An experimental investigation was carried out of the flow characteristic andhardening of normalized steel 16Mn subjected to biaxially nonproportional cyclic straining.For a fixed cyclic strain path, the steel behaves mainly cyclic softening when the amplitude ofstrain is small. While with the increase of strain amplitude, the softening disappears gradually,and even changes to cyclic hardening for certain strain path. The hardening of the steel mayrelate to the shape of strain path under nonproportional cyclic straining. Experimental resultsshow that there exists a coupling between the hardening/softening induced by strainamplitude and that by the strain path. The memory of the steel to the history ofnonproportional cyclic hardening and the validity of Lensky's hypothesis of localdeterminability were also examined.

The damage behaviour of Fe-Cr-Mn alloys during electron irradiation isshown to be different from that in Fe-Cr-Ni alloy. The difference appears to be a conse-quence of the different diffusion behaviour of Ni and Mn due to interaction between soluteatoms and point defects. Especially the interaction between Mn atoms and vacancies inFe-Cr-Mn is strong so that the migration energy becomes greater than that in Fe-Cr-Ni al-

Lower bainitic carbides in a steel 200Cr12 have been observed under TEM toprecipitate in front of superledges on the broad faces of lower bainitic ferrite plates, and to bewedge-shaped. The root of a wedge-shaped carbide originates at the junction of the riser andterrace of a superledge while the tip penetrates the austenite matrix. A lower bainitic carbidenucleates in front of the riser or in the γ matrix near the α/γ boundary, and also in theaustenite between two bainitic ferrite subplates. But wherever it nucleates, the carbide willgrow only towards the remained austenite. The nucleation and growth model of lower bainiticcarbides is proposed.

The thermal stability of Ti-24Al-11Nb-3V-1Mo alloy was studied after ex-posure at 650--750℃ for different time. The bending strength σ_(bb) and flexibility f decreasedwith increasing exposure temperature and exposure time in air, while only a little change ofσbb and f was noticed when samples exposed under vacuum in the same condition. This is dueto the formation of a brittle oxygen-enriched layer adjacent to the surface of material, inaddtion to the formation of TiO_2 on the surface after exposure in air. Thermal exposure of al-loy results in the change of microstructure, i.e., forming the "O" phase, which is not the ma-jor factor causing the degradation of mechnical properties.

The melting behaviors of directionally grown eutectic structures of Al-Cu,AL-Ni and Al-Si alloys have been investigated using directional solidification/remeltingtechnique. No complete reversibility of processes between melting of eutectic structure and itssolidification was revealed. The melting processes of eutectic structures, not only regularlamellar or rodlet but also irregular lamellar, may be that the two component phases of aneutectic structure are priorly decomposed on the melting interfaces simultaneously, and dis-persed into liquid region as their own phases, then these disperse phases of different composi-tions dissolved further to form a homogeneous single liquid phase at higher temperatures.

By investigating the criteria of slip initiation,fatigue fracture and surfacecrack propagation in a carbon tool steel under combined stresses, fatigue features of smoothand cracked specimens are discussed from the point of view of local stress. Results show that,for short cracks, linear elastic fracture mechanics is applicable provided that the nominalstress is smaller than the slip initiation threshold stress of the material, and the size of plasticzone around a crack tip is almost a constant regardless of the crack length and deformationmode under threshold condition.

The deformation and fracture behavior of an Al-Li alloy have been investi-gated under slow tensile loading. The relatioship between stress intensity factor and crackgrowth rate has been determined for various aging conditions of the alloy. Plasticdeformation mechanism, microfracture mode and crack growth resistance are different forvarious aging temperatures due to various microstructures. It was indicated that the strainlocalization was the reason for low plastisity and the strain localization closely related to thestate of grain boundaries. The relation between macroproperties and microdeformation char-acteristics has also been determined.

The morphology and feature of hot cracks in liquid forged steel flat frangeshave been observed. Once the cracks occur, they will propagate throguh 4 stages, and revealthemselves obviously as 4 featured zones. The growth of the hot cracks seems to be depen-dent upon certain technological factors, such as: liquid steel quality, solidification and stressedstate on workpieces, etc.

A mathematical model to represent the fluid flow, temperature distributionand mass transfer in raceway of blast furnace has been developed. The model is used for pre-dicting the velocity, temperature, and concentration field of raceway in different operationconditions of blast furnace. Results contribute to the understanding of the transport processinvolved in such a system. The model can also be used for optimising the blast furnace opera-tions and the calculation of combustion of pulverized coal.

The concentration distribution curves for Cu in the diffusion couples of Cemodified 2090 alloy with pure Al under different diffusing conditions have been measured.The Cu diffusion coefficients have been calculated by Boltzman-Matano method. The resultsindicate that adding minor Ce in the alloy may reduce the Cu diffusion coefficients. The Cudiffusion coefficients relates to its concentration distributions and gradients in the diffusioncouples. In general terms, the effect of adding 0.40% Ce on the Cu diffusion rate is generallysimilar to that of adding 0.23% Ce in the alloy.

