Results are Presented for the relationship between the number of(225)_γ mar-tensite plates per unit volume,N_v,and the mean diameter of prior austenitegrain,D,for steel T10A and GCr15 being N_v=N_0 (?),where N_0 is a con-stant.This relationship may be derived by the theory of dislocation of plastic de-formation in polycrystal at lower temperature under applied driving force of phasetransformation.Accordingly,the nucleation of(225)_γ martensite is the result ofon set of the motion of dislocation source under the applied driving force of phasetransformation.Consequently,these might be no pre-existing martensite nucleus,but are pre-existing dislocation sources.The austenite grain refinement may bean effective method for refining the martensite plates.

Six representative low carbon martensitic steels were analyzed under TEM,Observations showed as follow:The thin retained austenite films usually exist in the structure of the low car-bon(namely,0.1—0.25 wt-%C)martensitic steels;ε-carbides formed in auto-tempering precipitate on the matrix of the lath mar-tensites;Internal twins exist in part of some lath matrix of the six steels;ε-carbides transform into cementites when tempered at 300-400℃.Cementitesform in three sites,lath boundaries,{110}_M planes and twin boundaries;Twins disappear when tempering temperature raise to 500℃ but the outlineof lath boundaries still keeps its original shape.

The morphologies and substructures of bainitic ferrite formed isothermally inFe-Ni-C and Fe-Si-C alloys have been studied by means of SEM and TEM.Theseobservations are interpreted in terms of current ideas concerning the structureand migration characteristics of fcc/bcc interfaces.It is concluded that the bainiticsubunits are an autocatalytically nucleated variant of the bainite lath product,which grows with some departure from local equilibrium,and which neverthelessrequires carbon diffusion during growth,And the series of transformation productsin steel:Widmanst(a

The changes during reheating of the supersaturated solution boron in the40MnB steel previously formed by rapid cooling from elevated temperature weredetected by phase analysis and observed by track microphotography(boron autora-diography)and metallography.It was found that the boron-containing phases areprecipitated during heating from supersaturated solution boron as another differ-ent way of precipitation in comparison with that on cooling.X-ray diffractionshows that the major boron-containing phase is Fe_3(C,B),The correlationbetween its amount,size,precipitating rate,sites and heating temperature wasstudied.The similarities and differences as well as the connection each otherbetween these two precipitation ways were also discussed.

The effects of dynamic strain-aging and deformation twinning on the tensileproperties in a low stacking fault energy fcc alloy,brass H68(Cu-32wt-%Zn),were investigated.The experiments were carried out at 196 to 623 K with a strainrate of 4.9×10~(-4)s~(-1).The average grain size is 0.05mm.The results showed thatfor this alloy,the maximum uniform strain,the reduction of area and the twin-ned volume fraction at different temperature are all increasing by lowering tem-perature in the similar manner.It was also found that there is an evident work-hardening peak of this material in a certain temperature region.Another impor-tant result of this investigation is that the effects of deformation twinning onthe mechanical properties extend about 100 degrees above room temperature andthat therefore an overlap of the influences of deformation twinning and dynamicstrain-aging was obtained.It is believed that the changes of mechanical propertiesof this alloy in a certain temperature range,say from 333 to 400 K,is becauseof the combined influence of those two factors.

Symmetrical push-pull low-cyclic fatigues with constant strain amplitude,ranged from 2.7×10~(-3)to 4.9×10~(-3),were performed on well-annealed commercialpure(99.98%)Ni polycrystalline specimens with grain size about 30-40 μm underhydrogen-charged,hydrogen-free and hydrogen charged-dehydrized respectively.The cyclic peak stresses σ_P,friction stresses σ_F and back stresses σ_B were deter-mined by the fatigue hysteresis loops.It was shown that the σ_P at saturation,theσ_F and the hardening rate as well as the total fatigue life decreased remarkably withincreasing of strain amplitude but σ_B changed no more under hydrogen-charged.The influence of hydrogen on the cyclic deformation behaviour of pure Ni hasalso been discussed in combination with the SEM observation.

