• Journal of Welding and Joining
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• 제18권3호
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• pp.106-113
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• 2000

Single crystallization behavior ad high temperature tensile properties of TLP bonded joints of Ni-base single crystal superalloy, CMSX-2 were investigated using MBF-80 and F-24 insert metals. CMSX-2 was bonded at 1523~1548K for 1.5~1.8ks in vacuum. The (100) orientation of bonded specimen was aligned perpendicular to the joint interface. Crystallographic orientation analyzed points over the bonded region possessed the almost same orientation across the joint interface and misorientation $\Delta^{\theta}$ was negligibly small in as-bonded and post-bond heat-treated situations. It was confirmed that single crystallization could be readily achieved during TLP bonding. The tensile strengths of all joints at elevated temperatures were equal to or greater than those of base metal the range of testing temperature between 923K and 1173K. The elongation and reduction of area in values were almost the same as those of base metal. SEM observation of the fracture surfaces of joints after tensile test revealed that the fracture surface indicated the similar morphologies each other, and that the fracture of joints occurred in the base metal in any cases.

• Journal of Welding and Joining
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• 제19권4호
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• pp.423-428
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• 2001

The bonding phenomena of Ni base single crystal superalloy. CMSX-4 during transient liquid phase(TLP) bonding was investigated using MBF-80 insert metal. Bonding of CMSX-4 was carried out at 1,373∼1,548K for 0∼19.6ks in vacuum. The (001) orientation of each test specimen was aligned perpendicular to the bonding interface. The dissolution width of base metal was increased when the bonding temperature and holding time were increased. The eutectic width diminished linearly with the square root of holding time during isothermal solidification process. Borides were formed in the bonded layer during TLP bonding operation. The solid phase grew epitaxially into the liquid phase from substrates and single crystallization could be readily achieved during the isothermal solidification.

• 대한용접접합학회:학술대회논문집
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• 대한용접접합학회 2009년 추계학술발표대회
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• pp.59-59
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• 2009

The influences of B and Si in the filler metals on microstructure and isothermal solidification during transient liquid-phase (TLP) bonding of a nitrogen-containing duplex stainless steel with MBF-30 (Ni-4.5wt.%Si-3.2wt.%B) and MBF-35 (Ni-7.3wt.%Si-2.2wt.%B), were studied at the temperature range of $1030-1090^{\circ}C$ with various times from 60 s to 3600 s under a vacuum of approximately $10^{-5}$ Torr. In case of the former, BN, $Ni_3B$ and $Ni_3Si$ precipitates were formed in the bonding region. BN and $Ni_3Si$ secondary phases were present in the joint for the latter case. The formation of $Ni_3B$ within the joint centerline is dependent on B content. The morphology of $Ni_3Si$ is dominated by Si concentration. A difference between the times for complete isothermal solidification obtained by the experiments and the conventional TLP bonding diffusion model was observed when using MBF-35. According to the simulated results, the isothermal solidification completion time for MBF-35 case was smaller than that in MBF-30. However, this experimental value obtained using MBF-35 was notably larger than that obtained using MBF-30. Isothermal solidification of liquid MBF-30 is controlled by the first isothermal solidification regime dependent on B diffusion model, whereas that of liquid MBF-35 experiences two isothermal solidification regimes and is mainly controlled by the second isothermal solidification dependent on Si diffusion model. In addition, only if Si content exceeds a critical value, the slower 2nd solidification regime will commence.

• 한국분말야금학회:학술대회논문집
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• 한국분말야금학회 1995년도 춘계학술강연 및 발표대회 강연 및 발표논문 초록집
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• pp.38-38
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• 1995

• 한국분말야금학회:학술대회논문집
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• 한국분말야금학회 1997년도 춘계학술강연 및 발표대회 강연 및 발표논문 초록집
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• pp.20-20
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• 1997

• 한국분말재료학회지
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• 제9권3호
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• pp.189-198
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• 2002

In this work, transient liquid phase (TLP) bonding of Ni-Cr heat resisted cast alloy (HP) was investigated. And also the behaviors of the solid particles distributed in the interlayer during TLP bonding were investigated. The MBF-60 and solid particles (Ni, Fe, and $Al_2O_3$ powders respectively) added MBF-60 which will be a liquid phase coexisting with solid particles at the bonding temperature were used as insert metal. The effective and sound bonding was possible by spark plasma sinter-bonding due to the differences of electric resistance between base metal and liquid insert layer which creates high temperature region. During the isothermal solidification, $Al_2O_3$ particles and solid particles of liquid phase sintered insert metal have shown no growth, while Ni and Fe particles grow rapidly. In this TLP bonding using the MBF-60 and distributed Fe, Ni particles as insert materials, the whole isothermal solidification process was dominated by the growth rate of the solid particles distributed in the interlayer.