Phase relation of the system Na_2O-Ga_2O_3 containing more than 50mol%Ga_2O_3 was investigated by DTA and room temperature X-ray powder diffraction an-alyses. It was found that four compounds Na_2O·Ga_2O_3, 2Na_2O·3Ga_2O_3, Na_2O·3Ga_2O_3 and Na_2O·5Ga_2O_3 exist in the system. The compound 2Na_2O·3Ga_2O_3 decom-poses to Na_2O·Ga_2O_3 and Na_2O·3Ga_2O_3 at temperature above 976±8℃. Na_2O·Ga_2O_3, Na_2O·3Ga_2O_3 and Na_2O·5Ga_2O_3 melt all incongruently at 1382±1℃, 1285±5℃ and 1417±4℃ respectively. The previously unindexed X-ray diffraction data for2Na_2O·3Ga_2O_3 and Na_2O·3Ga_2O_3 are reported.

The short-time hot corrosion kinetics of Ni_3Al in the presence of a salt film(about 2mg/cm~2 (Na,K)_2SO_4) in O_2-0.5%(SO_2+SO_3) atmosphere at temperature range of600--850℃ has been studied by thermal gravimetry, chemical analysis, X-ray diffraction,metallography and SEM. Low temperature hot corrosion occured in Ni_3Al due to the forma-tion of liquidNi-Na-K sulphate eutectic phase. The corrosion rates reached maximum at750℃ in the condition mentioned above. Moreover, the effects of O_2/SO_2/SO_3 gas, saltfilm and CoCrAlY coating on the hot corrosion behavior of Ni_3Al have also beeninvestigated. The salt film may accelerate the oxidation of Ni_3Al in air, and CoCrAlY coatingmay improve the corrosion resistance of Ni_3Al in same environment.

Influence of tensile stress on the composition of surface oxides on the alloysNi-23Al-0.5Zr-0.1B and Ni-17Al-8Cr-0.5Zr-0.1B(at.-%) was studied. NiO content inthe oxide scale may increase obviously under tensile stress. Thermodynamic analyses showsthat, during oxidation, the volume expansion of Ni and Al are different, and the tensile stressmay influence the enrichment of NiO in oxide scales so as to reduce the elastic deformationenergy.

The (Er_(1-x)Sm_x)_2Fe_(17)C_y(x=0.2, y≤3.0; x=0.5, y≤2.0) compounds with a2:17-type single phase structure were prepared by melt-spinning. The formation, structure,stability and intrinsic magnetic properties of these carbides were studied. The experimental re-sults show that these carbidek are stable at high temperatures. With increasing carbon concen-tration x, their crystal structure changes from the hexagonal Th_2Ni_17-type to rhombohedralTh_2Zn_(17)-type. The introduction of interstitial carbon atoms results in the expansion of theunit cell volumes and the increase of the room temperature saturation magnetization andCurie temperature. The (Er_(1-x)Sm_x)_2Fe_17C_y carbides with y≥1.0 are found to have an easyc-axis anisotropy at room temperature.

In the present paper, the synthetical soft magnetic properties are reported fornewly-developed nanocrystalline Fe_(7l.5)(CuCrV)_(7.5)Si_(12)B_9 alloy. The levels of the typical mag-netic properties achieved in this new alloy are as follows. D.C. initial permeability μ_i=10.9×10~4, coercivity H_c= 0.56A/m, flux density B_80=1.04 T corresponding to H_m=80A/m;under the condition of the constant H_m=0.08A/m, a.c. effective permeability μ_e= 2.5×10~4 and 0.4×10~4 corresponding to f=0.1 and 1 MHz, respectively; core lossesP_2/100_k=195kW/m~3, P_2/200k=664kW/m~3, P_2/500k=3349kW/m~3 and P_(0.5)/1000k=720kW/m~3. The high-frequency core losses of the new alloy clearly are lower than thoseof Fe-Cu-Nb-Si-B nanocrystalline alloys and much lower than those of the superior powerMn-Zn ferrite H_(7C4). The application of the new alloy to switched mode power supply is also

To eliminate the deposition along BaCuO_2 grain boundaries, the 211(Y_2Ba_2CuO_5) powder was properly doped to the 123 (YBa_2Cu_3O_(7-x) compounds. Sufficienttime for mass transfer along a-b plane was allowed by lowering the cooling rate nearby thetemperature of peritectic transformation. Since the plane a-b is the fastest growing one, thelength of grains is controlled by the rate of mass transfer. XRD, SEM and EDXA analysesrevealed that the grains are strip-shaped, their orientation is perpendicular to c-axis and par-allel to surface a-b plane. Thus, the compound 123 (YBa_2Cu_3O_(7-x) has a strong texturalstructure.

Superplastic welding of steels 40Cr-CrWMn, with prior surface treatment oforganic solution protecting coating after thermo-mechanical treating, may be performed inair in a furance under conditions: temperature ranged 750--780℃, strain rate 2×10~(-4) s~(-1),pressure 50--90 MPa, and time 3--5 min. The welds seem to have similar strength to the basesteel 40Cr. The microstructure of welds was analyzed under SEM and TEM. Themicromechanism for superplastic welding of steels was suggested as the disappearance of orig-inal bond interfaces caused by atomic diffusion and grain sliding during superplasticdeformation.