The dynamically mechanical properties of Zn-22%Al alloys were measured with the low-frequency forced vibration mode by systematically changing the temperature varing rate and vibration frequency during eutectoid decomposition process. The experimental results indicated that the loss elastic modulus had different temperature varying rate and vibration frequency dependent behaviour from the storage elastic modulus, and the dependence of internal friction on temperature varying rate and vibration frequency has been discussed in the viewpoint of the complex elastic modulus. To analyse the complex elastic modulus may be more helpful to study the first-order phase transition than to only analyse internal friction.

Based on the eutectic growth model given by Jackson and Hunt, the principle of regular eutectic spacing selection is suggested by the quasi-kinetics way and, the upper and lower limit of eutectic spacing selection are presented. It is found that the lower limit corresponds to the case where the phase with smaller stability parameter will be critically grow out and, on the other hand, the upper limit to the case where a pocket forms in the center of the phase with larger stability parameter. The upper limit presented in the paper shows good agreement with the experiments contributed by Ourdjini et al and Trivedi et al, but there are some deviations in the lower limit.

The site occupation of substitutional elements Cr, Mo, Ti, Ni, Mn, Si at sublattices in DO3 type stoichiometric Fe3Al intermetallics, and effects of the elements on magnetic momentum of unit cell and DO3→B2 transformation behaviour have been determined by means of neutron diffractometry. The experimental results indicate that Cr, Mo and Ti atoms all occupy the next nearest neighbour of Al atom, Ni and Mn atoms the nearest neighbour, while Si atoms occupy the positions of AI atoms. All the alloying elements investigated in the present work decrease order degree of DO3-type Fe3Al alloy, and modify the magnetic momentums of two type Fe atoms in the unit cell. Correspondent: YANG Wangyue,(professor, Department of Materials Science, University of Science and Technology Beijing, Beijing 100083)

It is necessary to select a suitable size of calculation cell to study the interface by molecular dynamics method, which should both save the calculation time and reduce the effect of the cell size on the results of simulation. The present study indicated that when the cell contains about 1000 atoms, the simulation results are agreement with the macro-law. Correspondent: LUO Xuan,(Campus Box 433, Harbin institute of Technology, Harbin 150001)

The microstructural variations of the transition zone in the friction joints of Al-base composite with austenitic stainless steel were studied systematically. The scanning electron microscopy (SEM) observations found that the plastic deformation can be obviously caused in the side of the high strength stainless steel during the friction welding. The deformation characteristics and mechanism are different in the different parts along the weld interface. Transmission electron microscopy (TEM) observations found that the transition zone is composed of a micro-crystalline oxide Fe(Al,Cr)2O4 or FeO·(Al,Cr)2O3 layer and a FeAl3 intermetallic layer. Correspondent: PAN Chunxu,(associate professor, Laboratory of Electron Microscopy, Wuhan Transportation University, Wuhan 430063)

Effects of different melt temperatures before solidification on microstructures and mechanical properties of rapidly solidified Al-(14%-18%)Si alloy ribbons were investigated experimentally. It is found that the increase in melt temperature and/or homogenization treatment at high temperature (1200℃, 1.5 min) is favourable to the formation of highly refined and homogenized microstructure, which have good composite mechanical properties. Correspondent: WEI Pengyi, associate professor, State Key Laboratory of Solidification Processing,Northwestern Polytechnical University, Xi'an 710072

The sensitivity of microstructures to the thermal history of the melts in rapidly solidified Al-Fe-M-Si (M=Ti, Nb, Cr+Mo, W) alloys with different compositions were studied. It is shown that the microstructures in rapidly solidified Al-Fe-M-Si alloys are obviously different under the same system of the thermal history of the melts. Effect of the thermal history on the microstructures in rapidly solidified Al-Fe-M-Si(=Ti, Nb,Cr+Mo) alloy is not more sensitive than Al-Fe-W-Si alloys in the thermal history range from 1323 K to 1523 K for 5 min. Correspondent: GUAN Shaokang,(Department of Materials Science and Engineering, Zhengzhou University of Technology, Zhengzhou 450002)

