Behaviour of B segregation to grain boundaries in Fe-3% Si alloy has beenstudied by means of particle tracking autoradiography. Results indicate that B tends to equi-librium segregation to grain boundaries in Fe-3% Si higher than in austenitic alloys. No ob-servable nonequilibrium segregation of B to grain boundaries was revealed in Fe-3% Si alloyduring cooling and isothermal holding. The binding energy between B atoms and grainboundaries is 55.7±1.7 kJ/mol. Based on the complex mechanism of quenching-induce-nonequilibrium segregation, different behaviours of B segregation in γ-Fe and b.c.c.Fe-3% Si alloy were discussed.

Crystallization of amorphous Ce_2Fe_(23)B_3 alloys as well as structure and mag-netic properties of metastable compound Ce_2Fe_(23)B_3 were studied. X-ray diffraction analysisconfirmed that the crystal structure of Ce_2Fe_(23)B_3 compound is body-centered cubic, its lat-tice constant α=1.417 nm. Measurement of room temperature hyperfine field ofCe_2Fe_(23)B_3 observeed that the size of Fe magnetic moment in different Fe site is orderlyμ_(Fe)(48e_1)>μ_(Fe)(48e_2)>μ_(Fe)(48e_3)>μ_(Fe)(16c)>μ_(Fe)(24d). Average magnetic moments per Fe atomand per Ce atom are 1.94 and 0.85μ_B respectively.

The mixed-mode (Ⅰ/Ⅱ) fatigue crack growth threshold was studied. The fa-tigue crack growth threshold value of pure mode Ⅱ in dual-phase steel(DPS) was found to be1.9 times of that of pure mode Ⅰ; the tensile stess strength factor range of pure mode Ⅱbranch crack tip is 2.2 times of that of pure mode Ⅰ. The roughness-induced shear resistanceimpedes the mode Ⅱ crack growth; while roughness-induced crack closure reduces the drivingforce of mode Ⅰ crack tip; the resistance of the former is larger than that of the latter. Themode Ⅱ component in near-threshold fatigue crack growth may increase the plasticity ofcrack tip which accelerates the crack growth and introduce crack surface contact and rub toreduce the crack propagation rate. The difficulty for quantifying the shear resistance is readilysolved through measurement of crack closure in this paper. The friction shear stress strengthfactor range of pure mode Ⅱ still is far larger than the closure stress strength factor range ofpure mode Ⅰ. It is illustrated that the roughness enlarged the second role and played a role ofshielding crack tip from mode Ⅱ crack.

Micro-alloying of Mg, ranged from 30 to 70 ppm, may improve the high tem-perature ductility, stress rupture, especially, certain important mechanical properties, such ascyclic stress rupture, creep and fatigue interaction and crack propagation rate. The quantity,morphology and distribution of δ-phase may obviously influence the notched cyclic stressrupture life. The relevant microstructure shows that the Mg may also influence to a certain ex-tent on the feature of δ-phase. Thus, keeping the Mg and δ-phase under control may furtherimprove the mechanical properties of GH169 alloy.

The precipitation structure in Incone1718 and modified alloys has been stu-died by means of TEM. The morphology of associated precipitation and compactmorphology of γ′+γ″ were obtained by modifying the contents of Al, Ti and Nb. Experimen-tal results show that the compact morphology of γ′+γ″ has the best thermal structure stability.Instead of γ″ transformation in Inconel 718 the dissolution of strengthening phases in modi-fied alloy leads material degradation.

The diffusion hydrogen and its diffusion coefficient in rail steel U71 Mn bloomwere determined by paraffin oil method, and the hydrogen distribution over its cross-sectionwas examined by dissecting the slowly cooled stack blooms. Most hydrogen in bloom isdiffusible and its room temperature diffusion coefficient is equal to about (0.85-1.02)×10~(-6)cm~2 / s. The hydrogen content in blooms after stack cooling may reduce in great extentso as to be contributed to produce the heavy rail steel free from flake at the Panzhihua Ironand Steel Company.

Changes of fatigue crack growth rate, dα/dN, at affecting region of eitherplastic or elastic shock wave have been studied with three-point bending specimens made oflow alloy steel 16Mn. The dα/dN at whole affecting regions by shock wave, about 100 mmdepth, is significantly reduced, especially at the plastic wave affecting region. Thedα/dN keeps basically constant at pure elastic wave affecting region under same ΔK. It isconsidered that the decrease of effective stress intensity factor ΔK_(eff) of the material with crackclosure effect is the main reason for reducing dα/dN after shock wave treatment. At plasticwave affecting region, crack closure occurs mainly through plastic deformations at crack tipand oxides; at elastic wave affecting region, through plastic deformations and roughness.

Studies were made of the symmetric tensile-compressive low cyclic fatiguebehaviour and dynamic strain aging (DSA) pre-treatment influenced on 18-8 austeniticstainless steel. Within the tested amplitude range of strain: ±0.5%-±1.5%, the three pro-cesses of cyclic hardening, cyclic saturation and cyclic softening were observed. In the sameamplitude of strain, the peak stress of the samples pre-treated by DSA is higher than that ofsolid-solution and cold working pre-treatment, but almost no differences of the fatigue livesof them were found. TEM observation shows that the uniform and stable dislocation net-works with high density form after DSA pre-treatment, which increases the cyclic peak stress.The cyclic softening is resulted from the low dislocation density and elongated cell structurewith low energy.

