Analysis of kinetics of reactive diffusion in a hypothetical binary system

Kajihara, Masahiro

doi:10.1016/j.actamat.2003.10.047

Cited by 112 publications

(109 citation statements)

References 6 publications

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“…This is because the rate constant (k) is dependent on many factors, which include the solubility range in the IMC layer, the interdiffusion coefficient of the diffusing species, and the diffusion pathway. [7] Inferring any mechanism (e.g., identifying a rate controlling species) from fitted activation energy values is therefore erroneous. Instead, a more detailed understanding of the layer growth kinetics is needed, which can then be captured in a model that better considers the essential physics of the process.…”

Section: Lei Xu Joseph D Robson Li Wang and Philip B Prangnellmentioning

confidence: 99%

“…The Al-Mg couple also leads to the formation of a two-phase intermetallic layer structure, similar to the Al-Fe case. The model is based on extending a reactive interdiffusion model developed by Kajihara [7,9] for one-phase layers to the two-phase problem. The model properly accounts for the effect of the interfacial compositions on the layer growth, and the boundary conditions that are enforced at the interface between the phases involved.…”

Section: Lei Xu Joseph D Robson Li Wang and Philip B Prangnellmentioning

confidence: 99%

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The Influence of Grain Structure on Intermetallic Compound Layer Growth Rates in Fe-Al Dissimilar Welds

Robson

Wang

et al. 2017

Metall Mater Trans A

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The thickness of the intermetallic compound (IMC) layer that forms when aluminum is welded to steel is critical in determining the properties of the dissimilar joints. The IMC reaction layer typically consists of two phases (g and h) and many attempts have been made to determine the apparent activation energy for its growth, an essential parameter in developing any predictive model for layer thickness. However, even with alloys of similar composition, there is no agreement of the correct value of this activation energy. In the present work, the IMC layer growth has been characterized in detail for AA6111 aluminum to DC04 steel couples under isothermal annealing conditions. The samples were initially lightly ultrasonically welded to produce a metallic bond, and the structure and thickness of the layer were then characterized in detail, including tracking the evolution of composition and grain size in the IMC phases. A model developed previously for Al-Mg dissimilar welds was adapted to predict the coupled growth of the two phases in the layer, whilst accounting explicitly for grain boundary and lattice diffusion, and considering the influence of grain growth. It has been shown that the intermetallic layer has a submicron grain size, and grain boundary diffusion as well as grain growth plays a critical role in determining the thickening rate for both phases. The model was used to demonstrate how this explains the wide scatter in the apparent activation energies previously reported. From this, process maps were developed that show the relative importance of each diffusion path to layer growth as a function of temperature and time.

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Section: Lei Xu Joseph D Robson Li Wang and Philip B Prangnellmentioning

confidence: 99%

Section: Lei Xu Joseph D Robson Li Wang and Philip B Prangnellmentioning

confidence: 99%

The Influence of Grain Structure on Intermetallic Compound Layer Growth Rates in Fe-Al Dissimilar Welds

Robson

Wang

et al. 2017

Metall Mater Trans A

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“…75) Although the growth rate is not necessarily a simple mathematical function of the interdiffusion coefficient, it is surely a monotonically increasing function of the interdiffusion coefficient. [75][76][77][78][79][80][81][82][83][84] In the early stages, many fine Fe 2 Al 5 grains with random crystallographic orientations are produced at the Fe/Al interface. 72) Of these random grains, those with the c axis nearly perpendicular to the Fe/Al interface preferentially grow along the c axis over long distances without impingement.…”

Section: Microstructurementioning

confidence: 99%

“…As mentioned above, the interdiffusion coefficient of a growing compound is the most predominant parameter controlling the growth rate of the compound. 75) If compounds and are formed by reactive diffusion in a diffusion couple and the interdiffusion coefficient is much smaller for compound than for compound , the growth is much more sluggish for compound than for compound . At realistic experimental annealing times, the thickness becomes sufficiently large for compound but not for compound .…”

Section: Microstructurementioning

confidence: 99%

Morphology of Compounds Formed by Isothermal Reactive Diffusion between Solid Fe and Liquid Al

Tanaka

Kajihara

2009

Mater. Trans.

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“…As reported in a previous study, 24) the growth of the compound layer is determined by the mass transport across the compound layer. In the case of the diffusion ratecontrolling process, the mass transport is governed by the interdiffusion.…”

Section: Transition Of Rate-controlling Processmentioning

confidence: 57%

Kinetics of Solid-State Reactive Diffusion between Au and Al

Minho

Kajihara

2011

Mater. Trans.

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In the wire bonding technique, a thin Au wire is interconnected with an Al layer on a Si chip. During energization heating at solid-state temperatures, however, brittle Au-Al compounds with high electrical resistivities are formed at the interconnection by the reactive diffusion between Au and Al. In order to examine the growth behavior of the Au-Al compounds, the kinetics of the reactive diffusion was experimentally observed using sandwich Al/Au/Al diffusion couples. The diffusion couple was prepared by a diffusion bonding technique and then isothermally annealed at temperatures of 623-723 K for various times up to 103 h. Under such annealing conditions, the diffusion couple is practically considered semi-infinite. Owing to annealing, compound layers consisting of AuAl 2 , AuAl and Au 8 Al 3 are produced at the initial Au/Al interface in the diffusion couple. The volume fraction in the compound layers is larger for Au 8 Al 3 than for AuAl and AuAl 2 in the early stages but becomes smaller for Au 8 Al 3 than for AuAl and AuAl 2 in the late stages. However, there are no systematic dependencies of the volume fraction on the annealing time and temperature. The total thickness of the compound layers is proportional to a power function of the annealing time. The exponent of the power function is smaller than 0.5 at 673-723 K. The exponent smaller than 0.5 means that the interdiffusion across the compound layers governs the layer growth and boundary diffusion predominantly contributes to the interdiffusion. On the other hand, at 623 K, the exponent is equal to unity for annealing times shorter than 8 h but smaller than 0.5 for those longer than 8 h. The exponent of unity indicates that the layer growth is controlled by the interface reaction at the migrating interface. Thus, at T ¼ 623 K, the transition of the ratecontrolling process occurs at a critical annealing time of 8 h.

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Analysis of kinetics of reactive diffusion in a hypothetical binary system

Cited by 112 publications

References 6 publications

The Influence of Grain Structure on Intermetallic Compound Layer Growth Rates in Fe-Al Dissimilar Welds

The Influence of Grain Structure on Intermetallic Compound Layer Growth Rates in Fe-Al Dissimilar Welds

Morphology of Compounds Formed by Isothermal Reactive Diffusion between Solid Fe and Liquid Al

Kinetics of Solid-State Reactive Diffusion between Au and Al

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