The mechanochemical process were employed to prepare the red phosphors (Y,Gd). The main factors affecting particle size, particle distribution, and luminescent properties of the product were investigated in details. Particles sized around 200-600 nm are formed after intensive milling. The phosphors were characterized by X-ray diffraction (XRD), scanning electron microscope (SEM) and photoluminescence spectrum. Results revealed that phosphors with different morphology, small particle size and high luminescence intensity could be obtained by mechanochemical process

(x=0.69~0.74) powders synthesized by the thermal decomposition of organic acid salts. The obtained powders were uniform in composition and ultra-fine particle with about 400 nm. The amount of spinel phase of these powders was about 50% in X-ray diffraction patterns. The calcination of powder was carried out at for 2 hours in air. After the powders were calcined. the mean size of powder was about 500 nm and the amount of spinel phase was increased over about 65%. The maximum amount of spinel phase was about 75% in the specimen of X=0.72. The magnetic properties of calcined powders were the best among the different among the different compositions

Dispersions of non-soluble ceramic particles in a metallic matrix can enhance the strength and heat resistance of materials. With the advent of mechanical alloying it became possible to put the theoretical concept into practice by incorporating very fine particles in a flirty uniform distribution into often oxidation- and corrosion- resistant metal matrices. e.g. superalloys. The present paper will give an overview about the mechanical alloying technique as a dry, high energy ball milling process for producing composite metal powders with a fine controlled microstructure. The common way is milling of a mixture of metallic and nonmetallic powders (e.g. oxides. carbides, nitrides, borides) in a high energy ball mill. The heavy mechanical deformation during milling causes also fracture of the ceramic particles to be distributed homogeneously by further milling. The mechanisms of the process are described. To obtain a homogeneous distribution of nano-sized dispersoids in a more ductile matrix (e.g. aluminium-or copper based alloys) a reaction milling is suitable. Dispersoid can be formed in a solid state reaction by introducing materials that react with the matrix either during milling or during a subsequent heat treatment. The pre-conditions for obtaining high quality materials, which require a homogeneous distribution of small dis-persoids, are: milling behaviour of the ductile phase (Al, Cu) will be improved by the additives (e.g. graphite), homogeneous introduction of the additives into the granules is possible and the additive reacts with the matrix or an alloying element to form hard particles that are inert with respect to the matrix also at elevated temperatures. The mechanism of the in-situ formation of dispersoids is described using copper-based alloys as an example. A comparison between the in-situ formation of dispersoids (TiC) in the copper matrix and the milling of Cu-TiC mixtures is given with respect to the microstructure and properties, obtained.

The effects of boron or manganese added as , Mn, , B on TiC-30vo1.% cermet sintered at 1380 and for 1 hour, were examined in relation with shrinkage, relative density, microstructure, lattice parameter, hardness and fracture toughness (). The results are summarized as follows: 1) The highest shrink-age showed about 30.5% in the specimen added BC and the maximum relative density was about 99% in the specimen added ; 2) The grains of TiC were grown during sintering and made the surrounding structure by adding boron and manganese. The largest grain size showed about in the specimen with boron sintered at ;3) The lattice parameter of TiC was about and about by adding other elements; 4) The highest hardness was about in the specimen with B4C; 5) The fracture toughness () showed about in the specimen added .

fine powder was synthesized by hydrothermal process from the mixture of titania-hydroxide() and barium hexa-hydroxide () as starting materials. Fine powder(< 100 nm) was made under the reaction conditions of 18,10 atm, 1.5 hr in autoclave and showed cubic structure. The powders were sintered by a spark plasma sintering technique from 1050~115 for 5 min. The grains of sample sintered at 110 were about 0.9 in average size and showed the mixture of cubic and tetragonal structures.