Pure MgH2 was milled under a hydrogen atmosphere (reactive mechanical grinding, RMG). The hydrogen storage properties of the prepared samples were studied at a relatively low temperature of 423 K and were compared with those of pure Mg. The hydriding rate of the Mg was extremely low (0.0008 wt% H/min at n = 4), and the MgH2 after RMG had higher hydriding rates than that of Mg at 423 K under 12 bar H2. The initial hydriding rate of MgH2 after RMG at 423 K under 12 bar H2 was the highest (0.08 wt% H/min) at n = 2. At n = 2, the MgH2 after RMG absorbed 0.39 wt% H for 5 min, and 1.21 wt% H for 60 min at 423K under 12 bar H2. At 573 K under 12 bar H2, the MgH2 after RMG absorbed 4.86 wt% H for 5 min, and 5.52 wt% H for 60 min at n = 2. At 573 K and 423 K under 1.0 bar H2, the MgH2 after RMG and the Mg did not release hydrogen. The decrease in particle size and creation of defects by reactive mechanical grinding are believed to have led to the increase in the hydriding rate of the MgH2 after RMG at a relatively low temperature of 423 K.

The present study is to analyze the thermoelectric properties of thermoelectric materials fabricated by the mechanical grinding process. The powders were prepared by the combination of mechanical milling and reduction treating methods using simply crushed pre-alloyed powder. The mechanical milling was carried out using the tumbler-ball mill and planetary ball mill. The tumbler-ball milling had an effect on the carrier mobility rather than the carrier concentration, whereas, the latter on the carrier concentration. The specific electric resistivity and Seebeck coefficient decreased with increasing the reduction-heat-treatment time. The thermal conductivity continuously increased with increasing the reduction-heat-treatment time. The figure of merit of the sintered body prepared by the mechanical grinding process showed higher value than one of the sintered body of the simply crushed powder.

Two kinds of Bi2Te3 powders, pure Bi2Te3/2vol.%ZrO2, have been prepared by a mechanical grinding process process. Effect of mixing of the powders on thermoelectric of the sintered body has been investigated by measuring Seebeck Coeffcient, specific electric resistivity and thermal conductivity. With an increase in the weight fraction of the Bi2Te3/2vol.%ZrO2 powder from 0 to 40wt.%. Especially, the figure of merit of the mixedBi2Te3 sintered body increases and thereafter dedreases above 40wt.%. Especially. the figure of merit of the mixed Bi2Te3 sintered bodies with mixing of Bi2Te3/2vol.%ZrO2 powder increased about 1.3time in comparison with the value of the specimen before mixing. Mixing of two kinds of Bi2Te3 powders which have different theramal and electric propertries with each other seemed to be useful methob to increase the figure of merit of Bi2Te3 sintered body.

Nd5Pr7Fe82B6 및 Nd12Fe82B6 조성의 1차 용유된 ingot에 대하여 기계적 분쇄처리 및 열처리를 행하고 결정구조 및 자기적 특성을 측정하였다. Ar 분위기 하에서 330시간 분쇄처리한 결과 2~3μm크기의 입자가 얻어졌으며, x-선 회절도로부터 각 입자는 미세한 결정립으로 구성되어 있음을 알았다. 330시간 분쇄처리된 분말을 600˚C에서 2시간 열처리함으로써 항자계가 18.36-18.79kOe, 최대에너지적이 8.32-8.38 MGOe인 자기적 특성을 얻었다. 열처리 온도가 높아지면 자기적 특성이 향상되었으나, 기계적 분쇄처리에 의한 ingot의 미세결정화 과정이 최적의 자기적 특성을 얻는데 더욱 중요하였다.