The fine structure and crystallography of lower bainite produced in an exgerimental steel 38Si2Mn2Mo isothermally treated at 320℃ were studied using TEM. The lowerbainite contained midrib, subunit, retained austeuite and ε-carbide, and high density of dislocation exist in both the bainite and retained austenite. The habit plane (HP) of the bainitemeasured by double edge-on trace analysis was found ciose to {11,7,15}f, while its orieatationrelationship (OR) with the austeuite matrix was the G-T one. The bainite plates were related toeach other by a relative rotation of about 54.7° or 60° about the normal to their common planes{110}b, which resulted in an approtoate {112}b twin relationship between adjjacent plates. TheOR and HP of the lower bainite were found identical with, and close to tho1122se of the lath martensiterespectively, all in reasonable agreement with the predictions from the phenomenological theoryof martensite crystallography (PTMC). All these results show that the bainitic transformationpossesses the characters of matensitic transformation.

A non-linear fitting program based on Bevington method is designed to fitthe internal friction temperature spectrum. A spectre consisting of utmost six peaks with alognormal distribution in relaxation tabs and an exponential background could be fitted by theprogram. Upon this program, the relaxation paramaters of bamboo grain boundary peak inpure Al are analyzed quantitatively. It shows that the relaxation strength decreases with thedescending of peak temperature.

The liquid metal-induced embrittlement (LME) of 7075 aluminum alloy was investigated by using a special constant deflection device. The change in dislocation configuration ahead of a loaded crack tip for 7075 aluminum alloy before and after adsorping of Hg+3%Ga atoms, and the initiation of liquid metal-induced microcrack have been observed in TEM. The results showed that chemisorption of liquid metal atoms could facilitate dislocation emission,multiplication and motioll. When the chemisorption - facilitating dislocation emission and motionreach to a critical condition, a microcrack will initiate in dislocation free zone (DFZ) or at the crack tip, and propagate in cleavage mode.

The influences of melt spun parameters and dricro-addition of cerium on thermal stability of amorphous Fe-B-Si alloys have been studied. The higher cooling speed foras-quenched amorphous ribbon, the more difficult for structural relaxation in low-temperatureannealing process. Experimental results show no direct relationship between the quenching condition and crystallization for Fe80B11.5Si8.5 metallic glass. Optimal addition of cerium obviouslyretard the ductile-to-brittle transition process in structural relaxation stage, when annealingtemperature is low. At high temperature annealing stage, the addition of cerium lowers the onsettemperature of crystallization; and this effect is in direct proportion to the content of cerium inribbons.

In site synthesis of high toughness wear resistance coating alloy Fe-Cr-W-Ni-C(mass ratio are 10: 5: 1: 1: 1) by laser cladding was investigated by SEM and ATEM.Hypo-and hyper-eutectic microstructures, i.e., γ+(γ+M7C3) and M7C3+(γ+M7C3) are obtained while there are competition and selection of the primary phase. The γ-austenite ismetastabe phase with extended solid solution of alloying elements and a great deal of struc structures. There appear various morphologies of eutectic carbide, such as lamellar, honeycomb,herringbone, and network. During high temperature aging, the precipitation of M23C6 and M2Ccarbides from austenite and in site transformations of M7C3 →M23C6 and M7C3 → M6C areobserved in hypo-and hyper-eutectic ndcrostructures respectively. Based on the experimentalresults, transformation mechanism during rapid solidification and thermal aging are proposed.Two microstructures have evidently secondary hardening and the corresponding peak temperatures and peak microhardnesses (HV0.2) are 923 K, 1050 and 963 K, 1250 respectively.

The effect of silicon on the damping capacity of Fe-Cr-Al alloy has beeninvestigated with the inverted torsion pendulum teclmiques. The results indicate that, smallamount silicon (app. 1% mass fraction) addition to Fe-Cr-Al or substitution of silicon foraluminum in Fe-Cr-Al alloy can make the damping capacity of the alloys higher than that ofFe-Cr-Al alloy when annealed below 1273 K; substituting silicon for small amount aluminum inFe-Cr-Al, the damping capacity of the alloy is much higher than that of Fe-Cr-Al alloy whenannealed above 1373 K followed by air cooling. The curves of logajrithmic decrement versus strainamplitude reveal the damping of the alloys resulting mainly from magonetomechanical hystereses.

