Progress and perspective in martensitic transformation are described.The definition of martensite reaction, the thermodynamics of martensitic trans-formation, the effect of austenite condition on martensitic transformation, kinetics,nucleation and growth, as well as the crystallography of martensitic transformationare presented.

An approach for the thermodynamics of the thermoelastic martensitictransformation in β-Cu base alloys is suggested. Driving forces for martensitic trans-formation, T_0 and M_s temperatures in Cu-Zn, Cu-Al and Cu-Zn-Al alloys werecalculated and the calculated M_s are in good agreement with the experimental ones.Ordering of the parent phase lowers M_s in Cu-Zn and Cu-Zn-Al alloys, but risesM_s (T_0) in Cu-Al alloys. Two methods for estimation of the non-chemical freeenergy attending the thermoelastic martensitic transformation are also introduced.

In situ observations of the nucleation and growth of ferrous marten-sites, including ε-, lenticular, butterfly, thin-plate and composite-plate ones at lowtemperature stage on optical or transmission electron microscope were carried out.The results confirmed the faulting model for the formation of ε-martensite proposedby Olson and Cohen. The grain boundaries and triple points are the favourable nu-cleation sites for the thin plates, and their surface relief grown initially like asmall needle. The lenticular martensite was observed as two stages of formation.According to the dislocation resolving reaction:a/6[111]_b→a/3[111]_b+a/2[111]_b, the emission dislocation(b=a/2[111]_b) acting as thedislocation soulce for the transition of lattice invariant shear from twinning to slipwas proposed.

The butterfly martensite nuclei in an Fe-Ni-V-C alloy were observedunder TEM to consist of the enveloping dislocations with Burgers vector 1/2[011]_(fcc)and the arrays of dislocations with Burgers vector 1/2[110]_(fcc) piled up within theformers. The enveloping dislocations and the arrays of dislocations provide the re-quired shear when the planes (111)_(fcc) move over each other to alter their stackingorder and change into the planes (110)_(bcc) respectively. The neccessary adjustment ofthe spacings is provided by the dislocations in martensite. The crystallographic rela-tionship after double-shear is K-S one.

The shear components of strain tensors for matrix and twin crystal oftwinned martensite were opposite roughly after calculation, and the strain energywould be reduced. The growth of martensitic plates along the normal direction ofthe twin plane may depend upon the effect of self-accommodation between the ma-trix and twin crystals. Based upon the analysis on the displacement vectors of thenormals for different habit planes, the {10,3,15}_f plane could make up the macro-scopic invariant habit planes; but the (575)_f, (252)_f, (111)_f planes are difficult tobecome the invariant planes.

Observations were made of the martensite distributed along the austen-ite grain boundary and twin boundary in the Fe-C, Fe-Ni-C and Fe-Cr-Mn-Mo-Calloys. The martensite may nucleate preferentially and grow easily along these bound-aries. In the mixed martensites, the preferentially formed one is plate or butterflymartensite.

The martensite is featured as thin plate when the γ′dispersed precipi-tated particles are the size of about 20--50 nm formed at low temperature in Fe-iN-Oo-Ti alloys. The interface of martensite plate is not smooth. If the γ′particlesare sized less than 5 nm, the thin plate martensite with thermoelasticity may befound at low temperature, while greater than 5 nm, the intermittent martensite mayoccur, and increase both in size and quantity with the coarsening of the γ′parti-cles. The lenticular or butterfly martensite is formed at low temperature until theγ′particles up to 10--15 nm.

The transformation hysteresis and stability of strain martensite inNi_(47)Ti_(44)Nb_9 alloy have been studied by means of tensile test under various temper-atures, electrical resistance measurement and TEM observation. It was shown thatthere is a characteristic deformation temperature and a strain range, in which thecritical yield stress for stress-induced transformation acquires optimum matchingwith the yield strength of the β-Nb particles. In this case, deformation effectivelyincreases the transformation hysteresis, while the strain recovery ratio remains use-fully high. The martensite with irregular fine twin substructure and martensitecontaining some dislocations as well as martensite intersected by the β-Nb particlespossess high stability.

The internal friction as martensite state is believed to be an M/Minterface one, which can be explained as an expression deduced from the theory ofdislocation internal friction. The internal friction in the region of martensitic trans-formation consists of two parts, including ones of the M/M interface and of thephase transformation. The later is further composed of two portions, the majorproduced by reverse martensitic transformation and the other from stress-inducedmartensite. It was also found that the degradation of dampling properties of theCuZnAl alloys is related to the dislocation, which is introduced from the excitingprocess, and tends to a stable value after certain excitements.

The effect of the composition and thermal treatment on the phaseconstituent, the size of B2- and DO_3 derived domains and martensitic thermoelasticbehaviour in three CuAlNi alloys has been studied by means of metallography,TEM and X-ray diffraction analysis. It is shown that the martensite type changesfrom 18R_1 to 2H structure and the transition temperature decreases with the increaseof the Al content. Moreover, the size of the B2- and DO_3, derived domainsdecreases with the increase of the cooling rate.

