Interfacial Intermetallic Reaction for Oxide Layer Fragmentation: A Coating Strategy towards Aluminum-Based Energetic Materials

Suppression mechanism by a thin interface W oxide layer is investigated for intermetallic reaction at Al/W interfaces. The interface reaction scheme of Al/W was analyzed by in situ x-ray photoemission spectroscopy for the interface formation and subsequent annealing in ultrahigh vacuum. Without the W oxide layer at the interface, annealing at temperatures higher than 450 °C leads to an intermetallic reaction forming the bimetallic compound WAl12 through the entire metal layer, while no reaction between Al and W occurs at room temperature. The intermetallic reaction causes the lowering of W 4f core level by 0.7 eV. This is explained by the donation of a lone electron pair from an Al 3s orbital to a vacant W 6s orbital in bimetallic bonding. The interface thin W oxide layer, composed of WO3, is consumed in the oxidation–reduction reaction with metallic Al. The reaction product Al2O3 inhibits the intermetallic reaction. This results in an increase in annealing temperatures to as high as 600 °C and longer annealing time to form WAl12.

The effects of photoirradiation on the interfacial chemical reactions between indium tin oxide (ITO) films and layers of triphenylamine tetramer (TPTE) were investigated by using in situ x-ray photoelectron spectroscopy (XPS). Thin TPTE layers deposited onto sputter-deposited ITO films were irradiated with violet light-emitting diodes (peak wavelength: 380 nm). Shifts in the peak positions of spectral components that originated in the organic layer toward the higher binding-energy side were observed in the XPS profiles during the early stages of irradiation. No further peak shifts were observed after additional irradiation. An increase in the ratio of the organic component in the O 1s spectra was also observed during the photoirradiation. The ratio of the organic component increased in proportion to the cube root of the irradiation time. These results suggest that photoirradiation induces an increase in the height of the carrier injection barrier at the interface between TPTE and ITO in the early stages of the irradiation, possibly due to the rapid diffusion controlled formation and growth of an oxidized TPTE layer, which is considered to act as a high resistance layer.

On a microscopic scale, the reliability of a solder joint depends on the structure of the interfacial intermetallic compound formed by the interfacial reaction between the solder and the pad. In this paper, the reliability of solder joints is characterized by the interfacial reaction of gold-bismuth alloy solder joints and the change of microstructure with environment. The interface characteristics of AuGe alloy solder and eutectic sintering of Ni/Au pads with different gold thickness are studied. The solder wettability of AuGe alloy solder on common pads such as Cu and Ni and its soldering interface characteristics are summarized. The results of slicing analysis showed that after eutectic soldering, the Au-phase of the thick gold sample was cooled to form an irregular solder joint layer, and the thickness of the Au layer was reduced by about 50-60%. The Au layer of the thin gold sample was all. It disappears and a very thin layer of Ni-rich NiGe compound is formed at the interface. The experimental results show that the thick Au layer sample does not show the diffusion of Ni to the solder layer and the formation of NiGe compound. The thick gold layer acts as a barrier layer. In the thin gold sample, Ni slowly forms a NiGe compound with Ge through interdiffusion. In use, the solder layer will evolve through elemental diffusion, etc., transforming the entire solder layer into an intermetallic compound containing a multilayer structure such as an oxide layer, a P-rich layer, a NiGe layer, and an AuCuGe alloy layer, which reduces the solder joint strength and seriously affects the soldering. Layer reliability. This indicates that the intermetallic compound (IMC) is mainly formed by interfacial chemical reaction during the welding process; it mainly evolves in the form of elemental diffusion during the service.

A diffuse interface phase‐field model is developed to study alumina seamless laminate composites formation via reaction interlayer diffusion bonding. The model was designed to indicate the important role of interface on phase transition and interfacial chemical reactions. The model has indicated the interfacial reactions, phase transitions, and phase evolution along the alumina/reaction layer interface. The theoretical results were assessed, validated, and confirmed by experimental data at similar bonding conditions via targeted diffusion bonding in aluminum‐alkaline earth hydride and alanate interlayer systems Me (Me: Mg–Sr). The alanates and hydrides dissociations left pockets of intermetallic phases at interlayer as bonding constituents. The solid‐state bonds have formed by diffusion bonding at laminate interfaces and partial oxidations. The elemental analysis showed the alkaline earth rich zones at interlayer and near interfaces. The crystalline composition of the interlayer materials was combinations of polycrystalline mixed oxide layers, formed due to different oxidation kinetics and diffusion rates. Interlayer oxidation products were combination of complex oxides with SruMgxAlyOz (u: 0.8–1, x: 0.7–1, y: 2–10, z: 4–17) stoichiometry.

High temperature oxidation behavior of alloys is mostly affected by an external loading. The growth of oxide scale, oxide products, interfacial reactions and other characteristics have be affirmed to be affected by the external loading. Here, it provided the oxidation kinetics of several metals under the compressive loading. And the growth of oxide scale was distinguished in the form of thin oxide layer and thick oxide layer. Different compressive effect on the growth of oxide scale was summarized. At the initial oxidation stage, the applied compressive stress induced more defects on the surface of alloy, supplying more oxide neclei, thereby increased the growth of the thin oxide layer. In the case of the growth of the thick oxide layer, it was attrbuted to the short circuit paths of the oxide grain boudary inherited from the initial oxidation stage and the cracks or other defects deduced by the applied compressive stress. Thus the oxide kinetics of alloys was promoted. However, considering the interfacial reaction at scale/metal, the coarsens of vacancies would occur after a long time of oxidation, decreasing the growth of oxide scale.

