关键词： 304 stainless steel   amorphous foil   microstructure   shear strength   Ti-6Al-4V titanium alloy   vacuum brazing  

摘要： Dissimilar metal vacuum brazing between TC4 titanium alloy and 304 stainless steel was conducted with newly designed Cu-Ti-Ni-Zr-V amorphous alloy foils as filler metals. Solid joints were obtained due to excellent compatibility between the filler metal and stainless steel substrate. Partial dissolution of stainless steel substrate occurred during brazing. The shear strength of the joint brazed with Cu43.75Ti37.5Ni6.25Zr6.25V6.25 foil was 105 MPa and that with Cu37.5Ti25Ni12.5Zr12.5V12.5 was 116 MPa. All the joints fractured through the gray layer in the brazed seam, revealing brittle fracture features. Cr4Ti, Cu0.8FeTi, Fe8TiZr3 and Al2NiTi3C compounds were found in the fractured joint brazed with Cu43.75Ti37.5Ni6.25Zr6.25V6.25 foil, and Fe2Ti, TiCu, Fe8TiZr3 and NiTi0.8Zr0.3 compounds were detected in the joint brazed with Cu37.5Ti25Ni12.5Zr12.5V12.5 foil. The existence of Cr-Ti, Fe-Ti, Cu-Fe-Ti, and Fe-Ti-V intermetallic compounds in the brazed seam caused fracture of the resultant joints.

关键词： Carbon-carbon composites (CCCs)   Joints/joining   Wettability   Ceramic/metal interface  

摘要： A novel method based on the modification of a commercial brazing alloy was evaluated and used for joining CFC (carbon fiber reinforced carbon composite) to pure copper. This paper deals with the development of a flat and curved joint concept providing a versatile and cheap joining technology, i.e. a single step brazing process by using an innovative brazing alloy deriving from a commercial one. The brazing of CFC to Cu was performed by using a commercial non-active braze. RF-magnetron sputtering and galvanic processes have been used to modify the commercial non-active braze by coating it with Cr, an active element. The aim is to increase its wettability on CFC, instead of using an active braze, having potential embrittlement issues. Optical microscopy and scanning electron microscopy coupled with energy-dispersive spectroscopy were used to evaluate the microstructure and composition of the CFC/Cu joints. In order to evaluate the mechanical strength of the joint, a lap test in compression has been performed. (C) 2013 Elsevier Ltd. All rights reserved.

关键词： 非晶合金变压器   背景   推广  

摘要： 介绍了非晶合金变压器的在世界各国获得积极推广，行业背景，政策背景，市场背景及较好的发展前景。

关键词： MICROSTRUCTURE   ISOTHERMAL processes   SOLIDIFICATION/STABILIZATION   BRAZED joints   ZIRCONIUM alloys   AMORPHOUS alloys   RIBBONS   COPPER alloys  

摘要： The microstructure and growth characteristics of Zircaloy-4 joints brazed by a Zr48Ti16Cu17Ni19 (at.%) amorphous filler metal have been investigated with regard to the controlled isothermal solidification and intermetallic formation. Two typical joints were produced depending on the isothermal brazing temperature: (1) a dendritic growth structure including bulky segregation in the central zone (at 850 degrees C), and (2) a homogeneous dendritic structure throughout the joint without segregation (at 890 degrees C). The primary alpha-Zr phase was solidified isothermally, nucleating to grow into a joint with a cellular or dendritic structure. Also, the continuous Zr2Ni and particulate Zr2Cu phases were formed in the segregated center zone and at the intercellular region, respectively, owing to the different solubility and atomic mobility of the solute elements (Ti, Cu, and Ni) in the alpha-Zr matrix. A disappearance of the central Zr2Ni phase was also rate-controlled by the outward diffusion of the Cu and Ni elements. When the detrimental Zr2Ni intermetallic phase was eliminated by a complete isothermal solidification at 890 degrees C, the strengths of the joints were high enough to cause yielding and fracture in the base metal, exceeding those of the bulk Zircaloy-4, at room temperature as well as at elevated temperatures (up to 400 degrees C). (C) 2013 Elsevier B.V. All rights reserved.

关键词： brazed joints   Mechanical properties   Amorphous alloys   Shear Strength   COOLING RATE   BRAZING FILLERS   high vacuum   HEATING TIME   brazing temperature   microtectonics   METAL ALLOY  

摘要： Ceramic ZrO2 and metallic Ti-6Al-4V alloy are jointed by using a Ti33Zr17Cu50 (at.%) amorphous alloy as a solder at 1123-1273 K in a high vacuum. It is demonstrated that the microstructure and mechanical properties are significantly influenced by the brazing temperature, the heat time and the cooling rate. The brazing seam jointing ZrO2 with Ti-6Al-4V is composed of ZrO2/Cu2Ti4O, (Ti,Zr)(2)Cu/TiO, Ti2O/CuTi2, (Ti,Zr)(2)Cu/CuTi2/Ti-6Al-4V alloys and compounds, of which the increasing thickness weakens the shear strength as the brazing temperature, the heat time the cooling rate increase. The maximum shear strength of the brazing joints reaches 162 MPa with the optimal technical parameters: the brazing temperature of 1173 K, the heat time of 10 min and the cooling rate of 5 K/min. The fracture of the joint occurs in the brittle seam layer nearby the side of ZrO2. (c) 2012 Elsevier Ltd. All rights reserved.

