A cast Ni-base superalloy containing very high contents of Al and Ti (Al+Ti=13.5 wt-％) has been treated by laser rapid melting and solidification. Influence of laserglaze on microstructure and distribution of alloying elements have been studied by TEM, SEM and EMPA. Results showed that the microstructure has changed obviously in the laser treated region, in which alloying elements distributed homogeneously. All the large γ+γ' eutectic, γ'+β peritectic and MC carbides were eliminated. Particularly, microstructure of the laser treated region is excellently thermal stable. Due to extremely high Al+Ti content the σ-phase already existed in cast structure, after aging at 950℃ for 18h, precipitated in enormous quantity. But after laserglaze, no σ-phase was found even aging for 264h. It was evident that if alloy specimen with large quantity of σ-phase was laser treated, not only all the σ-phase particles have been dissolved, but also they could not reprecipitate out even after prolonged aging. Laserglaze can be applied to improve the microstructure and properites of known superalloys, suppressing the precipitation of harmful phases by prior laser surface treatment on machine parts, or eliminating harmful phases present in used parts. It can also be adopted as a powerful means to extend the solid solubility of alloying elements in order to develop new materials.

The process of deformation and crack initiation of high temper (550℃) medium-carbon steel 40Mn has been investigated using smooth tensile specimens. The midgage length part of the specimen was spark cut into 0.3mm thick sheets. The direct transmission observation of thin foil specimens was carried out on TEM. The evolution of the dislocation structure with elongation in the steel of hardened and tempered condition was studied. In the lath ferrite, the feature of dislocation structure is irregular network. At the stage of comparatively small elongation (δ=0.2-2.7％), near the interface of ferrites and the ferrite-cementite interface, regular dislocation networks appear and the dislocation density increases. At the deformation stage of δ=4.7％, the dislocations tangle and desify. At the deformation stage of δ=6.8-10％, the feature of dislocation structure becomes elongated dislocation cells. The crack nucleation in hardened and tempered steel has been observed by SEM and optical microscope. When the deformation attains δ=4.7％, the submicroscopic cracks are initiated at interface of metal matrix and inclusion. At the deformation stage of δ=6.8％, the submicrocrack initiated at interface of lath ferrites and interface of ferritecementite. The submicroscopic crack propagated through the formation and joining up of void groups.

Samples of casting high-Mn steel with structure of stable austenitic cells were prepared by strictly controlled directional solidification. With the increasing of the Ce content, the cell structure changes gradually in the front of crystals into dendrites and then into separate crystals, so as to narrow the columnar crystal region. An EPMA was performed quantitatively on the influence of Ce upon the Mn segregation in cellcrystals, columnar and Equiaxial dendrites of high-Mn steel. Considering the solute diffusion in solid state together with the previous works, an expression of Mn distribution in high-Mn steel was approached. After quite a few theoretical analysis on the experimental data, it seems to be indicated that the solute equilibrium partition coefficient, K_0, is the determinant factor of influence on dendritic segregation.

The investigations were conducted by TEM, SEM and IMP techniques on the problem of "bright band" defect found occasionally on the longitudinal macroscopic fracture surface in commercial Cr-Ni structural steels, e. g. 30CrMnSiNi, 40CrNiMo, 4SCrNi, etc. The influence of "bright band" on their mechanical properties has also been evaluated. Results showed that the "bright band" defect is the hydrogen damage which is caused by hydrogen interdendritic segregation during solidification of steel ingots. This defect may lower obviously the impact toughness, reduction of area as well as elongation of the steels. The mechanism of its formation and the prevention have been discussed.

The effect of Mn and Si contained on the notch sensitivity of an Fe-Ni base superalloy has been studied. It was shown that the overabundant contents of Mn and Si lead the alloy to notch sensitivity which can hardly be improved even by heat treatment. Analysis and observation under electron microscope indicated that it seems to attribute the notch sensitivity of the alloy to the film-like boride along the grain boundaries substantially.

The stress-rupture life of a Ni-base superalloy has been evaluated under the cyclic temperatures by using the sinusoidal or the specified program-controlled waveform. It was shown that its stress-rupture life is considerably reduced by the temperature cycle. The extent of reduction is depended on the amplitude of the cycle. The formulation of life prediction for specified program-controlled temperature cycle is proposed. The fracture surface of the superalloy has also been observed by SEM.

