Internal friction and micro-creep measurements were performed withhigh-purity Al bamboo-crystal specimens. The relaxation strength was found to de-crease with the decrease of the temperature of measurement and became zero at about0.4T_m (T_m being melting temperature). This reflects the occurrence of local disorder-ing in the bamboo boundary region at this temperature. This result conformsto the picture of grain boundary disordering constructed by atomic simulationstudies.

A new "mid-relief" plate martensite was observed together with lenti-cular plate and thin plate martensites in the specimen of Fe-29.37Ni-0.34C alloyafter twice fractiona lcooling: -100/-120℃,-120/-140℃,-155/-165℃ and -165/-196℃, by means of colour metallography and TEM. Those 3 types of martensiteswere formed as the temperature decreases. The "mid-relief" plate martensite ischaracterized by the marked mid-relief, and the substructure of the symmetric doubletwins or half twins and half dislocations. The formation of this martensite wouldbe interpreted by the stress-induced mechanism of martensite.

With the increase of Y content in the Fe-20Cr-4Al-Y alloy, the uni-form deformability of tensile specimens was found to be slightly decreased, as wellas, the fracture strength and reduction of area after necking remarkably dropped.This seems to be dependent upon the brittle phase containing Y. The behaviour ofY-containing phase may be improved by adjusting the metallurgical technologicalprocess.

The microstructure and phase composition of FGH95 Ni-base super-alloy powder of different mesh size solidified from chemical deposition of prealloy-ed Ni have been investigated. The microstructure transition was found from dendrite inmajor into cellular precipitate as the reduction of powder size and the increase ofcooling rate. The principal phase was identified as different morphologies of MC-type carbides, which may be related to their composition and the condition of solid-ification. Minor phases, such as Laves, primary γ' and boride are also present,and they exist as associated with carbides.

After cold-rolled 70--90%, strong {111} 〈110〉and weak {111} 〈112〉cold-rolled textures, and perfect {111} 〈112〉 recrystallizatinn texture were obtained.The cold-rolled textures with different orientation possessed different ability for re-covery because of the difference of dislocation structure and store energy after cold-rolled. The recovery taking place at {111} 〈112〉 orientation region was prior tothat at {111} 〈110〉 orientation region. These subgrains with {111} 〈112〉 orienta-tion became recrystallization nuclei during their growth at expending the surround-ing matrix which was sluggish in recovery process. The development of recrysta-llization textures may be suggested as process of "nucleation in-situ-selective gro-wth". The formation of (111) textures in low carbon steel sheets has been discussedin the light of this suggestion.

The segregation behaviour of P and its effect on structure of 70%-re-duction cold rolled Fe-P alloys containing different contents of P, e. g., 0.007, 0.06and 0.09%P, during annealing at 200--700℃ under vacuum have been studied bymeans of metlallography and EPMA. The P was found to segregate preferentiallyalong dislocation line during recovery annealing. The P-riched dislocation densingregion, the P-depleted region and the sub-grain-like boundary are thus formed. Thenuclei grow preferentially during recrystallization in such region that the P segre-gation is more evident and the residual strain by dislocation densing increases tolarge extent. After recrystallized, the P segregates along grain boundaries and makesfine grain of the alloys.

The fatigue limit of Ti-6Al-4V alloy could be improved over 28% byimplantation of a dose of 3×10~(17) ion/cm~2 of C at 80 keV under stress-controlledtension-zero condition. The microstructure of surface layer, whether implanted ornot, and before or after fatiguing, as well as the concentration distribution of imp-lanted ion along the depth of surface layer were examined by SEM, TEM andSIMS. A great deal of radiation damages and a good many fine TiC particles arefound in the implanted layer. The fatigue cracking origins, implanted or not, occurin subsrface under lower stress and longer fatigue life. And the implanting speciesdiffuse into substrate under cyclic loading.

