Processing and properties of composites with Ni-Fe content of 10 and 15 wt% were investigated. Homogeneous powder mixtures of /Ni-Fe alloy were prepared by the solution-chemistry route using , and powders. Microstructural observation of composite powder revealed that Ni-Fe alloy particles with a size of 20nm were homogeneously dispersed on powder surfaces. Hot-pressed composites showed enhanced fracture toughness and magnetic response. The properties are discussed based on the observed microstructural characteristics

요각류는 수서생태계 내에서 1차 소비자로서 매우 중요한 생물이다. Harpacticoida 목에 포함되는 대부분의 저서성 요각류는 중형저서생물에 포함되며, 전세계적으로 3,000여 종 가량의 해산종이 알려져 있다. 저서성 요각류의 다양성을 파악하는 일은 기본적으로 새로운 생물자원과 유전자원의 발굴이라는 측면에서도 중요하다. 해산 저서성 요각류 다양성 연구의 중요성 및 앞으로의 연구 전망에 대해서 논의하였다.

The synthesis and characteristics of W-Ni-Fe nanocomposite powder by hydrogen reduction of ball milled W-Ni-Fe oxide mixture were investigated. The ball milled oxide mixture was prepared by high energy attrition milling of W blue powder, NiO and for 1 h. The structure of the oxide mixture was characteristic of nano porous agglomerate composite powder consisting of nanoscale particles and pores which act as effective removal path of water vapor during hydrogen reduction process. The reduction experiment showed that the reduction reaction starts from NiO, followed by and finally W oxide. It was also found that during the reduction process rapid alloying of Ni-Fe yielded the formation of -Ni-Fe. After reduction at 80 for 1 h, the nano-composite powder of W-4.57Ni-2.34Fe comprising W and -Ni-Fe phases was produced, of which grain size was35nm for W and 87 nm for -Ni-Fe, respectively. Sinterability of the W heavy alloy nanopowder showing full density and sound microstructure under the condition of 147/20 min is thought to be suitable for raw material for powder injection molding of tungsten heavy alloy.

The property and performance of the nanocomposites have been known to strongly depend on the structural feature of Ni nanodispersoids which affects considerably the structure of matrix. Such nanodispersoids undergo structural evolution in the process of consolidation. Thus, it is very important to understand the microstructural development of Ni nanodispersoids depending on the structure change of the matrix by consolidation. The present investigation has focused on the growth mechanism of Ni nanodispersoids in the initial stage of sintering. powder mixtures were prepared by wet ball milling and hydrogen reduction of and Ni oxide powders. Microstructural development and the growth mechanism of Ni dispersion during isothermal sintering were investigated depending on the porosity and structure of powder compacts. The growth mechanism of Ni was discussed based upon the reported kinetic mechanisms. It is found that the growth mechanism is closely related to the structural change of the compacts that affect material transport for coarsening. The result revealed that with decreasing porosity by consolidation the growth mechanism of Ni nanoparticles is changed from the migration-coalescence process to the interparticle transport mechanism.

An optimum route to fabricate the nanocomposites with sound microstructure and improved mechanical properties was investigated. Microstructural investigations for the composites prepared using -nitrate showed that fine Cu particles with average size of 150 nm were homogeneously distributed within the matrix grains and at the grain boundaries. Fracture strength of 953 MPa and toughness of 4.8 Mpa(equation omitted)m were measured for the composite. The strengthening and toughening of the composites are explained by the refinement of the microstructure and the crack bridging/deflection, respectively.