摘要： Braying of stainless steel easing nickel based alloys has sometimes been avoided, in spite of its various advantages, because it is a somewhat unreliable process in terms of the mechanical characteristics and corrosion resistance of the brazed joints. Addition of copper to amorphous Ni-Cr-B-Si brazing alloys has been shorn to be a promising method of improving the performance of joints. Because copper cart forma a solid solution with nickel at arty concentration, addition of copper has a great effect on the microstructures of the nickel based filler metal and bra-a seam, by improving the volume ratio of nickel based solid solution to the embrittled intermetallic compounds. As a result, a significant increase in the critical brazing clearance (CBC) was obtained in the present work. Furthermore, copper might increase the electrode potential of nickel based solid solution, so that addition of copper could improve the corrosion resistance of the brazed joints. The results show that can appropriate copper addition to the present Ni-Cr-B-Si group amorphous brazing foil provides an effective method of overcoming the weaknesses of joints brazed using conventional nickel based filler metals, such as low value of CBC and low corrosion resistance.

关键词： CARBON   THIN films   GERMANIUM alloys   SPUTTERING (Physics)   X-ray diffraction  

摘要： Thermomechanical properties of amorphous hydrogenated carbon-germanium alloys prepared by the rf sputtering technique were determined for films in the Oat. % to 100 at. % carbon content range. The stress, thermal expansion coefficient, and elastic modulus were obtained using the thermally induced bending technique. The stress was related to the concentration of hydrogen and argon, to the difference in the Ce-Ge and Ge-C bond length, and to the carbon hybridization. The thermal expansion coefficients of pure amorphous germanium and amorphous carbon are higher than that of their corresponding crystalline counterparts, which was attributed to the compressive stress of the films. The biaxial modulus, on the other hand, are always smaller than that of their crystalline counterparts, but increases as the concentration of carbon increases due to the substitution of Ce-Ge bonds by energetically stronger Ge-C and C-C bonds.

关键词： C290   A200   78.66.Jg   81.10.Jt   81.40.Ef  

摘要： We have investigated the solid-phase crystallization (SPC) process of a-Si1-xGex:H (x = 0, 0.21,0.67) alloy films by using X-ray diffraction and electron spin resonance measurements. The films were deposited on Coming 1737 glass at 200 degrees C in a plasma-enhanced chemical vapor deposition system using SiH4 and GeH4 gases. The deposited films were then annealed to be crystallized at 600 degrees C in a N-2 atmosphere. The variation of spin densities due to the annealing was found to be strongly related to the variation in the crystalline fraction of the films. It was observed that the SPC process was dominated bq Ge dangling-bonds rather than Si dangling-bonds for Ge-rich samples (x = 0.21 and 0.67). Furthermore, the H evolution time fi om Ge-H bond for I = 0.67 film was significantly faster than for the x = 0.21 film, which was attributed to the composition-dependent Ge-H dissociation energy. (C) 2000 Elsevier Science B.V. All rights reserved.

关键词： Iron alloys  

摘要： The behavior of Au in the course of the primary crystallization process of Fe87Zr7B5Au1 amorphous alloy was examined by use of atom probe field ion microscopy and transmission electron microscopy. In the early stage of crystallization, Au atoms were still distributed uniformly in the amorphous matrix. Au atoms form clusters at a later stage when more alpha-Fe particles are present. The Au clusters were observed to be separated from alpha-Fe particles, indicating that Au clusters do not stimulate nucleation of alpha-Fe particles. During the growth of alpha-Fe grains, cosegregation of Au and Zr occurred without any influence on the alpha-Fe grain growth. We conclude that Au addition has no effect on nanocrystallization of Fe-Zr-B amorphous alloys.

关键词： Semiconducting films  

摘要： Thin films of amorphous silicon-germanium alloy (a-Si1-xGex) were prepared by sputtering silicon and germanium targets with argon in a radio-frequency (rf) magnetron sputtering system. For the film prepared at an rf power of 200 W, the energy gap and the refractive index showed monotonous changes between those for silicon and germanium with a deviation from linearity in the correlating line of the energy gap. The deviation was attributable to the decrease in structural disorder in the film as shown in Tauc coefficient B. For the film prepared at an rf power of 50 W, some deviations of the energy gap and the refractive index from the monotonous changes increased with decreasing x, because of an excess amount of dangling silicon bonds. Fourier transform infrared spectra indicated absorption due to the modes derived from the dangling bonds. The absorption coefficient showed that the deviations of the energy gap and the refractive index at x = 0 were proportional to the excess amount of dangling bonds of silicon. The excess amount of dangling bonds of silicon retarded crystallization in the solid state. (C) 2000 The Electrochemical Society. S0013-4651(99)05-003-X. AU rights reserved.

