Interfacial Reaction Zone Research Articles

Interfacial thermal fatigue behavior of cast tungsten carbide particle/steel matrix surface composites

Abstract

Microstructure and shear property of In-Sn-xAg solder joints fabricated by TLP bonding

Transient liquid phase (TLP) bonding was applied to prepare Cu/In-Sn-xAg/Cu (x = 20, 30, 40, 50, 60, 70 wt%) solder joints, and the effect of Ag particle content on joint microstructure, shear property and growth mechanism of intermetallic compound (IMC) was studied. The results indicated that the microstructure of solder joint consists of interfacial diffusion reaction zone and particle in situ reaction zone. The IMC in interfacial diffusion reaction zone is Cu3(In, Sn) phase and the IMCs in in situ reaction zone is composed of In-rich phase + Ag particle + ζ-Ag3In + Ag3(In, Sn). With the increasing Ag particle content, the thickness of IMC layer in diffusion reaction zone is decreased, the total amount of In-rich phase and Ag3(In, Sn) phase in in situ reaction zone is decreased, the quantity of Ag particles and ζ-Ag3In phase is grew. The AgIn2 phase is a stable IMC formed as a preferential reaction because it requires less Gibbs free energy than Sn-Ag phase, and it is transformed to ζ-Ag3In phase with increasing bonding time to 10 min. The void ratio of solder joints is decreased firstly and then increased with increasing Ag content. The shear strength of the joint is increased firstly and then decreased with increasing Ag particle content, and the maximum shear strength 22.2 MPa is obtained by Cu/In-Sn-50Ag/Cu solder joints. The shear fracture mechanism of solder joints is changed from ductile–brittle mixed fracture to brittle fracture.

A study of interface reaction zone in a SiC fibre/Ti-17 composite

The interface reaction zone (RZ) in a unidirectional continuous carbon-coated SiC fibre reinforced Ti-17 titanium alloy composite is investigated. Micro-computed tomography (CT), scanning and transmission electron microscopy are employed to characterize the fibre/matrix interface. It is revealed that the interface RZ is a 400 nm thick titanium carbide (TiC) layer which is composed of two sublayers, a 60 nm thick fine-grained sublayer and an approximate 340 nm thick coarse-grained sublayer. The RZ is formed through chemical reaction between carbon coating on the SiC fibre surface and Ti, Zr and Sn in the alloy matrix. The reaction is controlled by atom diffusion occurring at the fibre/matrix interface. However, in the reaction process, Al, Cr and Mo in the matrix are rejected and piled up in front of the RZ on the matrix side. A structure model is proposed to describe the formation mechanism of the interface RZ.

Interfacial reactions in the SiCf/Ni3Al composites by employing C single coating and C+Y2O3 duplex coating as barrier layers

Inhibiting terrible interfacial reaction between reinforced SiC fiber and Ni3Al matrix has become the primary task for developing SiC fiber reinforced Ni3Al composite (SiCf/Ni3Al), which is strongly desirable by aerospace vehicles and propulsion systems as promising high-temperature and high-strength structural material. Herein, C single coating and C+Y2O3 duplex coating were respectively introduced into SiCf/Ni3Al composites as reaction barrier layers for comparative study on their interfacial reactions, providing micro/nanoscale insight into the formation processes and products distribution of interfacial zones via transmission electron microscope observation. It reveals that C single coating can provide complete hindrance effects on the Al and Si atoms, but just slow down Ni diffusion instead of inhibiting, and thus the diffusion of Ni atoms dominates the formation of interfacial reaction zones; reaction zones can be divided into two sublayers, including Ni-rich sublayer composed of Ni silicides (Ni3Si and Ni2Si) and tiny graphitic C particles, and Ni-poor sublayer consisted of Ni silicides (Ni2Si and Ni3Si2) and large graphitic C particles. In contrast to C single coating failing to protect on SiC fiber, unbroken C+Y2O3 duplex barrier coating can perfectly protect the SiC fiber. However, C+Y2O3 duplex barrier coating is not completely inert to Ni3Al matrix, evidenced by forming Y4Al2O9 product to further hinder Ni atoms diffusion, simultaneously, some nanoscale cracks may be introduced by volume change as diffusion path; they induce the formation of Ni3AlC0.5 nanoclusters in the C coating next to matrix. Accordingly, it suggests that Y4Al2O9 should be potential reaction barrier coating in the SiCf/C/Ni3Al composite or Ni3Al/Si-based ceramic.

