Interfacial Diffusion Behavior Research Articles

Investigation on failure mechanism and interfacial diffusion behavior of NiCoCrAlYTa coating at high temperature

The isothermal oxidation behavior of NiCoCrAlYTa coating deposited by arc ion plating (AIP) technology on DZ22B substrate was systematically investigated at 1050 ℃ and 1100 ℃ for 200 h. The results revealed a transition in oxide scale composition, which of undulation degree was also increased. The growth process of oxide scale involved additional control mechanisms except internal diffusion of oxygen. Interdiffusion at coating/substrate interface transformed γ into γ' phase in substrate, precipitating MC carbides. MC carbide underwent progressive disintegration, transforming into M6C carbide. The results could provide experimental data and theoretical support for the design of long-life protective coatings at ultra-high temperatures.

Interfacial diffusion behavior and properties of hot-pressed Kovar/Cu composites

Kovar/40Cu composites for electronic packaging were prepared by hot pressing at 700–1000 °C. The interface diffusion behavior, microstructure, and properties of Kovar/40Cu composites were studied. The results show that the interfacial diffusion of elements from Kovar to Cu matrix occurs when the temperature reaches 800 °C, and the diffusion rate of elements from Kovar to Cu matrix is greater than that from Cu matrix to Kovar. The strength of the composite material increases with the temperature, and the strength can reach 547.6 MPa after hot pressing 1000 °C/1 h. However, the elongation of composite material increases first and then decreases. After hot pressing at 800 °C/0.5 h, the maximum elongation is 20.1 %. Under the influence of solid solution atoms, the thermal conductivity of the composite decreases continuously, and the thermal expansion coefficient increases first and then decreases. The optimal sintering parameter is 800 °C/0.5 h.

Interfacial diffusion and Kirkendall voids evolution in the Copper-Zinc alloy binary interface revealed by in situ transmission electron microscopy

Investigating the diffusion behavior of binary system is crucial for understanding the solid-state diffusion in metallic joints, as it affects the interfacial reaction that forms intermetallic components (IMCs) and introduces Kirkendall voids that change the interfacial microstructures. In this study, we intuitively investigated the interfacial diffusion behavior of Copper-Zinc alloy binary interface by in situ transmission electron microscopy. Our findings revealed the interfacial diffusion of atoms, the growth processes of intermetallic phases, and the evolution of the Kirkendall voids during thermal diffusion. We observed that the Zn atoms diffuse rapidly into Cu and form the β phase at the onset of thermal diffusion at 200 ℃. Additionally, with increasing temperature, Cu atoms control the diffusion and the formation of IMCs due to their higher diffusion coefficient in the β and α phases, which are 2.09 ± 0.63 × 10−16 m2/s at 250 ℃ and 3.44 ± 0.44 × 10−17 m2/s at 300 ℃, respectively. Furthermore, we found that the interface significantly influences the interdiffusion rates of the IMCs and the formation of Kirkendall voids. The emergence of voids, which are formed at the initial defective site and the IMC layer at the temperature of 250 and 300 ℃, respectively, leading to a considerable decrease in interdiffusion at the binary interface of two orders of magnitude in comparison to unaffected regions. Moreover, we revealed the evolution of Kirkendall void, involving the formation and merging of holes, as well as the gradual thinning of atomic layers during diffusion. These findings are essential for understanding the formation and evolution of IMCs and Kirkendall void in binary interfaces.

Effect of Ni additions on microstructure, interfacial diffusion behavior and properties of Fe-based/B4C composite coating by vacuum cladding

In order to improve the hardenability and toughness of Fe-based/B 4 C composite coatings, which were bonded on ASTM 1045 steel by vacuum cladding, nNi ( n = 0, 1, 3, 5, weight %) were added into the coatings. The influences of Ni additions on the microstructures, interfacial diffusion behavior, impact toughness and three-body abrasive wear behavior of composite coatings were investigated systematically. The results indicated that coatings were completely fused with steel substrate without micro-defects. When the amount of Ni was increased, the activity of the C atom on the coating side was enhanced, the decarburization zone near the interface disappeared, and the metallurgical bonding state of interface was strengthened. Furthermore, the increment of Ni improved the hardenability of coating and promoted the transformation from pearlite to martensite in the matrix structure of the coating. The impact toughness of the coating samples also increased with the increment of Ni additions, and reached the maximum of 4.8 J/cm 2 at 5Ni sample. The three-body abrasive wear test implied that when 3 wt% Ni was added to the coating, the mass loss was 0.14 g, which was much lower than that of other samples and exhibited the best wear resistance. The wear mechanism of coatings changed from partial plastic cutting and fatigue spalling to single fatigue spalling. • Ni addition strengthens the metallurgical bonding state of the coating interface. • The increase of Ni addition improves the hardenability of the coating matrix. • Ni addition improves the impact toughness and wear resistance of the coating.

