The effect of graphite particulate reinforcement on the resultant damping behaviour of ZA27metal matrix composites (MMCs) has been investigated in an effort to develop a new functional material. The MMCs were processed by a spray atomization and deposition technique. The damping capacity, as well as the relative dynamic modulus, was measured at frequencies of 1and 4 Hz in the 30 to 200℃ temperature range. There exists a transformation point at 55℃in the internal friction and temperature spectrum of the MMCs. It is shown from microstructural analysis that the damping capacity of ZA27 can be significantly improved by the addition of graphites particulates through spray deposition processing. Finally, the operative damping mechanism is discussed in light of the data obtained from characterization of microstructure and damping capacity.

Microstructures and room-temperature tensile properties of isothermally-forged γ-base (γ + α2)alloys in Ti-Al-Nb-Cr-V system with different heat treatments were investigated. The results show that the microstructures of Ti-47Al-2Nb-1Cr-1V and Ti-47Al-2V-1Cr (at. pct) alloys are mainly determined by heat treating temperature in the (cr + 7) tWo-phase field, and the joint additions of Nb, Cr and V in the Ti-47Al alloy afFect Ta significantIy. The microstructure of Ti-47Al alloy with additions of Nb, Cr and V (1~2 at. pct) can be dupIex or nearly-lamellar by a suitable heat treatment after isothermal forging at 1000℃ for over 50% plastic strains.Therefore its tensile properties can be improved at room temperature.

The (100) texture of solidified fcc metals, caused by the preferential (100) dendrite growth, could be closeIy related to solid/melt interfaces which behave differently along different crystallographic orientation. The stability and roughness of {111} and {100} solid/melt interfaces of fcc metals were investigated using a modified Temkin multi-layer model. It is demonstrated that {100}crystal/melt interface is more unstable and rougher than {111} interface. The effect of the stability of crystal/melt interface on the (100) texture formation in solidified fcc metals has been analysed and discussed.

Two low alloy steels 0.5Cr-0.5Mo-0.25V and H85 were pack-aluminized at 900°for 4 h by using Fe-Al powder mixture containing 48% Fe, 20.6% Al- 29.4% Al2O3 and 2% NH4Cl by weight. The microhardness and oxidation resistance at 900℃ of the aluminide coatings were studied. It was found that pack-aluminizing improves the microhardness of the 0.5Cro.5Mo-0.25V steel while it reduces the microhardness of the H85 steel. Pack aluminizing highly improves the oxidation resistance after 20h exposure at 900℃ in air for the investigated steels.

Samples of undoped, and CuO, CaO, Al2O3 as well as V2O5 doped MnZn ferrite were prepared using standard ceramic method. The X-ray diffraction results for the base and doped ferrite samples show a single phase with spinel cubic structure. The Mossbauer spectrum of the base sample indicates line broadening and overlapping due to relaxation of magnetic dipoles. The temperature dependence of DC-electrical conductivity has been discussed on the basis of electronic conduction (electron hopping) and ionic conduction mechanism.

Influence of Ti on MC carbide of M2 high speed Steel was investigated by experimental observation, thermodynamic calculation and crystallographic calculation. With addition of Ti into M2 steel, large quantities of dispersed TiC particles formed in the steel melt at higher temperature than that of the formation of MC carbide. TiC can act as heterogeneous nuclei for the crystallization of MC carbide particles, and therefore promote the formation of blocky MC carbide.

To obtain excellent magnetic properties of machinable REPM prepared by directional solidification (DS) technology Space A, a composition area with θ=0°~5° where easy axis is parallel to solidified direction of alloys, has been established in Zr-Sm-La-Co-Cu-Fe system. In 2/17+1/5+Co, and 2/17+1/5 region near Co phase of Space A, one obtains:Vf = 80.933 - 2.739Zr - 1.828Sm - 0.773Co - 0.147Cu + 0.415Fe + 0.218LaNonequilibrium solidification process of alloys in 2/17+1/5+Co region, is as follows: L→Co,L→2/17, L+2/17→1/5 and L→1/(5-x)+1/(5+x). The product of partially completed peritectic reaction, and 1/(5-x) and 1/(5+x) phases can all be transformed into a homogeneous 1/5 phase after solution treatment in 1413 K for 5 h. Containing 3~6% Co phase magnetically hardened by 0.5~2.5% V, the DS magnets have been achieved with both improved toughness and excellent coercive force of 520 kA/m.

The rare earth luminescence materials LaOBrfTb3+(Dy3+) were synthesized at high temperature,and the structure and luminescence characteristics were studied. The co-doping Dy3+ may make the energy of 5D3 of Tb3+ transfer to 5D4 level, which makes the emission of 5D4-7FJ (J=0,1... 6), specially of 5D4-7F5, enhance obviously, and the total brightness is increased by about 40% in comparison with the samples without Dy3+ cations, as a result of the energy transfer of dipole-dipole interaction.

