Analytical Modelling of Solidification during Temperature Gradient TLP Diffusion Bonding

In order to promote the molten metal penetration into the carbon/carbon (C/C) composite, a sequence of annular gaps is designed and prepared on the C/C surface. These gaps are created on the C/C surface under preoxidation conditions at 600–660 °C. The oxidized C/C composite is joined to Ti3Al via transient liquid phase (TLP) diffusion bonding at 880 °C with AgCuNiLi foil as an intermediate layer. The study investigates the effects of preoxidation temperature on the microstructure and characteristics of C/C composite and C/C–Ti3Al joints. The results show that a sequence of annular gaps with appropriate size can be established between the carbon fiber and pyrolytic carbon layer, while carbon fiber is barely oxidized after oxidation at 630 °C for 30 min. During the bonding process, the molten metal seeps through the C/C gaps, and a permeation layer composed of TiC, Ag (s, s), and C/C composite can be formed. The production of a permeation layer can enhance the bonding strength of the C/C–Ti3Al joint, and the maximum shear strength (42.12 MPa) of the joint can be 22% greater than the initial C/C–Ti3Al joint.

Surface and Interface AnalysisVolume 9, Issue 1 p. 67-67 Research Article Laser probe microanalysis: performance assessment and applications M. J. Southon, M. J. Southon Department of Metallurgy and Materials Science, Cambridge University, CB2 3QZ, UKSearch for more papers by this authorA. Harris, A. Harris Department of Metallurgy and Materials Science, Cambridge University, CB2 3QZ, UKSearch for more papers by this authorV. Kohler, V. Kohler Department of Metallurgy and Materials Science, Cambridge University, CB2 3QZ, UKSearch for more papers by this authorS. J. Mullock, S. J. Mullock Department of Metallurgy and Materials Science, Cambridge University, CB2 3QZ, UKSearch for more papers by this authorE. R. Wallach, E. R. Wallach Department of Metallurgy and Materials Science, Cambridge University, CB2 3QZ, UKSearch for more papers by this author M. J. Southon, M. J. Southon Department of Metallurgy and Materials Science, Cambridge University, CB2 3QZ, UKSearch for more papers by this authorA. Harris, A. Harris Department of Metallurgy and Materials Science, Cambridge University, CB2 3QZ, UKSearch for more papers by this authorV. Kohler, V. Kohler Department of Metallurgy and Materials Science, Cambridge University, CB2 3QZ, UKSearch for more papers by this authorS. J. Mullock, S. J. Mullock Department of Metallurgy and Materials Science, Cambridge University, CB2 3QZ, UKSearch for more papers by this authorE. R. Wallach, E. R. Wallach Department of Metallurgy and Materials Science, Cambridge University, CB2 3QZ, UKSearch for more papers by this author First published: July 1986 https://doi.org/10.1002/sia.740090113AboutPDF ToolsRequest permissionExport citationAdd to favoritesTrack citation ShareShare Give accessShare full text accessShare full-text accessPlease review our Terms and Conditions of Use and check box below to share full-text version of article.I have read and accept the Wiley Online Library Terms and Conditions of UseShareable LinkUse the link below to share a full-text version of this article with your friends and colleagues. Learn more.Copy URL Share a linkShare onFacebookTwitterLinked InRedditWechat No abstract is available for this article. Volume9, Issue1July 1986Pages 67-67 RelatedInformation

A parametric study is performed to investigate the solute redistribution during the transient liquid phase (TLP) diffusion bonding process. The macroscopic solute diffusion in the liquid and the solid phase, as well as the solid transformation to the liquid due to solute macrosegregation, are considered in this study. The effects of the following parameters are considered: ratio of solute diffusivity in liquid and solid state alloy (ξ = Dl/Ds), holding temperatures (θ), a combined parameter related to solidus and liquidus slopes in the phase diagram (ϕ), and the re‐melting and re‐solidification time (τ). The thickness of the pure liquid zone and the mushy zone of the TLP diffusion bonding process are demonstrated with respect to the above‐mentioned parameters. It is shown numerically that the holding time, the holding temperature, and solute diffusivity ratio influence the solute distribution strongly, which in turn influences the liquid zone and mushy zone thickness significantly. It is concluded that for the TLP diffusion bonding process, the optimal technique parameters are high holding temperature, long holding time, and a large liquidus and solidus temperature slope ratio (ml/ms) of the interlayer material.

Transient Liquid Phase Diffusion bonding (TLP bonding) is an effective method to achieve excellent joint of DD6, which is a new generation single crystal superalloy to manufacture aero-engine turbine blades. In this paper, the interlayer alloys for DD6 TLP bonding were designed. The alloy foils with thickness 40 μm ~ 60 μm, width 4 mm were prepared by using a single roller rapid solidification apparatus and the TLP bonding of DD6 was conducted. Then the joint microstructure and alloying elements diffusion behaviors were analyzed. The results indicate that microstructures of interlayer alloys prepared are fine and homogeneous, the melting point range of alloys from 1070°C to 1074°C and their melting temperature interval is merely 20°C, when the chemical composition of alloys are 1.5 ~ 2.0Cr, 3.2 ~ 4.0W, 3.7 ~ 4.5Co, 2.2 ~ 3.0Al, 0.7 ~ 1.0Mo, 3.2B, remain Ni (wt%). When the welding parameters are bonding temperature 1200?C, holding time 8.0 hour and welding pressure 0.3 MPa, the compacted joints obtained and the microstructure of TLP bonding seams were similar to base metal. The bonding joint is composed of weld center zone, isothermal solidification zone and diffusion-affected zone. Within joint, the elements diffusion is sufficient and borides in the diffusion zone are fewer.

