The subunit of bainite in a Cu-Zn-Al alloy has been observed by means of TEM. The shape, size and distribution of subunits under TEM are the same as those obtained by scanning tunneling microscope. The ledges on subunit were found to be grown up by ledgewise mechanism. The subunits are sympathetically nucleated. Three types of sympathetic nucleation were observed: face-to-face, edge-to-edge and edge-to-face.Correspondent: LI Chunming, (Laboratory of Laser Single Atom Detection, Department of Modern Applied Physics, Tsinghua University, Beijing 100084)

An investigation on the thermodynamic properties of α-Al_2O_3, γ-Al_2O_3,gibbsite, boehmite and diaspore: standard enthalpy of formation, standard entropy, standard free energy of formation, and heat capacity was made based on calorimetric determinations and the published literatures. The reliability and consistency of the recommended values of these thermodynamic properties were discussed in detail.Correspondent: CHEN Qiyuan, professor,(Department of Chemistry, Central-South University of Technology, Changsha 410083)

篈n experimental investigation was carried out of the cyclic properties of 316L and 316LN stainless steels subjected to uniaxial loading and biaxially nonproportional cyclic loadings. The properties of cyclic hardening, plastic flow and uniaxial kinematic hardening for the two kinds of steels were studied. It is shown that the properties depend not only on equivalent strain amplitude, but on strain path also. Some significant results were obtained.Correspondent: YANG Xianjie,(associate professor, Institute of Applied Mechanics, Southwest Jiaotong University, Chengdu 610031)

篈 method using one load-displacement curve to calculate composite hardness distribution of coating-substrate system was proposed and varified on Nano-Ⅱ indenter. To take into account the variation of composite elastic modulus through the indentation depth and its effect on hardness measurement, the Gao′s model was introduced in the present method. The results of electroless Ni-P coatings with different thicknesses indicated that the composite hardness calculated by the proposed method agrees basically with experimental data. It appeared to be most important that the true hardness of coatings can be predicted provided that several composite hardnesses have been obtained experimentally. Correspondent: XU Kewei, professor,(School of Materials Science and Engineering, Xi′an Jiaotong University, Xi′an 710049)

篈 Ni-P plated TiAl alloy specimen may protect the cathodic corrosion. The fracture toughness of TiAl alloy specimen saturated with hydride, KC(H), is less than that in air, Kc . Atomic hydrogen could induce the delayed failure of the specimen saturated hydride during dynamically charging with hydrogen. The ratio, KIH/ KC (H), of the critical stress intensity for hydrogen induced delayed failure is about 0.7.Correspondent: GAO Kewei,(Department of Materials Physics, University of Science and Technology Beijing,Beijing 100083)

The in situ TEM observations of dislocation emission, motion and the initiation of nanocrack in 310 stainless steel in water were carried out. Using a special constant deflection device,the dislocation configuration change ahead of a loaded crack tip before and after anodic dissolution in the the deionized water and the initiation, propagation of nanometre scale stress corrosion cracks have been oberved. The results showed that SCC in thin foil specimen of 310 stainless steel can occur in water.The localized anodic dissolution of 310 stainless steel in water at room temperature facilitated dislocation emission, multipication and motion. A nanocrack initated in the DFZ or at the blunted crack tip in corrosion solution after dislocations emission, multiplication and motion reached critical condition. Because of the influence of the corrosion solution, the nanocrack propagates and forms a cleavage microcrack during stress corrosion instead of blunting into a void as it does during a tension test without solution.Correspondent: HUANG Yizhong,(Department of Materials Physics, University of Science and Technology Beijing,Beijing 100083)

Based on SIMPLE algorithm, Navier-Stokes equations under threedimensional cylindrical coordinates were solved by using the special mesh method to eliminate the singularity at the axis, thereby the computation of three-dimensional turbulent fluid flow in cylindrical reactors can be performed on personal computer and the program developed can be applied in many fields.Correspondent: ZHAO Lian′gang,(National Research and Engineering Center of Continuous Casting Technology, Central Iron and Steel Research Institute, Ministry of Metallurgical Industry, Beijing 100081)

The thermal cycling tests between -196 and 350 ℃ were performed on Ti-6Al-4V alloy in as-quenched and aged states, and the tensile properties before and after thermal cycling were evaluated. The elongation of the as-quenched or aged alloy decreases after thermal cycling. The strength of the aged alloy does not change significantly, and that of the as-quenched alloy promptly increases first, and then falls down after 3000 thermal cycles.Microstructural analysis was performed by TEM before and after thermal cycling. The effects of thermal cycling on microstructure and tensile properties were discussed.Correspondent: GENG Hongbin,(College of Materials and Engineering, Harbin Institute of Technology,Harbin 150001)

The effects of Cl~- on the corrosive wear behaviour of stainless steel in H_2SO_4 solution were studied via the corrosive wear rate, the load bearing capacity of passive film and the relationship between pitting and corrosive wear. There is a critical load at natural potential, below which the corrosive wear rate is slightly lowered by Cl~-, but when the load is higher the corrosive wear rate increases with the increase in Cl~-. There are more pits at low load than at high load in the wear tracks and the pits is deeper at low load than at high load. The load bearing capacity is lowered by Cl~- at passive region and then the corrosive wear rate increased.Correspondent: HUANG Yanliang,(Institute of Metal Research, Chinese Academy of Sciences,Shenyang 110015)

