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41.
The oxidation behavior of a Cu60Hf25Ti15 bulk metallic glass was studied over the temperature range of 375–520 °C in dry air. The oxidation kinetics of the amorphous
alloy generally followed the parabolic law at all temperatures, with an oxidation rate increasing with temperature. The oxidation
rates of the amorphous alloy were much higher than those of polycrystalline pure-Cu, implying that the additions of Hf and
Ti accelerated the oxidation reaction. The composition of the scales formed on the amorphous alloy was strongly temperature-dependent,
since they consisted mostly of Cu4O3 and CuO with minor amounts of HfO2 at T ≤ 450 °C, while mostly CuO with minor amounts of HfO2 and Cu2TiO3 were detected at higher temperatures. In addition, nanocrystalline Cu51Hf14 and Cu3Ti2 phases were detected on the substrate after oxidation at T ≥ 450 °C, indicating the occurrence of phase transformation. 相似文献
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43.
A decision aid for scheduling production in glass fiber manufacturing industry is described. The methodology combines a linear programming (LP) optimization model with a heuristic model. The LP model determines production goals; the heuristic model then uses the LP output to incorporate system-specific constraints in developing processing sequences. 相似文献
44.
周静 《数码设计:surface》2012,(5):144-146
我国在商、周之交,就开始了早期的中西交流,而张骞西行后又开辟了新的中外来往的交通路线。我国的玻璃业尽管没能发展为重要的手工业门类,但它始终在持续而缓慢的发展,更重要的是,正是由于玻璃业的非主流,在发展过程中凸显了外部因素的重要性。丝绸之路在中国古代玻璃艺术的发展过程中起到了重要作用。 相似文献
45.
Nasir A. Al-geelani M. Afendi M. PiahRedhwan Q. Shaddad 《Applied Soft Computing》2012,12(4):1239-1246
A hybrid model incorporating wavelet and radial basis function neural network is presented which is used to detect, identify and characterize the acoustic signals due to surface discharge activity and hence differentiate abnormal operating conditions from the normal ones. The tests were carried out on cleaned and polluted high voltage glass insulators by using surface tracking and erosion test procedure of international electrotechnical commission 60587. A laboratory experiment was conducted by preparing the prototypes of the discharges. This study suggests a feature extraction and classification algorithm for surface discharge classification, which when combined together reduced the dimensionality of the feature space to a manageable dimension, by “marrying” the wavelet to radial basis function neural network very high levels of classification are achieved. Wavelet signal treatment toolbox is used to recover the surface discharge acoustic signals by eliminating the noisy portion and to reduce the dimension of the feature input vector. A radial basis function neural network classifier was used to classify the surface discharge and assess the suitability of this feature vector in classification. This learning method is proved to be effective by applying the wavelet radial basis function neural network in the classification of surface discharge fault data set. The test results show that the proposed approach is efficient and reliable. 相似文献
46.
何天淳 《昆明理工大学学报(自然科学版)》1992,(2)
若视加气砼为细观的“两相”材料,则可建立起其细观几何结构的随机直观数理模型,本文应用随机几何的方法探索了加气砼最佳合理内部细观几何结构模型的建立,及其计算机随机模拟,由细观角度讨论了改善加气砼性能的可能性。 相似文献
47.
压缩弧光等离子束熔覆层中晶相与非晶相 总被引:11,自引:1,他引:11
用压缩弧光等离子束在 45钢表面熔覆Fe Cr Si B粉末涂层 ,采用能谱、透射电镜、电子探针对熔覆层结构进行分析。结果表明 ,熔覆层中晶相与非晶相并存 ,晶相由A(Me)、F(Me)、Me2 3 C6 等相组成 ,且 [2 11]A∥ [2 11]Me2 3 C6 ,(111) A ∥ (111) Me2 3 C6 ,(0 11) A ∥ (0 11) Me2 3 C6 ,即A与Me2 3 C6 保持共格关系 ,而[111]F∥ [32 1]Me2 3 C6 ,(10 1) F∥ (111) Me2 3 C6 。非晶相中Si、Cr等元素含量较高 ,从动力学和热力学两方面对非晶的形成进行了分析 相似文献
48.
WANG Shuncai LI Chunzhi YAN Minggao Institute of Aeronautical Materials Beijing China BIAN Weimin Northeast Institute of Technology Shenyang China WANG Shuncai Graduated Student Institute of Aeronautical Materials Beijing China 《金属学报(英文版)》1990,3(2):104-109
X-ray microanalysis,convergent beam electron diffraction(CBD)and selected area electrondiffraction(SAD)studies on the structures and compositions of the constituent phases in2024 series Al alloys have been conducted.Partial substitution of alloying elements is found tooccur in all the constituent phases,which cause small deviations from the stoichiometric com-positions reported in these ternary compounds.The dominant phase is α-Al_(12)(FeMn)_3Si whichhas a body center cubic crystal structure with the Im■ space group and a=1.25 nm.The nextdominant phase is Cu_2FeAl_7 which has a primitive tetragonal crystal structure with theP4/mnc space group and a=0.6336 nm,c=1.487 nm.The minor phase is α'-Al_(12)Fe_3Si hav-ing α primitive cubic crystal structure with the Pm■ space group and α=1.27 nm. 相似文献
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50.
In this paper, the author dipped surface vapor oxidized H13 steel specimens into 700℃ molten aluminum liquid for a certain period of time. Analyze the intermetallic phases formed on the H13 samples surface with optical microscope and X-ray diffraction method. The observation of immersion test sample's cross-section shows that Fe3O4 film will protect die substrate from molten aluminum erosion. The identification of the intermetallic phases reveals that they consist of 2parts, which is named as the composite layer and the compact layer. Further investigations are made in order to know the phase constituents of the 2 layers, they are Al8Fe2Si (outer composite layer), (AlCuMg) and Al5Fe2 (compact layer),respectively. The experimental results show that on the same specimen, a convex surface with bigger radius of curvature is more likely to be molten and the melting loss speed is also faster than a flat and smooth surface. The thickness of compact layer on a smooth surface is much bigger than that of the convex surface. Therefore, the author supposes the compact layer is favorable in stabilizing the die surface material from further melting loss, as their formation on the die surface, the melting loss speed will decrease. 相似文献