The primary creep strain(PCS)of most directionally solidified Ni-base super-alloys at intermediate temperature of 700-800℃ and high stress of 490-784MN/m~2 is evidently higher than that of conventionally cast alloys.That is due tothe shearing of the γ′particles and the large gliding distance of dislocations.PCSin creases with increasing stress.The longitudinal PCS of DZ3 at intermediatetemperature is quite low and similar to that of the conventionally cast CCK3alloy.Directional solidification does not increase the longitudinal PCS of K3alloy at intermediate temperature and high stress.This is due to the creep mechan-ism of dislocation climbing over γ′particles.PCS increases slightly with increas-ing creep stress.The transverse PCS of the directionally solidified alloys is thesame of the corresponding conventionally cast alloys.The larger the γ/γ′latticemisfit and the higher the strength,the lower the longitudinal PCS of directionallysolidified alloys.At high temperature of 850-980℃ and low stress of 196-343MN/m~2,the PCS of DS Ni-base superalloys is similar to that of conventionallycast alloys and increases slightly with the increasing creep stress.

The dynamic microprocesses of fracture in martensite-ferrite dual-phase steelswere observed by the in situ technique in SEM equipped with tensile platform.The mechanism of crack nucleation has been clarified.The conditions of crack prop-agation and affecting factors have been discussed.It is believed that the propaga-tion of the microcracks depends on the combined effect of both tensile stress andplastic shear strain.The dislocation pile-up model can be successfully used for ex-plaining the effect of the volume fraction of martensite,the carbon content in itand the low temperature tempering on crack nucleation.Furthmore,the factorsaffecting the ductility of dual-phase steels were analyzed according to the specificfeatures of fracture processes.

The creep crack growth rate(CCGR)associated with the stress intensity factorin GH37 Ni-base superalloy was measured at temperature from 590 to 750℃ in airor vacuum.For a given stress intensity factor,the CCGR in air increases withthe increase of temperature up to 730℃.However,the CCGR at 750℃ is lessthan that at 730℃ in the region of lower stress intensity factor because of cracktip blurting caused by creep deformation.And the CCGR in air is higher than thatin vacuum owing to crack propagation accelerated by oxygen.The SEM examina-tion showed that the morphology of crack is of the intergranular mode at all testtemperatures.The creep crack propagation mechanism at high temperature has alsobeen discussed.

Let τ be the function of activity ratio of two components B and C definedby given equation.A new method is proposed which can be used for calculatingthe activities of all the components in a ternary system A-B-C from the knownτ function only by using one set of graphical integration and one set of graphicaldifferentiation.In order to make the calculation with greater accuracy,the discrim-inant which can verify the reliability of integration and differentiation resultsrespectively by using the selected thermodynamic properties of binary systems arealso suggested.The method may also be available to multicomponent systems.

The deoxysulphurization constant of Y and Y oxysulphide standard free energyof formation vs temperature have been determined in liquid Ni.(?)(?)After calculation by thermodynamic analysis,it was resulted that the equilibriumspace diagram for[Y]-[S]-[O]system and a_O-a_S equilibrium phase diagram in liquidNi are presented.Thus,the subsequence and type of the inclusion formation maybe predicted by them.And the formula controlling the morphology of inclusionformed in liquid Ni by Y addition,as well as the relationship between the Y ad-dition and the content of O_2 and S are also given.

The effect of the different quenching temperatures,780-1050℃,on the mor-phology of martensite formed under different temperatures in T12 steel has beenstudied by optical and electron microscope.It is believed that the microstructureof T12 steel quenched from elevated temperature seems to be quite complex.

The mixed reagent of hydroxamate and xanthate,instead of xanthate alone,has been developed in treating copper oxidized ores of skarn type with reducedconsumption and increased copper recovery.The newer progress in copper oxidizedores flotation has been made by the reasonable usage of the mixed reagent.Testresults indicate that under the synergistic action of combined regulator,the copperconcentrate of 26%Cu grade can be produced from the ore containing malachiteand pseudomalachite with 80% recovery.When this hydroxamate-xanthate collectorsystem used to float another highly siliceous pelitic copper oxide ore,a copperconcentrate of 25% Cu can be obtained with recovery of 85% for free copper oxide.The proposed flowsheet is most useful to the efficiency of hydroxamate-xanthatein flotation of a siliceous Cu-Fe intergrowth oxidized ore containing Au and Ag.With this process not only a high quality copper oxidized concentrate of 36%Cucan be produced,but also a Ag-rich Au concentrate containing 340 g/t Ag and108 g/t Au can be floated selectively.And it benefits the recovery of Fe concen-trate from copper railings.