• Journal of Welding and Joining
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• 제19권2호
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• pp.191-199
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• 2001

The oxidation and recrystallization behaviors of Ni-base single crystal superalloy, CMSX-2 were investigated to determine the condition of the preparation for transient liquid phase (TLP) bonding operations. The faying surfaces of CMSX-2 were worked by the shot peening, fine cutting and mechanical polishing treatments and the degree of working of treated surfaces was evaluated by the hardness test and X-ray diffraction method CMSX-2 was heat-treated at 1,173∼1.589k for 3.6ks in vacuum of 4mPa. The mechanically polished surface was slightly oxidized after heat treatment even in the vacuum atmosphere of 4mPa. The thickness of an oxide film increased with increasing the heating temperature and the surface roughness of the faying surface. Recrystallization occurred at the surface after heat treatment at above 1,423K when the hardness was increased more than Hv600 by the shot peening treatment while the mechanically polished or fine cut surfaces didn't recrystallized. Based on these results, it was clearfied that the mechanically polishing with fine abrasive grit could be used for the preparation of faying surface of CMSX-2 before bonding operation.

• 한국분말재료학회지
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• 제8권4호
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• pp.258-267
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• 2001

In this work, the conventional transient liquid phase(TLP) bonding was modified. An attempt was made of using a liquid phase sintered alloy, which will be a liquid phase coexisting with a solid phase at the bonding temperature, as an interlayer for bonding metals. With an aim of revealing the fundamental features of this modified TLP bonding, the kinetics concerned with the growth of solid particles and the isothermal solidification process in Fe-1.16wt%B and Fe-4.5wt%P interlayers for the bonding pure iron, as well as the morphological change of the solid particle, were investigated.

• Journal of Welding and Joining
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• 제25권5호
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• pp.45-50
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• 2007

The Ni-base superalloy GTD111 DS is used in the first stage blade of high power land-based gas turbines. Advanced repair technologies of the blade have been introduced to the gas turbine industry over recent years. The effect of the filler metal powder on Transient Liquid Phase bonding phenomenon and tensile mechanical properties was investigated on the GTD111 DS superalloy. At the filler metal powder N series, the base metal powders fully melted at the initial time and a large amount of the base metal near the bonded interlayer was dissolved by liquid inter metal. Liquid filler metal powder was eliminated by isothermal solidification which was controlled by the diffusion of B into the base metal. The solids in the bonded interlayer grew from the base metal near the bonded interlayer inward the insert metal during the isothermal solidification. The bond strength of N series filler metal powder was over 1000 MPa. and ${\gamma}'$ phase size of N series TLP bonded region was similar with base metal by influence of Ti, Al elements. At the insert metal powder M series, the Si element fluidity of the filler metal was good but microstructure irregularity on bonded region because of excessive Si element. Nuclear of solids formed not only from the base metal near the bonded interlayer but also from the remained filler metal powder in the bonded interlayer. When the isothermal solidification was finished, the content of the elements in the boned interlayer was approximately equal to that of the base metal. But boride and silicide formed in the base metal near the bonded interlayer. And these boride decreased with the increasing of holding time. The bond strength of M series filler metal powder was about 400 MPa.

• Journal of Welding and Joining
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• 제9권4호
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• pp.28-39
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• 1991

The change of microstructure in the bonded interlayer and mechanical properties of the joints were investigated during Transient Liquid Phase Diffusion Bonding(TLP bonding) of STS304/SM17C and STS304/SM45C couples using Ni base amorphous alloys added boron and prepared alloy as insert metal. Main experimental results obtained in this study are as follows: 1) Isothermal solidification process was completed much faster than theoretically expected time, 14ks at 1473K temperature. Its completion times were 3.6ks at 1423K, 2.5ks at 1473K and 1.6ks at 1523K respectively. 2) As the concentration of boron in the insert metal increased, the more borides were precipitated near bonded interlayer and grain boundary of STS304 side during isothermal solidification process, its products were $M_{23}P(C,B)_6}_3)$ The formation of grain boundary during isothermal solidification process was completed at structural carbon steel after starting the solidfication at STS304 stainless steel. 4) The highest value of hardness was obtained at bonded interface of STS304 side. The desirable tensile properties were obtained from STS304/SM17C, STS304/SM45C using MBF50 and experimentally prepared insert metal with low boron concentration.