Failure mechanism and interfacial diffusion behavior of Ru-doped NiAlHf coatings at 1200 °C

Ru-doped NiAlHf coatings were deposited on Ni-based single crystal substrate by arc ion plating technology. The failure mechanism and interfacial diffusion behavior were comparatively investigated with NiAlHf coating using scanning electron microscopy, electron probe micro-analyzer, and transmission electron microscopy. The results indicated that microstructure evolution of oxide scale induced by element diffusion process significantly affected oxidation resistance of NiAlHf/Ru coatings, resulting in formation of cracks and voids, thereby accelerating failure process. The precipitates in interdiffusion zone and secondary reaction zone of the substrate initiated by interfacial element diffusion were P phase and σ phase, respectively. And the discrepancy in content was elucidated from the perspective of thermodynamics and kinetics. Besides, microstructural evolution between NiAlHf/Ru coatings and substrate was also deliberated. The research could not only provide profound understanding of NiAlHf/Ru coatings failure mechanism, but also had significant guidance for suppressing precipitation of topological close-packed phases and facilitating development of single crystal Ni-based superalloys.

The Growth of Intermetallic Compounds and Its Effect on Bonding Properties of Cu/Al Clad Plates by CFR

Cu/Al clad plates prepared using a corrugated + flat rolling (CFR) technique were annealed at 300–450 °C for 10–240 min. Furthermore, the interfacial diffusion behavior and the bonding properties of the Cu/Al clad plates were studied in detail. The results demonstrated that, at the initial stage of the annealing process, the development of the first IMCs layer was restrained by the high atomic concentration gradient in the new bonding interface zone, and the second intermetallic compounds (IMCs) layer preferentially formed in the new bonding interface zone, leading to a slight increase in the growth activation energy of the clad plates. In addition, the atoms’ diffusion behavior at the peak and trough interfaces was not significantly affected by the matrix microstructure, and there was no discernible difference in the growth activation energy at these two positions. Ultimately, it was shown that the maximum average peel strength at the peak and trough interfaces reached 53.07 N/mm and 41.23 N/mm, respectively, when annealing at 350 °C for 10 min.

Effect of adhesives on the interfacial diffusion behavior and mechanical properties of WC particle-reinforced Fe matrix composites

ABSTRACT Under the condition of high-stress abrasive wear, the strength at the interface of the WC/Fe matrix composites is significantly low, it is very easy to become the source of the overall damage to the material. In this study, the mechanical properties and interfacial organization of the WC/Fe matrix composites were analyzed by adding a binder and using a combination of powder metallurgy and gravity casting infiltration. The results showed that upon the addition of an adhesive, the width of the interface became twice as large as that without additives. Moreover, adding an adhesive also reduced the plastic deformation at the interface by more than three times. The best bonding agent was borax + sodium carbonate, which significantly increased the diffusion rate of atoms at the interface compared to sodium silicate and polyvinyl alcohol and also enhanced the interfacial mechanical properties.

Discrete interfacial effects of organic lead halide perovskite coating on magnetic underlayer: MAPbBr[formula omitted]/FePd heterostructure

Recent studies have shown promising results regarding the power conversion efficiency, band-gap tunability, and interfacial charge carrier ability of organic lead halide perovskites. In light of these fundamental abilities, we fabricated a heterostructure: MAPbBr3 spin-coated on an FePd alloy layer, consisting of both magnetic and optical capabilities. The perovskite’s discrete coverage across the FePd underlayer was confirmed by atomic force microscope, as made up of separate disc-like nanostructures that stand at ∼400 nm in height and a size width of up to ∼2 µm. We studied the thermal endurance and the inter-facial diffusion stability between MAPbBr3 and FePd alloy by post-annealing it to temperatures ranging 100–170 ∘C. The instable interfacial effects of perovskite/FePd was observed at 120 ∘C, as indicated by the drastic reduction in magnetic coercivity of FePd and the photoluminescence of MAPbBr3. This interfacial diffusion behavior between perovskite and FePd advances as the post-annealing temperature reaches 170 ∘C, supported by the enhanced noise to Kerr signal ratio.

