Internal friction of martensitic transformation of as-cast manga-nese-copper alloys with Mn-content 90% was studied. Results show that the peak tem-perature of the stable peak (T=0) at low frequencies is independent of the mea-suring frequency, but the peak height decreases with increasing frequency. It is,therefore, not of a static hysteresis mechanism. The peak height is dependent onT and f at a constant heating or cooling rate, but it does not show a linear rela-tionship with T, 1/f or T/f. The peak height is independent of the strain amplitudein the range (A_e: 1×10~(-5)-1×10~(-4)). Consequently the low frequency internal fric-tion of martensitic transformation is not only a volume effect, but also a surfaceeffect connected with coherent boundaries.

The surface morphology of niobium single crystals with [321]and [110] orientations during the deformation has been observed. Specimens withround cross section have been cycled to the saturated stage and the surface topog-raphy of rumpled bands has been observed using optical and scanning electron mi-croscope. In the present paper, the term of "deformation band", which is defferentfrom the kink band with special orientation, is used to define the rumpled band ofmaterial that has undergone inhomogenous plastic deformation. According to thedetailed topography, the deformation bands have been further subdivided into fivetypes and their formation process has been discussed. The deformation bands lie onthe plane of approximately 45° to the loading axis, i. e. the plane of the maxi-mum shear stress, which indicates that the macroscopic state of stress plays an im-portant role on the formation of deformation bands.

The pseudo-elasticity of NiTi(Fe) alloy has been studied at diffe-rent temperatures and the stressed in situ X-ray and electron diffraction analysishave been performed at room temperature. The following results were obtained: (1)Above incommensurate transition temperature T_i, the stress-strain curve appears assuperelastic loop of small loop area, due to the stress induced incommensurate phaseas confirmed by in situ electron microscope experiment. (2) When R_s≤T References | Related Articles | Metrics

A mathematical model of the diffusion coating, the compound layerand the temperature control on 42CrMo steel was developed on the basis ofexperimental data of tuff-ionitriding process with reference to relevant mathematicalrelations. The ionitriding parameters controlled by micro-computer were establishedby a software of computerization. It has been also observed that CO_2 may acceleratethe plasma ionitriding.

Notch tensile tests of samples after high temperature, high pressuregas charging of hydrogen were carried out for Fe-Cr-Ni-Mn-N austenitic steels.The results indicated that the increase of δ-Fe contents obviously enhances the hy-drogen embrittlement susceptibility of the steels.

The equilibrium intergranular segregation of Ce and P in α-Fehas been analyzed by employing the combination of TEM+EDAX and AES. Theeffect of Ce on the equilibrium segregation of P and the embrittlement of the alloyshas also been studied in detail. The results show that there is cosegregation of Ceand P at the grain boundaries in Fe-0.3%P-0.16%Ce alloy. The addition of Ce doesnot decrease the equilibrium segregation of P, but significantly lowers the ductile-brittle transition temperature. The interaction between Ce and P at grain bounda-ries was discussed from the point of the interfacial two-dimensional phase.

Combined creep-fatigue behaviour (i. e. cyclic creep) of a 12Cr1MoVsteel used in power plants has been studied at 550℃. Experimental resultsindicated that, at higher stress amplitude, the rupture life of cyclic creep is longerthan that of pure creep, and the rupture is mainly transgranular. At lower stressamplitude, the rupture life of cyclic creep is shorter than that of pure creep, andthe rupture is intergranular. Based on TEM observations of dislocation structuresand grain boundaries in ruptured specimens, the reason of cyclic strengthening andcyclic weakening at different stress amplitudes is considered to be: at higher stress,the damage in the interior of grains can be partly recovered during unloading inthe case of cyclic stress; while at lower stress, superposition of cyclic stress enhances the cavity formation and linkage at grain boundaries.

