A general mathematical model to represent droplet generation, movement and heat transfer in basic oxygen steelmaking furnaces (BOF) has been developed. Based on the investigation of gas flow, combustion and heat transfer in the converter, the authors introduce some distribution functions which control the generation of droplets. Monte-Carlo method was used to simulate randomly generated droplets(size, initial position and initial velocity). The droplet movement was calculated under the Langrangian framework. Heat exchange and temperature of droplets were calculated on its movement trace. Finaly, total droplet behavior were statistically described by some important physical parameters, such as,droplet average residence time in the gas, average maximum rising height as well as average amount of heat transfer from the gas to the metal bath.This model is characterized by the combination of probability statistics and differential equations to describe the behaviour of droplet, and it is believed to be very close to the actual problem described. It will also be beneficial for study other physical and chemical behavior of the droplet in the converter. As an example of using this model,the droplet behavior was researched in the 180 t BOF.(Correspondent: LI Baowei, associate professor, Baotou Universily of Iron and Steel Technology, Baotou014010)

Isothermal section of phase diagram in Ti-Al-Cr ternary system at 1000℃,which contains wide field upto 75 at.-% Al and 70 at.-% Cr, was determined using a method of multiple diffusion couple-electron probe microanalysis (EMPA) and X-ray diffractionanalysis. Ll2 ternary compound phase and its composition range were determined, and phase ranges and phase equilibrium relationships with regard to TiAl, Ti3Al, TiAl2 and TiAl3 were determined completely. Phase equilibrium relationship between β-Ti and TiCr2 and composition range of phase TiCr2 were defined. (Correspondent: HAO Shiming, Professor, Department of Materials Science and Engineering, North easternUniversity, Shenyang 110006)

Variation of structural defects of nanocrystalline Fe73.5Cu1Nb3Si13.5B9 alloy with the annealing temperature was studied by the positron annihilation technique and micromagnetism method. It is concluded that quasidislocation dipoles involved from the preparation of amorphous alloys and crystallization have a great effect on its soft magnetic properties and can explain the magnetic behaviours at the optimal annealing temperature. (Correspondent:LIU Tao, Department off Material Physics, University of Sciene and Technology Beijing,Beijing 100083)

Silicon nitride films were synthesized by ion-beam-enhanced-deposition (IBED) on an IBED system. Auger electron spectroscopy, X-ray diffraction (XRD). X-ray photoemission spectroscopy (XPS) and the scratch test were performed for investigating the composition. structure and the adhesion with the substrate of them. It was found that the silicon nitride film is composed of a thin silicon enriched top layer. a stoichiometric Si3N4 layer and a mixing layer at the film-substrate interface. Cyclic oxidation tests were carried out on the TiAl coated with the silicon nitride films of thicknesses of 0.5. 1 and 2 μm. The results revealed that IBED silicon nitride film is effective to improve the oxidation resistance of TiAl at high temperature. The 0.5 μm silicon nitride film demonstrated an excellent oxidation resistance at 1300 K for at least 30 cycle (600 h). However, this effect decreases as the thickness of coating increases. SEM and energy-dispersive X-ray spectroscopy revealed that the excellent oxidation resistance came from the formation of a thin layer rich in Al2O3 and silicon compound beneath the outer TiO2thin layer. (Correspondent: LIU Hianghuai, Professor, Shanghai Institute of Metallurgy, Chinese Academy of Sciences,Shanghai,200050)

Structural studies of the growth of oxide film on the glass sealing alloy Ni42Cr6Fe under high temperature moist hydrogen atmosphere were observed by using SEM, TEM and X-ray diffraction techniques. At initial oxidizing stage. Cr2O3 and spinel (Fe, Mn) Cr2O4 were nucleated simultaneously. The former mainly grew intergranularly and the latter intragranularly. Then, the growth of oxide film was mainly of Cr2O3 due to the selective oxidation of Cr. As oxidation goes on to a certain extent. the surface Cr depletes and the growth of oxide film changes into spinel as majority. Finally. the coarse spinel (Fe, Mn)Cr2O4 will form at outer surface, the fine Cr2O3 grains in the bed and the coarse spinel around fine Cr2O3 will be matured in the middle part of oxide film. (Correspondent: AN Bai, lecturer, Department of Materials Sciences, Tsinghua University, Beijing 100084)

TEM observation was carried out on the phase transformation of CoSi along Co/ Si interface of the film grown on the Si substrate annealed at 250, 450 or 500℃respectively. CoSi is found to be the polycrystalline grains and no epitaxial relationship occurred between Si substrate and CoSi. The sequence of phase transformation for Co/Si interface in the annealing temperature range may be：250-450℃ 450-500℃Co2Si+ CoSi─→ CoSi─→CoSi+CoSi2(Correspondent: ZHANG Zaoli, Department of Material Physics, University of Science and TechnologyBeijing Beijing 100083)

The kinetics of surface reaction of Fe3Al with water vapour or oxygen was investigated using AES and XPS. Both reactions are very rapid and initiate after 1.5×100-6 Pa·s exposure. The reaction of Fe3Al with water vapour saturates after an exposure of 1×10-4 Pa·s and the oxide formed is Al2O3, the reaction of Fe3Al with oxygen shows an initial saturation after an exposure of 1.5×10-5 Pa·s, followed by a further stage of reaction. These two stages were supposed to correspond to the oxidation of Al and Fe respectively. The kinetics of these reactions can be used to explain the different ductility behaviour of aluminides in various environments. (Correspondent: WAN Hiaojing , professor, Institute of Metallurgy and Materials Sciences, ShanghaiUniversity, Shanghai,200072)

The microstructure togtether with the formation and growth of reaction phases in the interfacial diffusion zone of the explosive cladding. TA2/A3 has been investigated by means of OM. SEM, TEM, AES and XRD techniques. When the specimen is heat-treated at temperature under the β-Ti-α-Ti transformation. i.e., below 1173 K. only TiC forms along TA2 side of interface and hinders the interdiffuion of Fe and Tiatoins. thus Fe2Ti or FeTi is unable to occur. While it is treated up to the transformation temperature of β-Ti. e.g., over 1223 K, the parabolic growth of intermetallic compounds of Fe2Ti and FeTi with layer structure may form intergranularly and the formation of β-Ti or β-Ti + α-Ti structure at the Fe-enriched side of TA2 and of the martensitic transformation products at the Fe-depleted side were observed owing to diffusion of Fe. Furthermore, the growth of β-Ti transformation layer is revealed to follow the parabolic rule. (Correspondent:YANG Yang, Department of Materials Scince and Engineering, Cemral South University of Technology Changsha 410083)