A new viewpoint on the mechanism of preferential sputtering of Au-Cu alloys suggests that the so-called preferential sputtering in Au-Cu alloys may be caused by the bombardment-induced Gibbsian segregation, but when ion energy decreases to,ward a near-threshold condition, the maBs-correlating preferential sputtering also plays a role.

A method has been advanced to determine precisely the orientation difference of the crystals between low-angle boundaries and sub-boundaries of high purity Al by convergent beam electron diffraction studies. The results show that the ones of low-angle and sub-boundaries are 1.55±0.051° and 0.32+0.037° respectively, as well as the curved angle of the crystal by single edge dislocation is 0.22±0.036°. The accuracy and error of the method have been analysed. Some problems concerning their structure of dislocation network and type were also discussed.

The attachment energy and specific surface energy of important faces of a ZrAl_3 crystal have been calculated by computer using the periodic bond chain method and the Lennard-Jones n-m potential parameters. The equilibrium form and growth form of the crystal have been deduced, and the theoretical growth form has been compared with the actual growth form observed in a melt growth experiment.

Plate-like solute atom clusters parallal to (0001)_(Mg) and {1010}_(Mg) planes have been observed in the as-quenched alloy. The age-hardening process of the alloy at 150℃ is: super-saturated solid solution→β_1'→redissolved→β_2'→β_2'+β; and that at 220℃ is: super-saturated solid solution→β_2'→β_2'+β. The results show that β_1' pocesses two-and three-dimensinal morphologies and β_2' is one-dimensional rod precipitates perpendicular to (0001)_(Mg) plane. β_1' particles precipitated out from the matrix at the initial stage of 150℃ aging, which exist only for a very short period. However, β_2' and β coexisted for a long time at the later stage. The structural parameters of β_1' and β_2' as well as their orientational relationships with the matrix have also been determined. The addition of Al promotes the age-hardening process and enchances the thermal stability of β_2'.

The formatiin rule of precipitation in Ni-rich, containing 51.6 at.-%Ni, NiTi alloy and its influence on properties have been investigated by means of observation under TEM and measurements of temperature dependence of resistivity, stress-strain curve and microhardness. The precipitate may be formed by aging at 300—600℃ and grown up with the increase of aging temperature and time. It Influences remarkably the shape-memory properties of the alloy.

The precipitation of secondary carbides in low alloyed high speed steel W3-Mo,2Cr4VSi during tempering and the influonce of Si, containing 0.2-2.3%, upon it were observed under TEM. It is shown that the disc-shaped carbide of MC-type, the ratio of thickness to diameter about 0.3-0.4, is the predominant finely dispersed secondary precipitate which is responsible for the peak hardness during tempering at 560℃. The orientation between MC carbide and matrix is found to be fulfilled the Baker-Nutting's relation: {010}_(MC)//{010}_α, <001>_(MC)//<101>_α The MC carbide is made fine during tempering at 560℃ when Si is added to steel, and the coarse M_6C carbide accelerated to precipitate along martensite boundary at 650℃. The MC morphology and the effect of Si on the precipitation of MC carbide are also discussed.

The behaviour of grain bondary segregation and precipitation of B in B-bearing low C Mn-Mo steels and Fe-30%Ni alloys during isothermal holding has been investigated with particle tracking autoradiography. Specimens were quenched from 1350 or 1200℃ then isothermally held at 550—1000℃ for different periods. It is shown that the nonequilibrium grain boundary segregation pf B occurs as a dynamic process and the magnitude of it could be many times as large as that of equilibrium segregation. After cooling from the higher temperature, the B segregation, which is probably brought there by the complex of B atoms with supersaturated vancancies, increases at first with time, then upon the annihilation of vacancies, it becomes supersaturated with respect to equilibrium segregation concentration and thus decreases by diffusing back into the grains, giving a peak on the degree of segregation-holding time curve. The height and position of the peak depends on the initial heating and subsequent holding temperature. On the otherhand, if the holding temperature is lower, the nonequilibriumly segregated B becomes supersaturating and will precipitate at the grain boundaries, giving a curve increasing at first stage and then reaching a steady segregation. Thus, three kinds of grain boundary segregation kinetic curves are obtained at different isothermal temperatures.

The distribution of La in a superalloy Ni-20Cr-20Co.-18W is found out to be enriched mainly along its grain boundaries as oxide and oxysulphide. Some of the oxide may be formed the nuclei of the carbide M_6C. The La improves significantly the stress rupture life under 39 MPa at 1000℃ and raises the creep activation energy of the superalloy. The grain boundary energy was evaluated by thermal etching technique and the vacancy formation energy was measured by temperature dependence of resistivity. A theoretical interpretation was made that the contribution of La to decreasing boundary energy and increasing the vacancy formation energy is the main causes of the improvement of stress rupture property of the superalloy.