The structure and crystallization on heating of the amorphous alloy Fe_(100-x)P_xduplicated film made by electrodeposition have been examined by DTA,TEM andX-ray diffraction.The observation on alloy Fe_(86)P_(14)which is approach to the eu-tectic composition of Fe-P system is shown as diffuse scattering ring pattern ofelectron diffraction and broadened peak of X-ray diffraction.The crystallization ofthe Fe_(100-x)P_(14)deposited film seems to be the processes of low temperature relaxa-tion,formation of supersaturated solution of α-Fe(P),precipitation of Fe_3P fromα-Fe(P)as well as formation of stable phases of α-Fe(P)and Fe_3P.The Fe_(86)P_(14)grain growth is initiated above 745℃ with a steady exothermal peak on DTAcurve.The initial temperature of crystallization of Fe_(100-x)P_x amorphous alloy in-creases and of precipitation of Fe_3P decreases with the increase of its P content.The initial crystallization temperature of Fe_(86)P_(14)is about 250℃.

The kinetic behaviour of the reversible magnetic permeability relaxation inthe amorphous(Fe_(0.1)Ni_(0.35)Co_(0.55))_(78)Si_8B_(14)and Fe_(40)Ni_(38)Mo_4B_(18)alloys has been inves-tigated under the temperature range of 0—300℃.The isochronal relaxation spec-tra were found and each of them is characterized by three relaxation peaks.Thedistributions of the relaxation times and the most probable values of the activationenergies were estimated.The effect of the annealing and rather slow cooling aboveCurie temperature on the kinetics of relaxation was also studied preliminarily.Sincea quite similar behaviour was observed on these two alloys with substantiallydifferent compositions,it is believed that the magnetic permeability relaxation ismainly resulted from the local motion of elemental mobile anisotropic structuraldefects and their compositional effect seems to be of minor importance.

The study of electronic structure for amorphous alloys Ni-P and Pd-Ni-P wasmade by X-ray photoemission,Auger electron spectroscopy and quantum chemicalcalculation.It was shown that the s and p orbitals on the P atom combinedwith the s and d orbitals of Ni and Pd atoms to form bonding molecular orbit-als(MO).This leads a drop of the den sity ofstates near the Fermi level.Thechanges of band structure are obvious.The“rigid band-charge transfer model”which was used to explain the variation of magnetic and nuclear magnetic prop-erties of amorphous alloys such as Ni-P and Pd-Ni-P seems to be unreliable.

The ribbon samples of Fe-base amorphous alloys Fe_(80)B_(20)(A),Fe_(77.84)B_(16.81)Si_(3.49)C_(1.86)(B),Fe_(65.66)Co_(17.3)B_(15.84)Si_(1.2)(C)and Fe_(65.92)Co_(17)B_(13.29)Si_(1.59)C_(1.1)P_(1.1)(D)wereprepared by melt spinning.Their saturation magnetization at 12 KOe was deter-mined by extracting sample magnetometer and magnetic balance in the tempera-ture range of 1.5—300 K or 300—1200K respectively.It was obtained that themean magnetic moment per atom of transition metal,μ,is(2.03—2.07)μ_R forall samples.Both alloys A and B have similar room temperature saturation mag-netization,σ_S(R.T.),and Curie temperature,T_C,but alloys C and D are higherabout 6% and 10% than those of A respectively.As the experimental results ofthe thermomagnetization,resistivity,DSC and X-ray diffraction,the crystallinephases were also analyzed.The crystallization temperature,T_(cr),of alloys C andD is similar to that of alloy A,and T_(cr)of alloy B is higher about 80 K thanthat of A.The effect of chemical bond,T_(cr)vs e/a and the complexity crystal-line phases on the stability of the Fe-base amorphous alloys has been discussed.

A systematic study of ion beam mixing was conducted in eight selected bina-ry metal systems to investigate the effects of metallurgical factors on the char-acter of the ion mixed phases.The experimental results indicate that the crystal-line structure of the constituent metals is the most important one in determiningthe structure of the mixed phase,and lead to two sufficient conditions for syn-thesizing amorphous alloys by ion beam.The mechanisms of ion induced phaseformation are considered to be two-step processes,i.e.atomic collision and relax-ation processes,and the final structure of the phase obtained is formed duringthe relaxation processes.A thermodynamic and kinetic model is proposed and itexplains the formation of the metastable phases obtained in this study as well asthose reported earlier in the literature.

A new quantitative method for the determination of fractures of metals underSEM is described using the stereoscopic principle.It is suitable for detecting theorientation of facets,their components and the real distance between two pointson the pattern.

The Zr-Nb alloy was determined directly on the excited specimen with theenergy dispersion X-ray spectrometer by the fundamental parameter method with-out any reference standard.The result was then calculated using the program byTQ-6 computer.The content of Nb in alloy was showen as(2.58±0.078)% whichis in good agreement with the chemical analytical method.