The relationship between creep behavior and dislocation substructurein Ni-20Cr alloys has been studied over the temperature range of 1173-1323K. A stage of substeady-state creep was observed in which creep rate ε_t is al-most constant in the primary stage of creep. TEM observation confirmed that thesubsteady-state creep corresponds to relatively homogeneous dislocation structurewhile the steady-state creep corresponds to subgrain structure. The creep rate reducecontineously from ε_t to ε_m, which has been attributed to the gradual substitutionof subboundaries for grain boundaries as dislocation climb site. The substructural parameter, subboundary misorientation, θ, or subboundarymesh size, h, has been related to the steady-state creep rate in recovery creep, whichcan be discribed as ε=αρ_t bV_c/h. A mechanism of recovery creep involving dis-location annihilation at subboundaries or grain boundaries was proposed and theeffect of solute carbon and grain boundary carbides on creep behavior has beendiscussed using above michanism.

The effect of negative overload (S_p) on fatigue-creep interaction forNi-base sup eralloy GH698 has been studied at 700℃. It was found that thiseffect depends on the magnitude of S_p The cyclic fracture lives for the tests withS_p of 0 to-400 MPa are longer than those without S_p, but this effect shall be ne-gative while the S_p value was higher or lower. The changing tendency of dynamiccreep rate exhibits an inverse character. It was considered that the mechanisms ofS_p effect are as follows: 1. it reduces the dynamic creep rate, 2. it promotes thefatigue damage and causes the change of fracture mode, 3. it retards the crack pro-pagation and 4. it cause the fatigue damage due to the S_p cycles itself. How thesefactors work depends. on the magnitude of stress of basic and S_p cycles.

The results of conventional and high frequency fatigue tests of 55SiMnVB spring steel were reported. The fatigue rupture of the steel concerned hasbeen discussed together with the microstructure and fracture morphology observedand the fracture toughness obtained.

Rapidly quenched cobalt-rich alloys Co_(100-x) Er_x (14≤x≤26) weremade by melt spinning in He atmosphere. For x≈20, the Co-Er alloys show X-raydiffraction patterns in which the dominant phase can be indexed successfully withicosahedral lattice vectors. The quasicrystal Co-Er alloys are strongly magneticshowing many characteristics of sperimagnetism observed in amorphous films ofsimilar composition. The experimental results show typical magnetic properties ofthe icosahedral phase lying between those of the amorphous phase and the crystal-line phase of similar compositions. The quasicrystalline-to-crystalline transforma-tion was observed in the temperature range 385 to 630℃. The observations fuelthe assertion made by Steinhardt et al., that the icosahedral phase is a new typeof structural formula of materials.

Isothermal transformation of austenite to bainite of different merphologies in somelow carbon Mn-Nb-V and Mn-Mo-Nb-V steels was investigated.The experimentel results showed thatboth granular and featherlike bainite formed over the bainitic transformation temperature range anddid not contain carbide. The granular bainite with non-directional islands formed in the hightemperature range of bainitic transformation, the granular bainite with directional islands formedin the medium temperature range. The bainite which formed in the lower temperature range istypically featherlike. But it was found that the carbon-rich austenite islands, Present betweenferrite laths, transformed to martensite on cooling. Acicular lower bainite was not observed inthe steels.

Monotectic solidification has been observed for (Fe-10Ge)-O alloy under laserglaze.It was also found that pre-treatment of the surface evidently influences the microstructure of thesurface layer.

The slit island method is employed to measure fractal dimensions D_F of fracturedsurfaces under plane strain conditions with the help of an image analysis technique for twohigh strength steels under different heat treatment conditions and at different test temperatures.It is shown that the fractured surfaces are of fractals. The values of D_F decrease smoothlywith an increase of the logarithm values of fracture toughness K_(IC), i. e. the fractal dimensionsD_F are approximately a linear function of the logarithm values of fracture toughness K_(IC). Thisrelationship might reflect the changes in the microstructure that occured during different heattreatments and the changes in the fracture mechanism that occured at different test temperatures.The fractal dimension D_F could be regarded as a measure of fracture toughness in metels. Fi-nally, the experimental results are explained in terms of the relation between critical crack exten-sion force and the true total area of the irregular fracture surfaces.

