INTERFACIAL STRUCTURE AND PHASE REACTION IN SiC/NiCr ALLOY JOINT

Bonding of SiC to SiC using Ni and Ni - 25at%Cr foils was performed at high temperature.Interface structures and reaction phases were investigated by EPMA analyses and XRD diffraction method, re- spectively. At a bonding temperature of 1273K Ni reacts with SiC and forms various Ni silicides con- taining graphite baside SiC. Ni3Si without graphite was formed at Ni side.The interface structure of SiC/Ni joint was SiC/Ni2Si + C/Ni31 Si12 + G/Ni3 Si/Ni. At the interface between SiC and Ni- 25at%Cr alloy the Ni silicide was only Ni2Si at the same bonding temperature,and further(Cr, Ni)7 (Si, C)3 carbide was formed between Ni silicide + graphite zone and Ni - 25at%Cr alloy.The interface structure of SiC/Ni - 25at%Cr alloy was SiC/Ni2Si + C/(Cr, Ni)7 (Si, C)3+Ni(ss. Cr, Si)/Ni - 25at%Cr.

Relationship between interfacial structure and property of steel-mushy Al-28Pb bonding pate

The interfacial properties of steel-mushy Al-28Pb bonding plate with different interfacial structures, and the influence of ratio of Fe-Al compound at the interface on interfacial shear strength were investigated. The results show that there is a nonlinear relationship between the ratio of Fe-Al compound at the interface and the interfacial shear strength. When the ratio of Fe-Al compound at the interface is smaller than 71.4%, with the increase of the ratio of Fe-Al compound at the interface, the interfacial shear strength increases gradually; when the ratio of Fe-Al compound at the interface is larger than 71.4%, with the increase of the ratio of Fe-Al compound at the interface, the interfacial shear strength decreases continuously; when the ratio of Fe-Al compound at the interface is 71.4%, the largest interfacial shear strength 70.2MPa is obtained.

SPATIAL HIERARCHY AND INTERFACIAL STRUCTURE IN INJECTION-MOLDED BARS OF POLYPROPYLENE-BASED BLENDS AND COMPOSITES

The hierarchical structure and interfacial morphology of injection-molded bars of polypropylene （PP） based blends and composites have been investigated in detail from the skin to the core. For preparation of injection-molded bars with high-level orientation and good interfacial adhesion, a dynamic packing injection molding technology was applied to exert oscillatory shear on the melts during solidification stage. Depending on incorporated component, interfacial adhesion and processing conditions, various oriented structure and morphology could be obtained. First, we will elucidate the epitaxial behavior between PP and high-density polyethylene occurring in practical molded processing. Then, the shear-induced transcrystalline structure will be the main focus for PP/fiber composites. At last, various oriented clay structures have been ascertained unambiguously in PP/organoclay nanocomposites along the thickness of molded bars.

Influence of Diffusion Time on Steel-Aluminum Solid to Liquid Bonding Interfacial Structure

The bonding of steel plate to aluminum liquid was conducted using rapid solidification. The influence of diffusion time on interfacial structure was studied. The results showed that under the condition of 750癈 for the temperature of aluminum liquid and 200癈 for the preheat temperature of steel plate, when diffusion time was shorter than 4.3 s, there was only Fe-AI solid solution at the interface. When diffusion time was longer than 4.3 s, Fe-AI compound began to form at the interface. The relationships between diffusion time t and thickness of Fe-AI compound layer H are H=-9.72+2.62t-0.08t2 (4.3 s<t<15 s) and H=2.79+0.647t-0.033t2 (t>15 s).

Interfacial Structure of Steel-Mushy Al-20Sn Bonding Plate

Fe-AI compound at the interface of steel-mushy AI-20Sn bonding plate was studied quantitatively. The relationship between ratio of Fe-AI compound at interface and bonding parameters (such as preheat temperature of steel plate, solid fraction of AI-20Sn slurry and rolling speed) was established by artificial neural networks perfectly. The results show that when the bonding parameters are 505℃ for preheat temperature of steel plate, 34.3% for solid fraction of AI-20Sn slurry and 10 mm/s for rolling speed, the reasonable ratio of Fe-AI compound corresponding to the largest interfacial shear strength of bonding plate is obtained. Its value is 72%. This reasonable ratio of Fe-AI compound is a quantitative criterion of interfacial embrittlement, that is, when the ratio of Fe-AI compound at interface is larger than 72%, interfacial embrittlement will occur.

