On the basis of the mathematical model of the magnetic field proposed by the authors, a mathematical model for the electromagnetically driven component of the flow field of the melts in ESR system has been developed and applied to the laboratory unit with a mould of 200 mm in diameter. For the practical remelting of a low carbon low alloy steel used an electrode of 76 mm in diameter with 3000 A(rms) current and CaF_2+30mass% Al_2O_3+20mass% CaO slag system, the flow field in the slag bath has been computed using the parameters selected reasonablly. The results indicate that two vontexes are generated in the bath, which circulatively move upwards along the inside wall of mould and through the slag/gas interface and the conical electrode tip, then downwards along the symmetry axis of the system. The maximum velocity of the moving slag reaches approximately at the middle part of the axis in the bath. Also, modelling and simulating under the assumed operative con ditions have been carried out in order to consider the influence of the remelting current and fill ratio, as well as the shape of electrode tip. (Correspondent: WEI Jihe, professor, Department of Materials Science and Engineeing, Shanghai University,Shanghai 200072 )

The reduction of CaO-SiO_2-Al_2O_3-Fe_tO quarternary slag system by CO has been investigated. Apparent reduction rate constant K_ a was determined by mesuring CO_2 evolution from reaction tube with an infrared gas analyser. Adding Al_2O_3 to CaO-SiO_2-Fe_tO ternary slag increases both K_a and reduction rate constant K of CaO-SiO_2-Fe_tO ternary slag. K_a increases and K changes parabolicly with increasing Fe_tO content for CaO-SiO_2-Al_2O_3-Fe_tO slag system at constant slag basicity (B=CaO/SiO_2),and K approaches to the minimum when Fe_tO content is about 60%. K_a increases linearly and K takes a decrease tendency with the increase of optical basicity for A_(FeO) chosen as 1.0 or 0.87. The equation of calculating a_(Fe_tO) for CaO-SiO_2-Al_2O_3-Fe_tO slag system has been derived based on regular solution model and calculated a_(Fe_tO) values are in fairly agreement with bibliography reported data except for extremely Fe_tO rich region.(Correspondent: YANG Xuemin, Institute of Chemical Metallurgy, Chinese Academy of Sciences, Beijing 100080)

The microstructure of Sn-Bi nanometer powder prepared by the electrohydrodynamic technique has been examined in site on the analytical transmission electron microscope. It was found that each Sn-Bi nanometer powder particle is either β-Sn or supersaturated Bi with the structure of single crystal. The formation mechanism of Sn-Bi nanometer powder has been analysed.(Correspondent: LIU Xiang, professor, Departments of Materials Science, Northeastern University, Shenyang 110006 )

The quality TiN film was deposited onto GCr15 steel substrate by the pulsed high energy density plasma technique at room temperature. The adhesive strentgh of TiN coating to GCr15 steel substrate has been satisfactorily measured using automatic scratch tester. The critical load with remarkable higher values may be available to characterize theadhesive strength of the coating. The critical load of the TiN coating was revealed to be varied with numbers of pulsed plasma, the discharge voltage between inner and outer electrodes and pressure of working gases. These have been discussed and explained on the theoretical bases. (Correspondent: YAN Fengxun, associate professor, Institute of physics, Chinese Academy of Sciences, Beijing 100080)

A wear-resistant graded layer on low carbon steel A3 substrate was made of repeated coating and CO_2 laser-remelting Ni35 alloy powder together with Ni-clad WC grains. The metallurgical structure, composition, hardness and abrasive wear resistance of the layer were examined. The volume fraction of hard ceramic phases, mainly WC grains, varied gradually from surface to subatrate. The layer, 0.4-0.8 mm in thickness, had a uniform structure, good toughness, surface hardness about HV_0.21100, excellent bonding with substrate and free from pore and crack. (Correspondent: ZHOU Changzhi, professor, Department of Materials Science and Engineering, Tsinghua University, Beijing 100084)

A combustion reaction of a compact of 45(Ti+C)+55Fe(wt-%)mixture powders was interrupted by forced cooling so as to maintain the microstructural features revealing the reaction process in the combustion product. Phase compositions and microstructural development in the product were analysed with X-ray diffractometer and scanning electron microscope respectively. Adiabatic temperature, T_ad, was calculated, actual combustion temperature, T_c, and the temperature profile of combuction wave were measured. The results show that the combustion is primarily a solid state reaction which results in a non-simultaneity and incompleteness of the reaction, i. e. TiC particles form first in original Ti powder and then in original Fe powder successively, a small area without TiC particle has been remained within the larger Fe powder.(Correspondent:FAN Quncheng, associate professor, Department of Materials Engineering, Xi'an Jiaotong University, Xi'an 710049)

The grain boundary morphology, dislocation structure and fatigue property change of 16Mn steel weld before and after endured with reflected tension shock wave have been investigated by attaching a momentum trap to the welded plate to filter the shock wave.It is believed that the dislocation tangle or pinning extricated partly themselves in ferrite of the weld endured with reflected tension shock wave is main cause of the deterioration of its fatigue properties priorly improved by the explosive treatment of reflected tansion shock wave.(Correspondent: CHEN Liangshan, professor, Institute of Metal Research, Chinese Academy of Sciences,Shenyang 110015)

Creep behaviour of the composite made of an unidirectional T300(PAN) carbon fibre reinforced CVD pyrolytic carbon was examined in range of 1990 to 2350℃. The temperature was monitored by infrared spectrometer within ±2℃. Calculational results indicate that the activation energy is 84.8 kJ / mol and activation volume is 0.754 nm_3. The creep friction stresses are 127, 115, 95.6 and 90.3 MPa at 1900, 2050, 2200 and 2350℃ respectively. By extrapolation of the temperature dependence upon zero creep friction stress, the temperature seems to be about 3375℃ just to approach the sublimation one of carbon.(Correspondent: QIAO Shengru, associate professor, Faculty No.401, Northwestern Polytechnical University,Xi'an 710072 )