关键词： Semiconducting films  

摘要： Thin films of amorphous germanium-nitrogen (a-GeNx) alloys were prepared by the reactive sputtering method. The germanium target was sputtered with argon and nitrogen gases in radio-frequency (rf) magnetron sputtering equipment. Changing the composition of the sputtering gas can adjust the composition, x, of the film in the range from 0 to 1.5 and the corresponding optical energy gap in the range from 0.68 to 2.7 eV. The structures of the film are discussed on the basis of measured X-ray photoelectron spectroscopy and Fourier transform infrared spectrometry. The film prepared at an rf power of 200 W includes more defects and structural disorder compared to film prepared at an rf power of 20 W. (C) 1999 The Electrochemical Society. S0013-4651(98)03-032-8. All rights reserved.

关键词： Ge-Si alloys   hydrogen   amorphous semiconductors   semiconductor thin films   plasma deposited coatings   Raman spectra   infrared spectra   secondary ion mass spectra   dark conductivity   photoconductivity   photoluminescence   optical constants   energy gap   band structure   noncrystalline structure  

摘要： Hydrogenated amorphous silicon germanium alloys (a-SiGe:H) have been prepared by rf glow discharge of silane, germane, and hydrogen gas mixture at substrate temperature of 200 and 250 degrees C. The structural properties of the films have been investigated by infrared, Raman, and secondary ion mass spectroscopy. It is found that there is a preferential incorporation of germanium into the film relative to silicon and the films with high germane gas phase composition X-g > 0.4 tend to oxidize in atmosphere. Besides, polysilane is enhanced in the films with low germane gas phase composition. The electrical properties including dark, photo conductivities, and conduction activation energy are measured. As for the optical properties, optical transmission is adopted to determine the optical gap while photoluminescence spectra together with temperature variation are used to study the band tail states of the films. By applying Brodsky's quantum well model, the various optical and electrical properties could be explained successfully. (C) 1998 American Institute of Physics.

关键词： radiofrequency   noncrystalline   LIGHT(ENERGY)   Amorphous films   Argon   tin alloys   Tin   thin films   middle frequency magnetron sputtering   magnetron sputtering   energy gap   Films   METAL ALLOY  

摘要： Thin films of amorphous germanium-tin alloy (a-Ge1-xSnx) have been prepared by sputtering germanium and tin targets with argon in a radio-frequency magnetron sputtering system. X-ray diffraction reveals that the film for x < 0.38 is amorphous but that crystalline beta-Sn is formed in the amorphous film for x greater than or equal to 0.38. The optical energy gap is expressed by Eg = 0.68 - 0.85x [eV] for x < 0.38. The equation also correlates the pseudo-optical energy gap for the GeSn-beta-Sn composite film.

关键词： Zirconium alloys  

摘要： The thermal stability and brazing characteristics of Zi-Br binary amorphous alloys as a new filler metal for joining zirconium alloy were investigated in order to supersede physically vapor-deposited (PVD) beryllium used conventionally with many disadvantages. The Zr1-xBex (0.3 less than or equal to x less than or equal to 0.5) binary amorphous alloys were produced by melt-spinning method. In the selected composition range the Zr-Be amorphous alloys have two crystallization modes which are dependent on beryllium content in alloys. The temperatures and activation energies for crystallization depend on crystallization-mode as well as beryllium content. These amorphous alloys were put into practical use in joining bearing pads on zircaloy cladding sheath. Using Zr-Be amorphous alloys as filler metals, the reduction in thickness of cladding sheath wall are prevented. Especially, in the case of using Zr0.65Be0.35 and Zr0.7Be0.3 amorphous alloys, smooth interface and spherical primary alpha-Zr particles appear in the brazed layer, which is desirable microstructure in the view of the corrosion-resistance. (C) 199S Elsevier Science B.V.

关键词： Germanium alloys  

摘要： Optimized deposition parameters for helium diluted a-SiGe:H material differ from those for hydrogen diluted a-SiGe:H material with the same optical gap(similar to 1.5 eV). Deposition rate of optimized helium diluted film is 3.3 times greater than that of hydrogen diluted film, however the photoconductivities of both type of materials are the same. Defect density (6.72 +/- 1 x 10(15) cm eV(-1)) and Urbach energy (46 +/- 1.5 meV) of helium diluted optimized film is less than corresponding values (8.45 +/- 1 x 10(15) cm(-3) eV(-1), 49 +/- 1.5 meV) of hydrogen diluted alloy materials. Schottky barrier solar cells have been fabricated using both optimized materials. Blue response is greater for the optimized helium diluted a-SiGe:H material than that of optimized hydrogen diluted alloy film. Red response is also greater in the first case in comparison to that in the second case.