The polycrystalline yttrium aluminum garnet （YAG） fibers were prepared with sol-gel method. The investigations were made of the viscosity, spinnability,infrared absorption characteristics and thermal decomposition properties of the YAG sol. Meanwhile, the phase structure and microstructure of the YAG fiber were analyzed. The results show that the spinnability of the YAG sol is the best when the solid content of the sol is 26%-28% and the spinning temperature is 20 ℃ There are lots of hydroxyl groups of Al-OH and Y-OH exsiting in the YAG sol,and the two kinds of hydroxyl groups can be condensed to form macromolecular chains by losing H2 O, macroscopically exhibiting the spinnability. Weight-loss of the YAG sol mainlY occurs below 600 ℃ in the thermal decomposition process. The YAG fibers with pure phase can be obtained with sol-gel method. The YAG fiber grains grow up gradually as the calcination tem- perature and time increase, resulting in the quantity and size increase of the holes among grains and property degradation of YAG fiber.

Five-layer YBa2Cu3O7-δ film was prepared on LaAlO3 single crystal substrate by TFA-MOD, with total film thickness of 1 μm,critical current density （Jc） of 1.6 MA/cm^2 and critical current （L） of 160 A/cm. The Jc values of single-layer film and three-layer film are 3.5 MA/cm^2 and 1.75 MA/cm^2 ,respectively. No cracks and obvious pores are observed in cross-sectional TEM images of three-layer film and five-layer film, and interfaces among the layers are smooth. With the increase of film thickness, critical current density decreases ,probably caused by film performance degradation.

Investigation was made of the continuous cooling transformation （CCT） curves of the weathering steels with Nb and without Nb by Gleeble-1500D thermal simulator,and the influences were analyzed of the Nb element and cooling rate on CCT curve and microstructure changing law. The results show that the addition of Nb inhibits phase transformation of the weathering steel and decreases its phase transformation temperature,causing CCT curve to move to the lower right. Under the condition of cooling rate 15 ℃/s,the microstructure of the weathering steel with Nb significantly changes. With the increase of cooling rate, the hardness of the weathering steel with Nb increases gradually. Lots of bainite forms at the cooling rate of above 5 ℃/s,and some martensite forms at the cooling rate of over 20 ℃/s,which is good for strength and performance improvement of the weathering steel.

Ni-based cladding layer reinforeed by in-situ grown VC-WC-W2C particles was prepared on the surfarce of 45# steel substrate by laser cladding technology,and its corrosion resistance was studied in 10% H2SO4 solution with static immersion method. The results show that all the Ni-based cladding layers with different contents of V2O5 ＋WO3 ＋C exhibit good corrosion resistance in 10% H2SO4 solution, of which the corrosion resistance of Ni-based cladding layer with 25 % （V2O5 ＋ WO3 ＋ C） is the best, almost three times as much as that of pure Ni-60 cladding layer.

Plate sample of Ni-based superalloy DZ408, with compact structure and good orientation, was pro- duced by laser melting deposition with single- and multi-channel scanning. Orientation growth law and formatioh mechanism of as-deposited microstructure were analyzed. The results indicate that plate sample prepared by single-channel scanning is of regular shape and polished surface, and well-orientated dendrites form in solidification direction. However in scanning direction,the dendrites tilt towards the scanning direction due to the influence of the shape of molten pool. Z-type microstructure perpendicular to scanning direction is obtained in the plate sample prepared by multi-channel scanning. The thickness of laser single-chan- nel depositing layer parallel to the scanning direction in the sample border is twice as much as that in the sample insider for long ending time of laser single-channel scanning and short cooling time,and its bath line collapses duwn. The gravity of liquid metal is greater than its surface tension, thus the metal droplets are formed and finally,lots of metal tumors appear in the surface of the multi-channel scanned samples.

Study is made of the effects of different heat treatment on creeping property of GH4169 alloy through the testing of creeping property and microstructure observation. The results show that the hot continuous rolled alloy after standard heat treatment precipitates less 8 phase and has better creeping property than the radial forged alloy after the standard heat treatment. The hot continuous rolled alloy after di- rect-aged treatment precipitates little 8 phase with longer creeping life, which is twice as much as that of the radial forged alloy after standard heat treatment. The radial forged alloy produces transgranular fracture during creeping,while the hot continuous rolled alloy produces intergranular fracture.

The migration behavior of Ta, Si and N single particles on TaN （001） surface was studied by first -principles calculation. The adsorption energy was calculated of these single particles on TaN （001） surface, as well as their energy change along the migration paths to obtain their migration activation energy. The migration activation energies of Ta,Si and N single particles are 0. 561 eV,1. 386 eV and 0. 940 eV,respectively. Their migration paths are similar to those of Ti,Si and N single particles on TiN （001） surface, but their migration is more difficult.

The preparation processes of lanthanum metal are described, and its application is reviewed. It is pointed out that the research on the preparation and application of lanthanum metal is of significance. Some proposals on its future application and research are also presented.

Review is made of the latest development of the main preparation methods of NbC and its application in many fields. It is pointed out that NbC will have wide application in the future in such fields as metallurgy, machinery industry and aerospace technology.

Experimental study was made in view of accumulation of the main impurities P, As, Si, Cl ere in the tungsten raffinate recycled to the leaching process, and the effects of two purifiers were tested for the removal of impurities in the aqueous phase during leaching. The results show that direct leaching with un- treated tungsten raffinate results in accumulation of various impurity ions to different degrees. By adding appropriate purifiers and controlling the dosage of sodium phosphate, the concentrate of P is controlled steadily in a certain range and high W leaching rate is achieved.