马光
,
李银娥
,
刘啸锋
,
贾志华
中国材料进展
采用钎焊接头楔形间隙图,对BNi-2钎料钎焊1crl8Ni9Ti的最大钎焊间隙进行分析,考察BNi-2钎料钎焊1Cr18Ni9Ti的钎焊工艺及钎焊后扩散热处理工艺对最大钎焊间隙的影响.实验结果得出,BNi-2钎焊1Cr18Ni9Ti的最佳钎焊温度为1150℃,保温时间为55 min;钎焊后合适的扩散热处理温度为:1000℃,保温时间为60~90 min.
关键词:
BNi-2钎料
,
钎焊
,
最大钎焊间隙
吴玉琨
金属学报
利用X射线衍射及透射电镜观察到单辊急冷法制备的BNi2(~Ni_(70)Cr_7Fe_3Si_3B_(12)条带的内部为正常非晶结构,而上下表层则由具有111纤维织构的Ni固溶体组成。这种结构不均匀性可用急冷条带形成时动量传导起主要作用来解释。此外还证实了BNi2非晶合金在晶化第二阶段析出的未知亚稳相为具有100与110纤维织构的M_(28)B_6型面心立方相,点阵常数约为1.04nm。
关键词:
Yuhua LIU
金属学报(英文版)
A commercially available Ti47Zr28Cu14Ni11 (at. pct) amorphous filler foil was used to join ZrO2 ceramic and Ti-6Al-4V alloy. According to experimental observations, the interface microstructure accounts for the mechanical properties of the joints. The effects of brazing conditions and parameters on the joint properties were investigated. The joint shear strength showed the highest value of about 108 MPa and did not monotonously increase with the brazing time increasing. It was shown that decreasing of brazing cooling rate and appropriate filler foil thickness gave higher joint strength.
关键词:
Brazing
Journal of Materials Processing Technology
The effects of brazing temperature on microstructure and bonding strength of vacuum brazed joints of Ti(C,N)-based cermet and 17-4 PH stainless steel, using filler metal BNi-2, were investigated. At a lower brazing temperature of 1050 C. the distribution of melting point depressants (MPD) concentrated on the diffusion affected zone (DAZ) and the brazing seam near the Ti(C,N)-based cermet, the generation of brittle phases in the brazing seam was unavoidable. The uniform distribution of the MPD and full solid solution of gamma-nickel occurred in the brazing seam at a higher brazing temperature of 1150 degrees C. A maximum shear strength of 690 MPa was achieved at a brazing temperature of 1150 degrees C. (C) 2011 Elsevier B.V. All rights reserved.
关键词:
Brazing;Ti(C,N)-based cermet;Steel;Microstructure;Mechanical;properties;isothermal solidification
Journal of Crystal Growth
The dynamic crystallization process in a two-dimensional (2D) amorphous Ni-P foil was investigated by the use of in situ transmission electron microscopy (TEM) observation. On annealing the amorphous foil, it has been found that the clusters of the Ni3P phase were formed in the amorphous matrix with random orientations before the crystals nucleated and grew. During the crystal growth process, transformation of the clusters was found to be in the form of shearing deposition onto the crystal front. A new micromechanism for universal crystallization processes was proposed based on experimental results of the 2D crystallization. It is composed of two processes: (i) formation and growth of precursory ordered clusters in amorphous matrix; (ii) crystal nucleation and growth which involve atoms jumping and clusters shearing deposition or combination. The new mechanism is discussed with respect to the existence of ordered clusters and their effects on the crystallization kinetics.
关键词:
ni-p glass;kinetics;growth
International Journal of Thermophysics
A contactless, compact, low-cost dilatometer based on a laser-pulse thermal-conductivity apparatus has been developed to measure the linear thermal expansion of foil materials. The two sample-edge images are projected onto the array of a charge-coupled device (CCD). Changes in sample length are determined from measurements of the corresponding displacements of the sample-edge images focused on the CCD. The dilalometer performance was tested by comparing results of measurements of the thermal expansion for pure copper with published data. The linear thermal expansion of an L-16-type foil of 20-mu m thickness, which is a candidate material for thermocontrol layers (in engineering), was measured with the apparatus.