The effect of Al, Si and Cr on the temperature dependence of susceptibility, X, and resistivity, ρ, of γ-Fe-Mn (23.8-31.6at.-%) alloys containing Al, Si and Cr has been investigated over the temperature range of 77-750K and 4.3-48GK. respectively. The Cr was detected to be slightly influenced upon their x and X-T or ρ-T. And it does not enable the matrix to form a localized net moment associated with Fe atoms. While the addition of certain amount of Al or Si may remarkably modify the magnetic structure as well as the temperature dependence of X or ρ. With the increase of antiferromagnetic transition resistivity below the Neel temperature, a resistivity minimum appears and then present a negative tem- perature coefficient. Down to 4.3 K, neither anomaly for resistivity of γ-Fe-Mn and γ-Fe-Mn-Cr alloys was found within experimental accuracy, but the secondary resistivity minimum was observed in γ-Fe-Mn alloys containing Al or Si. The temperature of minimum T_(min)~(2), and the depth of minimum △ρ(ρ_(4k)—ρ_r_(min)~(2)) of resistivity increase with the increase of concentration of Al or Si. The resistivity increases linearly with the decrease of lgT between T_(min)~(2) and 4K. It seems to be proposed that the formation of a localized magnetic net moment on Fe atoms and the transition from the incommensurate SDW state to commensurate SDW one are caused by the resistivity minimum in antiferromagnetic γ-Fe-Mn alloys with an addition of Al or Si, thus the low temperature resistivity minimum is due to the Rondo-like effect.

Study was made of the superplastic deformation mechanism for two selected Mg alloys of either coarse or superfine grain by means of an advanced testing technique. It was shown that the mechanism under superplastic deformation for these two alloys is mainly due to the grain boundary sliding together with the coordination of diffusion creep and dislocation slip. A complex deformation mechanism model including the above mentioned three ones is believed to be proposed. The metal grains may progressively emerge from underneath up to surface during superplastic deformation through grain boundary sliding in the site on which the broadening and cavities along transverse grain boundaries appeared, thus, the number of grains along the tensile axis may be continuously incressed. This seems to be the origin of the extreme elongation of the specimen under tensile deformation.

The driving force for martensite transformation,-△G_(M_S)~(γ→α)(=△G~(α→M)) has been evaluated using three different thermodynamic methods, namely, LFG method, Hsu method and the authors' method. The results show that the relationship between driving force and σ_(0.2)(M_s) can be expressed as: AG~(α→M)=A'σ(M_s)+908 J/mol wher eA' is a constant which slightly deviated for different methods. The M_s temperatures of Fe-Ni-C alloys have been calculated, and the results of calculation are in good agreement with the previous experimental values.

A new approach has been suggested for the determination of the C-C interaction energy, the partial molar enthalpy and nonconfigurational entropy of carbon in the Fe-C austenite and ferrite from available activity data. By application of the values obtained through the approach to the calculation of the Fe-C phase diagram, the results in the equilibrium region are in very good agreement with the experimental one. From the scattered and limited experimental activity data, the C-C interaction energy obtained through the present approach should be more reasonable than that through previous efforts. Further analysis indicates, however, that up to now the activity data on carbon in ferrite are not accurate enough for obtaining the C-C interaction energy in ferrite with the clear physical significance.

Notch fracture machanics was used to investigate the fatigue crack initiation from the notch tip for medium carbon steels (0.4-0.6 wt-%C). The relationships between the maximum stress range at the notch root, △σ_(max), and the number of cycles before fatigue crack initiation, N_i, have been determined. Furthermore, the threshold stress of fatigue crack initiation, △σ_(max)th, as a function of C content or of yield strength of the steel has been proposed.

A comparative study of Zn-Ge eutectic with Al-Si system has been made by metallography and SEM. It is found that the chain Ge crystals connected each other with top corner of octahedrons formed in this system at lower cooling-rate solidification. This is believed to be effect of high viscosity in molten Zn matrix. Meanwhile, the effects of microamount Li, Na, Mg, Ca, Sr, Ba and La on microstructures of Zn-Ge eutectic were also scanned, Modified structures obtained only with additions of Na, Sr, La and Ba. Among those modifiers, Sr is the strongest, and the weakest is Ba. Modified structure of eutectic Ge were also in the form of chain crystals something like that in the mentioned blank system but smaller in the size. The appearance of modified Ge is quite different from that modified Si in Al-Si system. To these more equilibrium eutectic crystals, it is deduced that modifiers denucleated the melt, and eutectic Ge was solidified under a supercooling condition. Compared to the facts in system Zn-Ge, the modification of Al-Si eutectic was discussed as a multiple effects.

