The influence of base metal grain size on isothermal solidification during transient liquid-phase brazing of nickel

Saida, Kazuyoshi; Zhou, Yunhong; North, T. H.

doi:10.1007/bf01352207

Cited by 31 publications

(16 citation statements)

References 8 publications

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“…The activation energy value found when bonding CMSX-2 base metal would be determined by the diffusion of boron into the solid substrates. In contrast, it is known that grain boundary regions influence the rate of isothermal solidification and that finer grain sizes promote the increased solute diffusion into the base metal [13]. It follows that the difference in activation energies between the single crystal and the polycrystal superalloys base metal can be readily explained by the fact that grain boundary regions can act as high diffusivity paths and these do not exist in single crystal material.…”

Section: Isothermal Solidification Processmentioning

confidence: 68%

Bonding phenomena of transient liquid phase bonded joints of a Ni base single crystal superalloy

Kim

Nishimoto

2002

Met. Mater. Int.

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The bonding phenomena of Ni base single crystal superalloy CMSX-2 during transient liquid phase (TLP) bonding have been investigated using MBF-80 and F-24 insert metals. TLP bonding of the superalloy was carried out at 1373-1548K for 0-19.6ks in vacuum and the (100) plane of each test specimen was always aligned perpendicular to the joint interface. The dissolution width increased when the bonding temperature and holding time increased. The eutectic width decreased linearly with the square root of holding time during isothermal solidification. After homogenization treatment, the microstructure, distributions of hardness and alloying elements in the bonded interlayer become similar to those of the base metal.

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Section: Isothermal Solidification Processmentioning

confidence: 68%

Bonding phenomena of transient liquid phase bonded joints of a Ni base single crystal superalloy

Kim

Nishimoto

2002

Met. Mater. Int.

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“…The physical description of TLP bonding as a diffusioncontrolled phase change is well-established [4][5][6][7][11][12][13][14][15][16][17][18][19] and simulations made on this basis have been found to agree reasonably well with experimental observations [12,13]. Although the mathematical models used previously differ slightly from each other, there is general agreement on the nature of the underlying physical phenomena.…”

Section: Governing Equations and Boundary Conditionsmentioning

confidence: 89%

“…While some concerns have been expressed [5,12,[17][18][19] as to whether the interface remains planar during solidification if the parent material is polycrystalline, the process is usually modelled as illustrated schematically in Fig. 1.…”

Section: Governing Equations and Boundary Conditionsmentioning

confidence: 99%

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Modelling of transient liquid phase bonding in binary systems—A new parametric study

Illingworth

Golosnoy

Clyne

2007

Materials Science and Engineering: A

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An established mathematical model, describing the rate at which transient liquid phase bonding (TLP bonding) progresses in binary alloy systems, is subjected to careful scrutiny. It is shown that the process can be characterised using just two dimensionless parameters. An advantage of such dimensionless characterisation is demonstrated by analysis of the solution for solidification of semi-infinite systems. It is known that analytical formulae for the rate at which the liquid region solidifies are valid only for certain restricted cases. This is investigated by numerical modelling, and the requirements for the formulae to be applicable are rationalised. Maps presented here can be used to determine whether the semi-infinite solution would provide an acceptable approximation for any given system. Information is also presented concerning optimal combinations of phase diagram characteristics, diffusivities and system dimensions required for rapid TLP solidification, which can be used to identify the best melting point depressant (MPD) materials to use for particular TLP requirements. The analysis reveals that, as a consequence of their higher solubilities, elements forming substitutional solutes in the parent plates may often allow faster TLP solidification than those forming interstitial solutes, despite the fact that the latter group normally exhibits much higher diffusivities.

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“…[37] The isothermal solidification time is reduced significantly with fine-grained base metal; the difference in isothermal solidification rates between coarsegrained and single-crystal base metal is negligible. [10,37,38] The increase in interface kinetics with finer grain size has been attributed to enhanced grain boundary diffusion and grain boundary grooving, although support for this theory by numerical modeling has only been qualitative to date. On the other hand, for coarse-grained substrates bonded at higher temperatures and longer isothermal hold times, it has been shown that the effect of grain boundaries on solid/ liquid interface motion is much less significant and can be considered with an effective diffusivity if required.…”

Section: Effect Of Grain Boundariesmentioning

confidence: 99%

A study of transient liquid-phase bonding of Ag-Cu using differential scanning calorimetry

Kuntz

Zhou

Corbin

2006

Metall Mater Trans A

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A novel approach using differential scanning calorimetry (DSC) to quantify interface kinetics in a solid/liquid diffusion couple is applied to characterize the isothermal solidification stage during transient liquid-phase (TLP) bonding of Ag and Cu using a Ag-Cu interlayer. When the DSC results are properly interpreted, the measured interface kinetics are more accurate than those obtained using traditional metallographic techniques. Experimental results are compared to predictions for isothermal solidification given by a selection of analytical models. The comparison yields close agreement with a solution that assumes a moving boundary; but accuracy of the predictions is very sensitive to selection of solute diffusivity. Metallographic inspection of the DSC samples and traditional TLP bonds validates the kinetics measured using this technique, and supports the prediction given by the analytical model. This study shows that the method of using DSC to quantify interface kinetics is valuable in the refinement of process parameters for TLP bonding. Furthermore, simple analytical solutions can be applied to predict the process kinetics of isothermal solidification in simple binary systems with considerable accuracy when the effects of grain boundaries can be neglected, thus reducing the need for complex numerical models when developing process parameters.

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The influence of base metal grain size on isothermal solidification during transient liquid-phase brazing of nickel

Cited by 31 publications

References 8 publications

Bonding phenomena of transient liquid phase bonded joints of a Ni base single crystal superalloy

Bonding phenomena of transient liquid phase bonded joints of a Ni base single crystal superalloy

Modelling of transient liquid phase bonding in binary systems—A new parametric study

A study of transient liquid-phase bonding of Ag-Cu using differential scanning calorimetry

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