In situ observation of the growth process of bainitic plate in β brass by means ofhigh--temperature TEM is conducted. The lengthening and thickening kinetics of bainitic plateis analysed with Trivedi's model and Zener--Hillert's model, respectively. It is found that thestacking fault substructure exists just in the growth tip of fresh bainitic plate and so does theshear stress in the matrix around the tip. The measured lengthening rate of bainitic plate is notconsistent with Trivedi's model. The thickening process is only macroscopically controlled byvolume diffusion but its nature is a shear process.

A statistical distribution function of the dislocation link length, in unit volume ofthe crystalline materials has been derived theoretically after semi--infinite normalization by as-suming the distribution of actual links in all positions of crystalline materials with equal proba-bility, i.e.whele ρ is dislocation density. This assumption seems to be reasonable for polycrystalline fccmetallic materials, and confirmation has been found in pure Ni and stainless steel 1Cr_(18)Ni_9TiTEM experiments results.

Mechanism for diffusion of B in γ--Fe is believed to be mainly by means ofboron-vacancy complexes other than as interstitial atoms previously. This was made of calcula-tion on the basis of theoretical model proposed by the authors. The calculated diffusioncoefficient of B in γ--Fe after this mechanism is consistent with the experimental value. In addi-tion, this is also supported by the non--equilibrium segregation phenomenon of B at grainboundaries of γ--Fe and the lattice constant measurement of Fe--B alloy.

Contributions of weak grain boundary, cracking path deflection and grainboundary delamination to fracture toughness anisotropy of high strength Al alloys were evalu-ated based upon approaches of fracture mechanics and in conjunction with physical crackingmechanisms. The predicted results are close to those experimentally determined in the literatureand in this work. The strong anisotropy of fracture toughness of high strength Al alloys istherefore attributed mainly to weak grain boundary cracking, cracking path deflection and grainboundary delamination. With the methods of this work, short--transverse fracture toughnessvalues of some semi-products can be estimated from in--plane toughness values and corre-sponding fracture characteristics when it is difficult to be determined experimentally.

SEM photos for very coarse grained and high ductile polycrystalline pure Alshow certain following characteristics: A few fracture sources are concentrated, the fan--shapedcrack propagated near them, and the fatigue striations are cycle cleavage facets. Each striationconsists of wide cleavage facet and narrow cleavage step. These steps often blunt due to plasticdeformation; The fatigue striations are clear and continual, and distribute to whole fracture sur-face in propagation zone of II stage. Two fatigue striations, formed in different level, areconjoined by a "twisted baked piece of pastry" band; The secondary crack along fatiguestriations were observed frequently. Some of them have already developed into secondarymacrocracks and secondary fatigue striations were found clearly on fracture surface of secon-dary crack; The whole fracture surface can be divided into two parts, crack initiation and crackpropagation zones, however, no statical--fracture zone was observed. The mechanism of fatiguestriation formation was preliminarily discussed.

The crack propagation resistance for alloy 8090 sheet decreases with the increaseof content of Na and K impurities. An improvement over the fracture toughness and crack initi-ation resistance for the alloy containing Na and K within certain limit may be made by adding0.05% Ce. This beneficial modification would not be manifested if the alloy contained moreenough Na and K. One of the reasons why Na and K injure the toughness of the alloy might bedue to that they cause the precipitation of T_1 phase along grain and subgrain boundaries andaccelerate the abnormal growth of recrystallized grains.

Creep fracture behaviour of <001> oriented single crystalline Ni--basesuperalloys CMSX--2, SRR99 and RR2000 has been investigated in the temperaturerange of 750--1000℃ and under stress with in the scope of 150--680 MPa. The creepfracture surfaces and logitudinal sections of crept specimens have been examined bySEM. Creep cracks seem always to initiate at inherent casting pores and slowly propa-gate anisotropically along the (001) planes, perpendecular to axis of stress applied, upto the final fast fracture. Creep cracks can also nucleate at fractured carbides or at in-terfaces between carbides and matrix in the alloys containing more carbon. Although athigher testing temperatures, oxidation masked strongly the fracture surface, the creepdamage mechanism did not seem to vary in the temperature and stress range explored.The size distribution and the area fraction of (001) facets on fracture surface character-ize the creep crack damage level reached just before the collapse.

The cleavage rupture behaviour of the TCll Ti alloy with variousmicrostructures, i.e., equiaxed, duplex and interweaving, has been studied under fatigue--creepinteraction at 520℃. It was found to be not only related to the rate of creep void initiating, butalso controlled by the creep strain accumulation on holding under tension test and stress state atcrack--tip. This seem to be combinably affected by both value of critic void initiating strain andparameter, V_(GC), of critic void growth.

Effect of γ--irradiation on the shape memory alloy CuZnAl has been studied by the techniques ofTEM, positron annihilation etc. The martensitic transformation temperature of the alloy increases obviously af-ter γ--irradiation at a dose of 2×10~7 Gy but not for a dose of 1×10~7 Gy. The shape memory effect in bothirradiated alloys remains unaffected.

A comparative investigation was carried out of the routine mechanical properties, fracturetoughness, microstructure and hardness of slack--quenched rails containing different carbon contents. After therails slack--quenched, their strength and toughness, together with ductility, are obviously improved, and thehigher the quench hardening is, the more the resistance to wear and shell will be. Discussion was also made ofthe reason for this improvement and of the effect of carbon content and quench hardening on the properties ofrails in combination with the rail--laying trial.