关键词:
CCD;contactless;dilatometer;foil;thermal expansion;thermal-expansion;specimens
Huaqing XIE
,
Tonggeng XI
,
Qinghong ZHANG
,
Qingren WU
材料科学技术(英文)
Nanosized amorphous TiO2 powders with a specific surface area of 501 m2•g-1 were prepared by hydrolysis. After calcined at 400 °C for 2 h, the prepared amorphous TiO2 powders were fully transformed into anatase crystallites with a specific surface area of 141 m2•g-1. Differential scanning calorimetric (DSC) experiments were performed on the samples of nanosized amorphous TiO2 mixed with microsized anatase, nanosized anatase, or nanosized α-Al2O3 respectively. Effects of sample packing, anatase addition, or α-Al2O3 addition on the crystallization behavior of nanosized amorphous TiO2 were analyzed.
关键词:
Crystallization behavior
,
null
,
null
,
null
S.J. Yan
金属学报(英文版)
A practical technique to prepare transmission electron microscopy (TEM) thin foil containing powder particle was described and the data for the codeposition of two type particles with copper in the electroplating were presented. By depositing the particles which were distributed in CuSO4 electrolyte on cathode together with Cu2+ in electrodeposition bath, composite coating with suitable thickness could be formed. The thin coating was separated from the substrate and cut into a disc with diameter of 3mm for electropolishing. When the Cu matrix was thinned during electropolishing, the particles contained in the coating plate were also thinned to meet the suitable thickness for TEM observation. Various experimental results revealed that during electrodepositing the current density, pH-value of electrolyte and stirring mode all have significant effects on the distribution of particles in composite coating and the surface quality of the composite coating. The proper parameters used during electrodepositing to prepare TEM thin foil containing powder particle were discussed.
关键词:
electrodeposition
,
Powder
,
particles
,
TEM
,
t
Nanotechnology
Nanostructured amorphous and anatase TiO(2) are both considered as high rate Li-insertion/extraction electrode materials. To clarify which phase is more desirable for lithium ion batteries with both high power and high density, we compare the electrochemical properties of anatase and amorphous TiO(2) by using anodic TiO(2) nanotube arrays (ATNTAs) as electrodes. With the same morphological features, the rate capacity of nanostructured amorphous TiO(2) is higher than that of nanostructured anatase TiO(2) due to the higher Li-diffusion coefficient of amorphous TiO(2) as proved by the electrochemical impedance spectra of an amorphous and an anatase ATNTA electrode. The electrochemical impedance spectra also prove that the electronic conductivity of amorphous TiO(2) is lower than that of anatase TiO(2). These results are helpful in the structural and componential design of all TiO(2) mesoporous structures as anode material in lithium ion batteries. Moreover, all the advantages of the amorphous ATNTA electrode including high rate capacity, desirable cycling performance and the simplicity of its fabrication process indicate that amorphous ATNTA is potentially useful as the anode for lithium ion batteries with both high power and high energy density.
关键词:
nanocrystalline rutile tio2;electrochemical properties;high-power;mesoporous nanocomposite;intercalation properties;electrode material;titania nanotubes;ion insertion;storage;performance
Journal of Alloys and Compounds
The crystallization of amorphous SiO(2) with different forms of H(2)O under high pressure and high temperature was investigated experimentally, and it was first discovered that Si-OH could effectively promote the synthesis of coesite at lower temperature in a very short time. Using amorphous SiO(2) with Si-OH as the initial material, single-phase coesite has been synthesized under 4.2 GPa and 190 degrees C for 30 min. (C) 2008 Elsevier B.V. All rights reserved.
关键词:
Amorphous materials;X-ray diffraction;High pressure;spectra;quartz