The flotation behaviour and mechanism of bastnaesite with N-hydroxylphthalicimide were investigated by ζ-potential measurement, infrared spectrum and quantumchemistry calculation. The results show that 3 oxygen atoms from N-hydroxyl phthalicimidechelate the rare earh ions on the surface of bastnaesite to form double five-chainO=C-N-O-RE (Ⅲ)-O chelate which is chemically adsorbed on the surface of bastnaesite,thus making N-hydroxyl phthalicimide an effective collector for bastnaesite.

Ni_(100-x)Mo_x(x=20, 30, 38) alloys have been synthesized by mechanical al-loying. The structure evolution of powders during mechanical alloying has been monitored byX-ray diffraction, SEM and TEM analysis. The Ni_(62)Mo_(38) sample becomes partially amor-phous after high energy ball milling, while the Ni_(80)Mo_(20) and Ni_(70)Mo_(30) become no-equilib-rium nano-crystals.

The solid complexes of 16 rare earth elements with bis (2,4,4-trimethylpentyl)phosphinic acid (HBTMPP) were synthesized and their composition was identified to beRE(BTMPP)_3. The thermal analyses of the complexes were studied in Ar or air. Thethermo-decomposition residues of the complexes were verified by element analysis, infraredspectra and X-ray diffraction to be RE_4(P_2O_7)_3 in Ar or RE_2P_4O_(13) in air. The infrared andRaman spectra were measured for RE(BTMPP)_3 and principal absorption bands were as-signed. The results showed that the RE-O bands of RE(BTMPP)_3 are principally ionic.

The ribbons of amorphous Al-La-Y-Ni (Fe) quarternary alloys, prepared bysingle-roller melt spinning technique under vacuum, superior strength, ductility and thermalstability may be achieved when the alloy contains 85-90 at.-% Al and less than10at.-% La+Y. The maximum tensile fracture strength and microhardness are as high as 760MPa and 294 DPN, respectively. As-quenched ribbons can be bent 180 deg without frac-turing. The dominant factors for formation of amorphous Al-La-Y-Ni (Fe) are the strongattractive interaction among Al, La, Y and a low melting temperature.

Oxidation behaviours of high Cr cast iron at 950 and 800℃ have been investi-gated on the basis of. Cr content and carbide volume. Type and morphology of oxide film andmicrostructure of subsurface after oxidation have also been examined. The original Cr con-tent, to be related to the type of oxide film, is an important factor of resistance to oxidation ofthe high Cr cast iron. Resistance to oxidation of the cast iron may be improved with the in-crease of carbide volume owing to the decomposition of the carbide during oxidation at950℃. While it does not be improved because the carbide is not yet decomposed at 800℃.

A computerized digital speckle-interferometry(SPI) system has been set up todetermine the in-plane distribution of displacement and strain at crack tip of CF specimens.The effect of corrosion factors on plastic deformation at crack tip in CF process has been ex-amined by comparing the near-tip strain fields of steel A537 before and after hydrogen char-ging, and of pure Cu before and after applying an anodic current in 3.5% NaCl. The resultsshowed that the clasic finite element mathematical models were not suitable to describe thenear-tip deforamtion under the experimental conditions. Hydrogen charging made the cracktip plasticity decreased for steel A537 and the anodic dissolution enhanced the near-tipdeformation of pure Cu specimen.

Influences of applied potentials and loading waveform on the fatigue crackgrowth for steel A537 in 3.5%NaCl solution, and corresponding straining electrode behaviourhave been studied. Under the applied potentials over or below-800 mV (SCE), the anodicdissolution or the hydrogen embrittlement is predominant, respectively. For applied anodicpotential, the acceleration effect of continuous loading pattern on the CF crack growth main-ly appeared at the range of low △K values, while for cathodic potential, it appeared at therange of high △K values. The continuous straining causes a decrease of natural potential andan increase of anodic dissolution current.

Quality 9Al_2O_3·2B_2O_3 whisker reinforced 6061Al or Al composites havebeen prepared by technique of squeexe casting. Mechanical properties of the 9Al_2O_32B_2O_3(w)/6061Al composites could be hardly improved by T6 treatment, owing to cause theremarkable interfacial reaction. An observation under high resolution transmission electronmicroscopy on interfaces shows that the serious chemical reaction occurs and the product isAl_2MgO_4. But no such reaction is found at the interfaces of 9Al_2O_3·2B_2O_3(w)/Al compo-site. EDS analysis on the interfaces shows that above mentioned interfacial reaction may beresulted from the interfacial segregation of Mg atoms in 6061Al matrix during sequeeze cast-ing.

A method for determining thin film texture by electron diffraction pattern ispresented. Using this method, the texture state of the ZrO_2 thin film has been determined.