Modeling the hot consolidation of ceramic and metal powders

Dutton, R.; Shamasundar, S.; Semiatin, S. L.

doi:10.1007/bf02670676

Cited by 21 publications

(10 citation statements)

References 29 publications

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“…This model was developed at the AFRL by Dutton et al [15] and applied later by DeLo et al [17] It is a hybrid continuum-micromechanical model. That is to say, it combines (1) continuum aspects relating macroscopic strain rates and macroscopic (deviatoric and hydrostatic) stresses and (2) micromechanical aspects such as the effect of pore geometry and deformation mechanism on densification.…”

Section: Dutton Et Al (Afrl) Modelmentioning

confidence: 99%

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The effect of strain-path reversal on cavitation during hot torsion of Ti-6Al-4V

Nicolaou

Semiatin

2006

Metall Mater Trans A

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The effect of strain-path reversal on cavitation behavior during the hot torsion testing of an alpha/beta titanium alloy, Ti-6Al-4V, with a colony-alpha microstructure was established. Optical microscopy was used to measure cavitation parameters such as cavity size, density, and area fraction. It was observed that when the torsion direction is reversed, the cavitation process is reversed as well; i.e., cavity shrinkage takes place. The experimental observations were interpreted in the context of previous models developed for the densification of porous bodies. For this purpose, the models were modified to treat the effect of colony orientation on the local stress state and the accommodation of the externally imposed strain, both of which affect the rate of densification/cavity shrinkage. A modified version of the AFRL PM-consolidation model was shown to provide reasonable estimates of the shrinkage kinetics. An alternate description of cavity shrinkage during reversed torsion, analogous to prior descriptions of cavity growth, was also developed. It was concluded that the absolute magnitude of the cavity shrinkage rate is smaller than its counterpart during growth because the local stress ratio is lower during reversed straining compared to that during forward straining.

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Section: Dutton Et Al (Afrl) Modelmentioning

confidence: 99%

“…To describe the rate of cavity shrinkage, therefore, two previously developed models for pore closure during powder consolidation were employed. The first approach was developed by Dutton et al, [15] and the second by Liu et al [16] The basic features of each model are summarized in this section.…”

Section: Solution Of the System Of Equationsmentioning

confidence: 99%

The effect of strain-path reversal on cavitation during hot torsion of Ti-6Al-4V

Nicolaou

Semiatin

2006

Metall Mater Trans A

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“…To provide a foundation for the discussion that follows, the yield function/flow rule derived by Dutton et al [4] and the method by which the stress intensification factor in the yield function/flow rule is determined in hot compression tests are briefly summarized here. As outlined in Reference 4, yielding of porous media is assumed to be a function of both deviatoric and hydrostatic stresses, as follows:…”

Section: Theoretical Backgroundmentioning

confidence: 99%

“…As in various micromechanistic models for the evolution of the stress intensification factor during densification, [7,8,9] the hybrid model of Dutton et al [4] assumes density isotropy; i.e., the pores are ''equiaxed'' and remain so during consolidation. However, the work of Liu, et al [10] suggests otherwise.…”

Section: Introductionmentioning

confidence: 99%

“…[1,2,3] Very recently, work has been conducted to develop and validate a hybrid yield function that utilizes the basic features of continuum models but is modified to incorporate microstructural influences and pore size/geometry. [4,5,6] Pore size and geometry effects are taken into account through a so-called stress intensification factor. Formally defined as the ratio of the cross-sectional area of the porous sample (A) to the actual load-bearing area (A e ), the stress intensification factor is a measure of geometric hardening during powder consolidation operations.…”

Section: Introductionmentioning

confidence: 99%

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The effect of density anisotropy on the yielding and flow behavior of partially consolidated powder compacts

Dutton

Semiatin

1998

Metall Mater Trans A

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The effect of density anisotropy on the flow behavior of partially consolidated powder compacts of an alpha-two titanium aluminide alloy (Ti-24Al-11Nb) was established by conducting hot compression tests on samples made by hot die pressing or hot isostatic pressing (''hipping''). For the former consolidation method, in which anisotropic density distributions were developed, the upset tests were conducted both parallel and perpendicular to the die pressing direction. The flow stress results from these experiments, as well as those from the tests on the ''hipped'' material, were interpreted in terms of calculations of the stress intensification factor (). When the stress intensification factors were plotted as a function of areal relative density, rather than volumetric relative density, a unique dependence of on density was obtained. This dependence showed a smooth transition from a behavior measured by others for the early stages of densification to a behavior theoretically predicted for the latter stages of densification, in which isolated pores are closed.

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Ceramic Processing

Rahaman

2014

Kirk-Othmer Encyclopedia of Chemical Technology

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Modeling the hot consolidation of ceramic and metal powders

Cited by 21 publications

References 29 publications

The effect of strain-path reversal on cavitation during hot torsion of Ti-6Al-4V

The effect of strain-path reversal on cavitation during hot torsion of Ti-6Al-4V

The effect of density anisotropy on the yielding and flow behavior of partially consolidated powder compacts

Ceramic Processing

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