The microstructures of sulfo-nitro-carburizing layer of Al-containing alloy steels were studied. The results reveal that in the white and transition areas, which are the subdivisions of the layer, nitrides preciptate greatly in the form of needle and at grain boundaries in the form of network. These cause about 100 μm microcracks in the white area. The extraordinary microstructure of the layer indicates that Al-containing alloy steels are not suited for sulfo-nitro-carburizing treatment in salt bath.Corresponaent: GONG Xiumin, (professor, Wuhan Automotive Polytechnic University, Wuhan 430070)

There are three types of yielding curves for steel 20CrMo tempered at 600, 450 and 200℃ after quanching, in which the first has upper and lower yield point, the second has yielding plateau but no upper yield point and the third is a continuous yielding. This paper studied the effects of Cottrell atmosphere on initial yield stress σ0(σ0.001) and fatigue threshold value △Ktn．The results show that, the Cottrell atmosphere still exists in the continuousyielding materials tempered at low temperature, yet the pinning strength of interstitial atoms on dislocations is weeker than that of the materials tempered at middle or high temperature.Both of σ0 and △Ktn is dropped greatly when depinning of interstitial atoms takes place.There is a good linear relation between △Ktn and σ0. Correspondent: LUO Jingxi,(State Key Laboratory for Mechanical Behaviour of Materials, Xi'an JiaotongUniversity, Xi'an 710049)

The room temperature fracture behaviours of the alloy prepared by rapidly solidified Al-8.5Fe-1.3V-1.7Si powders under different deforming conditions have been investigated. The results revealed that the propagation mode of main crack related to the orientation of powder boundaries when the specimen fractured. For the specimen tensed along extrusion direction, the microcracks along rolling plane did not affect propagation of the main cracks; the microcracks along vertical section might lead to unusual fracture; the cross-section boundaries are ready to become the low energy propagation path for main crack. Hot rolling improved cohesion strength for boundaries along the vertical section and cross-section more than ones along rolling plane, resulting in the change of fracture mode at a certain deformation (30%). The different variation regularities for fracture strength and elongation relate to the fracture mode and follow-on deformation hardening. Correspondent: LI Songrui, (professor, Department of Materials Sciences and Engineering, Central South University of Technology, Changsha 410083)

The initiating process of the hydrogen bubbles and microcracks caused by the hydrogen pressure was observed by TEM. The results showed that hydrogen charging can generate bubbles and then cause a great reduce of the cohesive strength. As soon as the hydrogen pressure within the bubble reaches to the cohesive strength decreased by hydrogen,microcrack will initiate at the wall of the bubbles. Correspondent: HUANG Yizhong,( Department of Materials Physics, University of Scicnce and Technology Beijing, Beijing 100083)

(Zr1-yTiy)(V,Mn,Pd,Ni,Fe)2 hydride electrodes have higher electrochemical capacities(371 mA . h/g at a current of 50 mA/g and room temperature). The electrochemical capacities of electrodes decayed during cycling due to severe oxidation of 3d transition metals and selective dissolution of some alloy components, which brings lattice distortion of C14 Laves phase and lose of hydrogen storage ability. The decrease in Ti content is favourable to prolong the cycling lives of hydride electrodes. Correspondent:( YANG Xiaoguang, lecturer, Department of Materials Scicnce and Engineering, Zhejiang University, Hangzhou 310027)

The electrochemical activation behaviours of the hydrogenstorage electrode alloys Ml(Ni,Co,Mn,Ti)5 produced by induction melting and then fornace cooling (FC) or Ar-gas atomizing (AGA) have been studied by comparing the activation of AGA electrodes aged at room temperature for 4 months with that of FC electrode. It is found that the surface oxide is only a minor factor to affect the activation, while the magnitude of internal energy change in the alloy before and after hydrogenation is the controlling factor. The increases in the internal energy of the alloy, caused by oxide and the H-atoms entering tetrahedral or octahedral sites during hydrogenation, make the activation difficult. Correspondent:(ZHOU Yu, postdoctor, Department of Chemistry, Peking University, Beijing 100871)

