Papers by Keyword: Interfacial Reaction

Abstract: The AuSn20 (mass fraction) solder was prepared by laminate rolling-annealing method, the AuSn20/Ni solder joints were prepared by the reflow process. The effects of the aging times and temperatures on the microstructure and shear strength of the AuSn20/Ni joints were investigated by the scanning electron microscope (SEM) with an energy dispersive X-ray (EDX). The results show that, the AuSn20 solder is composed of lamellar ζ-Au5Sn and δ-AuSn phases after preparing and the melting point approximates to the eutectic temperature of Au-20Sn alloy. A eutectic ζ-Au5Sn+δ-AuSn microstructure forms in the solder matrix and hexagon (Ni,Au)3Sn2 intermetallics nuclear at the as-reflowed joint. Then the AuSn20/Ni joint was aged at 150 and 200 °C for various times，and the thickness of the IMC layer at 150 °C changes few with the aging time increasing from 150 h to 1000 h, however, it grows rapidly at 200 °C.

Abstract: Diffusion bonding between the Cu-10%Fe and Al6061 alloys were successfully achieved at various temperatures (450-525°C) in the argon atmosphere. The bonding interface regions were analyzed using scanning electron microscopy and energy dispersive spectrometry and XRD. The presence of Fe particles in Cu was found to have an influence on the kinetics of intermetallic compound layer formation. Cu-Fe/Al 6061 exhibited the slower growth rate of intermetallic layers than Cu/Al 6061 after diffusion bonding. The movement of Cu-Fe/Cu9Al4 interface into Cu-Fe substrate appears to be hindered by the presence of populated Fe-containing particles and filaments. In addition to Cu9Al4, CuAl and CuAl2 intermetallic layers, Al7Cu2Fe and unreacted Fe were observed to be present in the intermetallic layers. The intermetallic layers which are close to Cu such as Cu9Al4 and CuAl were observed to be harder in Cu-10%Fe/Al 6061 than in Cu/Al 6061, suggesting Fe and its intermetallics have some strengthening effect on Cu9Al4 and CuAl.

Abstract: The Ti/TiC/C laminated composite material was fabricated with the sheet of Ti and C by spark plasma sintering (SPS) technology. The effects of thickness ratio on the interface characteristics and mechanical properties of interfacial reaction were studied. The results show that: the reaction layer thickness increases with the thickness ratio. When the thickness ratio was 3:1, the degree of interfacial reaction was better in the case of other conditions are the same. The thickness of reaction layer achieved 33.58μm. The laminated composite bending strength and fracture power reached the maximum 3494.52MPa and 614.89×103J/m2, respectively. The greater fracture power, the more energy absorbed in the process of damage, the higher toughness improved.

Abstract: Zn20Sn solder with the melting point of 383.9°C and a low cost is considered as an ideal high-temperature lead-free solder. In the paper a new solder alloys were made by adding trace Cu into Zn20Sn alloy through alloying principle. Interfacial reaction and solderability of Zn20SnxCu (x=0 wt.%, 2 wt.%, 4 wt.% and 6 wt.%) solder on the copper substrate were investigated. Results showed that β’-CuZn, γ-Cu5Zn8 and ε-CuZn5 IMC layers were formed at the interface of Zn20SnxCu/Cu. The spreading areas of the Zn20SnxCu solders were reduced linearly with the increasing of the content of copper. The spreading aera of Zn20Sn solder was 52.88 mm2 while that of Zn20Sn6Cu was 50.82mm2 which was approximately 3.9% smaller than that of matrix solder. It is mainly related to the formation of ε-CuZn5 phase and the metal intermetallic compound between the solder and the substrate.