The influence of interface reaction zone on interfacial fracture toughness of SiC fiber reinforced titanium matrix composites

A fiber-reaction zone-matrix three-phase model is developed to evaluate the interfacial fracture toughness of titanium alloys reinforced by SiC monofilaments. Based on fracture mechanics, theoretical equations of GIIc are presented, and the effects of several key factors such as crack length and the interface reaction zone thickness on the critical applied stress necessary for crack growth and interfacial fracture toughness are discussed. Finally, the interfacial fracture toughness of typical composites including Sigma1240/Ti-6Al-4V, SCS-6/Ti-6Al-4V, SCS-6/Timetal 834, SCS-6/Timetal 21s, SCS-6/Ti-24Al-11Nb and SCS-6/Ti-15V-3Cr are predicted by the model. The results show that the model can reliably predict the interfacial fracture toughness of the titanium matrix composites.

Characterization of the interface reaction zone between iron and NiZn ferrite in a composite material - Study of a silica layer as a diffusion barrier

Iron-ferrite composites fabricated by powder metallurgy processes were studied for electromagnetic and large band microwave absorption applications. The sintering behavior of such composites is not well-understood, and these materials have been found to lose their magnetic properties or mechanical properties. Different systems of Fe/NiZn ferrite composites were investigated in order to better understand the chemical reactions that occur between oxide spinel and iron particles during the fabrication process. Three different systems, two models and one reference material were studied to analyze the chemical reactions in the aforementioned fabrication process. The first model consisted of iron films deposited by Physical Vapor Deposition (PVD) onto an NiZn-ferrite substrate. The reference material was made of a mixture of hot pressed iron and ferrite powders. In the second model, a SiO2 layer was deposited by PVD onto the NiZn-ferrite substrate, followed by iron deposition by PVD to study the role of SiO2 as a diffusion barrier. The materials were characterized using scanning electron microscopy (SEM), transmission electron microscopy (TEM), dilatometry, electron probe microscopy analysis (EPMA) and X-ray diffraction (XRD). For the Fe/NiZn ferrite systems, the experimental results showed (i) an oxido-reduction reaction above 600 °C that produced FeO and FexNi1-x phases and (ii) a diffusion process of Ni and Zn. The combination of diffusion and oxido-reduction reaction induced the total consumption of the initial phase and a considerable decrease in magnetic properties. By adding a silica layer between the iron and ferrite layers, the redox interfacial reaction and iron diffusion were prevented at temperatures up to 800 °C.

Vacuum brazing Nb and BN-SiO2 ceramic using a composite interlayer with network reinforcement architecture

A novel composite interlayer with a reinforced network was designed using a SiC ceramic with a network structure and Ti-Ni-Nb composite filler foils, to which the Nb and BN-SiO2 ceramic were successfully brazed under vacuum. For a brazing temperature of 1160°C and holding time of 10min, the interfacial microstructure of the Nb/BN-SiO2 ceramic joint was Nb/(βTi,Nb)-TiNi eutectic structure+(βTi,Nb)2Ni+SiC+TiC/TiN+Ti2N+TiB+Ti5Si3+TiO/BN-SiO2 ceramic. In addition, the shear strength and nano-hardness were analyzed to evaluate the effect of the composite interlayer with a network reinforcement architecture on the mechanical properties of the joint. During brazing, the Ti-Ni-Nb filler metal infiltrated and reacted with the SiC to form the network reinforcement architecture, resulting in the residual stress being relieved and the mechanical performance of the joint being significantly improved. A maximum shear strength of 102MPa was achieved, which was 60MPa (142%) higher than that of the joint brazed without the network reinforcement architecture. A reduction in the residual stress on the BN-SiO2 ceramic side from 328MPa to 210MPa was observed with the network reinforcement architecture, and the fracture path of the joint changed from the surface of the BN-SiO2 ceramic to the interfacial reaction zone.