Studies by SEM and EDAX were carried out on the high temperaturecreep and fracture behaviour undergone tests in air or in SO_2 contaminated enviro-nment for both Fe-base wrought superalloy GH302 and Ni-base superalloy Rene 80,with two different microstructures: i. e., flat and zig-zag grain boundary or equi-exed and Columnar grain boundary respectively. Although the creep rupture strenqthof the superalloy GH302 of zig-zag GB was remarkably superior to that of flat GBin air, the properties of both dropped suddenly in 10% SO_2 contaminated air. Thecreep rupture properties of the directional solidification superalloy Rene 80 weremuch better than that of the conventionally casted alloy in air, and also remainedthe former ones in SO_2 contaminated air. Owing to the interaction between creepand sulphidation, the damage mechanism seems to be that the creep cracking ispropagated intergranularly by suffering sulphidation-oxidation corrosion under stress,and formation of a low melting point NiN_3S_2 eutectic leads to premature failure ofthe alloy.

Studies have been made of the torsional fatigue fracture life of notch-ed specimens, the macroscope fractograph and microscopic fracturing mechanism of40Cr steel as various tempered states under different stresses. With the increase ofstress, the fracture type changes from normal stress fracture to longitudinal shear oneand then transversal shear one. Under same stress but with the increase of strength,the fracture type transferred from shear to normal stress fracture. The mechanism ofnormal stress fracture may be: transgranular fracture→striation + intergranular frac-ture→dimple + intergranular fracture, and of shear fracture may be: transgranular

The symmetrical push-pull fatigue tests in load control were carriedout for prestrained polycrystalline Cu. The change in mechanical behaviour duringcycling was recorded in detail and the effect of various degree of prestraining onsaturated behaviour and dislocation structure was compared. The results show thatthe cyclic saturation state is still history-dependent at low stress amplitude and thedislocation structure after fatigue has "inheritance". The amount of softening hasbeen calculated at various load amplitudes and a softening threshold to be about0.43 to 0.45 of the flow stress, which is the same as low carbon steel, is obtainedby extrapolating method. Three stages cyclic process and their mechanism have beendescribed.

Threshold of short through fatigue crack for an Al-Li 8090 alloy wasevaluated to be lower than that of long crack, and to decrease with the shorteningof the crack length. The correlation among the threshold, crack wake and crack tipshielding of the short fatigue crack was discussed. The critical length and lowesttheoretical threshold of short through fatigue crack were presented.

The volume fraction variation of proeutectoid ferrite formed isother-mally from deformed austenite with isothermal time has been examined experimen-tally. The results show that ln ln (1--f_v)~(-1) vs ln t relation does not follow the Avr-ami equation strictly and consists of two straight lines. By comparing the differen-ces between the results and Cahn's theory, the authors' idea has been expounded.

The growth of thermoelastic martensit6 in a Cu-29%Zn-3%Al alloy has beeninvestigated experimentally and theoretically. The metallographic observations showed that thegrowth occurred thermoelastically, i. e. reversibly, in the radial direction as well as in thethickening direction. This is not consistent with the theories of Cohen and some others. A modelhas been suggested by the authors to explain the thermoelastidty of the growth. The basic ideais: the elastic strain distribution is highly heterogeneous and the growth is controlled by thelocal elastic strain energy at the growth frontier area. The calculation results from the modelbased on Eshelby's theory are consistent with the observations.

The "order-disorder" model was adopted to calculate the lattice vacancy relatedto the composition change in Ni_3Al alloys. A great deal of vacancies, i. e., the non-stoichiome-tric vacancies, may exist in the Ni_3Al alloys containing Al over stoichiometry, saying, 25 at.-%.This was confirmed by the positron annihilation technique. Therefore, the influence of Al con-tent on the bettering behaviour of B towards the ductility of Ni_3Al alloys can be understoodthrough the interaction of non-stoichiometric vacancy and B atom.

