Chemical leaching and magnetic properties of non-equilibrium Al(Co–Cu) powders produced by rod milling

We report upon the chemical leaching and magnetic properties of nanoscale crystalline Al_0.6(Co₂₅Cu₇₅)_0.4 alloy powders produced by rod milling. X-Ray diffractometry (XRD), transmission electron microscopy, differential scanning calorimetry, vibrating sample magnetometry, and superconducting quantum interference device magnetometry were used to characterize the as-milled and leached specimens. After 400 h of milling, only the b.c.c. phase of the intermetallic compound γ-Al_3.892Cu_6.10808 was detected by XRD. After annealing the leached specimen at 600 °C for 1 h, the nanoscale crystalline phase was transformed into the f.c.c. Cu phase, and this was accompanied by a change in the magnetic properties. The peaks of the magnetization shifted towards lower temperature with increasing external field. The temperature behavior at T_f (45 K) for direct current (d.c.) magnetic susceptibility measurements was quite different for field cooling and zero-field cooling. After cooling the leached specimen from 800 °C, magnetization increased gradually.     

PMMA／PBA乳胶IPN阻尼材料的研究

用乳液聚合方法合成了一系列的互穿聚合物网络，其中包括：ＰＭＭＡ／ＰＢＡ和Ｐ（ＭＭＡ－ｃｏ－ＰＭＡ）／ＰＢＡ乳胶互穿聚合物网络（ＬＩＰＮ），ＰＭＭＡ／ＰＢＡ乳胶双向互穿聚合物网络（ＬＢＩＰＮ）以及ＰＭＭＡ／ＰＢＡ界面交联互穿聚合物网络（ＩＣＬＩＰＮ）。动态力学谱和拉伸试验结果表明：（１）ＰＭＭＡ／ＰＢＡ互穿聚合物网络的两组分相容性和阻尼性能可通过ＭＭＡ和ＰＭＡ共聚来改善；（２）双向互穿技术是一种行之     

同步辐射X射线光刻掩模镀金工艺的研究

介绍了利用北京正负对撞机(BEPC)同步辐射X射线光刻装置,进行LIGA工艺技术深结构光刻实验研究,详细论述了X射线光刻使用的掩模制备过程及掩模镀金工艺,在国内最早曝光出直径为400μm、厚为27～45μm的三维立体齿轮胶图形。     

On the synthesis and characterization of a new manganite type CMR material: La0.7Hg0.3MnO3

A new manganite type CMR material, La_0.7Hg_0.3MnO₃ has been successfully synthesized and has been found to exhibit magnetoresistance (≈9%) at low fields (≈1.5 kG). The synthesis has been carried out through a solid state reaction route consisting of the formation of La_0.7MnO₃ followed by diffusion of Hg leading to La_0.7Hg_0.3MnO₃. The as grown samples are polycrystalline and correspond to an orthorhombic unit cell with the lattice parameters; a=5.5183 Å, b=5.6383 Å and c=7.5368 Å. The typical grain size as revealed by scanning electron microscopy is in the range of 0.5–2 μm. The ρ–T behaviour shows a peak at T_IM=227 K. The ρ–T behaviour above this temperature corresponds to that of an insulator and below this to that of a metal. The ρ–T behaviour remains unaltered when a magnetic field (H_dc=1.5 kG) is applied. However, with this magnetic field a drop in the resistivity is observed up to 77 K. At room temperature the magnetoresistance ratio (MRR) is too small but it steadily increases as the temperature is decreased. Thus, MRRs at 227.13 and 77 K are 3.41 and 9.05%, respectively, in an applied field of H_dc=1.5 kG. At a given temperature the variation in MRR with field H_dc is rapid at lower field values (H_dc<1.2 kG) and scales linearly for higher field values (H_dc>1.2 kG). It may be mentioned that the present work on the synthesis and magnetoresistance behaviour of La_0.7Hg_0.3MnO₃, is the first of its type.     