Study on interfacial structure and strength of Si_3N_4/Ti/Cu/Ti/Si_3N_4 PTLP bonding

Partial transient liquid-phase bonding （PTLP bonding） of Si3N4 ceramic with Ti/Cu/Ti multi-interlayer is performed with changing the thickness of Ti foil. The influence of Ti foil thickness on interface structure and joint strength was discussed. The joint interface structures are investigated by scanning electron microscope （SEM） and energy dispersion spectroscopy（EDS）. The results show that the maximum joint strength of 210 MPa is obtained at room temperature in the experiments. When joining temperature and time are not changed and the process of isothermal solidification is sufficient , interface structure, reaction layer thickness and isothermal solidification thickness change with the thickness of Ti foil.

Interfacial Structure of Nanocrystalline SnO_2 and SiO_2-doped SnO_2

The study of nanocrystalline SnO2 (n-SnO2) and SiO2-doped SnO2 (n-Si-SnO2) samples pre-pared by the sol-gel process showed that SiO2 doping can effectively restrained the growth of nanocrystalline SnO2 grains, thus improving thermal stability of the materials.

Fabrication and Interfacial Structure of Ni-YSZ-LSM Porous Scaffold for Solid Oxide Fuel Cells

A novel process route using tape casting and stacking for fabricating porous scaffold of solid oxide fuel cells （SOFC） was demonstrated. The linear shrinkages of anode （Ni-YSZ, YSZ stands for 3% Y2O3 （mole fraction） stabilized ZrO2 ） and cathode （LSM-YSZ, LSM stands for La0.8Sr0.2MnO3 ） were optimized to be uniform with that of electrolyte during sintering, by controlling the content of pore former. The micromorphology and interface microstructure of the cross-section of the porous scaffold were observed by optical microscope and scanning electron microscope, respectively. The element distribution and phase composition were analyzed by energy dispersive spectrometer and X-ray diffraction, respectively. The results showed that the porous scaffold with regular pore shape and high specific surface area was obtained after sintering at 1 350℃. The fabricated porous scaffold had defect free interracial structures due to the uniform shrinkage of anode, cathode and electrolyte layers. In addition, it was shown that diffusions of Zr, Ni and La caused a progressive boundary between YSZ, Ni-YSZ and LSM-YSZ layers. The interface between anode and electrolyte （Ni-YSZ/YSZ） was mainly composed of Ni, YSZ and a small amount of NiO, and the interface between cathode and electrolyte （LSM-YSZ/YSZ） was mainly composed of YSZ, LSM and a small amount of La2Zr2O7.

Interfacial Structures Governed Plastic Deformation Behaviors in Metallic Multilayers

In this work, we have investigated the mechanical properties of Cu/Ta, Ag/Cu and Ag/Nb multilayers with different heterogeneous interfaces. The results suggest that when individual layer thickness （h） is larger than 5-10 nm, the hardness/strength of three different multilayer systems has the similar length scale effect with decreasing layer thickness, while when h ≤ 5 nm, the three multilayer systems show remarkably different plastic deformation behaviors. The strength curves exhibit the variation trends of unchanging, softening and increasing corresponding to Cu/Ta, Ag/Cu and Ag/Nb multilayers, respectively. The microstructure analysis shows that three kinds of multilayers have totally different interfacial structures, which lead to the different strengthening or softening mechanisms.

Strength and interfacial microstructure of Si3N4 joint brazed with amorphous Ti-Zr-Ni-Cu filler metal

In this paper, the vacuum brazing of Si3N4 ceramic was carried out with Ti40Zr25Ni15Cu20 amorphous filler metal. The interfacial microstructure was investigated by scanning electron microscopy （ SEM ）, energy dispersive spectroscopy （EDS） etc. According to the analysis, the interface reaction layer was mode up of TiN abut on the ceramic and the Ti-Si, Zr-Si compounds. The influence of brazing temperature and holding time on the joint strength was also studied. The results shows that the joint strength first increased and then decreased with the increasing of holding time and brazing temperature. The joint strength was significantly affected by the thickness of the reaction layer. Under the same experimental conditions, the joint brazed with amorphous filler metal exhibits much higher strength compared with the one brazed with crystalline filler metal with the same composition. To achieve higher joint strength at relatively low temperature, it is favorable to use the amorphous filler metal than the crystalline filler metal.

