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Volume 0,Issue 6,1998 Table of Contents

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  • 1  Current Status of Development and Application of Metal Fibres
    Xi Zhengping Zhou Lian Li Jian Liao Jichang Wu Lujian Li Yalu Li Jianping Zhang Yanrong
    1998(6):317-321.
    [Abstract](1848) [HTML](139) [PDF 0.00 Byte](0)
    Abstract:
    The current status of development, fundamental characteristics, and applications of metal fibres are discussed. It is found that many new types of material have been developed by using metal fibres,and that these materials have direct impact on the human daily life. Progress in metal fibre research and fibre products in China are described. China has a considerable competitive advantage in research and development of metal fibres and fibre products. There is a fairly good technical bases for predicting significant advances in the industrialization of metal fibres and fibre products in China.
    2  Recent Advances in the Study of the Ti-Ni-Nb Shape Memory Alloy with Wide Hysteresis
    Yang Guanjun Deng Ju
    1998(6):322-326.
    [Abstract](1212) [HTML](133) [PDF 0.00 Byte](8)
    Abstract:
    The Ti-Ni-Nb shape memory alloy possesses a wide transformation hysteresis and excellent shape memory properties, so that it is expected to be used for pipe couplings and mechanical fasteners. The engineering significance of widening hysteresis is discussed. Recent advances in the study of this alloy are reviewed, including microstructure, martenstic transformation, mechanical behavior, strain recovery ratio, low temperature thermal capacity and machinability, etc. Future development of this alloy is also discussed.
    3  Study of the Bond Structures of an Anomalous Yield Behavior in TiAl
    Li Wen Guan Zhenzhong Zhang Ruilin
    1998(6):331-335.
    [Abstract](1462) [HTML](127) [PDF 0.00 Byte](1)
    Abstract:
    By means of the Empirical Electron Theory (E E T), the valence electron structures of ordered and disordered TiAl at various temperatures are calculated. The effect of crystal lattice expansion and decrease of long -and short-rang order parameter (with increasing temperature) on strengthening is analyzed. The reason of an anomalous yield behavior in TiAl is that the valence electron structures directly effected by temperature result in strengthening, and "disorder domain" strengthening (with short order -range parameter descending). According to this view point, an mechanism is proposed, and some experimental results that content and grain size have influence on anomalous yield behavior in TiAl are explained.
    4  Microstructural Characterization of a Superplastically Deformed TiAl-Based Alloy
    Zhou Kechao Huang Baiyun Qu Xuanhui Cheng Xiaoqun
    1998(6):336-339.
    [Abstract](1179) [HTML](140) [PDF 0.00 Byte](11)
    Abstract:
    采用金相显微镜,扫描电镜和透射电镜,对超塑性拉伸变形后的Ti-11Al-3Cr-0.5Mo(质量分数)合金的显微组织进行了观察和分析。研究发现,TiAl基合金在超塑性变形过程中发生了动态再结晶现象,动态再结晶使晶粒显著细化。透射电镜观察结果表明,γ晶粒内有位错运动,位错运动导致γ晶粒内形成位错墙,位错网。这些显微组织特征与TiAl基合金的超塑性变形机理有着密切的关系。
    5  Studies of High-Temperature Notch Fatigue Property and Fracture of a Directional Solidified Co-Base Superalloy
    Jiang Wenhui Yao Xiangdong Guan Hengrong Hu Zhuangqi
    1998(6):340-343.
    [Abstract](1415) [HTML](135) [PDF 0.00 Byte](0)
    Abstract:
    研究了定向凝固钴基高温合金DZ40M700℃和900℃缺口疲劳性能有疲劳断口。结果表明,DZ40M合金具有较高的抗高温缺口疲劳破坏能力,700℃和900℃缺口疲劳强度分别为285MPa和203MPa,且表现出低的疲劳缺口敏感性,700℃和900℃疲劳缺口敏感度仅为0.146和.153。在交变载茶作用下,700℃缺口疲劳裂纹是以小平面方式,沿着{111}滑移面扩展,而900℃缺口疲劳裂纹是在交变载荷
    6  Oxidation Behaviors of a Sputtered NiCrAlY Coating on the Surface of a High Temperature Titanium Alloy
    Cui Wenfang Luo Guozhen Zhou Lian Hong Quan
    1998(6):348-351.
    [Abstract](1371) [HTML](147) [PDF 0.00 Byte](10)
    Abstract:
    研究了Ti-1100高温钛合金表面溅射NiCrAlY涂层对钛合金在600℃-800℃空气中氧化性能的影响。结果表明:由于在涂层表面形成均匀连续的Al2O3保护膜而显著改善了高温钛合金的抗氧化性,涂层本身的微晶组织使其具有良好的抗剥落能力。但在800℃时,基体中少量Ti扩散到涂层表面形成TiO,同时涂层中的Ni强烈向基体扩散,在基体和涂层中分别形成扩散带和空洞。
    7  Effect of Ti on the Microstructure and Properties of the AB_5-type Cast Alloy
    Li Chuanjian Wang Xinlin Wang Chongyu
    1998(6):352-355.
    [Abstract](1521) [HTML](147) [PDF 0.00 Byte](8)
    Abstract:
    The electrochemical and microstructural properties of cast MlNi3. 8C0. 6Mn0.55Ti0.05 have been investigated in detail. The results show that the initial activation and the low-rate discharge capacity are promising, but the high-rate discharge capacity and the discharge voltage plateau are to be improved for this alloy. Segregation, mainly Ti(NiCoMn),was detected using in situ X-ray diffraction, scanning electron microscopy (SEM) and energy dispersive X-ray analysis (EDAX). Ti (NiCoMn) segregation makes the alloy easy to pulverize, and consequently decrease the cycle stability of the alloy. The segregation should be avoided to make the full use of Ti.