Starting from certain similarities in the structural distribution and the deformation behaviour between the martensite-ferrite dual phase steels and the composite materials reinforced by discontinuous short fibers, a new expression is proposed for the tensile strength of the steels on the basis of the shear lag analysis, i. e. σ_(bDP)=(β/3~(1/2)+0.65)1/Kσ_(bM)V_M+σ_(bF)(1-V_M) where σ_(bDP), σ_(bM) or σ_(bF) is the tensile strength of the steel, the martensite or the ferrite phases respectively, β is the aspect ratio of martensite islands, K is the strength ratio of martensite to ferrite strength, V_M is the volume fraction of martensite and then (1-V_M) is the volume fraction of ferrite. It is in good agreement after quite a few examinations on a variety of dual phase steels with different composition and structure. The load transfer from ferrite to martensite and the utility of strength of martensite have been also discussed.

Based on the BLD method of the empirical electron theory of solids and molecules, the valence electron structure of Fe-C martensite was established. Each carbon atom making fractional covalent bonds with its 1st, 2nd and 3rd Fe neighbours forms a small cell to be called carbon involved unit. And the corresponding small cell of Fe atoms containing no carbon to be called no carbon unit. The martensite crystal structure is built upon by these two types of units. They distribute randomly in the martensite crystal. For the 1.7 wt-％ C martensite, the result shows: in the carbon involved units, there are three kinds of Fe atoms, Fe_Ⅰ, Fe_(Ⅱ) and Fe_(Ⅲ), on the 11th, 10th and 8th hybrid levels of A-type hybridization states of Fe respectively, and carbon atom is on its 6th hybrid level; in the no carbon units, the Fe is on the 8th level of A-type. In the carbon involved units, n_A=0.9991 and n_B=0.8479, and in the no carbon units, n_A and n_B have the same values as in α-Fe. The relative number of the two kinds of units changes with the content of carbon. Comparison of the values of n_A and n_B in the two kinds of units immediately shows that the hardness of martensite must increase with the content of carbon. This agrees with the experimental fact.

Desulphurization equilibria between Y-S in molten Ni at 1500, 1550 and 1600℃ have been determined and studied thermodynamically. The results are summarized as follows: 1. Temperature dependence of desulphurization constant for the formation of Y-S_(S) as the equilibrium phase in the temperature range of 1500—1600℃ is given by lg K_(YS)=47000/T+20.86 2. Temperature dependences of the first activity interaction parameters between Y and S in liquid Ni are determined to be e_S~Y=350200/T+179 in the temperature range of 1500—1600℃. 3. Temperature dependence of the standard free energy of formation of YS_(S) in liquid Ni is derived to be [Y]_(Ni)+[S]_(Ni)=YS_(S) △G°=-215000+95.53T cal/mol 4. Temperature dependence of the standard free energy of solution of Y in liquid Ni is derived to be Y_(1)=[Y]_(Ni) △G°=126200-79.31T cal/mol 5. Temperature dependences of activity coefficient and selfinteraction coefficient of Y in liquid Ni are derived to be lgγ_Y~0=27584/T-15.151 ∑_Y~Y=-127052/T+69.79 e_Y~Y=-364.8/T+0.2018 6. The minimum content of S in equilibria with Y in liquid Ni in the temperature range of 1500-1600℃ are given ~*[％S]=0.002-0.005 and ~*[％Y]=0.005-0.020. The S content raises with Y when exceed this minimum point.

The effect of individual additive at trace level of 25 select elements on the anti-oxidation susceptibility of the molten Sn-Pb eutectics has been scanned by the method of weighing the oxide films skimmed and collected fro mthe surface of molten alloys at 260±5℃. It was found that the elements in order of superlative susceptibility are Ga, Ge and P, and their best contents in wt-％ are 0.0008, 0.004 and 0.003 respectively. The anti-oxidation behaviour has been also examined by chemical analysis and X-ray powder diffraction as well as XPS technique for the study of surface layer of the alloy. Experiments indicated that the additive is highly enriched in the surface dense protective layer of 30-40 (A) thick, but for Ga up to 70-100 (A). The structure of the surface film is modified from porous into tenacious and compact one in the form of complex oxygen-containing acid salts of Sn with the oxide of enriched additive. The temperature dependence of antioxidation susceptibility is quite different, Ge and P additives no longer have any effect over 350℃, while alloy containing Ga is still stable even up to 400℃.

