A complete change into extraordinarily fine cells and cellular dendrites afterlaserglaze was presented from the γ/γ′-α-Mo DS eutectic which was composedof the γ/γ′matrix with aligned α-Mo fibre formed during directional solidifica-tion.The chemical composition is homogeneous in the irradiated zone and itis epitaxial in crystal growth.

The microstructure and strengthening behaviour of the internal nitrided layerin 18Cr2Ni4WA steel after one-and two-step nitriding at various temperatureshave been studied by observation under TEM.Results showed that the formationof the internal nitrided layer proceeds as two stages:(1)a mixed clustering-order-ing zone of alloying elements and nitrogen atoms is formed on{100}_α basal planeof matrix;(2)the clustering zone transforms into equilibrium precipitate CrN.Theorientation relationship between the precipitate and parent phase accords withBaker-Nutting relation,i.e.,(001)_(CrN)∥(001)_α;[110]_(CrN)∥[100]_α.The CrN may alsobe formed from alloyed carbide at lower nitriding temperatures.The main causefor the very high hardness of internal nitrided layer is considered to be the for-mation of such mixed clustering-ordering zones within ferritic matrix.For one-step nitriding,the hardness of internal nitrided layer achieved maximum value at420—500℃ and decreased as the increase of nitriding temperature.For two-stepnitriding,owing to the mixed clustering-ordering zone which first formed at lowertemperature is remarkably stable,the nitrided layer remains its higher hardness tillhigh temperatures.Therfore,the two-step nitriding may provide a way to accele-rate the nitriding process and to shorten the nitriding time,but the hardness ofinternal nitriding layer keeps in high extent.

An investigation was made of the effect of the isothermal quenching at dif-ferent temperatures in the martensitic range on the structure and properties of 30CrMnSiNi2A steel.To sum up the results from the tests of stress corrosion,lowcyclic fatigue,fracture toughness,fracture feature and conventional mechanicalproperties,the optimum isothermal quenching regime was ascertained.Experimentalresults show that the superior comprehensive properties of the steel may be ob-tained by treatment of isothermal quenching at 285℃ then tempering at 280℃.It is believed that the lower bainite and residual austenite are the chief factors inimprovement of toughness and plasticity of the steel,however,the tempered mar-tensite is an important factor to ensure its high strength.

The kinetics of austenitization during intercritical annealing at temperaturesbetween 740 and 820℃ has been studied on the low carbon low alloy steels witha prior microstructure of ferrite-pearlite.In austenitization process,two stages,namely,nucleation and rapid growth of austenite,and slow growth of austeniteinto ferrite are presented.The austenite nucleates mainly along the ferrite-pearliteinterfaces at 740℃,but part of the austenite nuclei forms along the ferrite-ce-mentite boundaries in pearlite colony at 780 and 820℃.The kinetics of the formerstage examined obeys the Cahn's theory of grain boundary nucleation transforma-tion.An attempt is made to discuss the kinetics of the later stage by the theoryof grain growth on recrystallization.

An investigation was made of the effect of minor Ni or/and Cr additions onthe structure and coherence of the oxidized layer with the low carbon steel substra-te prior to exposure under furnace atmosphere at 1100-1250℃ by means of metal-lography,X-ray diffraction and EPMA.It was observed that at temperature over1150℃,the minor Ni addition improves the coherence of the oxidized layer ofwhich the grain boundary oxidizing structure is formed with Nienriched net-worksand grains wedged into the substrate,while the minor Cr addition has no effecton the structure of the oxidized layer.If the minor Ni and Cr additions coexisted,their coherent layer thickens remarkably.Thus,The addition of minor Ni and Crmay significantly improve the coherence of their oxidized layer on low carbonsteel.

The stress-strain plot and microstructure of 51.6 at.-% Ni-Ti shape-memory alloywere examined and observed under different heat treatments.The phenomena andpossible machanism o f Premartensitic transition,the morphology and substructureof martensite induced by temperature or strain as well as the dispersed χ-phase pre-cipitation of the alloy were also discussed.

