1988 Fiscal Year Final Research Report Summary
Production of Nonequilibrium Alloy Powders by Ultrasonic and High-Pressure Gas Atomization Method and their Properties
| Project/Area Number |
61490003
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| Research Category |
Grant-in-Aid for General Scientific Research (B)
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| Allocation Type | Single-year Grants |
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| Research Field |
広領域
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| Research Institution | TOHOKU UNIVERSITY |
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Principal Investigator |
INOUE Akihisa Institute for Materials Research, Tohoku University, 金属材料研究所, 助教授 (10108566)
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| Co-Investigator(Kenkyū-buntansha) |
MATSUZAKI Kunio Institute for Materials Research, Tohoku University, 金属材料研究所, 助手 (20181711)
KIMURA Hisamichi Institute for Materials Research, Tohoku University, 金属材料研究所, 助手 (00161571)
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| Project Period (FY) |
1986 – 1988
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| Keywords | amorphous powder / high-pressure gas atomization / press-sintering / amorphous bulk / two-stage quenching / supercooled liquid / liquid quenching / 過冷却液体急冷法 |
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| Research Abstract |
A new liquid quenching equipment by utilizing an ultrasonic and high-pressure gas atomization method was designed and constructed with the aim of developing a method which can produce effectively amorphous spherical powders. Many factors of producing amorphous powders in Fe- and Co-based alloy systems were investigated and the atomization condition of producing the amorphous powders was established. Subsequently, the consolidation of the amorphous powders was tried by press-sintering at elevated temperatures. As a result, it was clarified that the consolidation is difficult for the spherical powders and the mixing of flaky powders to the spherical powders is very effective for the formation of amorphous bulks. From this information, the atomization equipment was modified so as to produce flaky powders as well as spherical powders. In the modification, the rotator was set up at the position just below the gas atomization nozzle and small atomized liquid droplets were flattened by the rotator, resulting in the formation of flaky powders with a small thickness of 1 to 3 m. Furthermore, the heat of relaxation was much larger than that for the melt-spun ribbons, indicating the achievement of much higher cooling velocities by the two-stage quenching method. The increase of cooling velocity is probably due to the subsequent cooling of super-cooled liquid droplets produced by gas atomization. In addition, the two-stage quenching technique was found to bring about the glass formation in new alloy systems such as Fe-C binary alloys and a remarkable extension of glass formation range in glass-forming alloy systems. These features of the newly developed two-stage quenching technique consisting of ultrasonic and high-pressure gas atomization followed by impact flattening of the supercooled liquid droplets are concluded to be attractive enough to confirm further progress of the two-stage quenching technique and the resulting nonequilibrium alloy powders.
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