A mathematical model torepresent turbulent fluid flow and mixing incontinuous casting tundishes has been developed. The model involves solution ofthe three-dimensional turbulent Navier-Stokes equation, turbulence being modeledby the so-called K-ε, two-equation model. Fluid flow parameters and residence timedistribution has been predicted in a tundish of rectangular cross section. The modelis later extended to predict fluid flow in typical industrial tundishes where wallsare not vertical, but slightly inclined from the vertical. This results in an interest-ing variation in fluid flow, which may have important technological implications.The theoretical predictions are compared with the measurements obtained in watermodels. The detailed understanding of the hydrodynamics of the tundish flow canbe used to optimize the design for steel cleanliness.

Iso-activity lines of Si in ternary Fe-B-Si melts were measured at1450℃ with Ag-bath medium method. The activity of Si in Ag-Si alloy was alsodetermined by means of the EMF measurement of a Si-concentration cell in whicha double-tubed ZrO_2 electrolyte was used. A method has been proposed for calculat-ing ln γ°_(Si) and the first and second order interaction coefficients from the experi-mental data; Following results have been obtained: ln γ°_(Si)=-3.19, ε_(Si)~(Si)=7.0, ρ_(Si)~(Si)=6.5, ε_(Si)~B=16.0, ρ_(Si)~B=-12.0 and ρ_(Si)~(Si,B)=40.8

To calculate the activity coefficient In γ_j in ternary Fe-i-j systems,a method of Gibbs-Duhem intergration using available data of ln γ_i with no extraneed of any binary data has been proposed. Activity coefficient of B and relevantinteraction coefficients have been derived by means of this method with In γ_(Si) valuedetermined experimentally in the part I of the present work: lnγ°B=-2.82,ε_B~B=5.7,ρ_B~B=-2.8l,ε_B~(Si)=16.0 ρ_B~(Si)=24.7 and ρ_B~(B,Si)=-34.3

The vapour pressure of Sb in liquid Cu-Sb alloys (x_(sb)=0.262--0.815)were measured at 820--1060K by means of torsion effusion method. Activities ofSb were calculated from the obtained data and those of Cu by Gibbs-Duhem inter-gration. Problems about the experimental techniques have also been discussed.

According to the classical theory of phase transformation, a relation-ship between crystallization temperature (the peak temperature in the exothermiccurve of crystallization, T_p) and the density of pre-existing nuclei in the sample,N_0, was derived in the crystallization process dominated by growth of nuclei: T_P~2exp(-E_g/RT_P)=L/N_0~(1/3)where Eg is the activation energy for growth of nuclei, L is a constant and R isthe gas constant. Different number of preexisting nuclei was formed by pre-anneal-ing treatment of a Ni-P glass at a temperature about 50K lower than crystalliza-tion temperature for different time. By means of a DSC determination, the crystal-lization temperature of as-quenched and the preannealed samples were obtained andit was found that the new equation successfully agrees with the experimental results.And the growth rate of crystal nuclei in the Ni-P glass can be estimated from therelationship. The onset temperature, T_x, decreases and the difference between T_p and T_x,△T_(px)=T_p-T_x, increases with the increase of annealing time.

Dynamic recrystallization of 09MnNb steel was tested with Formastor-Press simulator. An equivalent simulation of finishing unit of hot strip rolling millwas carried out for austenite recrystallization. Hot deformation equation of auste-nite of 09MnNb steel was established, and the critical regression equations of dy-namic recrystallization were described as: σ_P=ε/5.75×10~(-7)·exp(96.3/RT)~(1/6.13) Z=8.51×10~9·e~(32.18~εC) Z=6.32×10~9·e~(16.99~εS) Austenite recrystallization taking place during hot deformation was explainedwith residue strain theory. It has been concluded that austenite dynamic recrystalli-zation of 09MnNb steel during hot deformation is the principal fining mechanismof austenite grain before transformation.

The interface reaction between Nicalon SiC fibre and Al has beeninvestigated. The reaction occurs at the temperatures above 953 K and the reactionrate was found to be consistent with the parabola rule. The reaction rate constantsare 3.3×10~(-8) and 3.85×10~(-8)m·s~(-1/2) at 1013 and 1033 K respectively. Addition ofCu, Mg and Mn will cause the reaction to proceed severely.