Determination of the stacking fault energy, Y, of the solid solution strengthening superalloys with various contents of Co and W with relation to their steady-state creep rate, s was carried out by X-ray texture method. The stacking fault energy decreases with the increase of Co and W. An expression may be proposed as ε ∞ γ~m, where m=1.46.

The type, morphology, distribution and variation of the boride in the alloy Fe_(75)Cr_(18)Mo_2 SiB_9 were investigated as quenched rapidly from melt and then annealed under different temperatures.

Orthogonal design calculation of the composition of single crystal has been carried out using the method proposed by Watanabe. The effects of individual elements on the volume fraction of γ' phase, the electron vacancy number and the lattice parameters of γ and γ' phase as well as the lattice misfit between γ matrix and γ' precipitate have been predicted. Based on the calculation, the dependance of composition on microstructure and mechanical properties has been proposed and compared with experimental results. The composition designed by present provides about 60% of volume fraction of γ' in the alloy, good structural tability excellent high temperature mechanical properties were obtained.

The principle and mathods of calculation of phase diagram, especially the geometric models for determination of excess molar Gibbs energy and excess partial molar Gibbs energy in all phases have been reviewed. Considering the significance and the limitation of calculation of phase diagram, it is pointed out that the combination of calculation with measurement is the best method for construction of molten salt phase diagrams. The procedure of this method have also been described.

Four criteria of forming components by superplastic air bulge have been considered as: ratip of width to depth, W/H, ratio of rotary to bottom angle, r/r_0, distribution of forming material, F/S,and angle difference, θ-φ. An empirical dimensionless expression of combined criterion was proposed to be: Q=((WS)/(HF))+(π/180)(θ-φ)-(r/r_0)+0.55 The left-right crosswise duplex helix components were formed by superplastic air bulge. Their formability was determined by the criterion of typical case Q=l under given conditions. It is believed that the judgement of formability and evaluation of forming operation of components by the above mentioned criterion seem to be available.

The problem of the heat transfer of the electron beam surface hardening of steel 20 was considered from both theoretical Viewpoint and experiment. A steadystate, three-dimensional heat flow model in a moving semi-infinite workpiece subjected to a stationary uniform rectangular heat source was developed. The temperature distribution of the workpiece has been numerically derived by the finite difference method, from which some unmeasurable parameters such as peak temperature, heating and cooling rates are evaluated. For a given material, the relationship between the parameters and the surface melting point was obtained with the assumption of the constant thermal properties. It provides a basis for selecting proper operating conditions during the electron beam transformation hardening. In the experiment, on the other hand, the microstructures of the transformation zone were studied with varying parameters such as beam power, the travelling speed of the workpiece and the beam size. The microstructure, shape and depth of the transformation zone of the treated surface layer,o,n the steel 20 have been investigated and the starting of its surface fusion has been determined. The experimental results are quite in agreement with the numerical calculation. Thus, the model abovementioned seems to be available.

The error of average intensity of X-ray diffraction spectra, in the case of not more enough, from specimen of Fe, Al or Zn having obvious texture was studied. The error of average intensity obtained from measured intensity dividing by polar density factor of the inverse pole figure is so large that it can not be used for quantitative phase analysis. The error of average intensity obtained using oscillation sample holder (the intensity is averaged mechanically over the region from 0 to 60 degree of the pole figure) is improved slightly for Fe or Al, but still large for Zn. The satisfactory result is obtained by means of "the double correction method". The error is 2-5% for Fe or Al, and less than 10% for Zn.

The phase diagram of NaF-CaCl_2-LiCl system was studied by X-ray phase analysis. It was found that the NaF forms negative deviation molten salt solution with CaG_2-LiCl system. This result was discussed based on some conclusion obtained from the Monte-Carlo simulation of molten salt mixture.

The influence of rare earth elements on carbon solubility, interaction coefficients as well as equilibrium constants of REC_2 formation in liquid iron were investigated at. 1300, 1400, 1500 and 1600℃. Ce, Y, La, Nd and Sm may increase the solubility of C in liquid iron. The temperature dependences of interaction coefficients between rare earth elements and carbon in either carbon saturated or dilute liquid iron were estimated. It has been proved that various REC_2 are formed in liquid iron under observation of metallography and SEM. The temperature dependences of the equilibrium constants of the reactions of REC_2 formation and the standard free energy of formations of REC_2 in liquid iron were also determined. Five equilibrium diagrams of rare earth elements and carbon have been drawn.

X-ray diffraction fitting of the profiles for P-implanted monocrystalline Si was performed by means of Pearson Ⅶ and Pseudo-Voigt functions.It was found that the exactitude of the latter is better than the former.However, the former can be used to calculate the parameters easily.The correlation between 2ω/β and Pearson Ⅶ parameters m and a was presented and applied to phase analysis of SiO_2-SnO_2 mixture.