Fabrication, interfacial characterization and mechanical properties of continuous Al2O3 ceramic fiber reinforced Ti/Al3Ti metal-intermetallic laminated (CCFR-MIL) composite

Continuous Al2O3 ceramic fiber reinforced Ti/Al3Ti metal-intermetallic laminated (CCFR-MIL) composite was fabricated using a vacuum hot pressing (VHP) sintering method and followed by hot isostatic pressing (HIP). The microstructure characteristics of the interfaces between Ti and Al3Ti, as well as Al2O3 fiber and Al3Ti intermetallic were analyzed by scanning electron microscopy (SEM). Elemental distribution in the interfacial reaction zones were quantitatively examined by energy-dispersive spectroscopy (EDS). The phases in the composite were identified by X-ray diffractometer (XRD). The mechanical properties of the CCFR-MIL composite were measured using compression and tensile tests under quasi-static strain rate. The experimental results indicated that the residual Al was found in Al3Ti intermetallic layer of CCFR-MIL composite. The interfacial reactions occurred during HIP and the reaction products were determined to be Al2Ti, TiSi2, TiO2 and Al2SiO5 phases. Compared to Ti/Al3Ti MIL composite without fiber reinforcement, both the strength and failure strain of CCFR-MIL composite under both compressive and tensile stress states increased due to the contribution of the continuous ceramic Al2O3 fiber.

Formation mechanism and stability of the phase in the interface of tungsten carbide particles reinforced iron matrix composites: First principles calculations and experiments

Abstract

Improvement of mechanical properties of SiC(SCS-6) fibre-reinforced Ti3AlC2 matrix composites with Ti barrier layer

In this study, silicon carbide fibre-reinforced Ti3AlC2 matrix composites with a Ti barrier layer were prepared by hot-pressing at 1250°C and 1300°C. The microstructure of the composites was characterised by field-emission scanning electron microscopy. During consolidation, reactions of Ti with the fibres and the matrix led to the formation of an interfacial reaction zone between the fibres and the matrix and a matrix reaction zone within the matrix. Quantitative elemental distribution maps of both reaction zones were collected using energy-dispersive spectroscopy. The results revealed that the Ti layer effectively hindered the inward diffusion of Al from the matrix. In addition, the flexural strength of the composite was significantly improved with the addition of the Ti layer. Furthermore, noncatastrophic fracture behaviour was observed for the composites. The improvement of their mechanical behaviour is attributed to the added Ti layer, which prevented strength degradation of the fibres via a severe interface reaction.

Microstructure, tensile strength and thermostability of W-core SiC fibers with or without carbon coating

SiC fibers with carbon coating (SiC/C fiber) were prepared by three-stage chemical vapor deposition on W filament. In order to determine their thermal stability, tensile test was then performed after thermal exposure at 900°C and 1000°C in vacuum. The microstructure and chemical composition of the fibers were investigated by scanning electron microscopy, transmission electron microscopy and electron probe microanalysis, respectively. The results show that the average room-temperature strength of the 900°C thermally-exposed SiC/C fiber had little loss in comparison with the as-prepared fibers, while a notable strength degradation occurred for the fiber after 1000°C thermal exposure. The degradation of the tensile strength is due to the growth of W/SiC interfacial reaction layer and the coarsening of SiC grains in the SiC-2-I zone. In addition, the formation mechanism of the W/SiC interfacial reaction zone and its microstructure evolution were also discussed.

Interphase formation on lithium solid electrolytes—An in situ approach to study interfacial reactions by photoelectron spectroscopy

Interfacial reactions of solid electrolytes play an important role in all-solid-state batteries. The interface resistances—describing charge transfer between electrode and solid electrolyte—and the cycle stability of the battery depend on the chemical and physical properties of the interfaces. As buried interfaces in all-solid-state batteries are difficult to investigate, the knowledge on interfacial reactions and the interfacial kinetics is poor—especially in case of the interface between solid electrolytes and alkali metal. Here, a simple and straightforward technique for the investigation of the formation of an interfacial reaction zone (interphase) at the surface of a solid electrolyte is presented. The key concept is to use the internal argon ion sputter gun in a standard lab-scale photoelectron spectrometer to deposit thin metal films (e.g. lithium) on the sample surface and to study the reaction between metal and solid electrolyte by photoelectron spectroscopy directly after deposition. As an example for the formation of interphases on solid electrolyte materials, lithium is deposited on lithium lanthanum titanate (LLTO), and the reaction is observed by XPS in situ. The obtained spectra show the formation of reduced titanium ions and titanium metal due to the reaction of LLTO with Li—i.e. by lithium insertion. The presented experimental approach can be used for the deposition of virtually any metal on the sample and can be easily adapted to a wide range of applications such as enhancing the electronic conductivity of samples in situ, studies of electronic contact properties in devices, detailed analysis of emission depth distribution functions for thin overlayers or to create internal binding energy standards.

