The ductility loss in 60Ni40Fe alloy and the threshold stress intensity, K_(lH),in 50Ni50Fe alloy during dynamic charging have a minimum value. The variations ofamounts of hydride phase and hydrogen evolution and dislocation structure with compositionhave been investigated. The difference between variation of hydrogen embrittlement suscepti-bility measured by ductility loss with composition and that by K_(lH) or K_(lH)/ Kc could be ex-plained by use of synthetical effects of amount of hydride and solutionizing hydrogen and ex-tent of dislocation planarity on hydrogen embrittlement suceptibility.

Effect of Ca on hardenability and CCT diagram of 58CrV steel has been inves-tigated by means of end-quenching and thermal expansion. An addition of 0.006 wt-%Ca tothe stpel may improve the hardenability, reduce the critical cooling rate of transformation ofpearlite or bainite under continuous cooling and increase the M_s. AES analysis showed thatthe Ca segregates markedly along austenitic gfain boundaries, and accelecrates the segrega-tion of C, Cr and Si. It is believed that besides towards deoxidizing and desulphurizing as wellas imperoveing sulphide morphology, a trace of Ca in 58CrV steel behaves towardsmicroalloying.

A secondary twinning orientation relationship between A and B martensitevariants in CruZnAl shape memory alloy was confirmed under TEM observation. The twinplane, (13 20 50), is a linear combination of (1 2 8) and (1 0 10) planes, which are twin

Determianation of (Fe, Cr)_7C_3 in a Cr27 cast iron results about 30 v.-%. Mi-nor Si and Mn are present. Sectional area of the M_7C_3 grains is 1-50 μm~2. Combining ma-trix analysis of electron diffraction pattern with calculated angle between plane traces, (011)twins and also (013) twins producing local environment for Ru_7B_3 are observed in theorthorhombic M_7C_3. A crystallographic model for M_7C_3 is proposed.

Two driving forces △G~(β_1+α') and △G~(β_1→β_2+α) for the baintic transformationhave been calculated for a Cu-24at.-% Al alloy. Results reveal △G~(β_1 →α')> 0 within the trans-formation temperature range 60--750 K. Therefore, the bainitic transformation cannot beinitiated by the β_1→α' shearing mechanism. On the other hand, the driving force △G~(β_1→β_2+α)to produce 5% of the α becomes negative only when the composition of the α satisfiesx_(Al)~α≤0.204 at 700 K or x_(Al)~α=0.209 at 750 K. So the bainitic transformation can only proceedby β_1→β_2+α diffusional reaction with diffrent diffuson amount at different temperatures.

Investigation was made of the ductility and microstructure of a series of castNi_3Al-basb alloys, containing alloying element corresponding to equivalent Al ranged 19--23at.-%, with relation to their alloying elements. An obvious improvement on morphology, dis-tribution, amount and size of primary Ni_3Al(γ') intermetallic compound was approached bysuch alloying elements as Hf, Ti, Zr, but no more by Nb, W, Ta. The formation of ductileγ'-γ-γ' boudary in the alloys with refined primary γ'-phase may eliminate the weakened na-ture of brittle γ'-γ' boundary, and reduce the size of primary γ'-phase to tens of μm. thus, theductility of the alloys, especially at intermediate temperature may be markedly improved. Inaddition, an alloy free from Cr is still significantly ductile, only its structure refined. Theavailability of Cr to improving the intermediate temperature ductility seems to be due to thechange of amount and distribution of γ-phase.

Studies were made of the variation of stress response, σ, internal friction, Q~(-1), and ultrasonic attenuation Aa, during cyclic deforamtion and correlation among them withdifferent slip orientation Al single crystals. Results indicate that they have obvious depen-dence upon slip orientation of Al single crystals. They are many differences for Q~(-1), △αand σbetween mono-slip and multi-slip Al single crystals. For the Al single crystals with sameorientation, the increase of σ corresponds with reduction of Q~(-1) and increase of △α, yet therequired number of cycles approaching the maximum of △α may be less than that of α up tomaximmu. And the Q~(-1) and σ may reach minimum and maximum, respectively, at samenumber of cycle.

Influence of residual stress and surface morphology, resulting from shot-peen-ing, on fatigue behaviour of medium temperature tempered spring steel 60Mn have been stu-died. The induced compressive residual stress in near-surface region may improve fatigue lim-it from 930 to 1010 MPa, and the very high tensile residual stress in the interior may reduce itfrom 1010 to 940 MPa, whereas the severe surface damage may cause a drop-off of it from1010 down to 800 MPa. Fatigue cracks initiated in such position where the equivalent Misesstress, including residual stress, exceeded the local strength of the material. The compressiveresidual stress, induced by shot-peening, may intensify the effect of crack closure, so as to de-crease the crack growth rate.