A study was made on the fatigue fracture behaviour under different aging cond-itions of two Al-Mg-Si alloys with different chemical composition and dispersoid contents.The dispersoid phase can alter the mode of fatigue fracture by the influence on the deformationuniformity of alloy. The dispersoid itself may decohere from the dispersoid/matrix interface undercyclic fatigue stress to form small-sized dimples.

By expanding the Gibbs free energy of ternary system into a Taylorseries with respect to the composition, a thermodynamical criterion of spinodal de-composition is conducted as G_(xx)(δ_x)~2 + 2G_(xy)δ_xδ_y + G_(yy)(δy)~2<0, from which, various con-ditions of spinodal decomposition are discussed. When G_(xx)<0, G_(xx)~2-G_(xx)G_(yy)<0, it iscalled as unstable decomposition unrestricted by the direction of composition fluctu-ation; when G_(xx)<0, G_(xy)~2-G_(xx)G_(yy)>0, or G_(xx)>0, G_(xy)~2-G_(xx)G_(yy)>0, as well as G_(xx)=0,are all considered as unstable decomposition restricted by the direction of composi-tion fluctuation δ_x and δ_y. The phenomenon of turning round in composition duringspinodal decomposition is attempted to be explained from above poiat of view. Thecomputer calculated ranges of unstable decomposition according to the criterion ofspinodal decomposition on Cu-Ni-Fe ternary system is consistent with the experi-mental results obtained from literatures.

A model of butterfly catastrophe was studied on the basis of matchingand fitting the previous experimenial data to confirm the alumina electrolysing pro-cessing when anode effect occurs. The complicated behaviours in the cryolite alumi-ha melts systems with varing (controllable) parameter would be generally described.Therefore, the anode effect and its occurrence may be thoroughly understood.

The effect of pre-annealing treatment on the crystallization kinetics pa-rameters of amorphous Ni-P alloys has been investigated. Experimental resultsshowed that the crystallization temperature, T_p and T_x, the apparent activationenergy, E_c, as well as the Avrami exponent for isothermal crystallization, n, decreasesignificantly, while △T_(px)=T_p-T_x increases with the elongation of pre-annealingtime at 570K.

The mechanical alloying was successfully utilized to make an amor-phous Al_80Fe_20 powder from pure crystalline Fe and Al powders, but no other con-ventional rapid solidification process to be formed. The amorphization process wasexamined by X-ray analysis and Mossbauer spectroscopy, and the thermal behavi-our was studied by DSC. The results show that the rate of amorphization is con-trolled by the diffusion reaction at the interfaces and changes with the milling time.The effect of milling conditions on amorphization by mechanical alloying was alsoinvestigated.

The magnetic properties and the cryst8llization and its influence onthe magnetic and structural properties for amorphous Nd_6Fe_(81)B_(13) alloys were studi-ed. Low temperature magnetic properties and the Curie temperature were discusscd.A new phase was obtained in the sample annealed at 873K.

The surface segregation of P and the embrittlement, also their rela-tions, of Ni-P amorphous annealed at temperatures below crystallization have beeninvestigated. A P-depleted layer was found nearby the surface during annealing.The P-depleted layer became thicken and the depletion of P became severe as theincrease of annealing temperature. The mechanism of elementary redistrib utionand annealing embrittlement during relaxation Was discussed on the viewpoint ofthe activation energy of atomic diffusion in Ni-P amorphous being variables.

The equations for numerical simulation of channel segregation basedon a model of continuum approach to porous medium were advanced. In order tosolve non-linear computation problems caused by the interaction with each other ofunknown variables in the equations, the trial-and-error method is used. The com-putation results showed that radial back-flow due to natual convection in mushyzone indeed exists in the Al-4.5wt-%Cu alloy ingot under the condition of lowcooling rate, and the numerical simulation of channel segregation is available dueto coincidence of calculating final concentration with the test values.

