Stress relaxation study of commercial pure titanium under tensile de-formation shows that the stress relaxation behaviour of it relates to the level ofdeformation. The relaxed stress △σ is independent of amplitude of stress dip in therange of certain deformation, and it is dependent of stress level at beginning ofstress relaxation in determined relaxation time t_R. The back (critical) stress σ_c andflow stress σ_c exhibit same change with the strain. The effective stress at the dislo-cation in materials σ~* increases with increasing strain ranging under low strain, andkeeps constant under higher strain.

The characteristics of the low freqency internal friction and moduluseffect associated with the non-equilibrium spinodal pretransformation and the follow-ing discontinuous transformation was investigated in an as-quenched eutectoid Al-Zn alloy. It was observed that the loss of the stability in the Iattice, which corre-sponded to the large-amplitude long-wavelength static concentration wave in thenon-equilibrium spinodal pretransformation, did not induce any effect of localizedsoft modulus. Although there are two aging internal friction peaks in phase transfor-mation which correspond to the appearance and disappearance of the coherency andthe maximum of the interface area in the discontinuous transformation, respectively,the effect of localized soft modulus did not take place yet.

Based on the feature of crystal sites occupied by alloying elements, amodel cluster, investigating the interaction mechanisms of nonmagnetic element Cuin RECo_5 type alloy, has been presented. The electronic structure has been calcula-ted with SCF-X_α-SW method. The calculating results show that, after Cu replaced2c crystal site Co, the energy spectrum of the model cluster will move towards shal-low trap potential, energy gap will become small, the charge among the atoms willredistribute, and some new states to which impurity contributes will produce. Partial-wave local density of states gives the interactions between atoms. Results of Hellm-man-Feynman force show that thermal expansion anisotropy of the model clusterdecreases considerably after Cu substitutes for 2c crystal site Co.

Based on the thermodynamics of phase transformation, a linear relation-ship between the starting temperature of martensitic transformation and the recipro-cal of the squareroot of grain size has been obtained, i. e. M_s temperature decreaseswith the increasing grain size. It shows a good agreement with the results of elec-tric resistance measurements. Application of Landau's theory gives a quantitative re-lationship between M_s temperature and the ordering parameter of the parent phase,which is well confirmed by the results of X-ray diffraction and electric resistancemeasurements. The activation energy of the DO_3 ordering process in the parent phaseof the alloy is calculated to be 46 kJ/mol.

A theoretical expression for the driving force and M_s point of mar-tensitic transformation has been proposed. The M_s values calculated using this exp-ression are in good agreement with that obtained experimentally. It was foundthat the values of M_s and M_f are not only related to the carbon content in mar-tensite, but also to the volume fraction of ferrite.

The variations of structures and properties of some structural steelssubjected to tempering at a series of temperature after austempering or continuouscooling at certain rates, have been investigated. Based on the experimental results,the behavior and mechanism of the tempered bainite embrittlement have been dis-cussed.

The effect of different microstructures of steel 30CrMnSiNi2A on thesusceptibility of cadmium embrittlement has been studied and compared under theunique yield strength level. The results show that the tempered martensite exhibitsthe maximum susceptibility to cadmium embrittlement, while the lower bainite showsthe minimum susceptibility. The mixed microstructure of the above two has asusceptibility in between.

Nb single crystals of both [321] and [110] orientations have been cy-clicly deformed in tension-compression at constant strain rate 8×10~(-4)s~(-1) over arange of plastic strain amplitudes between 10~(-3) and 10~(-4). The cyclic hardening, thechanges in shape of crystals and the asymmetry of stress have been studied. Thehardening curve can be divided into three stages, i. e. first, rapid-hardening andsaturated stage. In the first stage of cyclic hardening curve dominant features of dislocationconfigurations are high density networks and debris loops. In the rapid-hardeningstage the main feature is the formation of dislocation bundles. In the saturateda well defined bundle structure fully develops and between them it is filled withonly screw disloca tions and the imposed strain is accommodated mainly bythe motion of screw dislocations travelling to and from between the bundles.Three-dimention cell, two-dimention cell or bundle structures are summarized as thesaturated structures of bcc metals.

The crack tip stress-strain fields of the elastic-plastic cracked speci-mens have been analyzed using finite element calculations, the crack initiation andsteady propagation behaviours have also been investigated by means of slip linepattern etching technique and mechanical tests. The results showed that there areHRR near field and distant field in the crack tip region, the latter depends on thespecimen configuration. The crack initiation behaviour is controlled by the singleparameter J, in contrast, the crack steady propagation is affected by the distantstrain field and can not be described by single parameter only.

