic). The effects of fluid yield stress are simulated for the case where τy = 1.59 N/m2, representing a 0.5% xantham gum aqueous solution. Typical velocity and temperature distributions, along with extended results for isothermal friction factor ƒ and Colburn factor j are presented. The effect of the yield stress is found to be most dominant at low Reg regardless of the power law index n, and the recirculation or swirl in the wall trough regions is weaker than in the cases of Newtonian and power-law liquids. At higher Reg, the performance of the Herschel-Bulkley fluid asymptotically approaches that of the non-yield-stress power-law fluid. At low Reg, the yield stress increases ƒ by an order of magnitude and j is enhanced because of the higher wall gradients imposed by the plug-like flow field. The relative heat transfer enhancement, represented by the ratio (j/ƒ), and the role of the fluid yield stress and shear-thinning (or pseudoplastic) behaviors are also discussed.

Influence of a Yield-Shear-Thinning Rheology on the Flow Behavior of Submerged Annular Jets

2020 ◽  
Author(s):  
Khaled J. Hammad
Keyword(s):  
Flow Field ◽  
Power Law ◽  
Numerical Solutions ◽  
Flow Behavior ◽  
Shear Thinning ◽  
Momentum Conservation ◽  
Recirculation Region ◽  
Substantial Impact ◽  
Laminar Jet ◽  
Power Law Index

Abstract The flow structure and decay characteristics of submerged annular yield-pseudoplastic jets are investigated. Numerical solutions to the governing mass and momentum conservation equations, along with the Herschel-Bulkley rheological model, are obtained using a finite-difference scheme. A parametric study is implemented to investigate the effects of annular nozzle diameter ratio, κ, the power-law index, n, and yield number, Y, over the following range: κ = {0, 0.5}; n = {1, 0.6}; and Y = {0, 1, 5}. The Reynolds number was fixed at Re = 100, which ensured steady and laminar jet flow conditions throughout the whole flow field. The selected yield number and power-law index values allowed for the investigation of the presence of yield stress and shear-thinning effects on the resulting structure and evolution of the flow field. The results demonstrate the substantial impact of the inflow conditions and rheology on the annular jet evolution, and on the extent of the outer recirculation region and recirculation strength of both the outer and central regions.

scholarly journals Pressure-dependent flow behavior of Zr41.2Ti13.8Cu12.5Ni10Be22.5 bulk metallic glass

2003 ◽  
Vol 18 (9) ◽  
pp. 2039-2049 ◽  
Author(s):  
Jun Lu ◽  
Guruswami Ravichandran
Keyword(s):  
Metallic Glass ◽  
Bulk Metallic Glass ◽  
Inelastic Deformation ◽  
Shear Failure ◽  
Flow Behavior ◽  
Shear Bands ◽  
Ductile Deformation ◽  
Multiaxial Compression ◽  
Dependent Flow ◽  
Tresca Criterion

An experimental study of the inelastic deformation of bulk metallic glass Zr41.2Ti13.8Cu12.5Ni10Be22.5 under multiaxial compression using a confining sleeve technique is presented. In contrast to the catastrophic shear failure (brittle) in uniaxial compression, the metallic glass exhibited large inelastic deformation of more than 10% under confinement, demonstrating the nature of ductile deformation under constrained conditions in spite of the long-range disordered characteristic of the material. It was found that the metallic glass followed a pressure (p) dependent Tresca criterion τ = τ0 + βp, and the coefficient of the pressure dependence β was 0.17. Multiple parallel shear bands oriented at 45° to the loading direction were observed on the surfaces of the deformed specimens and were responsible for the overall inelastic deformation.

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.

scholarly journals EFFECT OF STRUCTURAL RELAXATION ON THE DEFORMATION BEHAVIOR OF A Zr64.13Cu15.75Ni10.12Al10 BULK METALLIC GLASS UNDER NANOINDENTATION

2010 ◽  
Vol 24 (15n16) ◽  
pp. 2320-2325 ◽  
Author(s):  
JIANSHENG GU ◽  
BINGCHEN WEI ◽  
TAIHUA ZHANG ◽  
YIHUI FENG ◽  
YANPING HU ◽  
...  
Keyword(s):  
Metallic Glass ◽  
Bulk Metallic Glass ◽  
Structural Relaxation ◽  
Deformation Behavior ◽  
Isothermal Annealing ◽  
Flow Behavior ◽  
Thermal And Mechanical Properties ◽  
Scanning Calorimetry ◽  
Obvious Effect ◽  
Dsc Curves

Structural relaxation by isothermal annealing below the glass transition temperature is conducted on a Zr 64.13 Cu 15.75 Ni 10.12 Al 10 bulk metallic glass. The effect of structural relaxation on thermal and mechanical properties was investigated by differential scanning calorimetry and instrumented nanoindentation. The recovery of the enthalpy in the DSC curves indicates that thermally unstable defects were annihilated through structural relaxation. During nanoindentation, the structural relaxation did not have a significant influence on the serrated plastic flow behavior. However, Structural relaxation shows an obvious effect in increasing both the hardness and elastic modulus, which is attributed to the annihilation of thermally unstable defects that resulted from the relaxation.

scholarly journals In-situ study of crystallization kinetics in ternary bulk metallic glass alloys with different glass forming abilities

2014 ◽  
Vol 105 (20) ◽  
pp. 201906 ◽  
Author(s):  
Si Lan ◽  
Xiaoya Wei ◽  
Jie Zhou ◽  
Zhaoping Lu ◽  
Xuelian Wu ◽  
...  
Keyword(s):  
Metallic Glass ◽  
Bulk Metallic Glass ◽  
Crystallization Kinetics ◽  
Glass Forming ◽  
In Situ Study
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