Large undercooling up to 397 K (0.283T_E) have been obtained for Ni-32.5%Sn eutectic alloy melt by superheating-cooling cycles and denucleating withinorganic glasses. The predominant dissipation of heat for highly undercooled alloymelt is through radiation. An approximate method was consequently derived to cal-culate its mean specific heat from measured cooling curves. With the aid of highspeed cinematography, it was revealed that the surface or interface heterogeneousnucleation takes place in preference to homogeneous nucleation even though theundercooling exceeded 0.2T_E.

Two-dimensional explosive consolidation under the cylindrical con-verging shock wave has been studied by use of coated fine iron wire compacts toreplace conventional metallic powder, so the randomness of three-dimensional spa-tial distribution of metallic powder might be avoided. The deformation and surfaceflow pattern of particles as well as the mechanism of consolidation have been cla-rified experimentally. The distribution of high temperature area is in agreementwith the result of numerical simulation by Williamson. A model for the explosiveconsolidation was given.

Metal Fe/Cu superlattice films deposited on glass substrates were pre-pared by a dc-magnetron sputtering system. The modulated structures and crystalstructures of films were examined by X-ray diffraction and TEM. The magneticproperties were studied by ferromagnetic resonance and vibrating sample magnetome-ter. The noval results show that the magnetic coupling between the neighbouringFe layers existed and affected the magnetic properties of superlattices.

The superplasticity of the Al-Zn-Mg-Zr-RE (alloy A) and Al-Zn-Mg-Ti (alloy B), their change of volume fraction of metastable micro-cavitiesunder various reduction and strain rates, as well as the growth of stable cavitiesin them have been studied by small X-ray scattering analysis and quantitative me-tallography respectively. Experimental results show that the volume fraction ofmetastable micro-cavities of the alloy A is more than that of the alloy B, butthe growing rate of stable cavities of the alloy A is less than that of the alloyB. Thus, it is believed that the superplasticity of the al1oy A is superior to thatof the alloy B.

Mossbauer spectra reveal that Sn exists in YBa_2Cu_(3-x)Snx O_(7-y) system(x=0.05, 0.10, 0.20, 0.30 and 0.40) in the form of Sn~(4+) and occupies Cu(Ⅰ) andCu(Ⅱ) sites. The relative rate at which Sn~(4+) occupies Cu(Ⅰ) or Cu(Ⅱ)sites varies with x. The superconductivity transition temperature, T_c, depressesa little due to the substitution of Cu for Sn.

The 0.05--0.08mm thick splat foils of Ag-Tb alloy, containing Tb up to 10 at.-%,were made by the hammer-anvil technique. The cooling rate was in order of 10~6K/s. The me-tastable extension of solid solubility of Tb in the rapidly solidified Ag-Tb alloy was measuredto be up to 5 at.-% by lattice paramter method. The secondary phase in metastable eutecticstructure was identified as Ag_3Tb from diffraction pattern. The microstructure and micro-defect in as-quenched Ag-Tb splat foil were also observed.

The formation of a special Si-rich layer on the periphery of Al-si eutectic alloyspecimen during directional solidification in rotary electromagnetic field has been investigated.This layer seems due to the migration of some Si grains onto the crucible wall, then stagnatingand coarsening further.

The change of temperature field on the friction facing during contact wearing for3 wear-resistant alloys: Co-Cr-Ni-Si, Co-Cr-Mo and Co-Cr-W has been monitored by theinfrarod sensing thermography. Their flash temperature of the wearing area was measured.

The regularity of carbonization process for alumina production has been summa-rized by the pattern recognition and regression. A mathematical model has been proposed todescEribe the factors affecting the silica content of aluminium hydroxide product. The high con-ecranttion of aluminate ion in solution will prodoce aluminuium hydroxide with low content ofSiO_2 under the condition of Al_2O_3/SiO_2 ratio kept unchanged. This was confirmed by the auth-ors′certain scale experiments.KEY