Interfacial Diffusion of Hydrated Ion on Graphene Surface: A Molecular Simulation Study.

Hydration plays an important role in the diffusion and sieving of ions within nanochannels. However, it is hard to quantitatively analyze the contribution of hydration to the diffusion rates due to the complex hydrogen-bond and charge interactions between atoms. Here, we quantitatively investigated the interfacial diffusion rates of a single hydrated ion with different number of water molecules on graphene surface through molecular dynamics simulation. The simulation results show the ballistic diffusion mode by analyzing the mean-square displacement, and the diffusion rates change nonmonotonically with the hydration number. The potential energy profiles with the changing position of the hydrated ion on graphene surface were further analyzed, which shows the dominant factor for interfacial diffusion changing from ion-graphene interaction to water-graphene interaction as the number of water molecules increases. Besides, it was found that the surface hydrophilicity weakened the influence of hydration number on the diffusion rates of hydrated ion. Finally, the diffusion properties of different hydrated ions on graphene surface were investigated, and the hydrated Li+, Na+, and K+ containing three, four, and five water molecules, respectively, show the fastest diffusion rate. This work demonstrates the interfacial diffusion behavior and mechanism of hydrated ions at the molecular level, which can provide valuable guidance in nanosensors, seawater desalination, and other hydrated ion-related fields.

Unveiling the impact of interfacially engineered selective V2O5 nanobelt bundles with flake-like ZnO and Co–ZnO thin films for multifunctional visible-light water splitting and toxic gas sensing

We report on novel interfacial assembly behavior of V2O5 nanobelt bundles (V2O5 NBBs) paired with flake-like ZnO (V2O5/ZnO) and Co (1.8 at.%)-ZnO (V2O5/Co–ZnO) thin films for the first time. This work accomplished highly stable visible-light-driven photoelectrochemical (PEC) water splitting and toxic NO2 gas sensing. Mainly, charge carrier acceleration ability is associated with the interfacial diffusion behavior between nanobelt and flake-like morphologies. Structural studies revealed strong network formation between predominant ZnO (002) and V2O5 (001). Because of nanobelt/flake-like intimate interaction, we fairly established the flake-like ZnO and Co–ZnO morphological features on V2O5 NBBs. Accordingly, chemical analysis of V2O5/Co–ZnO illustrated a shift in the O 1s peak position towards lower binding energy, which is ascribed to the impressive combined oxygen bonding formation at the interface of Co–ZnO and V2O5. Taking advantage of the interfacial interaction and abundant hydrophilicity (63°) of V2O5/Co–ZnO, we controllably achieved stable water splitting activity about 21.0 min. In an effort, V2O5/Co–ZnO composite outperformed the photocurrent generation with 1.45 × 10−4 A/cm2, which is 42.0 times higher than ZnO. Also, V2O5/Co–ZnO attained NO2 gas response (130.0%) at 50 ppm. Comprehensively, nanobelt/flake-like morphological integration serves as a highly stable photoanode in the PEC cell as well as a toxic gas sensor.

Vacancy effect on the preparation of high-entropy carbides

High-entropy carbides (HECs) are novel advanced materials composed of covalently bonded multicomponent transition metals and carbon. The transition metal atoms of all the precursor components are randomly distributed at the cation sublattice. Recently, a series of HECs with a non-stoichiometric compound (NSC) as one of the precursors have been synthesized. However, the effect of vacancies on the formation of HECs has not been addressed well. In this paper, NbC0.5 was selected as the NSC to study the interfacial diffusion behavior of NbC0.5 and other covalent transition metal compounds (MCs: M represents one of V, Ti, Ta, and W). The presence of vacancies resulted in a carbon concentration gradient, reduced the diffusion activation energy of metal atoms in NbC0.5–MC and increased the diffusion driving force. In addition, the diffusion process of WC in NbC0.5 was analyzed. Phase transformation of WC to W2C was found during diffusion. The experiment proves that HECs may be easily prepared with the participation of the NSCs, and this work provides the theoretical basis for the alloying of covalent transition metal compounds.

