Analysis of Diffusional Solidification in a Wide-Gap Brazing Powder Mixture Using Differential Scanning Calorimetry

Corbin, Stephen F.; Murray, D C; Bouthillier, Alain

doi:10.1007/s11661-016-3799-6

Cited by 7 publications

(4 citation statements)

References 10 publications

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“…[14] Rapid surface diffusion of MPD and dissolution of HMP decrease the volume and fluidity of the liquid, resulting in a decrease in the particle densification and rearrangement of the semi-solid WGB mixture. [23] Therefore, a higher brazing temperature is needed in WGB, compared with TLP, to achieve a joint with lower porosity. The higher temperature leads to an increase in the amount and fluidity of the liquid.…”

Section: Methodsmentioning

confidence: 99%

“…Porosity is one of the main problems in WGB, which is a function of brazing temperature and the amount of LMP. [23] Increasing the weight fraction of LMPs or the superheating increases the amount of liquid and decreases porosity. [31] The interface area between the HMPs and the LMPs in WGB is much higher than that between the BM and the braze alloy in conventional brazing.…”

Section: ! L þ C ½1mentioning

confidence: 99%

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Wide Gap Brazing of Inconel 738LC Nickel-Based Superalloy: Metallurgical and Mechanical Characteristics

Alinaghian

Farzadi

Marashi

et al. 2020

Metall Mater Trans A

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This paper addresses the microstructure properties relationship of wide gap brazed Inconel 738LC. Amdry 718 and a Ni-Cr-Fe-Si-B alloy were used as high melting particles (HMPs) and low melting particles (LMPs), respectively. The effect of the amount of LMPs, 30, 40, and 50 pct, on the microstructure and the shear strength of the joint, was investigated. The microstructure in the brazing zone consists of Ni-based solid solution and eutectic-type microconstituents that is nickel-rich and chromium-rich borides. Nickel-rich borides only observed in the presence of the high amount of LMPs, because of the low Cr-B ratio in the filler alloy. At the brazing/base metal interface, high diffusion of melting point depressant (MPD) elements to the base metal led to the formation of small blocky Cr-rich borides in Ni-rich solid solution matrix. The nickel-rich and chromium-rich borides have a hardness value of about 1200 and 830 HV, respectively, which is remarkably higher than the other regions. By increasing the amount of LMPs from 30 to 50 pct, the joint shear strength decreases from 422 to 373 MPa due to the higher volume fraction of the brittle boride phase in the joint. For all brazed joints, the cleavage fracture mode was observed, which can be ascribed to the interlinked network of the brittle eutectic-type microconstituents. The X-ray diffraction pattern confirms that the preferred location for crack propagation is eutectic boride phases.

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Section: Methodsmentioning

confidence: 99%

Section: ! L þ C ½1mentioning

confidence: 99%

Wide Gap Brazing of Inconel 738LC Nickel-Based Superalloy: Metallurgical and Mechanical Characteristics

Alinaghian

Farzadi

Marashi

et al. 2020

Metall Mater Trans A

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“…The goal is that the solidification in the joint is isothermal, being brought about by the change of composition as the molten filler metal interacts with the solid additive metal [182]. Very little interdiffusion takes place in the solid state, but it is rapid once liquid; use of a foil form of filler metal has been found to increase the densification and to result in reduced formation of intermetallic phases [190].…”

Section: Wide Gap Brazingmentioning

confidence: 99%

Brazing filler metals

Way

Willingham

Goodall

2019

International Materials Reviews

103

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Brazing is a 5000-year-old joining process which still meets advanced joining challenges today. In brazing, components are joined by heating above the melting point of a filler metal placed between them; on solidification a joint is formed. It provides unique advantages over other joining methods, including the ability to join dissimilar material combinations (including metal-ceramic joints), with limited microstructural evolution; producing joints of relatively high strength which are often electrically and thermally conductive. Current interest in brazing is widespread with filler metal development key to enabling a range of future technologies including; fusion energy, Solid Oxide Fuel Cells and nanoelectronics, whilst also assisting the advancement of established fields, such as automotive lightweighting, by tackling the challenges associated with joining aluminium to steels. This review discusses the theory and practice of brazing, with particular reference to filler metals, and covers progress in, and opportunities for, advanced filler metal development.

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“…During the entire wide-gap brazing process, additive powder with a high melting point remains largely unmelted, thereby providing the necessary capillary force to retain the molten braze powder that would otherwise be too fluid to bridge the faying gap surfaces [ 16 , 17 ]. However, the formation of hard and brittle eutectic structures with uneven distribution cannot be avoided due to their sensitivity to the chemical composition of the filler metal, brazing temperature, and brazing time [ 22 , 23 , 24 , 25 ].…”

Section: Introductionmentioning

confidence: 99%

Wide-Gap Brazing of K417G Alloy Assisted by In Situ Precipitation of M3B2 Boride Particles

Zhang

et al. 2020

Materials

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In this study, K417G Ni-based superalloy with a 20-mm gap was successfully bonded at 1200 °C using powder metallurgy with a powder mixture. The results indicated that the microstructure and mechanical properties of the as-bonded alloy were highly dependent on the brazing time (15–45 min), mainly due to the precipitation and distribution characteristics of M3B2 boride particles. Specifically, alloy brazed for 30 min exhibited desirable mechanical properties, such as a high tensile ultimate strength of 971 MPa and an elongation at fracture of 6.5% at room temperature, exceeding the balance value (935 MPa) of the base metal. The excellent strength and plasticity were mainly due to coherent strengthening and dispersion strengthening of the in situ spherical and equiaxed M3B2 boride particles in the γ + γ′ matrix. In addition, the disappearance of dendrites and the homogenization of the microstructure are other factors that cannot be excluded. This powder metallurgy technique, which can avoid the eutectic transformation of traditional brazing, provides a new effective method for wide-gap repair of alloy materials.

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Analysis of Diffusional Solidification in a Wide-Gap Brazing Powder Mixture Using Differential Scanning Calorimetry

Cited by 7 publications

References 10 publications

Wide Gap Brazing of Inconel 738LC Nickel-Based Superalloy: Metallurgical and Mechanical Characteristics

Wide Gap Brazing of Inconel 738LC Nickel-Based Superalloy: Metallurgical and Mechanical Characteristics

Brazing filler metals

Wide-Gap Brazing of K417G Alloy Assisted by In Situ Precipitation of M3B2 Boride Particles

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