A transmission electron microscopy and X-ray photoelectron spectroscopy study of annealing induced γ-phase nucleation, clustering, and interfacial dynamics in reactively sputtered amorphous alumina thin films

Pure α-Al2O3 exhibits a very high degree of thermodynamical stability among all metal oxides and forms an inert oxide scale in a range of structural alloys at high temperatures. We report that amorphous Al2O3 thin films sputter deposited over crystalline Si instead show a surprisingly active interface. On annealing, crystallization begins with nuclei of a phase closely resembling γ-Alumina forming almost randomly in an amorphous matrix, and with increasing frequency near the substrate/film interface. This nucleation is marked by the signature appearance of sharp (400) and (440) reflections and the formation of a diffuse diffraction halo with an outer maximal radius of ≈0.23 nm enveloping the direct beam. The microstructure then evolves by a cluster-coalescence growth mechanism suggestive of swift nucleation and sluggish diffusional kinetics, while locally the Al ions redistribute slowly from chemisorbed and tetrahedral sites to higher anion coordinated sites. Chemical state plots constructed from XPS data and simple calculations of the diffraction patterns from hypothetically distorted lattices suggest that the true origins of the diffuse diffraction halo are probably related to a complex change in the electronic structure spurred by the a-γ transformation rather than pure structural disorder. Concurrent to crystallization within the film, a substantially thick interfacial reaction zone also builds up at the film/substrate interface with the excess Al acting as a cationic source.

Preparation and analysis of SiCf reinforced GH4738 composite

SiC fibre reinforced GH4738 composite, a new composite material with excellent elevated temperature mechanical properties and light weight, shows great potential to replace Ni based superalloys turbine disc for aerospace engines. Continuous Ti3Al coated SiC fibre reinforced GH4738 matrix composite was fabricated by hot isostatic pressing (HIP). Physical vapour deposition was used to deposit GH4738 on the surface of the Ti3Al coated SiC fibre. The elevated temperature tensile strength was established for the composite. The fracture surface, fibre surface, interfacial reaction zone and phase composition were analysed by scanning electron microscopy, energy dispersive spectrometer and X-ray diffraction. The composite shows higher elevated temperature tensile strength than GH4738 and the composite without coating, but only reaches 30% of its theoretical strength value, which can be explained by matrix diffused through the barrier coating and reacted with SiC fibre in HIP processing. The reaction was complicated, and the products were mainly Ni2Si and Cr23C6.

Investigation of interfacial reaction in SiC fiber reinforced Ti–43Al–9V composites

SiC fiber reinforced titanium aluminides matrix composites based on TiAl (Ti–43Al–9V) were fabricated by means of matrix-coated fiber method through hot isostatic pressing. Microstructure of the SiCf/Ti–43Al–9V interfacial reaction zone in the composites was identified by means of scanning electron microscopy and transmission electron microscopy. The results show that three types of reaction products TiC, Ti2AlC and (Ti,V)5(Si,Al)3 are formed between carbon coating of SiC fiber and the matrix. TiC is adjacent to the carbon coating of the SiC fiber, and (Ti,V)5(Si,Al)3 is close to the matrix. Ti2AlC layer exists as columnar grains between TiC and (Ti,V)5(Si,Al)3 layers. The TiC layer can be divided into fine-grained layer and coarse-grained layer. The fine-grained TiC layer contains amorphous carbon, and the coarse-grained TiC layer is separated from fine-grained TiC by an intermittent carbon layer. In addition, TiC particles are also formed between carbon coating and SiC. Furthermore, the formation mechanism of the interfacial reaction products was discussed.

