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1.
α—Ti氢处理后的组织结构与性能 总被引:4,自引:0,他引:4
研究了氢化处理退火α-Ti板材的组织,结构及性能的影响,α-Ti在室温出现两种结构的氢化物:有序的fctγ相(TiH)和Fccδ(TiH)2。分析了X射线衍射只查觉到δ相的原因,氢化物的数量及形态影响除氢后基体的晶粒组织。控制氢含量可以改善伸性能及疲劳性能。 相似文献
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利用TiH2,Si和B4C之间的化学反应制备TiB2-SiC复相陶瓷,研究了反应时物相生成机理及添加Ni对材料力学性能的影响.采用SEM观察复相陶瓷的显微结构及裂纹扩展过程,用XRD法测定了复相陶瓷内的残余应力,探讨了复相陶瓷的增韧机理同时,残余应力测试结果表明,精磨会给材料表面带来一定的机械加工应力,但随方向而异,并对残余应力的测定造成影响 相似文献
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反应烧结TiB2—SiC复相陶瓷的物相反应,力学性能及残余应力 总被引:3,自引:0,他引:3
利用TiH2,Si和B4C之间的化学反应制备TiB2-SiC复相陶瓷,研究了反应时物相生成机理及添加Ni对材料力学性能的影响,采用SEM观察复相陶瓷的显微结构及裂纹扩展过程,用XRD法测定了复相陶瓷内的残余应力,探讨了复相陶瓷的增韧机理,同时,残余应力测试结果表明,精磨会给材料表面带来一定的机械加工应力,但随方向而异、并对残余应力的测定造成影响。 相似文献
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研究了真空烧结炉的不同漏气率对TiB2Ni金属陶瓷的机械性能的影响。结果表明:低漏气率真空烧结炉烧出的TiB2Ni试样性能比高漏气率炉烧出的试样性能优异得多。 相似文献
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研究了真空烧结炉的不同漏气率对TiB2-Ni金属陶瓷的机械性能的影响。结果表明:低漏气率真空烧结炉烧出的TiB2-Ni试样性能比高温气率炉烧出的试样得多。 相似文献
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Knowledge about vapour-liquid (VLE) is required as a basis of reliable calculations for separation processes. Correlations available for the prediction of T, p, x, y data are less accurate for mixtures at high pressures and mixtures containing supercritical components. The results of VLE experiments are reported and compared with data calculated with equations of state. 相似文献
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We prepared weakly agglomerated powders of ZrO2-CeO2 and HfO2-CeO2 solid solutions 5–8 nm in particle size, consisting of monoclinic and tetragonal phases. After heat treatment at 1200°C, the crystallite size was 30 and 14 nm, respectively. We also examined the effect of precipitate freeze drying on the crystallization of hafnia-based solid solutions containing up to 20 mol % CeO2. 相似文献
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Thermal diffusion coefficients were measured in two gaseous mixtures, in which one component was close to the critical temperature, in the pressure range (19.6–127.4)·104 N/m2 and at a freon concentration of 0.25–0.8. 相似文献
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C. Bersier E. P. Stoll P. F. Meier T. A. Claxton 《Journal of Superconductivity and Novel Magnetism》2002,15(5):399-402
First-principles cluster calculations are reported of the local electronic structure of the three compounds: La2CuO4, Sr2CuO2Cl2, and Sr2CuO2F2. The copper ${\text{3d}}_{x^2 - y^2 } $ and the planar oxygen 2p σ atomic orbitals exhibit a similar degree of covalency. The out-of-plane orbitals, however, are quite different with the ${\text{3}}d_{3z^2 - r^2 } $ atomic orbital lowered significantly in energy for chlorine and fluorine apical positions. 相似文献
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A series of GRIN glass rods have been developed in Li2O-Na2O-Al2O3-TiO2-SiO2 systems. Negative radial refractive index profiles were generated by exchanging Na+ for Li+ ions in these glass rods. It has been observed that TiO2 plays a vital role in increase in the profile depth and maximum change in the refractive index because of its ambivalent nature. Change in the refractive index can be further increased by increasing the concentration of exchanging cation in the base glass. 相似文献
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V Vijayashree C K Subramaniam R Srinivasan I K Gopalakrishnan PVPSS Sastry J V Yakhmi R M Iyer 《Bulletin of Materials Science》1991,14(3):827-830
Single-phase 2122 samples of thallium and bismuth superconductors were made by the precursor matrix method. The thermopower
of these samples was measured in the temperature range 250 K-T
c
. The thermopower was positive and decreased linearly with increasing temperature aboveT
c
(onset). The exponential enhancement of thermopower seen in the undoped and doped YBCO was not observed in these samples.