By using WDS method of EPMA and EDS technique of STEM, 550℃ and450℃ isothermal sections of Fe-Ni-C phase diagram were determined.

The parameters in the polynomial expression of partial mole free energy of Cwere evaluated by value fitting method on the basis of boundary conditions of liquid domainon the system C-Fe-X(X=Si, Mn, Cr, Ni). Then the activity coefficient of the element Xmaybe calculated with the I-D method. The approach suggested is proved to be useful for theactiveity evaluation of every element in the whole liquid domain of the concerncd 4C-Fe-Xternary systems. The results are found in a good agreement with those of citedprovious literatures.

The stress corrosion cracking (SCC) susceptibility of an Al-Li-Cu-Mg-Zr al-loy (2091), heat-treated under different regimes, has been investigated by means of tensile testat slow strain rate. The microstructures has been examined with TEM. The deformation be-havior has also been analysed. The stress corrosion resistance of the alloy was revealed to bemainly affected by the covering of T_2-phase over grain boundaries and by the average dis-tance between T_2-phase particles. An improvement of SCC resistance may be obviously madeby pre-deforming the alloy at room temperature to reduce the precipitation of T_2-phasealong grain boundaries.

Kinetic and isothermal oxidation test at 800 and 660℃, and abrasive wear testat 800, 660 and 520℃ were carried out for the Fe-Cr-Mn alloys containing various contentsof C ranging from 0.50 to 2.69%. The morphology of oxidation film and microstructure ofsubsurface were examined. Results show that with increasing content of C, the amount ofeutectic carbide increases resulting decrease of Mn in matrix to participating in oxidation. Theoxidation resistace is thas improwed. The high temperature wear resistance is closely relatedto the bulk hardness and eutectic carbide contained. The higher the hardness, the better thewear resistance will be. However, the support provided by the matrix seems to be very impor-tant to ensure the wear resistant effect of the carbide.

A method was developed for preparing nanocrystalline alloy made of the iden-tical compositional Fe_(78)B_(13)Si_9 amorphous ribbon by suitable isothermal annealing. Itsmicrostructure and some structure-sensitive properties, including thermal expansion, specificheat, etc., have been studied and measured. Comparative analysis of properties was also car-ried out with amorphous and coarse-grained crystalline alloys of same composition. thus, it isbelieved that so novel differences in properties from usual materials would be made by theparticular microstructure of short range disorder of the nanocrystalline alloy.

Three new Fe-based microcrystalline alloys, i. e., Fe_(73.1)Cu_(1.2)Nb_(3.2)Si_(12.5)B_(10),Fe_(73)Cu_1Nb_(1.5)Mo_2Si_(12.5)B_(10) and Fe_(73)Cu_1Zr_3C_(0.5)Si_(12.5)B_(10), were developed with superior magneticproperties, e. g., high relative initial permeability of μ_i≥5×10~4, low coercivity of H_c≤1.0A/ m, high effective permeability and low core loses in a considerable wide frequency rangeand high pulse-magnetic permeability under narrow pulse. the optimum value of relative ef-fective permeability, μ_5 is 16×104 under condition of f=1 kHz and H_m=0.4 A / m. Theoptimum values of core loss reach 57.9, 30.2 and 68 W / kg under condition of f=50, 100, 100Hz and B_m=0.5, 0.2, 0.3 T, respectively, These three alloys have superior stability of magneticproperties. Initial permeability may be not chaned duing heating at 130℃ up to 216 h. Themain crystalline phase is ordered phase Fe_(75+y)Si_(25-y) which is ultrafine particles of average size10--20 nm.

Eutectic Bi / MnBi magnetic alloy was prepared by directional solidification.When the growth rate, R>2 cm / h, the MnBi fibre spacing, λ, distributed homogeneously inBi matrix, follows λ~2R=constant. The thermal gradient, G_L, does not influence λ. The mag-netic property, B_r of Bi / MnBi alloy decreases with the increase of R and increases with theincrease of G_L

The effect of subzero treatment on the microstructure and mechanical proper-ties of Y_2O_3-ZrO_2ceramic have been investigated with TEM, X-Ray diffraction and tests ofmechanical properties. It was shown that the microstructure of 3Y-PSZ after subzero treat-ment by liquid nitrogen exhibit more longer and parallel lath of m-phase. Suitable subzerotreatment can improve the strength and toughness of Y-PSZ efficiently because of decreasingthe stability of t-phase and increasing the level of t→m transformation at an applied stress.However, when the time of subzero treatment excesses, the overaging effect may arised, whichcan decrease the strength and toughness of the material.