Abstract: Interfacial behaviors of SiC fiber reinforced titanium matrix composites during thermal exposure were investigated by SEM, EDS and XRD. The effect of C coating was mainly analyzed. The results showed that C coating can be an effective barrier of the diffusion of Si element. And the C coating of SCS-6 SiC reinforced Ti6Al4V will be almost completely consumed after thermal exposure for 25 hours at 925°C. TiC will be found in the interface when the C coating exists. After C coating is completely consumed, there is Ti₃SiC₂ occurring besides TiC and the interfacial debonding strength is high. However, without the protection of C coating, the fibers will be consumed and their longitudinal tensile strength will be decreased, and this will affect the service performance of the composites.

Abstract: Al₂O₃ is brazed with mild steel using 70Ag-27Cu-3Ti (wt.%) active filler alloy at 900°C for 5 min. The interfacial reaction products are analyzed with X-ray diffraction (XRD)．The interfacial phases are analyzed with EDAX. According to the experimental observations, the interfaces developed during brazing have been systematically characterized and the structure are separately Ti₃Cu₃O/Ti₃Al+ TiMn+TiFe₂ +Ag(s,s)+Cu(s,s)/TiC from alumina ceramics side to mild steel side.

Abstract: Silicide sequential phase formation during tens-of-nanometer-thick metallic film reaction on Si substrate has been extensively studied. Nevertheless, the reasons of sequential phase formation are still under debate, and have been poorly studied at the atomic scale. Using atomistic kinetic Monte Carlo simulations, we show that considering a binary fcc non-regular solid solution, without diffusion asymmetries, the diffusive reaction of a sub-nanometer-thick film (~5 atomic monolayers) on a semi-infinite substrate leads to the sequential formation of all the phases present in the binary phase diagram, starting with the film atom richest phase. These predictions are supported by experimental observations: the dissolution of a 4 monolayer-thick Si film on a Ni(111) substrate, during in-situ ultra high vacuum Auger electron spectroscopy, shows delays and kinetic changes in the dissolution process that may correspond to the sequential formation of the Ni-Si compounds, i.e. NiSi₂, NiSi, Ni₃Si₂, Ni₂Si, Ni₃₁Si₁₂ and Ni₃Si.

Abstract: Novel AZ91D Mg alloy/fly-ash cenospheres (AZ91D/FAC) composites were fabricated by melt stir technique. The thermodynamic analyses of the interfacial reactions, the microstructure observation, and the phase analyses of the AZ91D/FAC composites were investigated. The results showed that the cenospheres were almost filled with Mg alloy matrix. In-situ MgO and Mg₂Si phases were formed in Mg alloy matrix and near the interfaces between the cenospheres and Mg alloy matrix. Through the thermodynamic calculation, it can be found that the standard free enthalpy changes of these interfacial reactions are all negative at the temperature of Mg alloy melt preparation in this work, and these reactions can occur.

Abstract: Ti-Cu laminated composites were fabricated by means of vacuum hot pressing (VHP). The Ti-Cu interfacial reaction was studied to observe the microstructural changes. Scanning Electron Microscopy (SEM), Energy Disperse Spectroscopy (EDS) and X-Ray Diffraction (XRD) were used to observe morphology and analyze phase composition of interfacial reaction zones. With increasing the holding time, the thickness of the reaction zones varies from 12μm to 16μm. The results show that there are 5 binary intermetallic compounds (Cu₄Ti, Cu₄Ti₃, CuTi, Cu₃Ti₂, CuTi₂) observed in the Ti-Cu diffusion couples held at 1073 K for 1h, 1.5h, 2h and 2.5h respectively under the pressure of 10MPa.

Abstract: Effect of rare earth content on microstructure and interfacial reactions of low Ag content SnAgCu solder is researched by adopting the X-ray diffraction, JSM-5610LV scanning electronic microscope, energy spectrum analysis and JEM2100 ultrahigh resolution electron microscopy. The results show that proper quantities of rare earth (0.1%) can refine the eutectic microstructure of the solder alloy; and petal-like rare earth compound can be found in the solder alloy while the rare earth addition is 0.5%. The growing rate of the interfacial intermetallic compound can be reduced during the soldering with adding 0.1% rare earth in the Sn2.5Ag0.7Cu solder alloy.