Q390高强抗震钢板残余应力检测方法对比及分析

利用盲孔法、X-Ray法、中子衍射法和超声法对Q390高强抗震板及U形弯曲件进行残余应力检测,并对这4种方法测试得到的应力结果进行分析研究。结果表明,以上4种检测方法均要考虑其特定的检测应用范围,X-Ray法针对钢板表面下微米级深度的微米级晶格尺度范围局部点应力进行检测,中子衍射法可在毫米级尺度局部区域进行应力检测,盲孔法反映的是因毫米尺度钻孔导致的钢板表面孔周边的应力变化,超声法则可以通过连续扫描检测整个钢板残余应力的宏观分布变化。因此,对于工业钢板,超声法测试残余应力更加科学、合理、准确。同时,通过U形试样建立稳定的应力应变场,利用超声设备使用不同参考态对Q390高强抗震板弯曲件及退火弯曲件进行测试,结果表明,测试参考态的选取对应力测试结果影响很大,材料各向异性的影响对应力测试结果不可忽视。     

Investigation of the titanium–indium system

The phase diagram of the Ti–In system was determined using DTA, XRD and EDX analyses. The existence of the phases Ti₂In₅ [Mn₂Hg₅ type structure, space group P4/mbm, a=0.99995(3), c=0.29960(2) nm] and Ti₃In [Ni₃Sn type structure, space group P6₃/mmc, a=0.5978(1), c=0.4812(1) nm] was confirmed. The phase previously labeled Ti₃In₂ was found to exist in a narrow homogeneity region near Ti₅₆In₄₄. Rietveld refinement of the XRD powder pattern yielded solutions compatible with a Cu₃Au-type or a BiIn-type crystal structure, but not with a CuAu-type crystal structure. Furthermore, at 38.5 at.% In, a new phase was observed having a γ-brass related crystal structure [Ti₈In₅, space group , a=0.99578(6) nm]. The intermetallic phases were formed by a cascade of peritectic reactions ending in a eutectic at >99 at.% indium between Ti₂In₅ and (In) at 0.4 K below the melting temperature of pure indium.     

Flakes of natural carbyne in a diamond mine

Flakes of natural carbyne were found in Liao-Ning diamond mine, China, and examined by HRTEM, XRD and EDX. Lattice fringes and clear SAD patterns were obtained. The interlayer spacings obtained with SAD were in good agreement with those determined on the powders found in Ries crater meteorite by X-ray diffraction. However, they are different in color and shape, the one found in China being black and flaky, but the one in Ries crater meteorite being silver-white and particulate. It was assumed that carbyne might be stabilized by the intercalation of either Si or Fe in nature.     

Solid state phase equilibria in the Fe–Ga–Sb ternary system at 600 °C

Solid state phase equilibria in the ternary Fe–Ga–Sb diagram were determined at 600 °C using experimental techniques such as X-ray diffraction, electron probe microanalysis and scanning electron microscopy. Very limited solid solutions were measured in the binary constituent Fe–Ga and Fe–Sb compounds except for the -phase (Fe_≈2.55Sb₂) which extends from 42 to 48 at.% Sb. In the Fe-rich part of the diagram, a ternary phase Fe_tGa_2−xSb_x (2.15≤t≤2.80) was evidenced which corresponds in fact to a solid solution into which Ga and Sb substitute one another on the same hexagonal sublattice. This phase, which can be truly considered as a pseudo-binary one since its origin results from the -phase, shows an extended homogeneity range with a Ga-rich limit corresponding to the formula Fe_tGa_0.8Sb_1.2. Moreover, it crystallizes in hexagonal symmetry with a disordered structure derivative from the NiAs-type (B8₁). This pseudo-binary phase is in thermodynamic equilibrium with all the binaries of the system except FeGa₃. The main result of the ternary Fe–Ga–Sb diagram remains the existence of a diphasic region between the Fe_tGa_2−xSb_x phase (1.2≤x≤1.6; 2.15≤t≤2.80) and the semiconductor GaSb. Nevertheless, at 600 °C, this pseudo-binary phase does not extend up to the Fe₃GaSb composition which is stoichiometric in Ga and Sb. Finally, a comparative study has been made with the three other ternary systems Fe–Ga–As, Ni–Ga–As and Ni–Ga–Sb previously reported, and the consequences for the solid state interdiffusions in Metal/III–V semiconductor heterostructures are discussed.