    8  Burn Resistant Characteristics and Microstructures of Ti-Cu-Al Alloys
    Zhao Yongqing Zhao Xiangmiao Zhu Kangying
    1998(6):360-362.
    [Abstract](1494) [HTML](133) [PDF 0.00 Byte](15)
    Abstract:
    研究了Ti-Cu-Al阻燃钛合金的阻燃性能和微观组织。结果表明:Ti-Cu-Al合金有良好的阻燃性能,合金的微观组织为a+Ti2Cu,Ti2Cu分布均匀。随Cu含量或退火温度升高,Ti2Cu颗粒长大,合金性能恶化。合金中是否含有合金元素Al对它的组织结构影响不大。
    9  Magnetization and Susceptibility of an Internal Sn Processed Nb_3Sn Wire
    Mao Dali Kikuo Itoh Hitoshi Wada
    1998(6):363-366.
    [Abstract](1052) [HTML](136) [PDF 0.00 Byte](0)
    Abstract:
    Magnetization (M) and susceptibility versus temperature (T) and magnetic field (H) of an internal-Sn processed Nb,Sn wire have been studied and the critical M-H-T surface has been plotted. The normalized magnetization vs. applied field has been filled to Kramer's equation. The effective filament diameter is estimated to be larger than the original filament size. Bridging between the filaments is account for the extra hysteresis. The values of X' and X" do not change much with AC amplitude in a certain background field and frequency, but do change with frequencies for a given AC amplitudes. The interfilament coupling is mainly from bridging, not from proximity effect.
    10  Processing of Ultrafine Ag-Pd Alloy Powders
    Zhang Jian Jiang Lijuan Li Xiaohong
    1998(6):367-369.
    [Abstract](1336) [HTML](148) [PDF 0.00 Byte](0)
    Abstract:
    研究了以水合联氨作还原剂,从硝酸银和硝酸钯溶液中直接还原出Ag-Pd合金超细粉末,通过化学势和学分析可知,水合联氨与银,钯反应的标准电极电位差值很大,远远高于银与钯标准电极电位的差值,可以实现银和钯同步还原。在溶液中银和钯离子浓度为70g/L.Ag:Pd=7:3,水合联氨的加入量为理论量6倍,还原温度为50℃-60℃条件下,可获得平均粒径为0.6μm的Ag-Pd合金粉末。
    11  Fabrication and Property of Multifilamentary Bi-2223/Ag Superconducting Tapes for Magnets
    Xiong Shougao Duan Zhenzhong Wu Suihua Teng Xinkang Zhen Hulling Wu Xiaozu
    1998(6):370-372.
    [Abstract](1321) [HTML](118) [PDF 0.00 Byte](0)
    Abstract:
    研究了用粉末装和技术制备磁体用多芯Bi-2223/Ag超导带材的工艺性能。结果表明,得到的氧化物芯丝均匀的多芯Bi-2223/Ag超导带材,其Bi-2223单相性较好且晶粒具有c轴取向。在77K,0T下,短带的临界电流密度JC达2.2×10^4A/cm^2(判据1μV/cm)。用此带制做的小型超导磁体(外径为85mm,内径10mm,高60mm),在4.2K和77K下,磁体通过的临界电流IC分别为1
    12  Study of the Melt-Textured Growth Process in Bi System Superconductors
    Cat Yurong Zhou Lian Sun Xiangyun Zhang Pinxiang
    1998(6):373-375.
    [Abstract](1098) [HTML](122) [PDF 0.00 Byte](0)
    Abstract:
    研究了连续区熔定向凝固工艺对铋系织构生长的影响。结果表明,选择合适的粉末名义配比,在最高熔化温度为880℃,样品移动速度为8mm/h的条件下处理样品,能够制得高度取向的Bi-2212晶体。但通过该工艺Bi-2223相织构生长过程的研究,发现这种方法不利于2223相织构的生成。
    13  Effects of Particle Size on the Electrochemical Properties of the Ml (NiCoMnTi)_5 Hydrogen Storage Alloy
    Chen Lixin Lei Yongquan Li Zhizun
    1998(6):376-378.
    [Abstract](1408) [HTML](135) [PDF 0.00 Byte](20)
    Abstract:
    The effects of particle size on the electrochemical properties of the Ml(NiCoMnTi)5 hydrogen storage alloy have been systematically investigated. The results show that the smaller the particle size, the higher the discharge capacity and the better the high -rate-dischargeability and the cycling stability. If two types of powder with different particle sizes are mixed, the smaller the particle size ratio (the average particle size of small component to that of the large one), the higher the discharge capacity. At a mixing weight ratio (the weight of large component to that of the small one) of 7: 3, the highest discharge capacity is obtained.
    14  Study of Some Factors Effecting the Porosity of Porous Tungsten
    Teng Xiuren Zhang Hanliang
    1998(6):379-380.
    [Abstract](1497) [HTML](159) [PDF 0.00 Byte](1)
    Abstract:
    Some factors effecting the porosity of porous tungsten, such as powder size, press pressure, sintering temperature, and so on, are discussed in detail. It is found that the porosity of the pressed blank is not only connected with the press pressure, but also with the size of tungsten powder. For the same size of powder, the porosity of the pressed blank decreases with the increase of pressing pressure. The porosity of pressed blank of coarse powder is smaller than that of fine powder for the same pressure. If the sintering temperature and time are the same, the porosity of porous tungsten made by fine powder is smaller than that of the coarse one. For the same size powder, the porosity of the pressed blank decreases with increase of sintering temperature. Therefore, the powder size and sintering temperature are major factors for the porosity of porous tungsten. The smaller the size of the powder and the higher the sintering temperature, the less the porosity of porous tungsten.

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