The difference between the chemical potential,μ_σ,of hydrogen atoms produ-cing a non-spherical symmetry strain in a solid sample under stress and that,μ_0corresponding to the state without stress has been studied.It is shown that μ_σ-μ_0=■=U,where σ_1——principal stress,■——strain component along thedirection of the principal stress,V——volume and U——interaction energy betweenthe strain field and external stress field.The hydrogen atoms producing the tetragonally symmetric strain are preferen-tially ordered in samples under stress.As a result,the variation of hydrogenconcentration with tensile stress σ will be different from that with compressive stressσ.For a general polycrystal the formulas are respectively■where C_t,C_p,C_0——hydrogen concentraiton under tensile stress,compressive stressand without stress respectively.Hence,ε_(11)/ε_(22)may be determined in terms of C_t/C_pwhich can be obtained by hydrogen permeation measurement.For example,according to Bockris's data,ε_(11)/ε_(22)=1.27 at temperature of 27℃ which impliesthat the strain field of hydrogen atoms in α-Fe is non-spherical symmetry.For a torsional stress τ,U=-0.55133Vτ(ε_(11)-ε_(22)).The interaction can resultin the enrichment of hydrogen atoms and hydrogen induced delayed crackingalong the planes inclined at an angle of α=45°to torsional axis,which was ob-served in pre-charged smooth torsional or type Ⅲ cracked specimens made of ultra-high strength steel.

The effect of either the temperature and time of aging tests or the cold de-formation on the phase precipitated along grain boundaries in Cu-20Ni-20Mn alloywas investigated under TEM observation.The results showed that the aging tempe-rature influences the situation,shape and size of the nucleation of phase precipi-tated.At the aging temperature over 400℃,its preferred precipitation along grainboundary is retarded and the precipitated phase becomes fine and spheroidized.The cold deformation may also retard its preferred precipitation along grain boun-dary and change its distribution,shape and size.The increase of deformation mayimpel the precipitated phase to distribute within the grain more finely and homo-geneously.At all aging test temperatures except 500℃,the fcc solid solution de-composes and the precipitation is NiMn phase of fct structure with lattice constantα_0=0.364 and c_0=0.363 nm.

An observation of the deformation and fracture behaviour of low carbonmartensite-ferrite dual-phase steel was performed using SEM with tensile-stage andautograph test machine.It was shown that the microcracks are nucleated at theinterface of martensite/ferrite and along the martensite boundaries of differentorientations,or initiated owing to the fracture of martensite laths under defor-mation of tensile stress.The cracks may propagate by the coalescence of maincrack and the growth of microcracks,then rapidly connect with each other alongthe strong shear deformation zone.Its micro-feature is appeared as the dimplefracture and seems to be of the ductile fracture mechanism.

The concentration of the α/β interface in the Cu:Cu-Al diffusion coupleswas determined by rapid quenching using“duplex tube technique”which ensuredthe phase in local equilibrium owing to its more rapid cooling rate.It was obser-ved that the conventional quenching seems not a rapid enough treatment to re-tard the decomposition of β-phase.A slower cooling rate results in apparent mo-dification of the morphology of the two-phase interface.The interfacial concen-trations measured are those establishing at lower temperature equilibrium.It isreasonable to believe that the consistently and significantly higher interfacialconcentration determined by Eifert et al.may be caused by the slow cooling ofthe experimental alloys.

The“interface withdrawal”across the α/β interface in Cu:Cu-Al diffusioncouples during quenching has been investigated.Using numerical analysis basedon the Fick's second law,the non-isothermal diffusion modeling across the α/βinterface was carried out in comparison with the experimental results.The distan-ce of interface withdrawal depends on the initial concentration profile at thehigh temperature,the diffusion annealing temperature,the diffusion coefficients,the cooling rate and the slope of the solves curves in the phase diagram.Thewithdrawal effect influences the shape of the concentration profile and the inter-facial concentration.

A criterion for ascertaining the accuracy of the free energy of formation ofan intermetallic compound has been obtained from a combination of the modifiedGibbs-Duhem equation,the function transformation and the phase diagram.Thefree energies of formation of InAs and GaAs have been selected on the basis ofthe above-mentioned criterion.The activities in the binary In-As and Ga-As sys-tems are then calculated by means of the modified Gibbs-Duhem equation in con-junction with the properly chosen free energies of formation of the compoundsInAs and GaAs and the binary In-As and Ga-As phase diagrams.