The effect of shock wave on the structure of amorphous alloy Fe78B13Si9 has been studied by means of XRD and DTA. It has been found that under the effect of some strong shock wave, this amorphous alloy has been transformed into a crystailine phase with nanometer sized grains. Corresponaent:(LIU Zuoquan, professor, Department of Physics, Yunnan University , Kunming 650091)

Effects of pressure and temperature on grain size of nanocrystalline α-Fe(Mo,Si) produced by annealing amorphous (Fe_(0.99)Mo_(0.01)_(78)Si_9B_(13) alloys in temperature range from 723 to 933 K under pressures range of 3 to 6 GPa were studied. It is found that the effect of pressure on α-Fe(Mo,Si) grain size results mainly from nucleation rate, and its basic cause is the effect on melting point. Yet the effect of pressure, decreasing growth rate, on the fomiation temperature and critical pressure of smallest grain size of α-Fe(Mo,Si) can be negligible. Correspondent: (YAO Bin, associate professor, Physics Department, Siping Normal College,Siping 136000)

The microstructure and magnetic properties of coercive powder prepared by hydrogenation disproportionation desorption recombination method (HDDR) and composed of dual phase Nd2(Fe, Co)14B and Nd2(Fe, Co)17 alloy have been investigated. The decrease in B content in monophase Nd2(Fe, Co)14B alloy induced the formation of Nd2(Fe,Co)17 phase. The remanence Br, of dual alloy Nd12.5 Fe81.5-xCo6Bx with x= 5.2 is higher than that of monophase Nd12.5Fe81.5-xCo6Bx with x=5.88. This may be due to an exchange-coupling interaction between Nd2(Fe, Co)14B and Nd2(Fe, Co)17 phase. Correspondent:( XIAO Yaofu, associate professor, Department of Materials Science, University of Science and Technology Beijing, Beijing 100083)

The diffusion behaviour of N atoms in Sm2Fe17 alloys has been studied. The relationship between the diffusion temperature, the diffusion time with average coneentration of N in samples and the distribution of N concentration in powder particle have been measured. The frequency factor D0 and activation energy Q for N atoms diffusion in Sm2Fe17 particle have been calculated. Using Fick second diffusion law the distribution of N concentration in Sm1Fe17 particles and the relationship between the distribution of N concentration with diffusion temperature, diffusion time and particle size are calculated. The calculated results are consistent with experimental results. Correspondent: (ZHOU Shouzeng, professor, State Key Laboratory of Advanced Melallic Materials, University of Science and Technology Beijing, Beijing 100083)

A new method was proposed to predict the earing behaviour of textured sheets.The type and relative magnitude of earing tendency for some important ideal orientations in cubic metals are calculated. It shows that the present predictions are better than those with the traditional crystallographic method, and can be applied to texture balance designfor suppressing earing. Correspondent:(LI Saiyi,Department of Materials Science and Engineering,Central South University of Technology, Changsha 410083)

The heat affected zone (HAZ) toughness of steel X-60 after simulation tests of molten welding was improved by means of the technology of intragranular ferrite plate (IFP).It was found that the absorbed energy during impect tests depends strongly on the quantity of IFP. If the volume fraction of IFP is larger than 60%, then the absorbed energy will go up to 150 J and more. The examination of optical microscopy and SEM exhibited that IFP consists of fine ferrite plates originating inside the initial austenite grains. These IFP forined by the so called "nucleating inclusions" as nuclei during the controlled cooling process after welding simulation. The nucleating inclusions are some fine and evenly distributed composite oxides with higher sulphur content, which result from the deoxidation by RE, Zr, Ti under a higher initial oxygen potential. Correspondent:(JIANG Guochang, professor, Shanghai Enhanced Laboratory of Ferrometallurgy (SELF),Shanghai University, Shanghai 200072)