An Overview of Selected Phenomena in Multicomponent Diffusion

2015 ◽  
Vol 4 ◽  
pp. 3-21
Author(s):  
Mysore A. Dayananda
Keyword(s):  
Single Phase ◽  
Multicomponent Diffusion ◽  
Nuclear Fuels ◽  
Uphill Diffusion ◽  
Diffusion Studies ◽  
Isothermal Diffusion ◽  
Diffusion Paths ◽  
Multiphase Diffusion ◽  
Layer Development

There exist several interesting phenomena and observations reported in literature for isothermal diffusion in multicomponent systems. Such phenomena include uphill diffusion, development of zero-flux planes and flux reversals for individual components, flux reversals at interfaces, and instability at interfaces and multiphase layer development. In addition, uncommon diffusion structures exhibiting unusual diffusion paths can develop in both single phase and multiphase diffusion assemblies. An overview of such phenomena is presented to highlight the role of interactions among diffusing components with the aid of selected diffusion studies carried out in multicomponent alloy systems, aluminides, silicides, and nuclear fuels.

Selected Analyses and Observations in Multicomponent Diffusion

2010 ◽  
Vol 297-301 ◽  
pp. 1451-1460 ◽  
Author(s):  
Mysore A. Dayananda
Keyword(s):  
Multicomponent Diffusion ◽  
Diffusion Couples ◽  
Uphill Diffusion ◽  
Diffusion Studies ◽  
Isothermal Diffusion ◽  
Mn Diffusion ◽  
Experimental Approaches ◽  
Diffusion Paths ◽  
Interdiffusion Coefficients

Selected isothermal diffusion studies in ternary and quaternary systems are reviewed in order to present analytical and experimental approaches adopted for the determination of interdiffusion fluxes of components, interdiffusion coefficients, diffusional interactions among components, and internal consistency in the experimental data. Several interesting phenomena and observations including uphill diffusion, zero-flux planes and flux reversals, and double serpentine diffusion paths are illustrated with selected single phase Cu-Ni-Zn, Fe-Ni-Al and Cu-Ni-Zn-Mn diffusion couples. The main challenges involved in the experimental determination of interdiffusion data from multicomponent diffusion couples and in the application of such data are also addressed.

An Examination of Diffusion Paths in Terms of Interdiffusion Fluxes and Interdiffusion Coefficients

2007 ◽  
Vol 266 ◽  
pp. 83-99 ◽  
Author(s):  
Kevin M. Day ◽  
Mysore A. Dayananda
Keyword(s):  
National Science Foundation ◽  
Single Phase ◽  
Diffusion Path ◽  
Diffusion Couples ◽  
Eigenvalues And Eigenvectors ◽  
Internal Constraints ◽  
Two Phase ◽  
Uphill Diffusion ◽  
Diffusion Paths ◽  
Interdiffusion Coefficients

Selected diffusion couples investigated in the Cu-based and Fe-based multicomponent systems are examined for diffusion path development, zero-flux planes, uphill diffusion, and internal constraints for diffusion paths. The couples are analyzed for interdiffusion fluxes and interdiffusion coefficients with the aid of the “MultiDiFlux” program. Eigenvalues and eigenvectors are also determined from the interdiffusion coefficients determined over various ranges of composition in the diffusion zone. Slopes of diffusion paths at selected sections, including the path ends, are related to interdiffusion coefficients, interdiffusion fluxes and/or eigenvectors. These relations are explored with selected single phase diffusion couples in the Cu-Ni-Zn and Fe-Ni-Al systems and the calculated path slopes are compared with those directly determined from the concentration profiles. Relations between the gradient of interdiffusion flux and the concentration gradient are examined for each component in a two-phase Cu-Ni-Zn diffusion couple. The research is supported by the National Science Foundation.