In order to improve the contact fatigue life of the bearing steel, the rare earth was used as deoxidizer partly instead of Al in the conventional processing. This RE ladle deoxidizer in amount of 0.08 wt-％ of the melt produces inclusions of Ce_2S_3, CeS, La_2S_3, etc. which tend to increase the fatigue life of the steel by 50％.

A new spheroidization process was developed for production of nodular cast iron from high-sulphur (0.1%S) molten iron. The solid slag cake of rare-earth oxide was used as desulphurizer and spheroidizer under the Ar-blowing operation. The results achieved after the experiments under 1380, 1410 or 1450℃. Treatment at 1450℃ for about 45 min attended 90% of success. The carbon equivalent and the content of rare-earth for nodular cast iron produced are about 4.7% and 0.020—0.081% respectively. Thermodynamic analysis on the desulphurization and the reduction of rare-earth oxides has proved available for the experimental conditions. And it was indicated by both thermodynamic calculation and experimental practice that the solid slag cake may be used repeatedly.

The glass and crystal transition temperatures, T_g and T_c, the free volume, the activation energy and the enthalpy change at T_g and T_c of the following noncrystalline glasses: (Fe_(0.1)Ni_(0.35)Co_(0.55))_(78)Si_8B_(14), (Fe_(0.1)Ni_(0.30)Co_(0.55)Mo_(0.05))_(78)Si_8B_(14) and (Fe_(0.1)Ni_(0.30)Co_(0.55)Nb_(0.05))_(78)Si_8B_(14) were studied by applying the conception of transition theory used in polymer science with torsional braid analyzer, linear expansion apparatus, DSC and X-ray diffraction technique. The T_g and T_c as well as the activation energy of glass transition are all increased with the increase of atomic radius of the extra metal added, but the activation energy of crystallization is in opposite way. A correlation between the enthalpy change and the peak of damping was also observed. The above results may be valuable to the non-crystalline glass designer.

The structural relaxation and transformation in the amorphous alloy (Fe_(0.1) Ni_(0.35)Co_(0.55))_(78)Si_8B_(14) have been investigated by measurements of ~(57)Fe M()ssbauer spectra, parameters of positron annihilation, permeability disaccommodation, magnetic torque and isothermic change of electrical resistance, as well as by DSC method. The results showed that four stages of the structural relaxation and transformation are presented in the temperature range of 50—500℃. Two different features of the structural relaxation in thet emperature range of 175—200℃ and 400—420℃ respectively are found to correspond with the different changes of the magnetic properties. The chemical and the topological short range orders are obviously developed in the structural relaxation so as to give rise to an induced magnetic anisotropy. The kinetic behaviour of the structural relaxation at low temperature and the transformation at elevated temperature was discussed. The variation of the defect structure in the structural relaxation was explained by the Egami's model of defect structure.

Thermomagnetic measurements of the amorphous (Fe_(1-x)Co_x)_(78)Si_(9.5)B_(12.5) alloys were made on a magnetic balance in the temperature range from 77 to 1200K under the external field 12 kOe. Conventional Fe~(57) M()ssbauer spectroscopy in a transmission geometry was employed at room temperature. It was found that the average moment per magnetic atom in units of the Bohr magneton decreased from 2.1μ_B for Fe_(78)Si_(9.5)B_(12.5) alloy to 1.2μ_B for Co_(78)Si_(9.5)B_(12.5) with increasing Co content. The variation of T_C with transition metal content for a fixed metalloid composition may be described by the moecular field model. The average hyperfine field at Fe nucleus with increasing Co content of x up to 0.7 first increased from 250 to 278.5 kOe, and then decreased to 262 kOe for x=0.9. Assuming the magnetic moment μ_(Co) per Co atom is independent of content, it was obtained that the magnetic moment μ_(Fe) per Fe atom increased with increasing Co content and gradually approaches to the saturation value, which is 2.6μ_B for x=0.9. The relation between the average hyperfine field (■)_f and the average moment (■) per magnetic atom fol lows equation of (■)_f/(■)=h_0+h_1μ_(Fe)/(■). The values of h_0=42.5kOe and h_1=80kOe were given using the least squares method. It was obtained from M(■)ssbauer spectrum that the angle of magnetization with respect to the plane of the ribbon decreased with increasing Co content, showing the stress-anisotropy energy decreased with increasing Co content.

