Nb-Ti alloys were hydrogenated to prepare fine and contamination-free powders. Cracks were introduced in the alloys when they were annealed at 1473 K and cooled in a hydrogen atmosphere. The fragments produced by hydrogen-induced cracking are brittle and the friability enhanced with the Ti content of the alloy, which is beneficial for further refinement of particle size. We also demonstrate that Nb-Ti powders with the average particle size less than 1 m can be produced by ball milling at a temperature lower than 203 K. Furthermore, hydrogen-free powders can then be obtained by annealing above the temperature corresponding to hydrogen desorption from Nb solid solution.

A QM-ISP-4 Planetary Mill was employed to activate mechanically the mixtures of anatase and corundum at room temperature for different times. The milled powder mixtures were then sintered at for 1 h. The XRD results showed that the milled powder mixtures were completely transformed into after sintering, except the mixtures milled for 5 and 10 hours. The SEM observations showed the typical morphology of rod-like vary in the range: widths from 0.6 to , and lengths from 3.0 to . The rod-like formation was attributed to the positive effects caused by the mechanical activation.

Ultrafine Au-Pb particles prepared by two method, (1) simultaneous evaporation of Au and Pb in inert gas and (2) subsequent vapor condensation of Pb in a differentially evacuated tube onto flying Au nanoparticles prepared by gasevaporation technique, were observed by electron microscopy. In the method (1), the particles that grew at the region where the two smoke masses converged, consisted of alloy phases. In the method (2), the particles consisted of two or three phases of Au, , and Pb phases in turn from the inner part, Pb-rich particles being composed of only two phases of and Pb.

이 연구는 학습에 대한 참여 비유(participation metaphor, PM)의 의미를 알아 보고 과학 교수 학습에의 시사점을 탐색하기 위한 이론 연구이다. 문헌 고찰을 통하여 참여 비유가 공동체 내에서의 사회 문화적 활동에 지속적으로 참여하는 것을 학습으로 보는 관점과 맥을 같이 하며, 인지적 도제(cognitive apprenticeship)가 참여 비유와 밀접하게 관련된 수업 모형이라는 것을 살펴 보았다. 이를 토대로 참여 비유에서 주장하는 것과 같은 과학 교수 학습이 실현되기 위해서는 과학 학습자 공동체의 육성이 필요하다는 점을 제안하였다. 마지막으로 과학 학습자 공동체의 한 사례로서 어느 고등학교의 과학 클럽 활동을 간략히 소개하였으며, 앞으로의 과학 교육 연구에서 고려해야 할 점들을 진술하였다.

In this study, nano grain W is fabricated by Severe Plastic Deformation-Powder Metallurgy (SPD-PM) process. W powder and W-Re powder mixtures are processed by SPD-PM process, a Mechanical Milling (MM) process. As results, a nano grain structure, whose grain size is approximately 20nm, is obtained in W powder after MM for 360ks. A nano grain W compact, whose grain size 630nm, has excellent deformability above 1273K. A nano grain W-10Re compact is composed of equiaxed grain, a grain growth is restrained and has low dislocation density after the large deformation; therefore it is considered that W-Re compact shows superplasticity.

Tin oxide nanoparticles (n-SnO and ) were synthesized by the inert gas condensation (IGC) method under dynamic gas flow of oxygen and argon at various conditions. Transmission electron microscopy (TEM) and X-ray diffraction (XRD) method were used to analysis the size, shape and crystal structure of the produced powders. The synthesized particles were mostly amorphous and their size increased with increasing the partial pressure of oxygen in the processing chamber. The particles also became broader in size when higher oxygen pressures were applied. Low temperature annealing at in air resulted to crystallization of the amorphous n-SnO particles to .

Cellular metals based on Iron have been intensively investigated during the last two decades. Because of the significant decreasing of the structural density of Iron based cellular structures, numerous technologies have been developed for their manufacturing. Besides the tremendous weight reduction a combination with other properties like energy and noise absorption, heat insulation and mechanical damping can be achieved. This contribution will give an overview about the latest state in Iron based cellular materials, including technologies in manufacturing, properties and potential applications.

Stainless steel sludge is generated as a waste in the grinding process, and the possibility of recycling stainless steel is considered here. In this study, we considered the possibility of using the stainless steel sludge as metal powder for MIM or raw material for metal foam. For the MIM process, the metal powder will need some improvement, and flotation and spheroidizing processes of the sludge are necessary. For fabrication of the metal foam, untreated sludge can be used, and steel foam about 90% porosity is produced.

In this contribution, we attempted a theoretical analysis on the validity of the widely-accepted idea that rough and singular surfaces can coexist in a crystal at equilibrium. By manipulating the Cahn and Hoffman capillarity vector, the conclusion that a crystal at equilibrium should be composed either of singular surfaces or of rough ones was reached.