Using a special constant deflection device, the in situ TEM observations of dislocation emission,motion and the initiation of nanocrack in 310 stainless steel in water were carried out. The results show that SCC in thin foil specimen of 310 stainless steel can occur in water. A nanocrack initiated in the DFZ or at the blunt crack tip in corrosion solution after dislocation emission,multiplication and motion, which were induced by the localized anodic dissolution, reached a critical condition. The nanocrack propagated by a cleavage mode because of the influence of the corrosion solution.

Effect of Li and Ti additions on Lα(AI)+Mg2Si pseudobinary eutectic reaction in ternary Al-Mg-Si system has been investigated by thermoanalysis, directional solidification and metallographic techniques in this study. It has been found that Li addition causes decreasing of the volume fraction of Mg2Si, while a little amount of Ti causes to increasing, which is of a great importance to the adjustment of phase constitution and alloy properties. Doping components have little influence on the eutectic temperature.

In this work, we demonstrated that the differential scanning calorimetry (DSC) is not always reliable in measuring thermal stability and grain growth process in nanocrystalline materials by a quantitative analysis and comparison of the DSC data measured in nanocrystalline Ni-P and Hf-Ni samples.

Using a fractat model, we give a new interpretation of the reversed sigmoidal curves of fracture surface profile length obtained in some experiments. It is pointed out that a single parameter (fractal dimension D) is not sufficient to characterize a fractal curve completely. It is shown that the initiator length L0 is also important to characterize a fractal curve. We have derived a formula which correlate the fracture energy with the fractal parameters of the fracture surfaces and analyzed some experimental data.

Silicon carbide (SiC) has been prepared by passing natural gas over (100) oriented hot Si substrate at different temperatures in the range 930~1000℃. Reaction times of 60 and 90 min are used.Depth profile, using Auger Electron Spectroscopy, shows the formation of SiC under a thin coating of carbon for the samples prepared at 930 and 950℃. Annealing, at 1050℃ for 12 h,results in a more pronounced formation of SiC. It is found that at the temperature of 1000℃and reaction times of 60 and 90 min, a hard diamond-like coating is formed.

Phase transformation and microstructural change of an extruded eutectoid Zn-Al alloy Zn76Al22Cu2 (wt pct) were investigated during creep testing by using SEM and X-ray diffraction techniques. Creep induced decomposition of a metastable η'T phase and a four phase transformation, α+ ε →T' +η, occurred during the creep testing. Also a microstructural change was observed from a lamellar structure into a spheroidized structure in the rupture part of the extruded alloy. It provided evidence of creep induced phase transformations which occurred in ageing process. The mechanism of creep rupture of the extruded Zn-Al alloy was also discussed.

The effect of austenite ageing on martensite transformation in an iron and nickel alloy was studied. Attention was paid to the variation of dislocation configurations in austenite before martensite transformation. The clusters or precipitates produced during austenite ageing and the alteration of dislocation configurations affect together the consequent martensite transformation.Dispersed fine clusters and precipitates cripple nucleus role of special dislocation configurations and drop M. Coarse precipitates make Ms rise again. Densely piled up dislocations in nuclei lead to rise of Ms. All the changes in austenite are of benefit to small martensite plates.

The microstructure and stability in a rapidly solidified Al-Fe-Nb-Si alloy were studied by using transmission electron microscopy (TEM) with energy dispersive X-ray spectrometry (EDXS) and X-ray difFraction technique. It is shown that the addition of Nb to Al-Fe-Si alloy may increase undercooling of melt, and form the featureless zone structure, the size of the intercellular phases and the distance betWeen intercellulars of Al-Fe-Nb-Si alloy are two times smaller than that of Al-Fe-V-Si alloy under the same conditions. Further, the microstructure of the featureIess zone has the better thermal stability after annealing at 623 K for 24 h.

Samples have been prepared at different temperatures by loading I2 molecules into the cages of zeolite 5A, and the measurements of the absorption spectra have been carried out for the prepared samples. It is shown that I2 molecular clusters are formed in the cages of zeolite 5A,and it is also found that moIecuIar clusters which are bonded with intermoIecuIar forces have an important feature, namely, the intermolecular distance in molecular clusters can be changed on different preparing conditions and the blue shift of absorption edges can not be as the criterion of forming molecular clusters.

With the chemical synthesis of zinc oxythiomolybdate (ZnMoO2S2), its characters were studied by thermal analysis and X-ray diffraction method. The tribological properties of ZnMoO2S2were studied by high-temperature pin on disc tester, the results show that ZnMoO2S2 has good lubricating property from room temperature to 700℃, especially from 100℃ to 300℃, the friction coefficient is about 0.1.

In the present work a thermodynamic model is presented for the nucleation of metastable Ag3Ge phase from the undercooled melt in Ag-Ge alloy system. It is shown that under kinetically induced favourable condition, nucleation of a single phase compound with an approximate stoichiometry Ag3Ge has greater affinity for nucleation over Ag and Ge based phases requiring diffusion in the liquid.