DSA pre-treatment processes increase remarkably the fatigue strengthand the strenthening effects increase with increasing prestrain temperature and pre-strain. TBM observation shows that the uniform and stable dislocation networkswith high density form after DSA pre-treatment, which suppress effectively the in-ititation and propagation of fatigue crack and increase the fatigue strength.

The morphology, subtructure and crystallography of martensite insteels 60 and 60Si2Mn have been Studied by means of optical and transmission elec-tron microscopy combined with B-M phenomenological crystallographic theory. Theaverage habit plane of martensite in medium carbon iron alloy is {225}_f. Experi-mental observations on habit plane and O-R are in agreement with the B-M theoryby using the Bain strain and lattice invariant shear on (100) [011]_f.

Creep behavior of Fe-15Cr-25Ni alloys with different grain boundaryfeatures has been investigated. The single-phase alloy exhibits typical recovery creepcharacter, and for the alloy with M_(23) C_6 precipituted at grain boundaries, the creeprate largely decreases and the creep behavior is also different from the former.Creep mechanisms for two grain boundary features have also been discussed.

The tendency of spalling of the nitrided layer of the hot rolled austenitic steel 4Cr-14Ni14W2Mo exhibits close relation to the nitrided surface orientation relative to the rolled steelrod It is found that the dislocations in the imperfactly recrystalized steel align as parallel dislo-cation walls in macroscopic extent, and the thickness of "white sublayer" in the nitrided layeris much larger at the surface which is parallel to the dislocation walls. At such surface spallingof the nitrided layer happens often.

A new kind of planar defect named non-basal plane stacking faults has been stud-ied using trace analysis and lattice image technique. It has been found that they are located in(125)_M plane of martensite lattice. By lattice image observation, the non-basal plane stackingfaults are argued to be induced by two incomplete basal plane stacking faults and may be theresults of fast quenching. The defects are regarded as anomalous structures of martensite.

The snap-action behavior of a NiTi alloy disk which is controlled by combinationof a nonlinear stress field and temperature has been studied. After treatment for two-way shapememory, all shape memory strain of snap-action finishes abruptlyat certain temperature within aintertal of less than 1ms. The results of resistance measurement and in-situ X-ray diffractionindicate that, snap-action strain is mainly resulted from snap-action β→?R transformation.

The microstructure of a laser-melted Fe-4%C-10%Sn alloy has been studied. A non-crystalline phase was found in the upper pard of the laser-melted zone. At the bottom of themelted zone, however, the microcrystalline zone which consists of α-Fe and a bct phase was ob-served. Fine twin martensite exists in the other area of the melted zone. The analytical solutionfor the moving Gaussian source model was successfully used to predict the geometry of the laser-melted zone and the cooling rate.

X-ray diffraction Fourier profile analysis has been performed for polycrystallineα-brass plate with 31.55 wt-% Zn after a series of uniaxial tensile tests with differentstrain rates.Dislocation density ρ and configuration parameter M may be presented as a function of appliedstress σ_a. A mechanism of alternative long-range and short-range strain hardening has been pro-posed.

A new equipment and method for measuring the kinetics of carboncombustion in plasma air have been designed. The activation energies of graphitecombustion in this condition have been given:E_1=74.780 kJ/mol (900--1560K)E_2=44.720 kJ/mol (1560--2100K)

A mathematical model to represent the fluid flow, temperature distri-bution and mass transfer in CVD reactors has been developed. The model is usedto predict the velocity, temperature, and molar concentration profiles in the taper-ed annulus of a reactor for silicon deposition from SiCl_4 in H_2. Results of theinvestigation contribute to the understanding of the transport processes involved insuch a system. The model can also be used for optimizing the design parameters,such as inlet flow rate, susceptor tilt angle, etc.

A direct reaction process for producing high T_c spuerconductor YBa_2-Cu_3O_x has been proposed. The T_c of it is 90--94.5 K and △T is 1K. The phaseequilibria in system Y_2 BaCuO_5-Y_2Cu_2O_5-CuO-YBa_2Cu_3O_x were studied and discussed.

The increase of thickness of carbide layer during carbide diffusioncoating is proportional to the root of carbon activity in various steels. Thus it wasdemonstrated that the controlling factor of the dynamics of carbide layer growthis carbon activity in steel matrix, but not carbon concentration.

