Comparing with ordinary ploycrystalline materials sized to μm grade, the slip morphology of the coarse grained polycrystalline pure Al is characterized by: (1) several slip domains occur in a grain, and in same domain, several slip systems operate at same time or one after another intensely, a beautiful and neat slip pattern is forming on the specimen surface; (2)for high-∑value coincident and random grain boundaries , the grain boundary affecting zone (GBAZ), about 50--120 μm wide, is favourable site to form intergranular crack at early fatigue life easily, and migration or slide of the boundaries were often observed. While low ∑--value near-coincident grain boundaries show a higher degree of slip continuity and strain compatibili-ty than high ∑--value ones. Intergranular crack is not easily nucleated at low ∑--value near--coincident boundaries; and (3) due to suppression of grain boundary slip at triple grain boundary node, the high ∑--value and random grain boundary among the three boundaries of tricrystal crack easily during cyclic deformation.

After exploring the influence of stress, cold--rolling reduction and copling rateon transformation induced strain, the transformation induced superplasticity forming techniqueof the 18Ni maraging steel (2450MPa) was developed. Through 14 times γ?α' cyclic transfor-mation, the limited elongation of 320% can be obtained in 60% cold--rolled specimen. TEM ob-servation revealed that the morphology of stress induced martensite is massive.

The morphology and crystallographic orientation of (a_2+γ) lamellar structure in duplex Ti--47.5Al--2.5V intermetallic compound have been studied by means of TEM,microdiffraction as well as 180°and non--180° rotation twinning analysis. A possible atomic model of the interface was suggested. Thus, approach was made to a mechanism on complex nucleation of α_2+γ two phases along α--Ti interface, and growth of α_2/γ/γ_t/α_2 or α_2/γ/α_2/γ as fundamental structural unit.

Both hydrogen induced cracking and overload crack initiated at same character-istic distance, r, within the plastic zone along the slip line when the plastic zone developed to a critical extent. For the overload crack:For the hydrogen induced cracking:Hydrogen pomoting the dislocation multiplication and motion would result in σ_o,(H)< σ_o,k> 1. Therefore, hydrogen promoting the cleavage fracture in titanum aluminde can be due to that hydrogen facilicates the local plastic deformation, which results in σ_F(H)< σ_F and then K_(IH)< K_(IC).

A laminar biphase structure may occur in rapidly solidified Ni_3Al and Ni_3Al(B)with over stoichiometrical Al content (25at.--%). Both electron and X--ray diffraction analyses showed that one is matrix phase γ' and other is a metastable phase. After calculation of lattice parameter by reduced cell method, the metastable phase is an orthorhombic structure of a=0.2355 nm, b=0.4157 nm and c=0.1683 nm. It was also proved experimentally that boron alloying does not influence the formation of laminar structure.

An addition of Ti as alloying element to Al--Si binary alloy will reducethe undercooling--ability on rapid solidification of the melt--spun ribbon. Themicrostructure will be encoarsened even at inititation of its solidification, so as to ag-gravate the cellular segregation of Si in the alloy ribbon.

An optimal two--dimensional transverse section of eutectic cells or ellipsoid austenite dendrites in the grey cast iron specimen was prepared by polishing layer by layer to- gether with etching and coloring. The segregation of Mn and Si with relation to their contents in the grey cast iron was examined by EMPA. The actual partition and segregation coefficients of Mn and Si in the grey cast iron were found to be not varied with their contents, but their segre-gation gradient to be different to various contents of them.

The softening of stainless steel 316 of non--detectable difference in magnitude induced by thermal pulse was found during fatigue with strain amplitude of 1.17×10~(-4) in temperature range of 333--573 K. And it occurred if the measurements of fatigue with thermal pulse were performed in range of 333--503 K. However, it will become of the hardening in range of 503--573 K. The temperature, at which hardening of the steel induced by thermal pulse emerges in fatigue process, increses with the increasing in strain amplitudes.

Hydrogen damage in Fe of 99.99% purity has been investigated by Doppler broadening measurement. Experimental results show that when the iron is charged with hydrogen in 0.5 mol / L H_2SO_4 so-lution, the critical current density to cause hydrogen damage is 20 mA / cm~2. While a little As_2O_3, saying 250 mg / L, added to H_2SO_4 solution, even rather small current density, <0.2 mA / cm~2, would cause hydrogen damage. With the help of slow tensile test, it revealed that the hydrogen damage occurred in the specimen may be influential to the subsequent process of deformation and fracture.