The reversible transformation between matrix and martensite in Ni-Tishape memory alloys has been dynamically observed under TEM. The orientationrelation between martensite and austenite as well as the structural change near thetransition temperature have been also studied with the help of HREM and SADP.The results show that the orientation relation between martensite and austenite is[111]_A//[110]_M, [110]_A//[001]_M, (110)_A/(001)_M and the angle between (110)_A and (010)_Mis about 6.5°. The crystal defects of martensite are found to be twin and stackingfault, and the twin plane as (100).

Based on the TEM analysis of substructures of lower bainite in twosteels containing Si, the lattice invariant shear elements were determined and a plasticaccommodation double-shear model was proposed. The theorotical predictions aboutcrystallography given by the model are in good agreement with the experimental da-ta for the steels tested.

The morphology and substructure of martensites in 7CrSiMnMoV steelwere observed under optical or electron microscope, and martensitic transformationwith its morphology was also analysed. In the normally quenched steel three typesof martensites are found, including the wide lath one of dislocation substructure form-ed preferentially along grain boundaries, the thinner inner laths and the twinningmartensite plate in interior of grain. Therefore, an attempt was made to substitutelower bainite, formed by short-term isothermal quenching, for intergranular marten-site, it is believed that the morphology would be very influential to the strength-toughness of the steel.

The heterogeneous distribution of C and metallic alloying elements as well asthe phase composition changed before and after cold deformation of a Fe-Mn-Cr-C alloyhave been studied by Mossbauer spectroscopy. The austenites without and with C and metallicalloying elements are found in the alloy as solid solution treated state. While the martensiteswithout and with C and alloying elements may be induced by cold deformation. The transforma-tion from austenite to martensite in the alloy is confirmed via theoretical computation andexperiments to be controlled by the number of covalent electron pairs forming covalent bondin austenitic crystal cell of the alloy. The formation of strong covalent bond between C andmetallic elements will vigorously retard the γ/α′transformation.

In sita observation under TEM was made of the dynamic process of martensitictransformation in the (Y, Mg)-PSZ ceramics. A group of substructural martensite variantsmay occur priorly under the contact stress between tetragonal ZrO_2 precipitates, the anotherone may be induced by the elastic strain relaxation, and both form (100) twins further. Thecrystallographic aspect of the martensitic transformation was also discussed.

The formation of Ti(C, N) occurs principally on the interfacial reac-tions between slag and coke as well as between slag and liquid iron in the blast fur-nace. The mechanism and state of formation for these two paths are different. Atthe slag-coke interface, TiC is formed first, and the unhomogeneous interstitial solidsolution Ti(C, N) is then formed by nitrogen atom diffusion from furnace gas intoTiC lattice. The slag basicity and temperature are extremely influential in the forma-tion of Ti(C, N). The larger the slag-coke interface is, the more favourable the for-mation of Ti(C, N) will be.

A mathematical relation is derived for mass transfer coefficient at pha-se interface evolving inert gas bubbles based on the character of fluid flow andmass transfer, which is checked with literature data. It shows that the mass transfercoefficient induced by inert gas bubbles is not only proportiona to the square rootof the volume rate of gas, but also related to the behaviour of gas bubbles suchas bubble size, bubble distribution density and interface area.

Studies were made of the positive segregation of C and Mn as wellas negative one of Si along the original austenite boundary in 475℃ isothermalFe-C-Si-Mn alloy by means of Auger spectroscopy and SIMS. According to thethermodynamical calculation of partial molar free energy and activity of grainboundary segregation, it was indicated that the Si and Mn may promote the segrega-tion of C along grain boundary and depress its activity. Thus, the shift of theupper bainite TTT diagram to right may be easily explained.

The diffusion coefficients of Mn and Si in α(δ)-phase in an Fe-Mn-Siternary system have been determined at 1000℃. The composition profiles of Mnand Si at 1000℃ were made on the diffusion couples which composed of the alloyswith different compositions. Based on the composition profiles, the diffusion coeffi-cients of 18 compositions were obtained by using the Boltzmann-Matano method.The principal diffusion coefficients, D_(MnMn)~(Fe) and D_(SiSi)~(Fe) about 10~(-9) cm~2s~(-1), were foundto be fairly close each other, while the cross ones, D_(SiMn)~(Fe) and D_(MnSi)~(Fe), are less thanthe principal ones in one order of magnitude. D_(SiSi)~(Fe) increases slightly with the in-crease of Si and Mn compositions. And D_(MnMn)~(Fe) increases with the increase of Si com-position, but does not be affccted by Mn composition.

The kinetics of electrochemical reaction of Nd~(3+) reduced on liquid Gaelectrode has been studied by cyclic voltammetry (CV) in molten chloride at 1073K.The results show that the reduction of Nd~(3+)? on Ga electrode proceeds in consequenttwo steps. For the first step, it is found to be a diffusion controlled reversible re-action at higher rate of potential scan, i. c., Nd~(3+)+e=Nd~(2+) and an irreversible rea-ction controlled by following chemical reaction at lower rate, i. c., Nd~(3+)+e?Nd~(2+)+mCl NdCl'_m~(-m). For the second step, alloying reaction of deposited Nd with Ga canbe observed and the reaction is found to irreversible, Nd~(2+)+2e→Nd(Ga). The stand-ard rate constant of this reactiin is estimated to be 7.0×10~(-3) cm/s.

