Study on the Production of Amorphous Alloy Powders with Very Thin and Large Aspect Rations by a Two-Stage Quenching Method

点击翻译按钮获取中文摘要

In 1991, we constructed a two-stage rapid quenching equipment and determined appropriate conditions for the production of flaky amorphous powders with very thin thickness in Fe-, Co- and Ni-based alloys. Furthermore, we examined fundamental properties of thermal stability, corrosion resistance and magnetic properties for the flaky amorphous powders and clarified that the flaky amorphous powders have unique characteristics which were different from those for amorphous sheets and wires.In 1992, we searched alloy systems and alloy compositions in which a large glass-forming ability leading to the formation of flaky amorphous powders is achieved in refractory Ti- and Zr-based alloy systems. Subsequetly, the production of flaky amorphous powders was tried for the above-described alloys and the most appropriate atomizing conditions were determined. We also examined the morphology, thermal stability and corrosion resistance of the flaky powders.and investigated the relation between the proper … More ties and the preparation process of the flaky amorphous powders in their refractory metal base alloys.In 1993, the production of flaky amorphous powders was tried for Al-based alloys where the exfoliation of the powder from the rotating roter is difficult because of their low specfic weight and the production of the flaky amorphous powder is difficult. As a result, it was found that the modification of the surface state of the rotating roter enables a high production ratio of Al-based flaky amorphous powders. As similar for the Fe-, Co-, Ni-, Ti- and Zr-based amorphous powders with flaky morphology, the Al-based flaky powders also have the heat of structural relaxation which is about two times as large as those for the amorphous ribbons, indicating that the amorphous powders were produced at very large cooling rates.In addition, we evaluated the characteristics of the Fe- and Co-based flaky amorphous powders as magnetic shielding materials as well as the Ti- and Al-based flaky amorphous powders as corrosion resistanct painting materials. As a result, it was confirmed that the flaky amorphous powders in Fe, Co, Ti and Al based systems produced by the two-stage quenching technique have the characteristics which are good enough to use practically as magnetic shielding and corrosion resistant painting materials because of their extremely thin form and their unique amorphous structure. Less