Soft magnetic composite obtained by interface reaction upon spark plasma sintering using double-coated Al-permalloy (Ni71.25Fe23.75Al5) composite particles

Interfacial reactions between molten Al and a Co–Cr–Mo alloy with and without oxidation treatment

In order to suppress the interfacial reaction between the ceramic shell mold and the magnesium molten alloy during the investment casting process, a mold material with a high thermodynamic stability based on alkaline zirconium sol (CH4NO3Zr) binder and corundum (Al2O3) powder was prepared. The effects of the mold materials and casting thicknesses on the interfacial reaction were investigated by an optical microscope, X-ray diffraction, a scanning electron microscope, and an energy dispersive spectroscope analysis. The results suggested that the casting poured by the conventional ZrSiO4 mold has a serious reaction on the surface, and the reaction was more severe when the casting thickness was increased. The oxidation layer was approximately 300 μm in some severe areas of 45 mm thickness. The XRD and EDS results showed that the reaction interface mainly contains MgO and Mg2Si. While the casting poured by the Al2O3 mold provides a light and smooth surface, the reaction layer was only 1.5 μm on average. The reaction interface mainly contains MgO and Mg2F.

Interfacial reactions between a lead borosilicate glass containing CuO and an Al/Si alloy — evidence for galvanic cells

Interfacial reactions at room temperature in multilayer thin film systems have been investigated by the Auger Electron Spectroscopy method. The multilayer thin film structure consists of metal, native oxide, and/or deposited interfacial layers on metal and semiconductor substrates. Various combinations of metals and interfacial layers on different substrates have been investigated. For the multilayer systems Au, Ag, Cu, and Cr were used as metals, GeO2, Bi2O3, SnO2, Sb2O3, Ga2O3, and As2O3 were used as interfacial layers, and GaAs, Si, and Fe were used as substrates. Only ’metal’ atoms from the interfacial oxide layers (Ge from GeO2, Sb from Sb2O3, Bi from Bi2O3, Sn from SnO2, and Ga and As from the native oxide mixture of Ga2O3 and As2O3) were detected on the metal surface of Metal-Interfacial layer-Semiconductor and Metal-Interfacial layer-Metal-Semiconductor structures. This indicates that the interfacial reaction takes place only at the metal-interfacial layer interface. ’Drive-out’ diffusion is present at all interfacial reactions. The interfacial reactions and the drive-out diffusion processes are thought to play an important role in the degradation of thin film multilayer structures.

In this paper, the interfacial reactions between Sn-3.5Ag solder and Sn-3.5Ag-1.5In solder and Au/Ni/Cu pads in ball-grid-array (BGA) packages during solid aging were investigated by microstructural observations and phase analysis. During the solid aging, the intermetallic compound (IMC) layer in Sn-3.5Ag/Au/Ni/Cu solder joints evolved from the (Ni, Au)Sn4 phase to the Ni3Sn4 phase, but the rate of growth of the IMC layer did not change significantly. While, in Sn-3.5Ag-1.5In/Au/Ni/Cu solder joints, the phases evolved from the (Ni, Au)Sn4 and Ni3Sn4 phases into Ni3(Sn, In)4 phase. The distribution of In atoms in the solder alloy weakened interatomic force in the Sn-3.5Ag-1.5In solder alloy and the involvement of In atoms in the interfacial reaction generated more energy of distortion of the Ni3(Sn, In)4 and (Ni, Au)(Sn, In)4 lattices. These both accelerated the diffusion of Sn atoms and the rate of growth of the whole IMC layer, but this effect reduced gradually after prolonged aging.

The effect of high strain rate deformation on intermetallic reaction during ultrasonic welding aluminium to magnesium

During corrosion of Zr alloys in pressurized water at high temperatures a fraction of the corrosion-hydrogen is picked up by the metal. Long-term out-of-pile corrosion experiments have shown that chemical composition of Zr alloys and the size of second-phase particles (SPP) in Zircaloy-4 (Zry-4) affect the corrosion and the corrosion-hydrogen pickup fraction. The mechanism of hydrogen pickup is not well understood, although several influencing parameters were evaluated or discussed in the literature. One of the parameters that might influence hydrogen pickup is the electrical potential gradient that develops over the oxide during corrosion. Long-term electrochemical measurements of Zry-4 samples with different SPP sizes and Fe content and of Zr-2.5Nb in pressurized water at 350°C with and without polarization were used to check this influence. The potential difference between the reaction interface and the oxide surface is due to the oxidation reaction of the Zr metal resulting in electrons that have to move through the highly resistive oxide to the surface. Tests without polarization showed the potential difference proportional to the corrosion rate and depending on metallurgical aspects as the alloy composition and the SPP size. The lowest potential difference has been found for Zry-type material with large SPP and for Zr-2.5Nb. A negative polarization voltage of the samples against a Pt-reference electrode increases the H pick up and even leads to an accelerated corrosion at large potential differences. Analysis of H pickup clearly shows that, besides corrosion-H, H from the electrochemical surface reaction is also picked up. Samples with oxide layers exhibiting high electrical resistance pick up relatively more H than samples exhibiting oxide layers with low resistance. Zr-2.5Nb forming a very low-resistant oxide layer picks up only very little H. The effect of the SPP sizes can, at least partially, be explained by their influence on the electrical resistance of the oxide layer. The results of this study identify the potential gradient formed over the oxide layer as an important parameter for the relative amount of H pickup.

Formation of interfacial reaction layer for stainless steel/aluminum alloy dissimilar joint in linear friction welding

Effect of silicon on interfacial reaction and morphology of hot-dip aluminizing