The structures of rapidly solidified Cu_(30)Al_(70) alloy compared with conventional Cu_(30)Al_(70) alloy have been investigated. The structure in the rapidly solidified Cu_(30)Al_(70) alloy is more homogeneous than that of the conventional one and the aluminum phase is in the minor. The Al and Cu elements is also homogeneously distributed in the rapidly solidified Cu_(30)Al_(70) alloy. The rapidly solidified Raney copper has a smaller specific surface area and larger pore volume and diameter. The catalytic activity of rapidly solidified Raney copper is superior to that of the conventional Raney copper in hydrogenation.Correspondent: SUN Li, (State Key Laboratory of RSA, Institute of Metal Research, Chinese Academy of Sciences, Shengyang 110015)

The microstructure and magnetic properties of nanostructured soft magnetic alloy Fe_(73.5)Cu_(1.0)Mo_(3.0)Si_(13.5)B_(9.0) at different annealing temperatures have been analysed and measured by X-ray diffraction and correlated technigues respectively.The optimal annealing temperature for the soft magnetic properties of the alloy is between 500 and 520℃. They would worsen if the Fe-B compound occurred in the alloy.Correspondent: JI Song, (Research Institute No.52 of China Ordnance Industy, Ningbo Branch, Ningbo 315040)

The Sn-Bi nanometer powder was prepared by the electrohydrodynamic technique with quartz capillary nozzle. The processing parameters have been investigated.With the increase in DC voltage and the decrease in diameter of capillary nozzle, the particulate size of the Sn-Bi nanometer powder will be reduced. Moreover, the pressure feeding into the molten alloy is also an important factor controlling particulate size.Correspondent YU Xifeng,(Department of Materials Science, Northeastern University, Shenyang 110006)

Two interfacial reactions of the eutectic Sn-Zn alloy as filler on the Al substrate during soldering were indicated, i.e., Zn in filler penetrating into Al grain boundaries to form Al-Zn solid solution, and some needle-like Al-Sn-Zn solid solution phases forming and growing into Sn-Zn solid solution. The above reactions make the bonding between filler and substrate to be strengthened more and more.Correspondent: CHEN Rong,(Department of Chemistry, Peking University, Beijing 100871)

A series of Fe/Ti periodical nano-miltilayers was prepared by DC-magnetron sputtering. The modulation period is between 2.2 and 24 nm. The structure of the specimens was examined by TEM and small-or high-angle X-ray diffraction technique. Their magnetism was also studied by the vibratory sample magnetometer and Mossbauer spectrum. The face-centred cubic Fe was found in multilayers containing thinner Fe layers nearby 2 nm. The saturation magnetization increases and the coercivity decreases with increasing modulation period.Correspondent: WANG Zhenjun,(Department of Materials Physics, University of Science and Technology Beijing, Beijing 100083)

A multi-crack-interaction model has been proposed for analysis of the mechanical behaviours of metal-matrix composites reinforced by coated fibers. The stress concentrations and non-elastic effects such interface debonding and matrix yielding caused by the cracks can be calculated on the model. The result shows that there is high stress concentration in the fiber, which increases with increasing the matrix yielding width and the density of the cracks in the reaction zone, but decreases after interface debonding. There exists an optimum interfacial bonding with which the composites obtain the maximum strength. The optimum interfacial shear strength for SiC-coated C / Al composites is in the range of 100─300 MPa.Correspondent: XIA ZHENHAI, associate professor,(Department of Materials Science and Engineering, Hebei University of Technology, Tianjin 300130)

Trans-flexural free vibration tests of the cantilever beam have been used for studying the vibration damping characteristics of unidirectionally reinforced VIRALL (vinylon reinforced aluminum laminates) and the corresponding monolithic aluminum alloy plate. The results show that the former has higher vibration decay coefficient than the latter.It is also found that the vibration damping properties of VIRALL laminates are influenced by the fiber orientation in it.Correspondent: SUI Guoxin, Insitute of Metal Research, Chinese Academy of Sciences, Shenyang 110015

The better aluminum alloy composite reinforced with AIN-TiC particulates,by in situ reaction, was prepared as follows: an aluminum alloy, containing Ti and others,was melted at temperature ranged from 900 to 1200℃ , and the gaseous atomic nitrogen and carbon flow was injected by proper manner into the melting Al so that AIN (0. 2-1 .2μm) and TiC (2-5μm) formed by in situ reaction dispersed in aluminum matrix homogeneously.Correspondent: CUI Chunxiang,(Institute of Composite, Shanghai Jiaotong University, Shanghai 200030)

The software of transient temperature field for phase transformation hardening with laser treatment by means of finite difference method was developed. The whole course revealed with this software is even better in keeping with the practical circumstance.The real surface temperature fields on the laser processing of steel have been measured with the thermovision. Using thermodynamic calculation Ac1 and Ac3, the critical points in laser heating, have been determined. The relationship of the hardness of carbon steel after laser processing, HRC or HV, vs carbon content, c. and the diffusion of carbon during the laser processing have been pointed out.Correspondent:ZHU Zuchang, (Shanghai University of Engineering Science, Shanghai 200335)