To treat by CW CO_2 laser on the outer wall of 180 diesel cylinder, afine structure layer of quenched martensite or ledeburite may be formed. This layertested better in resistance to cavitatiin erosion during examination of either accele-rated cavitation erosion or diesel engine assembly. Experimental results show thatthe improvement on the resistance is dependent on the hardness change over the walland the grain size of steel structure.

The in-plane magnetic anisotropy of as-quenched Fe-base, FeNi-baseand Co-base amorphous alloy ribbons has been studied. The variation of anisotropywith stress relief annealing and the magnetization square dependence on anisotropyconstant were determined. It was found that the in-plane magnetic anisotropy con-sists of two components, i. e., one related to the coupling between magnetostrictionand stress, and the other originated from surface shape effect.

A high shock pressure was brought to bear on the grey cast iron totransform its graphite into diamond. Observations under SEM and TEM as well asX-ray diffraction analysis show that the diamond is coexisting structure of cubicand hexagonal lattices, and has a strict crystal orientation.

The high temperature pre-heat treatment was used for Rene95 pow-der-particles before HIP consolidation. It is shown that during pre-heat treatment,the microstrucutre of the powder-particles may be more homogenized and the non-equilibrium carbides can be transformed into stable carbides MC. The appropriatecontrol of this transformation may suppress the formation of detrimental PPB car-bides.

A Monte-Carlo comupter simulation has been performed to describe, atatomic level, the growth of TiN films formed by ion beam enhanced deposition(IBED). The simulation is based on a random target, fixed free path of moving par-ticles and binary collisions. An alternate process of deposition of titanium atomsand implantation of nitrogen ions is applied instead of the actual continuous andsynchronous process of IBED. According to the actual conditions, the adsorptionof nitrogen gas, which is leaked out from the ion source, at the fresh titaniumlayer surface has been considered. In addition, the change of the composition pro-file and the density profile during film growth is taken into account. It shows thatthe titanium deposition rate has strong influence on the film composition. Whenthe titanium deposition rate is low, the nitrogen concentration of the film is rela-tively insensitive to the atomic arrival ratio, R, of implanted nitrogen ions to de-posited titanium atoms. It is demonstrated that the width of the intermixed regionbetween the film and substrate increases with the increase of R. The results obtain-ed are in agreement with the experimental measurements.

A new method for correctly and reliably solving all available combina-tion of the least square simultaneous equations in the quantitative X-ray phaseanalysis has been proposed by treatment of selective average. It seems to be a sim-ple and applicable method after the adoption in actual practice.

The room temperature and 700℃ isothermal sections for the region containing0--33 at. -%Gd of Gd-Pd-Pt ternary system phase diagram have been determined by X-raydiffraction analysis and optical microscopy. Both sections consist of 5 single phase regions-Pd(Pt) or Pt(Pd), GdPd_3, GdPd_2, GdPt_5 and GdPt_2; 7 bi-phase regions-Pd(Pt)+GdPd_3, Pd(Pt)+GdPt_5, GdPd_3+GdPd_2, GdPd_2+GdPt_2, GdPt_2+GdPd_3, GdPt_2+GdPt_5 and GdPd_3+GdPt_5; and 3tri-phase regions-Pd(Pt)+GdPt_5+GdPd_3, GdPt_5+GdPd_3+GdPt_2 and GdPd_3+GdPd_2+GdPt_2 respe-ctively. No any ternary intermetallic compound is found.

The deposition processes of stoichiometric alumina by means of planar magne-tron dc reactive sputtering have been invastigated. The results indicate that the oxygen patialpressure (OPP) could dramatically affect the chemical composition and crystal structure of thedeposited films and two threthold values of the OPP (threthold pressures) exist during sputter-ing. If the OPP is lower than the threthold pressures the sputtered films are mainly compo-sed of metallic aluminium with little alumina in it. When the OPP is higher than the threth-old pressures the films are only composed of the alumina. When the OPP varies near thethrethold pressures, the total gas pressure, the sputtering voltage and the depositing rate appearadrupt change, and the V-I characteristic curves display different laws. The deposited aluminawere amerphous and could crystallize at high temperature. The dc reactive sputtering mecha-nisms were discussed in this paper.

The variation of magnetic properties with different regimes of magnetic anneal-ing and temperatures of heat treatment has been investigated on the ultrafine (nm order) softmagnetic material of Fe_(84.32)Cu_(1.06)Mo_(5.78)Si_(7.2)B_(1.64)(wt-%) alloy, prepared by annealing amorphousstate and single rolling over its crystallization temperature. A optimum performance with agingat 510℃ for 1h then slow cooling was found. The structural observation under TEM toge-ther with X-ray diffraction and thermomagnetic analysis were determined that the alloy iscomposed of two phases, i. e. a-FeSi solid solution about size 10--20 nm, and amorphousphase.