The degradation mechanism of cracking tube material during service was discussed on the basis of analysing the structural morphologies of the HP tube used. The resultsreveal that the carbide-free zone and carburized zone in the inner wall of tube is closely associatedwith the spalling and regeneration of surface chide layer, the formation of intergranular attackzone, the diffusion velocity of carbon and alloy elements in matrix and the solution limit of carbonin alloy. The formation and growth of filament catalyzed coke promote the structure degradationof inner wall of cracking tube, while the deposition of non-catalyzed gas coke can alleviate thedegradation degree of tube material to some extent. The cycle operation of coking/decoking isthe main reason for material degradation of cracking tube in service.

The mass percentages of δ phase in Inconel 718 cold rolled to different reductionsand then treated at different temperatures for different times were measured by X-ray diffraction,and the effect of cold rolling on the kinetics of δ phase precipitation was investigated. Therelationship between the mass percentage of δ phase and annealing time follows the Avramiequation. At 960℃, cold rolling has a little effect on the time exponent (n) and the rate constantof δ phase (α). Below 910 ℃, as cold rolling reduction and annealing temperature increases, theValue of n decreases, whereas the value of or increases. The relationship between the rate constantof δ phase and temperature follows Arrhenius equation. As cold roiling reduction increases,the apparent activation energy of δ precipitation decreases. Cold rolling promotes the γ" → δtransformation. According to the kinetics of δ precipitation, the precipitation-temperature-time(PTT) curves of δphase were given.It has been found that the C curve shifts left as cold rolling reduction increases.

An experimental study was carried out on the cyclic properties of pure coppersubject to nonproportional cyclic loading.The biaxial nonproportional cyclic strap testsfor circular and rhombic strain paths, and the cyclic cachetting tests for four nonpmportinnalcyclic paths with mean stresses were conducted. The operiment shows that the evolutionsof plastic strain rate direction and plastic modulus depend strongly on the shape aam equivaleatstrain amplitude of the strain path, and the nonproportional cyclic rstchetting behaviour dependssiedcatly on the shape and the amplitude, the mean stress and the mean stress history ofloading path.

After analyzing of the collision during the process of ball milling, an anglefactor is introduced, and a theoretical relationship between the physical parameters of powders(such as the deformation and the temperature rise, etc.) and the tecbocal parameters of ballmilling and the angle factor is settled. The temperature rise of powders can be expressed as △Tand the direct and shearing strain are respectively. It showsthe deformation and heat effect are determined by milling parameters, the angle faCtor and thepowder materials. The model in this paper is compared with the Maurice model.

By means of pattern recoghtion technique the principal factors affecting thetensile strength and hardness of automobile cylinder block cast are discussed, and their optimizedrange determined also. Aritificial neural network, trained by known data, has been used topredict the values of both tensile strength and hardness. The predicted results agree well withthe experimental ones. It has been demonstrated that the mentioned optidsation techniqueprovides a technical approach to disprove the tensile strength and hardness of cylinder block castof automobile engine.

Theoretical analysis indicates that in order to make the yield strength and thethreshol stress for hydrogen-induced failure in H2S solution of the tubular steel satisfy theAPI standard, S, P and Si must be as low as possible, temper temperature should be as high aspossible and C, Mn, Cr and Mo are used as alloy elements. The contents of C, Mn, Cr and Moare determined based on the experimental design using the data in the datum bank. Accordingto the designed compositions and technology, the Plant has produced qualified C90 tubular steelsfor 1400t.

During dynamically charging four kinds of C90 tubular steels with hydrogen,the concentration of divisible hydrogen c0 is directly proportional to cathodic current i, and thenormalized threshold stress σc.(H)/σt decreases linearly with hi c0, i.e., σc(H)/σt=A-B ln c0.The concentrations of diffusible hydrogen in the steels during immersing in the H2S saturationsolution, c0*, have been measured. The values of σc(H)/σt during dynamically charging withic corresponding to c0* for the four steels are consistent with the threshold stress σc(H2S)/ctduring SCC in H2S solution. The result shows that the threshold stress during charging with asuitable current density ic can substitute for the threshold stress during SCC in H2S solution.