The continuous wave NMR (nuclear magnetic resonance) results of ~1Hin LaNi_5·H_6, LaNi_4Cu·H_x and LaNi_4Fe·H_x were reported. The line shape at bothhigher and lower temperatures, the activation energy of diffusion, the self correla-tion time and the diffusion coefficient calculated according to a model have beendiscussed. It was concluded that the partial substitution of Cu and Fe for Ni increasesthe stability of hydrogen in the host alloy.

Separation and concentration processes of Kr and Xe from hydrogenusing TiFe_(0.86)Mn_(0.1) alloy have been investigated at different temperatures. The resultsshow that the relation betwecn the concentration of Kr and Xe and the amountof desorpted hydrogen at 300 K obeys the equation N=αe~(-bV).

The radiation damage was studied on ~(111)In nuclei recoil implanted inAg following ~(109)Ag(α,2n)~(111)In reaction by TDPAC method. The Ag foils(20μm) wereirradiated with 30MeV α particles under room temperature, the particle dose ratebeing 4.2×10~(12)cm~(-2)s~(-1). The experimental results indicated that the radiation damagewas severe in Ag even at room temperature. An electric field gradient of 10~(18) V/cm~2which is due to the radiation damage has been put onto the ~(111)Cd probe. The cubic Ag lattice was destroyed and lots of vacancies and interstitials cre-ated in Ag by radiation. The divacancy trapping has been suggested and the laserannealing has been conducted.

Anodic polarization curves of amorphous Fe-Cr-P alloy plating foilswere measured in lN HCl solution at 25℃ with the apparatus of potentialstat. Thespecimens were prepared by electrodeposition. The curves show that these foils whichcontain certain amount of Cr are in the state of natural passivity. As the Cr con-tent increases, the anti-corrosion behavior of the foil will be improved. Comparedwith amorphous Fe-P alloy foil and 18-8 stainless steel, the amorphous Fe-Cr-Palloy foil with 7.30 wt-%Cr shows better corrosion resistances in acid solution.

The density, surface tension, wettability and adhesive power of liquid high purityAl (99.999 wt-%), technical pure Al (99.6 wt-%) and Al-RE alloy on BN plate were measuredusing sessile drop method. The results show that both the density and surface tension graduallydecrease but the adhesive power and wettability gradually increase with increasing temperature.The density increases and the shaface tension, wettability as well as adhesive power decreasewith the increase of RE content respectively.

The surface tension of quinary blast furnace type synthetic slags containg titaniumoxides has been measured by means of sessile drop method. The influences of TiO_2, MgO andbasicity on the surface tension of the slag has also been studied. It was found that TiO_2 is asurface active component. The surface tension of quinary slag may increase as TiO_2 was substi-tuted by the same quantity of lower-valent titanium oxides.

The wetting of graphite by liquid aluminium was studied by sessile drop method.The results show that in accordance with the variation of contact angle with time, the wettingprocess may be divided into three dynamic stages: nonwetting, abrupt change and gradual wetting.At the first stage, the contact angle between drop surface covered by aluminium oxide film andgraphite substrate was very large; while at the last stage, the formation of Al_4C_3 at the interfaceof aluminium and graphite led to the decrease of contact angle gradually. The transition pointfrom the second stage to the last one is defined as the "actual contact angle" by the authors,which can be used as an exact indication of wettability. By increasing the temperature, the wet-ting of graphite by liquid aluminium may be improved.

An improved calculating method has been developed to determine the diffusivityof hydrogen in lattice of metals through electrochemical permeation experiment. By employingthis method the hydrogen trapping effect can be eliminated completely and the diffusivity canbe measured more accurately. The permiation experiment of Armoc Fe was performed and thediffusivity of hydrogen in the lattice of α-Fe between 290K and 350K has been given asD_0=5.12×10~(-8)exp(-4320/RT) (m~2/s)

Specimens of Fe-22 at-%Al subjected to different heat treatment process have beenstudied using Doppler broadening measurements. The calculated data according to the trappingmodel was shown to be in good agreement with the measured, shape parameter. The microstruc-tural change during each stage of heating and cooling has been discussed in relation to the shapeparameter, which indicates that positron annihilation data is valuable for establishing the prac-tical heat treatment process of the alloy.