Influences of Ag and In alloying on Sn-Bi eutectic solder and SnBi/Cu solder joints

In this study, the Ag and In were alloyed to the Sn-58Bi solder, and their individual and combined influences on the SnBi solder and the SnBi/Cu solder joints were investigated. The results indicate that the In can effectively decrease the melting temperature and improve the wettability of the solder, while the Ag shows slight impacts on the melting behavior and the wetting properties. During the isothermal aging at 100 °C, growth rate of the intermetallic compounds (IMCs) layer at the Ag-bearing solders/Cu interfaces are lower, while that at the In-bearing solders/Cu interfaces are much higher, because the substitution of Sn in the Cu6Sn5 IMC by In alters the interfacial diffusion behavior and assist in faster growth of IMCs layer. The Bi segregation at the long-term aged SnBi/Cu interface is eliminated in the aged SnBiAg/Cu, SnBiIn/Cu and SnBiAgIn/Cu solder joints. Tensile strength of all the solders joints decreases with increasing aging time, while the sharp decrease in the strength of the long-term aged SnBi/Cu solder joints is inhibited once the Bi segregation is eliminated, and fracture occurs mainly around the IMCs/solder interface. For the In-bearing solder joints, the Cu6(Sn,In)5 decrease the adhesion force between the solder and the interfacial IMCs, while the SnBiAg/Cu joints shows the highest strength. Based on the results, a more practicable method to inhibit the Bi embrittlement at the aged SnBi/Cu solder joints is proposed.

An explanation of sintered silver bonding formation on bare copper substrate in air

Abstract The application of multiscale silver paste and bare copper could be a more economical way for power electronics. In this paper, bonding mechanism of die attachment on bare copper substrate using multiscale Ag paste containing nano- and micro-particles in air condition was clarified. After sintering, the oxide layer generated between sintered Ag and copper substrate was composed of Cu2O and Cu. The formation of Ag-Cu2O chemical bond and Ag Cu metallic bond was clearly confirmed based on the lattice structure analysis at the interface between sintered Ag and oxide layer. The lattice images also indicated Ag/Cu2O chemical bonding could be even stronger than Ag/Cu metallic bonding due to the smaller mismatch of lattice constant with Ag. Besides, two copper substrates with different grain sizes were designed to compare their corresponding interfacial diffusion behavior and fracture condition. The copper substrate with smaller grain size provided more grain boundaries to accelerate Ag atoms diffusion on the surface before oxidation, further increasing the adhesive area of Ag. Then the larger area of Ag aggregation decreased the content of oxide layer thickness and voids at the interface between copper oxide and substrate, leading to the stronger interfacial bonding and higher joint strength.

Failure analysis and reliability evaluation of silver-sintered die attachment for high-temperature applications

This study demonstrates the reliability of SiC chip attachment sintered by nano-Ag paste during high temperature storage (HTS) tests in air at 350 °C, which was twice as high as the maximum junction temperature in service of the Si chip. The failure mechanisms of die attachment at high temperatures were diffusion and oxidation. The residual organics in the Ag paste was enough to provide the oxygen to form the continuous NiO layer at the bondline/SiC chip interface, and the oxide growth obeyed a parabolic rate law. Based on the microstructural evaluation and interfacial diffusion behavior of die attachment during HTS, the electroplated Ag layer was designed and applied on the ENIG finish as a diffusion barrier. The results showed that the die attached on the electroplated Ag substrate could support more than 800 h during HTS at 350 °C in air, which was doubled the reliability of the ENIG finished substrate.

Pressureless sintering of nanosilver paste as die attachment on substrates with ENIG finish for semiconductor applications

In order to overcome interfacial delamination of pressureless sintered nanosilver as die attachment on the ENIG finish, we tried to clarify the densification and interfacial diffusion behavior of sintering nanosilver paste on Au finish. Two different electroless nickel immersion gold (ENIG-1, ENIG-2) and one electroplated nickel gold (electrolytic Au) were compared in the aspects of mechanical, thermal performance, and microstructures. Delamination was found at the as-sintered Ag in the vicinity of Ag/Au interface in the ENIG-1. It was likely that too much Ag atoms was diffused into the ENIG-1, the left Ag atoms of the Ag-NPs in the vicinity of the interface are not sufficient to be densified as a robust sintered Ag joint at the higher temperatures. Electron backscattered diffraction (EBSD) results confirmed that the grain size, the high angle grain boundary, and the (111) texture lead to the rapid non-densifying diffusion of the Ag atoms with the ENIG. We proposed a modified sintering profile and the rougher ENIG-2 with thinner Au finish to reduce the non-densifying diffusion. The performance, and microstructures of the sintered Ag on the ENIG-2 confirmed that it is reasonable to enhance the sintered Ag on ENIG by reducing the rapid non-densifying diffusion at above 150 °C.