Interfacial electronic structure at a metal–phthalocyanine/graphene interface:Copper–phthalocyanine versus iron–phthalocyanine

The energy level alignment of CuPc and FePc on single-layer graphene/Ni（111） （SLG/Ni） substrate was investigated by using ultraviolet and X-ray photoelectron spectroscopy （UPS and XPS）. The highest occupied molecular orbitals （HO- MOs） in a thick layer of CuPc and FePc lie at 1.04 eV and 0.90 eV, respectively, below the Fermi level of the SLG/Ni substrate. Weak adsorbate-substrate interaction leads to negligible interfacial dipole at the CuPc/SLG/Ni interface, while a large interracial dipole （0.20 eV） was observed in the case of FePc/SLG/Ni interface, due to strong adsorbate-substrate coupling. In addition, a new interfacial electronic feature was observed for the first time in the case of FePc on SLG/Ni substrate. This interfacial state can be attributed to a charge transfer from the SLG/Ni substrate to unoccupied orbitals of FePc.

XPS AND UPS STUDIES OF THE INTERFACIAL INTERACTION IN Ni ZrO 2 COMPOSITE PLATING

The interfacial interaction existing in the Ni ZrO 2 composite plating has been investigated. The experimental results show that no new phases were formed in the interfacial regions between matrix Ni and ZrO 2 particles, but an orbital interaction through the mutual overlap of the d orbits does exist in the interfacial regions between Ni atoms and Zr 3+ ions.

Interfacial Morphology and Bonding Mechanism of Explosive Weld Joints

Interfacial structure greatly affects the mechanical properties of laminated plates.However,the critical material properties that impact the interfacial morphology,appearance,and associated bonding mechanism of explosive welded plates are still unknown.In this paper,the same base plate(AZ31B alloy)and different flyer metals(aluminum alloy,copper,and stainless steel)were used to investigate interfacial morphology and structure.SEM and TEM results showed that typical sine wave,wave-like,and half-wave-like interfaces were found at the bonding interfaces of Al/Mg,Cu/Mg and SS/Mg clad plates,respectively.The different interfacial morphologies were mainly due to the differences in hardness and yield strength between the flyer and base metals.The results of the microstructural distribution at the bonding interface indicated metallurgical bonding,instead of the commonly believed solid-state bonding,in the explosive welded clad plate.In addition,the shear strength of the bonding interface of the explosive welded Al/Mg,Cu/Mg and SS/Mg clad plates can reach up to 201.2 MPa,147.8 MPa,and 128.4 MPa,respectively.The proposed research provides the design basis for laminated composite metal plates fabrication by explosive welding technology.

Interfacial mechanical property of steel-mushy Al-20Sn bonding

The bonding of a steel plate to Al-20Sn slurry was conducted using thecasting rolling technique. The surface of the steel plate was defatted, descaled, immersed (inK_2ZrF_6 flux aqueous solution) and stoved. Al-20Sn slurry was prepared using the electromagneticmechanical starring method. The interfacial mechanical property of the bonding plate was researchedto determine the relationship between the diffusion time and the interfacial shear strength. Inorder to identify the mechanism of bonding, the interfacial structure of the bonding plate wasstudied. The results show that at a prebeat temperature of the steel plate of 505 deg C and a solidfraction of Al-20Sn slurry of 35 percent, the relationship between the interfacial shear strength Sand the diffusion time t is S=28.8+4.3t-0.134t^2 +0.0011t^3. When the diffusion time is 22 s, thelargest interfacial shear strength is 70.3 MPa, and the corresponding interface is a new one whichis made up of Fe-Al compound and Fe-Al solid solution alternatively and in a right proportion. Inthis interfacial structure, the interfacial embrittlement does not happen and Fe-Al compound canplay its role in strong combination adequately.

TEM Investigations on Layered Ternary Ceramics

Layered ternary ceramics represent a new class of solids that combine the merits of both metals and ceramics.These unique properties are strongly related to their layered crystal structures and microstructures. The combination of atomic-resolution Z-contrast scanning transmission electron microscopy （STEM） and transmission electron microscopy （TEM）, selected area electron diffraction （SAED）, convergent beam electron diffraction （CBED） represents a powerful method to link microstructures of materials to macroscopic properties, allowing layered ternary ceramics to be investigated in an unprecedented detail. Vicrostructural information obtained using TEM is useful in understanding the formation mechanism, layered stacking characteristics, and defect structures for layered ternary ceramics down to atomic-scale level; and thus provides insight into understanding the ＂Processing-Structure-Property＂ relationship of layered ternary ceramics. Transmission electron microscopic characterizations of layered ternary ceramics in Ti-Si-C, Ti-Al-C, Cr-Al-C, Zr-Al-C, Ta-Al-C and Ti-Al-N systems are reviewed.