The linear variation of thermopower can be explained on the basis of either a two-band model or a narrow band model. 相似文献
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本文给出了 Si_2N_2O-Al_2O_3-La_2O_3和 Si_2N_2O-Al_2O_3-CaO 系统的亚固相图。实验结果表明:在 Si_2N_2O-Al_2O_3-CaO 系统中有一个未知结构的新化合物 CaO·Si_2N_2O,在3CaO·Si_2N_2O 和3CaO·Al_2O_3两化合物之间形成连续立方固溶体。而 Si_2N_2O-Al_2O_3-La_2O_3系统中则没有发现新化合物。在两个系统的富 Si_2N_2O区,过量的 Si_2N_2O 与 La_2O_3和 CaO 分别反应形成 Si_3N_4与 La_(10)[SiO_4]_(?)N_2(H-相)(和 CaSiO_3。所研究的这两个三元系统中,分别形成了如下几个四元相容性区。在 Si_2N_2O-Al_2O_3-La_2O_3系统内有:H-Si_3N_4-La_2O_3·Si_2N_2O-La_2O_3·Al_2O_3;H-Si_3N_4-La_2O_3·Al_2O_3-La_2O_3·11 Al_2O_3;H-Si_3N_4-La_2O_3·11 Al_2O_3-Al_2O_3;H-Si_3N_4-Al_2O_3-O′s.s;H-Si_3N_4-O′s.s-Si_2N_2O在 Si_2N_2O-Al_2O_3-CaO 系统内有:Si_3N_4-CaSiO_3-CaO·Si_2N_2O-3CaO·Al_2O_3;Si_3N_3-CaSiO_3-3CaO·Al_2O_3-2CaO·Al_2O_3·SiO_(?);Si_(?)N_(?)-CaSiO_3-2CaO·Al_2O_3·SiO_2-Al_2O_3;Si_3N_4-CaSiO_3-Al_2O_(?)-O′s.s;Si_3N_4-CaSiO_3-O′s.s-Si_(?)N_(?)O 相似文献
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I. R. Shein S. L. Skornyakov V. I. Anisimov A. L. Ivanovskii 《Journal of Superconductivity and Novel Magnetism》2014,27(1):155-161
The first-principles calculations were performed to predict the elastic and electronic properties of the superconducting ThCr2Si2-type phases CaPd2As2 and SrPd2As2 in comparison with the non-superconducting CeMg2Si2-type phase BaPd2As2. Besides, the same properties were compared for CeMg2Si2- and ThCr2Si2-type polymorphs of BaPd2As2. We found that all these phases are mechanically stable and belong to soft materials with low hardness. The near-Fermi region is formed by the valence states of the blocks [Pd2As2] with decisive contributions of Pd 4d states. The values of N(E F) increase in the sequence: CaPd2As2 < SrPd2As2 < BaPd2As2, i.e. in the reverse sequence relative to the transition temperatures T C. Thus, the change in T C cannot be explained by the electronic factor, i.e. by the simple correlation T C~N(E F). Most likely the decrease in T C in the sequence CaPd2As2 → SrPd2As2 and the absence of a superconducting transition in BaPd2As2 are related to the structural factors and the peculiarities of the electron–phonon coupling mechanism. 相似文献