The effect of phosphoric acid surface treatment on oxidation resistance of TiAlintermetallics was investigated. The results showed that this surface treatment reduced theoxidation rate of TiAl by one order of magnitude, and it is very effective in improving the cyclicokidation resistance. It is determined that the improvement of the oxidation resistance was dueto the formation of a nearly continuous inner A12O3 layer.Keywods:TiAl intermetallics, isothermal/cyclic oxidation, surface treatment

The okidation of pure Fe and Fe-Ce alloys containing 2 and 5 Ce (atomicfraction,%) has been studied at 600-800℃ in air. The okidstion curves of pure Fe at 600, 700and 800 ℃ follow the parabolic rate law. The oxidation curve of the Fe-5Ce at 800 ℃ followsthe approximately parabolic rate law, but includes two distinct parabolic stages at 600 and 700℃. The Fe-2Ce goes through an appropriately parabolic oxidstion at the three temperatures.The Fe-2Ce and Fe-5Ce alloys are oxidized slower than pure Fe at 700 and 800 ℃ except inthe initial oxidation stage of the Fe-5Ce at 700℃, while go through a faster oxidation thanpure Fe at 600 ℃. Besides three Fe chides, double chide CeFeO3 also forms in the inner part ofthe scale. Nevertheless, only Fe oxides and CeO2 form in the case of the oxidation at 600 ℃Moreover, FeO only accounts for a small part of the total Fe oxides. Additionally, the effect ofCe in the oxidation of the Fe-Ce alloys has been discussed.

Metal/semiconductor Fex (In2O3)1-x granular films were prepared by the rfsputtering. The microstructure was studied by using XRD, TEM and magnetic measurements.The results showed that the nanometer-sized Fe particles uniformly dispersed in the amorphousIn2O3. Appropriate annealing leads to the crystallization of In2O3 films and the growth of theFe particle size. As a result, the magnetic behavior of the films transits from superparamagneticto ferromagnetic. The variation of the lattice constant for In2O3 depends on the volume fractionof Fe particles.

Effects of Co concentrations on the structure and magnetic properties of Fe-Nfilms were investigated. Experimelltal results show that the saturation magnetic polarization Jsof (Fe,Co)-N films with 0-15%Co (atomic fraction) increases with the Co content, reachinga maximum value of 2.7 T at 15%Co, and then decreases with the increase of the Co content to30%, but the Js of (Fe,Co)-N film with 30%Co is still larger than 2.4 T, which is the maximumJs value of Fe-Co alloy. The Js of (Fe, Co)-N films with 35%Co is smaller than that of 2.4 T,but it is larger than that of pure iron (2.1 T).

The failure behaviors of ZrO2/Ni graded thermal barrier coatings under the conditions of thermal shock with fiame jet and water quenching have been studied. The one-dimensi-onal analytic model of temperature and stress field under these conditions for the coatings hasbeen established. The thermal shock resistance of coatings increases with the increase of layersunder the condition of fiame jet and decreases with the increase of layers under the condition ofwater quenching, which can be reasonably explained with the present model. The thermal shockresistance depends on the thermal shock conditions, and is determined by the magnitude anddirection of the surface heat exchange coefficiellt. Therefore, it is necessary to choose suitablethermal shock condition to evaluate the ability to resist shock of coatings. For thermal barriercoatings which are applied to the turbine blade of aeroengine or under the matchable thermalshock conditions, gradient structure mny sigIilficantly improve their ability to resist thermal shock.

The microstructure and mechanical properties of cast Fe-Cr-Ni matrix composite reinforced by TiCp synthesized with liquid state in site process have beed studied. Thecomposite is composed of γ-matrix and spherical or nodular TiC phase which is dispersed inmatrix uniformly with sizes of 1 -5μm. The interface between γ and TiC phase is net andclean. Dislocation with high density edests in matrix and TiC phase close to the interface. Thetensile property of the composites with the addition of 3% - 6% (Ti+C) is improved obviouslycomparing with that of the matrix alloy at ambient and high temperatures. The fracture surfaceof the composite with the addition of 6% (Ti+C) is of ductile feature at high temperature.