STRAIN INDUCED STRUCTURAL TRANSITION OF INTERFACES AND TWINS IN A HOT－DEFORMED DUAL－PHASE TIAL ALLOY

The structure characteristics of a2/γinterfaces and the features of deformation twins in a quasi-isothermal forged Ti-45Al-10Nb alloy were studied by highresolution transmission electron microscopy. Three types of strain induced a2/γinterfaces and two types of strain induced twin boundaries were identified The most,important features are high density of ledges and the existence of I/3[111] Frank partial dislocation. Mechanisms for the formation these interfaces were proposed Two types of deformation twins were observed These deformation twins always start from the ledges it seems that ledges at interfaces are important features of interfacial structure for the mechanical behavior of alloys.

Nucleation interface of Al-Sb alloys on single crystal Al_2O_3 substrate

Lattice structure information of heterogeneous nucleation at nucleation interface was present.The crystal orientation,and interfacial structure characteristic of liquid Al alloys nucleated on the basal surface(0001)Al2O3single crystal substrate were identified by X-ray diffraction(XRD),scanning electron microscopy(SEM)and high resolution transmission electron microscopy(HRTEM)analysis.The preferred crystal orientations of pure Al and Al-1%Sb(mass fraction)alloy adjacent to the nucleation interface were examined as(200)and(220)planes of Al,respectively,and two corresponding orientation relationships were obtained.An improved nucleation efficiency and refined grains were attributed to both the reduced interplanar spacing of preferred orientation and the decrease of lattice misfit from16.4%to7.0%in Al-1%Sb/Al2O3nucleation group.

Nanomechanical and Chemical Mapping of the Structure and Interfacial Properties in Immiscible Ternary Polymer Systems

It is a challenge to identify each phase in a multi-component polymer system and uniquely determine the interfacial properties between the different phases.Using atomic force microscopy nanomechanical mapping(AFM-NM)and AFM-based infrared spectroscopy(AFM-IR),we identify each phase,visualize structural developments,and determine the interfacial properties in a blend of three polymers:high-density polyethylene(HDPE),polyamide(PA6)and poly(styrene-b-ethylene-co-butylene-b-styrene)(SEBS).Each phase can be identified from the Young’s modulus,along with the structural development within the phases before and after compatibilization.The interfacial widths between HDPE/PA6,HDPE/SEBS and SEBS/PA6 were determined independently in one measurement from a Young’s modulus map.The structural,mechanical property development and identity of the phases were determined by AFM-NM,while AFM-IR,providing complementary chemical information,identified interfacial reactions,showed the chemical affinity of a compatibilizer with the component phases,and mapped the distribution of the compatibilizer in the ternary polymer blends.The chemical,structural and interfacial information obtained by these measurements provide information that is essential for producing mechanically robust materials from incompatible mixtures of polymers.

Technological parameters of stainless steel-aluminum alloy semisolid joining clad

By using semisolid joining technique, the bonding of stainless steel and semisolid aluminum alloy is successfully realized. The relationships between interfacial shear strength and solid fraction of aluminum alloy, bonding pressure and time of keeping pressure were studied by the method of orthogonal experiment. The interfacial structure and the fracture structure of the bonding plate are studied by means of optical microscope （OM） and scanning electron microscope （SEM）. The results show that there is the best solid fraction between the solid phase line and the liquid phase line of the semisolid aluminum alloy, with the increase of bonding pressure and pressure time, the interfacial shear strength increases rapidly, and then with further increase of bonding pressure and pressure time, the shear strength rises little. Along the interface, solid phase and liquid phase bond with stainless steel by turns because of the different diffusion ability. So, a new type of non-equilibrium diffusion interfacial structure is constructed at the interface of stainless steel and aluminum alloy, compound mechanism of plastic and brittle fracture interface was formed at the shear fracture interface.

Effect of Crushed Air-cooled Blast Furnace Slag on Mechanical Properties of Concrete

Morphology characteristics of mix aggregates with crushed air-cooled blast furnace slag（SCR） and crushed limestone（LCR） with 5-20 mm and 20-40 mm gradation were represented by numerical parameters including angularity number（AN） and index of aggregate particle shape and texture（IAPST）.The effect of mix aggregates containing SCR on compressive strength and splitting tensile strength of concrete was investigated.Fracture characteristics of concrete,interfacial structure between aggregates and matrix were analyzed.The experimental results show that porous and rough SCR increases contact area with matrix in concrete,concave holes and micro-pores on the surface of SCR are filled by mortar and hydrated cement paste,which may increase interlocking and mechanical bond between aggregate and matrix in concrete.SCR can be used to produce a high-strength concrete with better mechanical properties than corresponding concrete made with LCR.The increase of AN and IAPST of aggregate may enhance mechanical properties of concrete.