A study was made of the effect of magnetic field-and tension-annealing under temperature below T_c on the permeability of an Fe_(78)Si_(10)B_(12) metallic glass. Two anisotropies induced by magnetization and by strain were observed with K_(um)>0 and K_(us)<0 respectively. The variations of K_(um) and K_(us) with the magnetization and the strain respectively during anneals are reversible basically.

Effect of impurity Zr on the magnetic properties, electrical resistivity and thermal stability of amorphous Fe_(82-x)Zr_xSi_5B_(13) (x =0.02, 0.16, 0.87) alloys has been studied. It was observed that while the Zr content in the alloys increases from x=0.02 to 0.87, the crystallization temperature, T_(cr), increases from 755 to 782K at a rate on heating of 10 K/min, and the saturation magnetization, σ(RT), at room temperature also the Curie temperature, Te, decrease 3% and 4.5% respectively. The fluctuation of the exchange interaction of the alloys is increased by the increase of Zr addition. The resistivity minimum was also obtained at low temperature of 15K in the alloy containing Zr=0.87. It seems to attribute this to Kortdo-like effect.

The glassy alloys, Zr_(1-x)M_x (M=Fe, Co, Ni, Cu and Pd) and Cu_(67.5)Ti_(32.5), were prepared by the melt spinning technique. Their critical tangential speed of the glassy state formation was determined to be 31 m/s by means of changing the tangential speed of rotator. Their structure in a glassy state of all alloy tested has been confirmed by X-ray diffraction analysis. Their thermal behaviour was examined by differential scanning calorimetry (DSC) under different heating rates. An exothermic peak in DSC tracing was presented for glassy alloys Fe_(24)Zr_(76) and Ni_(24)Zr_(76), but two or three peaks for Co_(21)Zr_(79), Pd_(24.5)Zr_(75.5), Cu_(45)Zr_(55) and Cu_(67.5)Ti_(32.5). The activation energies for crystallization of these aUoys were evaluated by the Kissinger's method. Furthermore, the effect of heat of mixing on the formation and stability of these binary glassy alloys has been discussed after calculation used the Miedema's model.

TEM was employed to study the transition from crystalline Al to amorphous state Al_2O_3 by O~+-implantation. The structural feature of the thin film specimen appears to be fcc polycrystals between 200 to 600(■) and to refine obviously during O~+ implanting. The refinement may be down to 19-40(■) when the increasing of the dose of O~+-implanted up to 1×10~(17) ion/cm~2. The diffraction pattern becomes the faint diffuse scattering ring, i.e., an enough evidence of the order-disorder transition or the amorphous formation is given. ESCA has identified that the amorphous substance is Al_2O_3.

A simplified model for the method of no-standard microregion quantitative EDS analysis developed by the authors is described. The composition of specimens of Cu-Si, FeS, NaCl and GaAs as well as the multicomponent steels were calculated by this simplified model. The results obtained are in close agreement with that of previous model. It seems to be confirmed that this simplified model is available.

Measurements of the surface tension of the Pb-Sb binary melts were made by the sessile drop method. All the temperature coefficient of their surface tension was obtained in a negative quantity. At the same measuring temperature, the values of the surface tension of Pb-Sb melts lie between that of each pure component and vary non-linearly with their compositions which show a negative diviation from the "ideal solution". As the results of this liquid binary eutectic alloy, a concept of the "liquid similar eutectic atomic clusters" (LSEAC) may be approached by the authors to interpret the surface tension phenomena of the binary alloys of eutectic type.