Laser sintering and crystallization of a bioactive glass-ceramic

Glass-ceramics are formed from metastable glasses that crystallize to one or more ceramic phases upon heating. Most bioactive glass-ceramics require conventional sintering in an oven to devitrify due to slow crystallization kinetics. Apatite–mullite glass-ceramics can be crystallized at higher rates due to faster kinetics and are suitable for use with rapid sintering techniques. In particular, laser sintering is an attractive alternative to conventional heat treatment because the energy consumption is dramatically reduced and throughput time is extremely quick. Here, apatite–mullite glass-ceramics were examined in a preliminary study to elucidate the effects of laser sintering and crystallization of a bioactive glass-ceramic. The prospect of simultaneously laser enameling it to a titanium surface was also investigated. The laser power, laser traverse speed, and number of passes over the sample were varied. Minimum threshold values required to produce apatite and mullite were identified. Laser enameling of coatings on titanium showed that a smaller interfacial reaction zone occurs compared to conventional sintering but the coating was porous. This information can be used to develop more suitable glass compositions.

Effects of AlPO4 addition on the corrosion resistance of andalusite-based low-cement castables with molten Al-alloy

Abstract This paper investigates the effects of AlPO 4 addition on the corrosion resistance of andalusite LCC refractories. Corrosion tests using the Alcoa cup test (850 °C and 1160 °C for 150 h and 72 h, respectively) were conducted to determine the extent of penetration. The addition of AlPO 4 was shown to improve the corrosion resistance of the castables in contact with molten Al-alloy. SEM/EDS analyses of the interfacial reaction zone showed the formation of corundum in the interfacial layer, along with a significant decrease in the phosphorus content in the interface. Thermodynamic calculations revealed that reaction with the alloy leads to the formation of corundum as the reaction product along with gaseous products (phosphorus trioxide gas) and small amounts of aluminum phosphide. Corundum formation at the interface enhances the corrosion resistance of sample due to high stability of corundum against molten Al alloy, while the metal quality is enhanced due to absence of dissolved phosphorus in the metal.

Effect of Alloying Element Addition on Transition Interface Reaction Zone in Metal Matrix Composite Processing by Cast Infiltration

In metal matrix composite, the matrix and reinforced body is different in physical and chemical properties. The transition effect of reaction zone between the matrix and reinforced body is the hot point in research aboat metal matrix composite. The steel substrat casting tungsten carbide particle surface reinforced compostie is research object in this article. The interface reaction zone is measured by EDS line scaning. The problem is solved by statistic that interference between scaning neighbour points leads to the emergence of sawtooth wave, the processed curve is beneficial to observe. The effect and effect curve of W、Mo、Ni addion is received in the interface reaction zone.

Interfacial products in SiC fiber reinforced Ti-Al based intermetallic alloys

Continuous SiC fiber reinforced Ti-Al based intermetallic alloys were prepared by sintering pure Ti and Al foils as well as SiC fibers. Owing to a complex self-propagating combustion reaction and diffusion reactions occurring during sintering process, the emphasis of the present paper is on identifying the interfacial products between SiC fibers and matrix, which is crucial for the mechanical properties of the sintered materials. Microstructure observation reveals that the sintered alloys contain lamellar matrix and SiC fibers with various interfacial products. The lamellar matrix compose chicly of TiAl3, TiAl2, TiAl, Ti3Al and α-Ti phases, the SiC fibers locate in TiAl3/TiAl layer and/or Ti3Al/α-Ti layer. The Al content is very little in the interfacial reaction zone. The main interfacial products are considered to mainly be compounds of Ti5Si3Cx, Ti3AlC, and Al4C3Six, etc. The interfacial reaction layer in the Ti-rich phase (Ti3Al and α-Ti) is thicker than in the Al-rich phase layer (TiAl3, TiAl2 and TiAl).

SEM in situ study on the mechanical behaviour of SiC f/Ti composite subjected to axial tensile load

Ti–6Al–4V matrix composites reinforced by SiC fibers with and without carbon coating (SiC f/Ti–6Al–4V) were prepared by Foil–Fiber–Foil (FFF) method and subjected to heat treatment at 900 °C for 50 h. Subsequently in situ Scanning Electron Microscopy (SEM) technique was used to study fracture mechanism of the composites under axial tensile loads. The influence of fiber coating, interfacial reaction zone and titanium alloy microstructure on initiation and propagation of cracks was investigated in detail. The results show that upon loading, the non coated fibers crack and fracture into smaller fragments. However, the carbon coated fiber does not develop any fracture during the entire experiment and a part of the fiber is pulled out during the final fracture.