The diffusion coefficients of La in liquid Al-Si alloy have been mea-sured successfully with anodic chronopotentiometry. At 973K the diffusion coef-ficient of La in liquid Al-5.2-wt%Si alloy D(L_La(Al-s?)) equals (0.91±0.01)×10~(-5)cm.s~(-1). In the range of temperature 953--1053K, the relationship between diffusioncoefficients and temperature is represented by lgD_(La(Al-Sl))=-1.78×10~(-3)-4909/T.The activation energy Q=94.00kJ.mol~(-1). Using the diffuaion data of La, Sr, the in-fluence of the diffusion of modificator on the incubation period of modificationeffect and critical cooling rate has been discussed.

The stable ranges concerning composition and temperature have expe-rimentally been determined for the intermetallic compounds in high-temperature re-gion of Fe-Cr-Mo system. The isothermal section of the Fe-Cr-Mo ternary phasediagram at 1250℃ and the formation reaction for the imtermetallic compounds,which are different in part from those shown in the literature have been proposed.

The microstructures of both as-cast and annealed Nd-Fe-B alloys havebeen studied. The stable phase regions existing in Nd-Fe-B ternary system at room-temperature have been established by the microzone composition analysis and thephase identification. Based on the obtained results, an isothermal section of Nd-Fe-Bternary system at room-temperature was drawn.

According to the experimental date of phase transition taken fromDTA, metallography, SBM and microzone composition analysis, two vertical sectionsof the ternary phase diagram (B=5.88 at.-%, Nd≤45.41 at.-% and Nd_2Fe_(14)B-Nd_(1.1)Fe_4B_4, B≤44.56 at.-%) have been drawn in detail. It is verified that crystallizationof both Nd_2Fe_(14)B and Nd_(1.1)Fe_4B_4 phase, during cooling from melt, would take pe-ritectic reaction instead of solid-liquid congruent precipitation.

The structure of white iron treated with Si-Bi-Al complex inoculanthas been observed by means of SEM and TEM. The results show that, in compari-son with the samples treated with ordinary inoculants, disorder, overlapping andinflexion of the pearlitic lamella appear, besides, the dislocation density increasesapparently. The graphitization can be quickly realized at the temperature lower thanthat of austenitic transition (720℃)

The interaction of oxide film with molten flux during aluminumbrazing has been studied by means of X-ray powder diffraction. The following con-clusions have been deduced: The swelling of aluminum oxide film is caused byLi~+ inserting into the vacancies of octahedral or tetrahedral structure of O atomskeleton in γ-Al_2O_3. The strength of oxide film decreases as the crystallinity in-creases by the treating of flux containing LiF.

Accuracy of coefficient A_(isp) is related to the reference phase chosenduring analysis. The criterion of choosing reference phase which may minimize theerror of A_(isp) was deduced. The optimum results could be obtained by using the me-thod of least sqares if the number of samples for analysis is more than the phasein samples. The procedure presented here is satisfactory for ordinary phase analy-sis.

The carbon layers on implanted Steel surface have been studied by means of Augerspectra. It is showed that the thickness of the carbon layer is proportional to the dose of implant-ed ions. By comparison with the results of friction and wear tests, we found that the frictioncoefficient is smaller than 0.20 at the first part of the friction coefficient curve. It is consideredthat the graphitic carbon layer on the top of the steel is helpful to reducing the surface frictioncoefficient of the steel.

A great improviment on the corrosion resistance of Fe-Cr-P-C amorphous alloy bysubstituting boron for carbon can be made especially in an acid solution saturated with H_2S. Itwas confirmed by XPS analysis that the boron enriches in surface layer of the amorphous alloyand reacts with hydrogen to form B_(10)H_(14). Thus, the hydrogen intrusion into substrate may beprevented and the suscptibility of the amorphous alloy to hydrogeninduced destruction may begreatly decreased.

Activities and activity coeficients of Al in solid Cu-Al alloys have been determin-ed by means of solid electoriyte galvanic cellsAl(a_1, in alloy), Al_2O_3

Reaction of Ce with S and O in liquid Fe-V-Ce solution has beenstudied in the temperature range of 1550 to 1670℃. The temperature dependences ofthe equilibrium constant of reaction Ce_2O_2S=2(Ce)+2(O)+(S) and the starndard freeenergy of formation of Ce_2O_2S have been obtained. The temperature dependences ofthe interaction coefficients e_V~(Ce) and e_(Ce)~V. have also been determined.

Thirteen internal sections of Ag-Cu-Ge phase diagram have been determined bymeans of DTA technique. Liquidus of the phase diagram has been constructed with the data ofinternal sections.