High-temperature plasticity of cubic bismuth oxide

1996 ◽  
Vol 11 (6) ◽  
pp. 1433-1439 ◽  
Author(s):  
Anne Vilette ◽  
S. L. Kampe
Keyword(s):  
High Temperature ◽  
Strain Rate ◽  
Bismuth Oxide ◽  
Rate Sensitivity ◽  
High Temperature Deformation ◽  
Temperature Deformation ◽  
Cubic Phase ◽  
Superplastic Behavior ◽  
Wide Range

Cubic (δ) bismuth oxide (Bi2O3) has been subjected to high temperature deformation over a wide range of temperatures and strain rates. Results indicate that bismuth oxide is essentially incapable of plastic deformation at temperatures below the monoclithic to cubic phase transformation which occurs at approximately 730 °C. Above the transformation temperature, however, Bi2O3 is extensively deformable. The variability of flow stress to temperature and strain rate has been quantified through the determination of phenomenological-based constitutive equations to describe its behavior at these high temperatures. Analysis of the so-determined deformation constants indicate an extremely strong sensitivity to strain rate and temperature, with values of the strain-rate sensitivity approaching values commonly cited as indicative of superplastic behavior.

High temperature deformation behavior of titanium samples with superplastic layer

1995 ◽  
Vol 10 (4) ◽  
pp. 864-869 ◽  
Author(s):  
M.G. Zelin ◽  
Q. Li ◽  
R.Z. Valiev ◽  
P. Lukač ◽  
A.K. Mukherjee
Keyword(s):  
High Temperature ◽  
Grain Boundary ◽  
Strain Rate ◽  
Strain Rate Sensitivity ◽  
Rate Sensitivity ◽  
Grain Boundary Sliding ◽  
High Temperature Deformation ◽  
Temperature Deformation ◽  
Layer By Layer ◽  
Boundary Sliding

The progress of high temperature deformation in samples of two commercial titanium alloys with superplastic (SP) structure, non-SP structure, and with an SP layer sandwiched between the non-SP regions has been studied on the scale of the entire deformed volume and on the scale of grain groups. The results of mechanical behavior showed that samples with SP layer exhibit higher stress level than those with completely SP structure and higher strain rate sensitivity than those with completely non-SP structure. Samples with SP layer demonstrate a more pronounced deccrease in strain rate sensitivity with the increase of strain than samples with completely SP structure. Deformation in the SP layer proceeds as grain shear in a layer-by-layer manner. The deformation of SP layer through the operation of cooperative grain boundary sliding, i.e., sliding of grain groups as an entity along certain grain boundary surfaces, provides the main contribution to the total strain.

scholarly journals High Temperature Deformation Flow Of A ZK60A Magnesium Alloy After Extrusion

2015 ◽  
Vol 60 (2) ◽  
pp. 1327-1330
Author(s):  
M. Kawasaki ◽  
H.-J. Lee ◽  
M.C. Oh ◽  
B. Ahn
Keyword(s):  
High Temperature ◽  
Magnesium Alloy ◽  
Strain Rate ◽  
Flow Behavior ◽  
Rate Sensitivity ◽  
Initial Strain Rate ◽  
High Temperature Deformation ◽  
Temperature Deformation ◽  
Strain Rates ◽  
Testing Conditions

Abstract Flow behavior of a ZK60A magnesium alloy after continuous casting and subsequent extrusion was examined in tension at a range of strain rates of 3.0×10−6 − 1.0×10−2 s−1 at temperatures of 473-623K. The results demonstrated that the alloy exhibited a maximum elongation of ~250% at 523K when tested at an initial strain rate of 1.0×10−5 s−1 and strain rate sensitivity, m, of ~0.3-0.4 and the activation energy of ~94 kJ/mol were calculated under the testing conditions. The detailed investigation suggested that the high temperature flow of the ZK60A alloy having submicrometer grains demonstrates quasi-superplastic flow behavior controlled by a dislocation viscous glide process.

Large Deformability of Wrought Magnesium Alloys: Is Superplasticity Needed?