The mechanism of extraction of Pt(Ⅱ)or Pd(Ⅱ)with N,N-disecondaryoctylg-lycine was investigated in the extraction system:H_2PtCl_4(or H_2PdCl_4) (?)/HCI(0.05—9 N)/(i-C_8H_(17))_2 NCH_2COOH CHCl_3(50 v.-%)-kerosene.The effects of con-centration of HCl,initial concentration of Pt(Ⅱ)or Pd(Ⅱ)and ionic strength(LiCl)in aqueous phase,extractant concentration in organic phase and phase ratio(A:O)on distribution ratio(D)were studied and the composition of the extrac-ted species of Pt(Ⅱ)and extractant was evaluated as H~+[PtCl_3(i-C_8H_(17))_2NCH_2-COOH]~- or[(i-C_8H_(17))_2NHCH_2COOH]~+[PtCl_3(i-C_8H_(17))_2NCH_2COOH]~-.And the extra-cted species of Pd(Ⅱ)and extractant was considered as(R_2NHCH_2COOH)~+[PdCl_3(R_2NCH_2COOH)]~-.

The hematite and pseudo-hematite can be separated effectively from the gan-gue minerals like quartz by using hydroxamic acid as collector.In the treatmentof the rough concentrate from the magnetic separation for iron ore,the resultsfrom direct flotation using AHA and diesel oil,each 71 g/t,are similar to thatfrom reverse flotation using etheramine 106 g/t and H_2SO_4 95 g/t.In weaklybasic pulp,the rough flotation froth collected by AHA and diesel oil was subjec-ted to gravity separation,the total concentrate grade may be up to 65.7% Fe ata recovery about 82%.By floating the lean iron ore with 305 g/t THA,theiron grade may be raised from 27—29 % to 62—64 % Fe for recovery of 88—90%.This means that an increment of 8 % recovery may be gained with no morereagent cost and with better economic benefit in comparison with flotation byusing 1200 g/t oxidized paraffin soap.

The modification of the magnetic anisotropy of the amorphous alloyFe_5Co_(73_Si_(10)B_(12)influenced by the annealing in rotary magnetic field under differenttemperatures,times and cooling rates has been investigated by means of the mea-surement of the magnetization difference between parallel and perpendicular tothe longitudinal direction of the ribbon specimens.It was obtained that under theconditions of 400℃,30 min and 6℃/min,the anisotropy may be reduced up toabout 80%.The proposal has also been analyzed that the above-mentioned modi-fication of magnetic anisotropy is caused by dispersing the directional orderingof the coupling of stress-magneto-striction and atomic pairs.

The torsional vibration of blooming mill may be classified into impulsivetorsional vibration and self-excited oscillation.The various conditions causing tor-sional vibration have been analyzed.The calculational method of TAF valuesfor various torsional vibrations and the prediction about the level of which theTAF might be reached were proposed.The dangerousness and preventive measur-es were also pointed out.

The alloyed amount of Ce in aluminum of commercial purity has been deter-mined by using radioactive isotope ~(14)Ce and by the method of low tempera-ture electrolysis in organic electrolyte.The distribution of alloying Ce in the Alhas also been detected by means of EPMA,autoradiography and autoradiographySEM.Results showed that the most of Ce in Al is in an alloying state and im-pels the enrichment of Si along grain boundaries.The compounds of CeAl_4 andCe_5Si_3 in the Al as well as the eutectic network structure at grain boundary arefound with the increasing of the amount of Ce contained.The Ce is obviouslyenriched itself along the grain and dendrite boundaries in the as-cast Al withor without annealing.

Based on the gnomonic projections and on the rotational reciprocal coordi-nate axes,a computer program,written in BASIC,is compiled for the simulationof various kinds of projections and diffraction patterns of crystals.These includethe standard gnomonic and stereographic projections,the transmission and back-reflection Laue patterns and the electron diffraction patterns.The projections anddiffraction patterns of both matrix and twin can be drawn together.In the caseof electron diffraction,the pattern may contain spots on any reciprocal layer be-sides the zero one.It is shown that these projections and patterns can be conve-niently used for the indexing of the diffraction spots and the determination of thecrystal symmetry,the type of the twin and the orientation relationship betweenmatrix and twin.