Transient liquid phase diffusion bonding under a temperature gradient: modelling of the interface morphology

Solid state welding is a most appropriate welding process for joining aluminium matrix composites (AMCs). Diffusion bonding process, as a solid state welding process is proven that it exhibits better quality of joint strength. In transient liquid phase diffusion bonding (TLPB) process, interlayer plays a vital role in the microstructure of the joints which causes the mechanical properties of the joints. This review paper provides an overview of interlayer used by various authors to join AMCs by TLPB process.

Commercially pure iron (Fe) and stainless steel 321 (SS 321) were transient liquid phase (TLP) diffusion bonded using Cu and/or Au-12Ge interlayers. The joining pressures, temperatures and times were investigated. Au atoms appeared to diffuse back at the joining interface during slow cooling from the joining temperature. A faster cooling method prevented the back-diffusion of Au atoms from interior to the joining interface. Residual interlayer disappeared when faster cooling methods such as air cooling, water cooling or water quenching were applied. However, microcracks appeared in the joint centerline if water cooling or quenching was applied. Au-rich particles also appeared in the joint microstructure. No microcracks appeared for the samples cooled in air from the bonding temperature. The highest strength of the TLP diffusion bonded Fe reached almost same as the normalized Fe. The maximum tensile strengths (UTS) obtained for the bonded Fe were 291 ± 2 MPa using a Cu interlayer and 315 ± 4 MPa. The maximum strength found was 387 ± 4 MPa for TLP diffusion bonded steel using an Au-12Ge interlayer. The maximum strength for steel was obtained for the samples bonded at 1050 °C for 20 h in vacuum and cooled in air. The maximum strength found was 387 ± 4 MPa which is 70.4 % of the base alloy strength.

Plastic deformation was newly introduced in transient liquid phase (TLP) diffusion bonding of steel sandwich panels. The effect of plastic deformation on bonding strength was investigated through lab experiments. It was assumed that three factors, including newly generated metal surface area, deformation heat, and lattice distortion, contribute to the acceleration of interface atoms diffusion and increase of diffusion coefficients. A numerical model of isothermal solidification time was developed for TLP bonding process under plastic deformation and applied to carbon steel sandwich panels bonding with copper interlayer. A reasonable isothermal solidification time was obtained when an effective diffusion coefficient was used. Based on lab experiments, the effects of plastic deformation on interlayer film thickness and isothermal solidification time were studied through theoretical calculation with the new model. The evolution of interlayer film thickness indicates a good agreement between the calculation and experimental measurement. The results show that the isothermal solidification time is obviously reduced due to the effect of plastic deformation. Furthermore, a new steel sandwich cooling panel for heat exchanger was fabricated by TLP diffusion bonding under 13.1% plastic deformation. The test results suggest that a steel sandwich panel of inequidistant fin structure can provide enhanced heat transfer efficiency.

Microstructure and mechanical properties of C/C composite| Ti3Al alloy joints prepared by transient liquid phase diffusion bonding using AgCuNiLi alloy as joining material

Stable bonding of W and ODS steel fabricated by TLP diffusion technology through inserting a novel composite interlayer Zr/Cu

Transient liquid-phase diffusion bonding of two-dimensional carbon–carbon composites to niobium alloy

Effect of micro-oxidation and Cu modification of C/C composite on microstructure and mechanical properties of C/C|Ti3Al joints

Transient liquid phase (TLP) diffusion bonding of Al-6061 containing 15 vol pct alumina particles was carried out at 873 K (600 °C) using electrodeposited nanocomposite coatings as the interlayer. Joint formation was attributed to the solid-state diffusion of Ni into the Al-6061 alloy followed by eutectic formation and isothermal solidification of the joint region. An examination of the joint region using an electron probe microanalyzer (EPMA), transmission electron microscopy (TEM), wavelength-dispersive spectroscopy (WDS), and X-ray diffraction (XRD) showed the formation of intermetallic phases such as Al3Ni, Al9FeNi, and Ni3Si within the joint zone. The result indicated that the incorporation of 50 nm Al2O3 dispersions into the interlayer can be used to improve the joint significantly.

An investigation of transient liquid phase (TLP) diffusion bonding of a nickel-base directionally solidified superalloy, DZ22, was presented. Two interlayer alloys developed for DZ22 were employed. They were: Z2P, a powder alloy and Z2F, an amorphous foil. The results show that the microstructures and compositions of the joints bonded with Z2F amorphous foil were obvious more homogenous than the joints bonded with Z2P powder alloy. And the joints bonded with Z2F possessed a better stress-rupture property. The final obtained joint stress-rupture properties reached 90% of that of the base metal.

Prediction of processing maps for transient liquid phase diffusion bonding of Cu/Sn/Cu joints in microelectronics packaging