Activity of TiO_2 in the molten blast furnaee slag containing titanium oxide has been examined at 1500℃ by means of "molten slag-Sn" chemical equilibrium method, using metallic Sn as flux and graphite as deoxidizer, together with phase diagram calculation. In the pentary slag sys-tem CaO--MgO--SiO_2--TiO_2--Al_2O_3, a_(TiO_2)=0.01--0.05 or 0.02--0.10 with pure liquid or solid TiO_2 as normal state, respectively. The activity and activity coefficient of TiO_2 in relation to concen-tration of titanium oxide have been discussed.

The kinetics of oxygen evolution reaction (OER) on PbO_2--Ti/ MnO_2 elec-trode has been studied using galvanistatic technique. In terms of kinetic parameters, the reac-tion path of OER is proposed. The electrocatalytic activity of lead dioxide and manganese dioxide has been discussed according to the theory of molecular orbit and quantum chemistry calculation. It is concluded that the electrocatalytic activity of manganese dioxide is higher than that of lead dioxid, which is in agreement with the experimental result.

The corrosion rate, together with corrosive wear and corrosion coefficient under load, of CD--4MCu alloy in 69% H_3PO_4 or 69% H_3PO_4+500 ppm NaCl solution was measured,and the morphology of their wear tracks was then observed by SEM. The CD--4MCu alloy isrevealed to be superior in corrosive wear resistance to 304 stainless steel and even to Carpenter 20Cb_3, a high corrosion resisting alloy. From its features of duplex phase structure, it could be suggested that the weight loss related to mechanical factor was improved by existence of austenitic phase due to its deformation strengthening.

Studies were made of the effect of mechanical pulverization on relaxation,crystallization and brittle--ductile transition of the anneal--embrittled Fe_(75)Si_(10)B_(15) metallic glass ribbon. Results show that the Curie temperature, T_c, decreases and the total enthalpy of relaxa-tion increases gradually with variation of pulverized time. DSC traces reveal an extra exothermicpeak, T_(x_1), and a distinct glass transition endothermic peak, T_(g_1), with increasing pulverizedtime, T_c, T_(x_1), and T_(g_1) decrease simultaneously, and the exothermic peak area correspondingto T_(x_1) increases gradually. The surface slip--steps of flaky particles and their corresponding shear are produced by pulverizing the pre--embrittled amorphous glass. The lost ductility of theglass may restore during annealing.

Curie temperature of amorphous alloys Co_(90-x)Cr_xZr_(10)decreases linearly with increasing x. Average magnetic moment per magnetic atom Co or Cr is 1.51 μB or --3.62 μB respectively. The temperature dependence of spontaneous magnetization at low temperatureis in agreement with Bloch's T~(3/2) law. The spin wave stiffness constant decreases with increasing x from 4 to 20. The range of interaction is 2--3 atoms for x=4 and neighbourest atom for x=20. The crystallization temperature increases monotonically with increasing x. It may be related toaverage number of outer electrons per atom. The crystalline phase components of heat-treated alloys were analyzed by X--ray diffration and thermomagnetic measurement.

Effects of isochronal annealing on the positron annihilation of glassy Bi_(1.6)Pb_(0.4)Sr_(1.9)Ca_2Cu_(3.1)O_y(BPSCCO) have been reported. It is shown that the crystallization in- fluences obviously the positron annihilation characteristics of BPSCCO. A maximum is found inthe region of crystallization temperature in curves of mean lifetime and peak / wing ratio, one of Doppler lineshape parameter, with annealing temperature; the bulk lifetime of positron annihi-lation in the glassy state is longer than that in the crystalline one. Positron annihilation spectroscopy could be used for studying structure of glassy BPSCCO and its change with heattreatment.

Enrichment of massive graphite on lateral surface and evident macro--segrega-tion along both longitudinal and axial directions were found by the influence of intense electromagnetic stirring during unidirectionally solidifying grey cast iron ingot. A secondaryflow within the region near solid--liquid interface seems to be the cause of axial segregation, and the solidification rate may also be influential to the macro--segregation.

The convection patterns were observed in laser cladding layer of FeCrSiB alloy.Laser beam symmetry, dilution of cladding layer by substrate, etc. with relation to convection patterns have been investigated. Macro--segregation and macroalloying in the cladding layer were found to be resulted by convection. The dilution rates of substrate materials into cladding layer are directly influential on microstructure and performace of the cladding. Ideal laser clad-ding conditions require that there is a minimum of dilution.

ZHENG Minhui;CHEN Yisong University of Science and Technology Beijing

The amorphizing transformation of Al--Y--Ni system by mechanical alloying was investigated in both thermodynamic and kinetic aspects. The amorphous powder of Al--rich composition Al_(8o)Y_(15)Ni_5 was formed after 70h milling. The process of the amorphization was monitored by X--ray diffraction. The depen-dence of the amorphization on the milling intensity was also discussed. The result shows that over milling with extra-high intensity has an unfavourable effect on amorphization of the system.