关键词： a-SiGe:H   Deposition temperature   PECVD   Bandgap   Photosensitivity  

摘要： Hydrogenated amorphous silicon germanium (a-SiGe:H) alloys were prepared by plasma enhanced chemical vapor deposition (PECVD) at different deposition temperatures. The optical, optoelectronic properties and the microstructure of the prepared a-SiGe:H alloys were investigated systematically by transmission, photo/dark conductivity, Raman, and Fourier transform infrared (FTIR) spectroscopy measurements. The Ge atom content was further determined by energy dispersive spectroscopy (EDS) and the surface roughness was checked by atomic force microscopy (AFM). It was found that the narrow bandgap (E-g) a-SiGe:H alloy with the enhanced photosensitivity (Ratio of photo conductivity to dark conductivity) and the rapid growth rate could be prepared when the deposition temperature was relatively high. The underlying mechanism was analyzed carefully. The results indicated that high temperature deposition might be an effective way to prepare a-SiGe:H alloys for solar cell application. (C) 2012 Elsevier Ltd. All rights reserved.

关键词： 非金合金   制样   切割   抛光  

摘要： 为了观察非晶合金激光焊接样品的截面形貌,本文对Zr55Cu30Al10Ni5非晶合金焊接接头进行了金相制样,详述了制样流程和制样过程中产生的问题,并讨论了解决问题的办法。对制好的样品使用Keyence和扫描电镜进行观察,能够清楚地观测到焊接头截面的形貌。结果表明所制样品达到观测要求。

关键词： Furnace brazing   Ti-6Al-4V alloy   Microstructure   Mechanical properties   XRD analysis  

摘要： Microstructural features developed along with mechanical properties in furnace brazing of Ti-6Al-4V alloy using STEMET 1228 (Ti-26.8Zr-13Ni-13.9Cu, wt.%) and STEMET 1406 (Zr-9.7Ti-12.4Ni-11.2Cu, wt.%) amorphous filler alloys. Brazing temperatures employed were 900-950 degrees C for the titanium-based filler and 900-990 degrees C for the zirconium-based filler alloys, respectively. The brazing time durations were 600, 1200 and 1800 s. The brazed joints were evaluated by ultrasonic test, and their microstructures and phase constitutions analyzed by metallography, scanning electron microscopy and X-ray diffraction analysis. Since microstructural evolution across the furnace brazed joints primarily depends on their alloying elements such as Cu, Ni and Zr along the joint. Accordingly, existence of Zr2Cu, Ti2Cu and (Ti,Zr)(2)Ni intermetallic compounds was identified in the brazed joints. The chemical composition of segregation region in the center of brazed joints was identical to virgin filler alloy content which greatly deteriorated the shear strength of the joints. Adequate brazing time (1800 s) and/or temperature (950 degrees C for Ti-based and 990 degrees C for Zr-based) resulted in an acicular Widmanstatten microstructure throughout the entire joint section due to eutectoid reaction. This microstructure increased the shear strength of the brazed joints up to the Ti-6Al-4V tensile strength level. Consequently, Ti-6Al-4V can be furnace brazed by Ti and Zr base foils produced excellent joint strengths. (C) 2012 Elsevier Inc. All rights reserved.

关键词： Soft magnetic properties   Crystallization   Ferromagnetic resonance  

摘要： In this work, we present a systematic study on the crystallization kinetics and the magnetic properties of melt-spun Fe80B10Si10-xGex (x = 0.0-10.0) amorphous alloys. The activation energy for crystallization, determined by differential scanning calorimetry, displayed a strong dependence on the Ge content, reflecting a deleterious effect on the alloys' thermal stability and their glass forming ability with increasing Ge concentration. On the other hand, the alloys exhibited excellent soft magnetic properties, i.e., high saturation magnetization values (around 1.60 T), alongside Curie temperatures of up to 600 K. Complementary, for increasing Ge substitution, the ferromagnetic resonance spectra showed a microstructural evolution comprising at least two different magnetic phases corresponding to a majority amorphous matrix and to Fe(Si, Ge) nanocrystallites for x >= 7.5. (C) 2012 Elsevier B.V. All rights reserved.

关键词： AMORPHOUS substances   SPUTTERING (Physics)   SURFACE coatings   ZIRCONIUM alloys   FILLERS (Materials)   BRAZING alloys   JOINTS (Engineering)  

摘要： Amorphous sputter coatings of a Be-free multi-component Zr-Ti-Ni-Cu alloy were applied as a novel brazing filler metal for brazing Zircaloy-4. The homogeneous and amorphous-structured layers were uniformly coated by sputtering the crystalline Zr47.6Ti19.9Ni17.4Cu15.1 target. By preserving the near equivalent target composition, the coating showed an excellent compositional uniformity in spatial distribution, as well as almost the same melting characteristics as that of the parent target. By applying the amorphous sputter coatings, the highly reliable joints were obtained with the formation of predominantly grown alpha-Zr grains due to a complete isothermal solidification, exhibiting strengths comparable to that of Zircaloy-4. The present investigation showed that a Be-free and Zr-base multi-component amorphous sputter coating can offer great potential for brazing and manufacturing a Zr alloy nuclear fuel bundle system. (C) 2012 Elsevier B.V. All rights reserved.