The splat foils, 0.04--0.06 mm thick, of Al--RE (RE=Y, La, Ce, Pr, Nd, Sm,Eu, Gd, Tb, Dy, Er, Yb) binary alloys were made by arc--melting and hammer--anvil techniqueat cooling rate in 10~6 K / s order of magnitude. The metastable extended solid solubilities ofthese RE elements have been evaluated by measurements of the lattice spacings of the rapidlysolidified Al--RE alloys, they are 0.4, 0.15, 0.21, 0.21, 0.3, 0.5, 0.1, 0.6, 0.65, 0.7, 0.75, 0.2at.--% for above mentioned individual RE metal, respectively. The secondary phase in rapidlysolidified Al--RE alloys was identified to be Al_4RE for alloys containing light RE and Eu andAl_3RE for alloys containing heavy RE and Y. Some factors influencing the extension of solidsolubility of Al--RE alloys were discussed.

An approach was made to correlate the proposed model of ion--cluster structureand structural parameter of TiO_2--bearing pentary system of molten slag with properties. Re-sults showed that an increase of ions with 4--coordination number in molten slag makes the in-crease of bulk viscosity and the decrease of density, while that with 6-coordination number iscontrary. The structural parameter proposed is so fairly interrelated to the properties of slag,that it may be available for the prediction about properties. In comparison with ions of4-coordination number, Ti is more effective than Al and Si.

The disaccommodation (DA) measurements of initial susceptibility were per-formed in amorphous Fe_(90-x)Ni_xZr_(10)(x=10, 20, 30) alloys. The DA was measured for two dif-ferent amorphous states: as--quenched and pretreated at 537 K for 45 min. For all theas--quenched samples, in the isochronal spectra of DA a well defined relaxation peak around350 K is accompanied by a small but distinct peak near the Curie temperature of Fe_(90)Zr_(10) Phase(T_c=230 K). The reversibility and annealing effect on DA are analyzed within the framework oftwo--level model. The fits of the theory to the experimental data of reversible relaxation pro-cesses gave a spectrum of activation energies and pre--exponential factor.

The cyclic vltammetry, electrode potential--time curve after potentiostatic elec-trolysis, potential step method and X--ray diffraction were used to study the electrode process ofPr(III) reduced on Ni electrode in molten NaCl--KCl--PrCl_3 and to determine the diffusioncoefficient of Pr into its alloy phase. The Pr-Ni alloys are formed before the deposition of me-tallic Pr. The PrNi_5 is formed on electrode first and then the intermetallic compounds containedmore Pr are formed in sequence. The standard free energy of formation for PrNi_5 has also beendetermined.

The magnetic properties, microstructure and magnetic hardening of sintered(Nd_(1-x)Dy_x)_(16)Fe_(77.2)B_(6.8)and Nd_(16)Fe_(77.2)B_(6.8)+y wt-% Dy_2O_3 magnets have been studied. As anaddition of Dy metal to the magnet during smelting, Dy atoms may enter the matrix phaseNd_2Fe_(14)B, so as to enable enhance H_A, fine grains and improve boundary structure, as well asto increase H_(ci) of the magnet. If Dy_2O_3 added to powder material prior to sintering, Dy atomsdiffuse into the epitaxial layer of grains of matrix phase causing enhancement of K_1~1, also refine-ment of grains and improvement of boundary structure. The NdFeB based permanent magnetswith higher H_(ci) and greater (BH)_m may be produced by adding Dy_2O_3 about 2--3 wt--%which make a favourable condition for lower cost.

Whatever the cast Pr_(19)Fe_(74.5)B_5Cu_(1.5) magnet deforms in various processes, itseasy-axes are aligned parallel to the compressive strain direction. During hot deformation, thecrushing of Pr_2Fe_(14)B matrix grains, the relative slip and rotation between the grains and thesqueezing out of Pr--rich melt of the magnet take place. Then a fine, dense and well--alignedmicrostructure may be formed in the fully deformed magnets with improved properties, B_r=990mT, _iH_c=880 kA / m and (BH)m=191 kJ / m~3. The increase of coercivity is attributed to thefine Pr_2Fe_(14)B grains and the thin Pr--rich phase layer continuously distributed at the grainbounbaries. The increasing remanence is resulted primarily from the development of theeasy--axis alignment as well as from the densification of the Pr_2Fe_(14)B matrix. The easy--axisalignment is developed by the relative slip and rotation of the crushed Pr_2Fe_(14)B grains. A fulland slow hot deformation is necessary for a good easy--axis alignment and high magnetic prop-erties.

Mechanical properties of steels ZG_(15)CrMoV and 35 in the temperature range of500--1400℃ have been investigated by means of Gleeble--1500. Taking experimental results asinput-output responses, a rheological model with 5 elements of the mechanical behaviour of thesteels at elevated temperatures may be determined by a system identification method. The identi-fied results are in fair agreement with the experimental ones.

A new method for preparation of hard TiN films has been developed by electronbeam evaporation--deposition of Ti and bombardment with tens keV Xe~+ ion beam in a N_2 gasenvironment. The TiN film, prepared by Xe~+ ion beam enhanced deposition, is superior to PVDand CVD ones in respects of improved adhension to substrate and low preparing temperature.It exhibited good wear resistance and high Knoop hardness up to 2200 kg / mm~2. Some indus-trial applications have been reported.

Impact toughnese of ductile nodular cast iron loaded perpendicular to theaustenitic dendrites is found to be 43% higher than thatparallel to ones. Yet tensile strength andelongation of the former are 23% and 30% lower than the later respectively. It is believed thatthe dendritic segregation may cause such differences.