2010 ◽  
Vol 433 ◽  
pp. 267-272 ◽  
Author(s):  
R. Boissière ◽  
Jean Jacques Blandin ◽  
Luc Salvo
Keyword(s):  
High Temperature ◽  
Strain Rate ◽  
Magnesium Alloys ◽  
Rate Sensitivity ◽  
Solute Drag ◽  
Mg Alloys ◽  
High Temperature Deformation ◽  
Temperature Deformation ◽  
Fine Grained ◽  
Superplastic Properties

The deformability of wrought magnesium alloys at room temperature is limited and a way to overcome this limit is to carry out forming operations in warm or hot conditions. In the case of fine grained alloys, superplastic properties can be generally achieved but in this regime, the Mg alloys are sensitive to strain induced cavitation. However, large grained alloys can also exhibit quite large deformabilities when they are deformed at high temperature. This can be due to the fact that on one hand, the Mg alloys may quite easily dynamically recrystallize and on the other hand, that dislocation movements may be controlled by a solute drag effect leading to significant strain rate sensitivity parameters. These various mechanisms of deformation will depend on the composition, the mean grain size and the conditions of deformation (i.e. temperature and strain rate). In this work, the high temperature deformation mechanisms as well as the associated damage mechanisms of two wrought magnesium alloys are discussed.

Beta-Forging of Titanium Ti6Al4V Alloy Powders: Phase Evolution Modeling and Strain-Rate Relation

2014 ◽  
Vol 622-623 ◽  
pp. 15-26
Author(s):  
Claudio Testani ◽  
Antonino Squillace ◽  
Antonello Astarita
Keyword(s):  
High Temperature ◽  
Strain Rate ◽  
Rate Sensitivity ◽  
Phase Evolution ◽  
High Temperature Deformation ◽  
Fatigue Properties ◽  
Temperature Deformation ◽  
Compression Tests ◽  
Process Modification ◽  
Deformation Tests

Ti6Al4V is one of the best known and studied titanium alloy for the optimization of the thermo-mechanical treatments. The Ti-forgings represent a valid opportunity for the aircraft manufacturers and designers because of high tensile and fatigue properties. Nevertheless the total-cost reduction of the manufacturing-chain requires both: the ability to manufacture nearer-shaped components by mean of forging-process-modification and less final machining (material scraps). Even if Ti6Al4V is a well known alloy, any process parameters modification introduced still represents a challenge for the metallurgists and manufacturers.The idea, at the base of the present work, has been the feasibility study of forging experiments in the Beta-field using Hot Isostatic Pressed (HIP) powders billets. The preliminary compression tests has been carried out in laboratory and the results have been validated in a industrial Forging-Workshop. The deformation behavior of Ti6Al4V HIPped powders during high temperature deformation tests is reported. Laboratory compression and tensile tests have been coupled with relaxation tests in order to achieve robust data about strain rate sensitivitym-coefficient and activation energy Q.The obtained results have been fitted for the assessment of generalized exponential deformation law. The final result is a “Dorn model” that takes into account and compares all the results from the three different deformation tests: compression, tensile and relaxation. The deformation tests have been carried out at temperatures ranging from 1173 K up to 1373 K and strain rate from 0,01 s-1up to about 1 s-1, trying to describe the high temperature complex shape forging operations.Finally the recorded deformation curves has been used for modeling by means of FEM DeformTM code the deformation process and microstructure evolution by means of an Avrami type law.

High Temperature Deformation Mechanism Maps of NiAl

2004 ◽  
Vol 449-452 ◽  
pp. 57-60
Author(s):  
I.G. Lee ◽  
A.K. Ghosh
Keyword(s):  
High Temperature ◽  
Strain Rate ◽  
Deformation Mechanism ◽  
Calculation Method ◽  
Deformation Behavior ◽  
Tensile Tests ◽  
High Temperature Deformation ◽  
Temperature Deformation ◽  
Grain Sizes ◽  
Temperature Strain

In order to analyze high temperature deformation behavior of NiAl alloys, deformation maps were constructed for stoichiometric NiAl materials with grain sizes of 4 and 200 µm. Relevant constitute equations and calculation method will be described in this paper. These maps are particularly useful in identifying the location of testing domains, such as creep and tensile tests, in relation to the stress-temperature-strain rate domains experienced by NiAl.

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