Evolution of Concentration Profiles and Diffusion Paths in Single-Phase Multicomponent Multilayered Assemblies

2009 ◽  
Vol 289-292 ◽  
pp. 593-599 ◽  
Author(s):  
Kaustubh N. Kulkarni ◽  
Mysore A. Dayananda
Keyword(s):  
Single Phase ◽  
Middle Layer ◽  
Diffusion Path ◽  
Alloy Layer ◽  
Concentration Profiles ◽  
Uphill Diffusion ◽  
Diffusion Paths ◽  
Set Up ◽  
The Individual ◽  
And Diffusion

An analysis of multilayered assemblies set up with multicomponent alloys selected in a single phase field has been recently developed on the basis of a matrix of constant interdiffusion coefficients. This analysis employs a transfer matrix method and is applicable to a study of evolution of concentration profiles and diffusion paths as a function of time for multilayered diffusion assemblies (MDAs) where any number of finite layers is sandwiched between two bulk terminal alloys. The analysis is utilized in this study to simulate concentration profiles and diffusion paths for MDAs assembled with (fcc) Cu-Ni-Zn alloys with two terminal alloys, A and B, sandwiching an alloy layer C in the middle. For short diffusion times the diffusion path of the ternary MDA, A/C/B, corresponds to two segments corresponding to the diffusion paths of the infinite diffusion couples, A/C and C/B. At longer times the diffusion zones of the two individual couples overlap and the diffusion path of the MDA varies continuously with time. The evolution of the concentration profiles and diffusion paths is presented and each intermediate path configuration is associated with a unique ratio of the middle layer thickness to the square root of diffusion time. The simulated concentration profiles clearly show the development of uphill diffusion and zero-flux planes (ZFP) for the individual components due to diffusional interactions among the components. At very long times, the diffusion path of the MDA approaches that of the infinite couple A/B between the two terminal alloys.

The Role of Cost Breakdown Structure in Life Cycle Cost Model

2015 ◽  
Vol 74 (2) ◽  
Author(s):  
Ooi Chu Hui ◽  
Abdul Hakim Mohammed
Keyword(s):  
Life Cycle ◽  
Life Cycle Cost ◽  
Water Distribution ◽  
Single Phase ◽  
Cost Model ◽  
Pipeline Networks ◽  
Useful Life ◽  
Cost Breakdown Structure ◽  
Cost Breakdown

This paper highlights the basic process of developing a life cycle cost model and the role of cost breakdown structure for water distribution pipeline networks. A life cycle cost is the total cost of owning an asset during its predicted useful life, while a cost breakdown structure illustrates all the costs emerged in each single phase of the asset’s life cycle cost. Its purpose is to identify, define and organize all cost elements to be taken into account in a life cycle cost. Each cost element included in developing a cost breakdown structure will also be discussed in this paper.

Role of size, alio-/multi-valency and non-stoichiometry in the synthesis of phase-pure high entropy oxide (Co,Cu,Mg,Na,Ni,Zn)O

2020 ◽  
Vol 49 (21) ◽  
pp. 7123-7132 ◽  
Author(s):  
Nandhini J. Usharani ◽  
Rajat Shringi ◽  
Harshil Sanghavi ◽  
S. Subramanian ◽  
S. S. Bhattacharya
Keyword(s):  
Phase Formation ◽  
Single Phase ◽  
High Entropy ◽  
Phase Pure ◽  
Single Phase Formation

Presence of multivalency/non-stoichiometry to accommodate a different-sized cation and maintaining electroneutrality were identified as the critical criteria for single-phase formation in multicomponent/high entropy systems.

Low temperature synthesis of ultrafine Pb(Zr, Ti)O3 powder by sol-gel combustion

1997 ◽  
Vol 12 (10) ◽  
pp. 2518-2521 ◽  
Author(s):  
J. Schäfer ◽  
W. Sigmund ◽  
S. Roy ◽  
F. Aldinger
Keyword(s):  
Lead Zirconate Titanate ◽  
Single Phase ◽  
Sol Gel ◽  
Combustion Process ◽  
Lead Zirconate ◽  
Homogeneous Distribution ◽  
Low Temperature Synthesis ◽  
Metal Nitrates ◽  
Gel Combustion ◽  
Diffusion Paths

Lead zirconate titanate powders are derived from a novel aqueous-based citrate-nitrate/oxynitrate sol-gel combustion process. Aqueous solutions of metal nitrates or oxynitrates are transformed into gels with citric acid under heating. The received gels undergo a self-propagating combustion reaction on heating to 180 °C and subsequently yield voluminous ashes. These ashes form single phase perovskite Pb(Zr0.53Ti0.47)O3 powder with a specific surface area of 8 m2/g upon calcination at 550 °C. The ashes show a homogeneous distribution of lead, zirconium, and titanium ions which guarantees short diffusion paths in solid state formation of PZT perovskite. The redox behavior of the gels was studied with the help of DTA experiments. Powders are characterized in terms of XRD, SEM, and EDX analysis.

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