High-temperature observations of braze alloy spreading by oxide penetration

Cohen, Julien; Castle, J. E.; Waldron, M.B.

doi:10.1179/msc.1981.15.10.455

Cited by 12 publications

(4 citation statements)

References 1 publication

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“…However, in the cases of the coated steel plates, the wrinkled, cracked ceramic layers can be observed, suggesting that Cu undermined the ceramic layer or the ceramic layer floated up to the Cu surface. This observation is similar to the literature reports [12][13][14][15] on liquid metals undermining the surface oxide layers on solid metals. This finding is further confirmed by the cross sectional elemental map taken after the experiment (Fig.…”

Section: Inner Structural Changes Of the Samples After Melting Cu On Their Topsupporting

confidence: 92%

“…Interesting phenomena have been reported as a side product of development of brazing technologies, in which metal-1 melted on the surface of oxidecoated solid metal-2 spread along the oxide/metal-2 interface. For example, Cohen et al [12] found that a liquid gold-nickel (82Au-18Ni) alloy undermined the surface oxide layer of a chromium-containing stainless steel. This phenomenon consisted of two successive sub-processes: the breakthrough of the liquid alloy through the oxide layer, followed by spread of the same along the oxide/steel interface.…”

Section: Graphical Abstract Introductionmentioning

confidence: 99%

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Spontaneous inversion of the submicron ceramic layer deposited on steel and the copper droplet positioned on their top (case of ceramic poorly wetted by liquid Cu)

et al. 2022

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In this paper, 50 … 680 nm thick AlN-Al2O3 coatings are deposited by magnetron sputtering on the surface of a steel substrate and a piece of copper is melted on top of the ceramic. Upon heating the ceramic layer is cracked, and the phase inversion of the two top phases from steel/ceramic/copper configuration to the steel/copper/ceramic configuration takes place within 30 s of liquid time of copper. This phase inversion process is accompanied by a Gibbs energy change of about − 1.78 J/m2, due to good wettability of solid deoxidized steel by liquid copper in contrary to poor wettability of the ceramic by the copper. When copper is melted on AlN-Al2O3 coating with its thicknesses smaller than a critical value of about 170 ± 60 nm, liquid copper droplets hanging down into the cracks within the ceramic reach the solid steel surface at the bottom of the cracks, thus the flow of Cu down along the cracks is enabled. However, when copper is melted on AlN-Al2O3 with its thickness larger than the critical value of 170 ± 60 nm, Cu first forms a non-wetting droplet on top of the ceramics, and only after a certain incubation time it starts flowing down the cracks. This incubation time was found to depend linearly on the thickness of the ceramic, as cracks are filled from the bottom upwards by liquid copper via the evaporation–condensation mechanism. By the end of the process, the steel/copper/ceramic configuration is further stabilized by gravity. Graphical abstract

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Section: Inner Structural Changes Of the Samples After Melting Cu On Their Topsupporting

confidence: 92%

Section: Graphical Abstract Introductionmentioning

confidence: 99%

Spontaneous inversion of the submicron ceramic layer deposited on steel and the copper droplet positioned on their top (case of ceramic poorly wetted by liquid Cu)

et al. 2022

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“…In regard of initiation of undermining, Brooker et al 69 suggested penetration could occur at pre-existing defects in the substrate oxide. In contrast, Cohen et al 68 envisaged (and produced some experimental support for) disruption of the continuity of the oxide owing to reaction between the substrate oxide and substrate constituents (compare this with the work of Lugscheider and Zhuang, 66 as discussed above).…”

Section: Surface Oxide Effectsmentioning

confidence: 97%

Transient liquid phase bonding

Gale¹,

Butts²

2004

Science and Technology of Welding and Joining

272

138

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A review of the transient liquid phase (TLP) bonding process is presented in this paper. This review concentrates on the mechanisms of the TLP process, including both microstructural development and wettability aspects. However, design related issues and engineering applications are also considered. The paper explains how the TLP bonding process offers the potential for producing joints with microstructures and hence mechanical properties that are similar to those of the parent materials. The process of isothermal solidification is discussed at some length. The paper considers the ways in which specific microstructural features of the substrate material-interlayer material combination influence microstructural development. A distinction is drawn between cases where the progression of isothermal solidification dominates the final microstructure and those where events occurring after the completion of isothermal solidification are paramount. The paper describes the practical limitations on the production of parent-metal-like microstructures and the complexity of microstructural development in real materials, especially where dissimilar substrates are involved. Modification of the TLP bonding process to accommodate cases of limited solid solubility and/or low diffusion coefficients is discussed. STWJ/447

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“…[30] A similar chemical reduction mechanism for the sub-oxide spreading of gold-nickel braze alloy on stainless steel was also described by Cohen et al [31] E. Observations of the As-Cast Interface ingots cast with the following process parameters: [10] casting speed 1.27 mm/s, clad pouring temperature 898 K (625°C), and core pouring temperature 973 K (700°C). In both cases, the interface is not planar and exhibits some undulations or scallops.…”

Section: Possible Aa3003 Surface Oxide Penetration Mechanismsmentioning

confidence: 94%

Interface Formation During Fusion™ Casting of AA3003/AA4045 Aluminum Alloy Ingots

Ciano

Caron

Weckman

et al. 2015

Metall Mater Trans B

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Fusionä casting is a unique Direct Chill continuous casting process whereby two different alloys can be cast simultaneously, producing a laminated ingot for rolling into clad sheet metal such as AA3003/AA4045 brazing sheet. Better understanding of the wetting and interface formation process during Fusionä casting is required to further improve process yields and also explore use of other alloy systems for new applications. In this research, AA3003-core/AA4045-clad ingots were cast using a well-instrumented lab-scale Fusionä casting system. As-cast Fusionä interfaces were examined metallurgically and by mechanical testing. Computational fluid dynamic analyses of the Fusion TM casts were also performed. It was shown that the liquid AA4045-clad alloy was able to successfully wet and create an oxide-free, metallurgical, and mechanically sound interface with the lightly oxidized AA3003-core shell material. Based on the results of this study, it is proposed that the bond formation process at the alloys interface during casting is a result of discrete penetration of AA4045 liquid at defects in the preexisting AA3003 oxide, dissolution of underlying AA3003 by liquid AA4045, and subsequent bridging between penetration sites. Spot exudation on the AA3003 chill cast surface due to remelting and inverse segregation may also improve the wetting and bonding process.

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High-temperature observations of braze alloy spreading by oxide penetration

Cited by 12 publications

References 1 publication

Spontaneous inversion of the submicron ceramic layer deposited on steel and the copper droplet positioned on their top (case of ceramic poorly wetted by liquid Cu)

Spontaneous inversion of the submicron ceramic layer deposited on steel and the copper droplet positioned on their top (case of ceramic poorly wetted by liquid Cu)

Transient liquid phase bonding

Interface Formation During Fusion™ Casting of AA3003/AA4045 Aluminum Alloy Ingots

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