Low-Temperature Co-Fired Behavior of ZMT Dielectric Ceramic and NZC Ferrite Composites

Adopting laminated dry pressure molding process, the HH2 (mixing powder of (Zn0.7, Mg0.3)TiO3(ZMT3) and (Ni0.8Zn0.12Cu0.12)Fe1.96O4(NZC) in weight ratio of 1:1) and (Zn0.9, Mg0.1)TiO3(ZMT1) were designed to be interlayer, which was co-fired with ZMT3((Zn0.7, Mg0.3)TiO3) and NZC((Ni0.8Zn0.12Cu0.12)Fe1.96O4) at 900°C to synthesize layer composition. The study of interfacial microstructure SEM and diffusion mechanism shows that the co-fired layer composition could alleviate the interfacial stress and eliminate warp defects resulting from the co-fired process. The interfacial diffusion behavior of co-fired layer composition was researched，which provide a promising solution of warp and distortion resulting from different materials co-fired process.

Interfacial diffusion behavior in Ni-BaTiO 3 MLCCs with ultra-thin active layers

The interfacial structure and diffusion behavior between the dielectric layers (BaTiO3) and internal electrode layers (Ni) in X5R-type multilayer ceramic capacitors (MLCCs, from −55°C to 85°C, at a temperature capacitance coefficient within ±15%) with ultra-thin active layers (T = 1–3 µm) have been investigated by several microstructural techniques (SEM/TEM/HRTEM) with energy-dispersive x-ray spectroscopy (EDS). In the MLCC samples with different active layer thicknesses (1–3 µm), weak interfacial diffusion was observed between BaTiO3 and Ni. It was also found that the diffusion capability of Ni into the BaTiO3 layer was stronger than that of BaTiO3 to the Ni electrode, which indicated that the diffusion of Ni was the dominant factor for the interfacial diffusion behavior in the ultra-thin layered MLCCs. The mechanism of Ni diffusion is discussed in this study as well.

Improvement of adhesion and interfacial diffusion behavior in Cu/glass structures using OsOx layers for microelectromechanical systems

We demonstrated that a Cu/Ni/OsOx/glass structure fabricated by using supercritical fluid chemical deposition has high adhesion strength. The adhesion strength was determined with a scratch tester, and the films and interfaces were characterized by transmission electron microscopy. Ni deposition resulted in the reduction of the pre-deposited OsO2 layer, and an OsOx layer formed again during the subsequent post-Ni-deposition annealing. We observed an extreme adhesion improvement. The high adhesion strength originated from the presence or re-formation of the OsOx layer and the diffusion of Cu, Ni, and Si into the OsOx layer.

Single Molecule Observations of Multiple Protein Populations at the Oil−Water Interface

Single-molecule total internal reflectance fluorescence microscopy was used to observe the dynamic behavior of >4000 bovine serum albumin objects at the silicone oil-water interface. The surface residence time distribution indicated the presence of three populations at the interface. Each population had a characteristic fluorescence intensity and distinctive interfacial diffusion behavior. Larger fluorescence intensity correlated with longer residence times and slower diffusion. These combined observations of fluorescence intensity, surface residence time, and interfacial diffusion suggested that the three populations represent monomers, dimers, and trimers respectively.

Bonding Strength and Microstructure of Cermet/Cu-Based Alloy Composite Brazed Coatings

WC-TiC-Co cermet and CuZnNi alloy composite coatings were produced on mild steel by a high temperature inside-furnace brazing technique. The microstructure, phase constituents and interfacial diffusion behavior of cermet and Cu-based alloy were investigated by means of scanning electron microscopy (SEM), transmission electron microscopy (TEM), electron probe microanalysis (EPMA) and X-ray diffraction. The tensile strength and wear property of composite coatings were also investigated. The results show that crème particles were not decomposed severely during the inside- furnace brazing process. The microstructure of the matrix is α and β phases. Diffusion occurred at the cermet/Cu-based alloy interface. The tensile strength of the composite coatings reached 240-300MPa, which depended on the brazing temperature and was far higher than that of the flame hardfacing layers. Cermet fracture was basically a brittle fracture in nature and matrix involves ductile fracture.