The rheological properties of cast steel in the range of liquid state and solid liquid coexistence region have been examined under the modified test equipment for rheological properties of superalloy, particularly with refractory fittings. The γ─t curves at various temperatures were plotied so as to propose their mechanical model and the constitutive equation. The inherent correlation between the rheological propertics of alloy and the structural change of steel during solidification together with the action among particles was analyzed.Correspondeni: (LI Defu, Deparment of Malerial Science and Technology, Harbin Institute of Technology.Harbin 150001)

The La sensor was composed of polycrystalline La0.95Ca0.05Fz.gs as solid electrolyte, pure La as reference electrode and Mo wire as lead wire. It can be expressed as:Mo

On the base of studying morphologies and compositions of the a-AlaO3 scales formed on the NiAl bases with CeO2 dispersion during initial oxidation stage at 1000 and 1100℃, the effect of the dispersive CeO2 in the NiAl base on the element diffusion flux in surface zone was analysized. According to the analytic formula for the diffusion flux. the results that the dispersive particles promote the formation of nodule-like Al2O3 oxides were explained by analysizing some influencing factors such as temperature of oxidation, size. Con tent and distribution of the dispersive particles. In the meantime. the mechanism that the dispersive particles promote the nucleation and re-formation of protective Al2O3 scale was proposed .Correspondent:(MA Xinqing, Institute of Corresion and Prolection of Metals. Chines Academy of Sciences. Shcnyang 110015)

For Ti-24Al-11Nb alloy,the hydrogen induced crack (HIC) propagation was facilitated through the crack cleavage on the slip planes during dynamic hydrogen charging under either constant or alternating loading at room temperature. The discontinuous HIC was preferentially nucleated in a2-platelets. The α2/βboundaries are effective barriers to HIC nucleation and propagation. Hydrogen induces cleavage fracture by promoting the emission of dislocation at the crack tip as well as the nucleation and propagation of microcracks in the DFZ.Correspondent:(ZHANG Yue, associate professor, State Key. Laboratory .for Synthesis and Processing of Advanced Materials, Wuhan University. of Technology, Wuhan 430070)

The experimental results for three selected pseudoternary alloy systems (Ti3Al-Mo-Nb, Ti3Al-Nb-V and Ti3Al-Zr-V) show that the α2/α+β phase boundary obeys the electron concentration rule, and the valence electron number of the alloying elements depends on their own electronic structures. The valence electron for the transition elememts Ti, Zr, V, Mo, Nb, is s+d electron, i.e.NTi=Nzr=4(s2d2),Nv=5(s2d3), NNb=5(s1d4),Nmo=6(s1d5);the valence electron for the non-transition element Al is s+p electron, i.e.Nal=3(s2p1). The calculated model for a2 phase can be expressed as:N=ΣNifi,and the characteristic electron concentration for the α2/α+βphase boundary at 700℃may be expressed as .Nc=ΣNifi=3.787.Correspondent:(CUI Yuyou, Institule of Metal Research, Chinese Acadeiny of Sciences, Shenyang 110015)

The correlation between the stress relief and magnetism optimization of amorphous Fe79B16Si5 alloy during annealing process has been analyzed. After annealing,the saturation induction Bs and maximum permeabilityμm of as-quenched amorphous alloy increase by 72% and 22 times, concurrently with the reduction of coercive force Hc and power loss P(0.3 T, 10 kHz) by 86% and 83%, respectively. These changes during the annealing process are primarily due to the effective removal of the stress-induced anistropy.Correspondent: (CHE Hiaozhou, postdoctoral, Departinent of Materials Scicnce, Shanghai Jiaotong University, Shanghai 200030)

In this paper. Si3N4has been joined successfully to 40Cr steel with amorphous Cu50Ti50B foil and ductile metal Ni interlayer by diffusion bonding at the first time. The experimental results showed that bonding time, temperature and thickness of Ni interlayer had influence on the strength of joint considerably. The optimum bonding parameters and thickness of Ni interlayer were 900℃. 40 min, 30 MPa and 1 mm, respectively. The analysis of microstructure of joint showed that the decrease of joining strength was due to the interaction between amorphous Cu50Ti50B and Ni interlayer, which reduced the activity of element Ti in the amorphous Cu50Ti50B foil and formed brittle intermetallics. The strength of joint was enhanced by using Mo insert-layer to restrain the interaction between amorphous Cu50Ti50B foil and Ni interlayer. New laminated interlayer model for diffusion bonding of ceramic to metal is proposed as follows：ceramic/active interlayer /isolation interlayer/ductile metal interlayer/metal.Correspondent:(ZHAI Yang, Faculty of Welding, Tsinghua University, Beijing 100084)

The model proposed by Joensson and Hogmark takes the parameter, C, as a constant for different film-substrate systems. The parameter was modified in the present paper according to different hardness ratio of film to substrate and used them to study the variation of the hardness of PCVD Ti(C, N) films with the composition and the microstructure.Comparing with bulk materials, Ti(C, N) films have a relative high hardness due to the smaller crystal size and the higher compressive residual stress. It is controlled by the carbon content and hold a linear increase with the carbon content for a definite deposition technique.Correspondent:(XU Kewei, professor, Hi'an Jiaotong University, Hi'an 710049)