Using the nano Fe powders having 50 nm in diameter, Fe compact bodies were fabricated by injec-tion molding process. The relationship between microstructure and material properties depending on the volume ratio of powder/binder and sintering temperature were characterized by SEM, TEM techniques. In the compact body with the volume percentage ratio of 45(Fe powder) : 55(binder), which was sintered at the relative density was about and the values of volume shrinkage and hardness were about and 242.0 Hv, respec-tively. Using the composition of 50(Fe powder) : 50(binder) and sintered at the values of relative density, volume shrinkage and hardness of Fe sintered bodies were and 152.8 Hv, respectively. They showed brittle fracture mode due to the porous and fine microstructure.

The microstructure and mechanical property of hot-pressed composites with a different temperature for atmosphere changing from H to Ar have been studied. When atmosphere-changed from H to Ar gas at 145, the hot-pressed composite was characterized by inhomogeneous microstructure and low fracture strength. On the contrary, when atmosphere-changed at low temperature of 110 the composite showed more homogeneous microstructure, higher fracture strength and smaller deviation in strength. Based on the thermodynamic consideration and microstructural analysis, it was interpreted that the Cu wetting behavior relating to the formation of CuAlO is probably responsible for strong dependence of microstructure on atmosphere changing temperature. The reason for a strong sensitivity of fracture strength and especially of its deviation to atmosphere changing temperature was explained by the microstructural inhomogeneity and by the role of CuAlO phase on the interfacial bonding strength.

Fe nanopowders were successfully synthesized by plasma arc discharge (PAD) process using Fe rod. The influence of chamber pressure on the microstructure was investigated by means of X-ray Diffraction (XRD), Field Emission Scanning Electron Microscope (FE-SEM), Transmission Electron Microscopy (TEM) and X-ray Photoelectron Spectroscopy (XPS). The prepared particles had nearly spherical shapes and consisted of metallic cores (a-Fe) and oxide shells (FeO), The powder size increased with increasing chamber pressure due to the higher dissolution and ejection rate of H and gas density in the molten metal.

Aluminum based metal matrix composite reinforced with SiC particles was fabricated by the powder-in sheath rolling method. A stainless steel tube with outer diameter of 12 mm and wall thickness of 1mm was used as a sheath. Mixture of aluminum powder and SiC particles of which volume content was varied from 5 to 20vol.% was filled in the tube by tap filling and then rolled to 75% reduction at ambient temperature. The rolled specimen was sintered at 56 for 0.5hr. The tensile strength of the (SiC)/Al composite increased with the volume content of SiC particles, and at 20vol.% it reached a maximum of 100㎫ which is 1.6 times higher than unreinforced material. The elongation decreased with the volume content of O particles. The mechanical properties of the (SiC)/Al composite fabricated by the powder-in sheath rolling is compared with that of (AlO)/Al composite by the same process.ess.

The effect of extrusion temperature on the microstructure and mechanical properties was studied in gas atomized TEX>Al81Si19 alloy powders and their extruded bars using SEM, tensile testing and wear testing. The Si particle size of He-gas atomized powder was about 200-800 nm. Each microstructure of the extruded bars with extrusion temperature (400, 450 and 50) showed a homogeneous distribution of primary Si and eutectic Si particles embedded in the Al matrix and the particle size varied from 0.1 to 5.5 . With increasing extrusion temperature from 40 to 50, the ultimate tensile strength (UTS) decreased from 282 to 236 ㎫ at 300 K and the specific wear increased at all sliding speeds due to the coarse microstructure. The fracture behavior of failure in tension testing and wear testing was also studied. The UTS of extrudate at 40 higher than that of 50 because more fine Si particles in Al matrix of extrudate at 40 prevented crack to propagate.

나노입자는 일반적인 크기의 입자에서 볼 수 없는 특성을 나타내므로 촉매, 광학, 자성기록매체, 자성유체로의 자유로운 응용이 기대되어지고 있으며, 다양한 조성의 나노재료 및 제조공정에 관한 연구개발이 활발히 이루어지고 있는 추세이다. 이중 나노재료제조공정은 기상응축, 열분해법, 플라즈마법 및 볼밀링법 등이 상용화되어 있으며, 본 연구에서는 화학적균일성과 다양한 조성으로의 응용이 용이한 화학기상응축공정을 이용하여 Fe/N나노분말을 제조하였다. 제조된 Fe/