1994 Fiscal Year Final Research Report Summary
A Study on Amorphous Formation of Alloys Solidified Under High Pressure
| Project/Area Number |
05650735
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| Research Category |
Grant-in-Aid for General Scientific Research (C)
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| Allocation Type | Single-year Grants |
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| Research Field |
Metal making engineering
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| Research Institution | Nagasaki University |
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Principal Investigator |
KAGAWA Akio Nagasaki University Materials Science and Engineering, Associate Professor, 工学部, 助教授 (00093401)
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| Co-Investigator(Kenkyū-buntansha) |
SAKAMOTO Yoshiichi Nagasaki University Materials Science and Engineering, Professor, 工学部, 教授 (50026019)
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| Project Period (FY) |
1993 – 1994
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| Keywords | High Pressure / High-Pressure phase diagram / Bismnth / Antimony / Germanium / High-Pressure phase / Metastable phase / Amorphaus |
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| Research Abstract |
On Several combinations of volume-expanding and -shrinking elements on solidification, their high-pressure phase diagrams were estimated and three alloy systems where amorphous formation could be expected, i.e., Bi-Sb alloys (homogeneous solid solution-type), Bi-In alloys (intermediate compound formation-type) and Al-Ge alloys (eutectic-type), were subjected to the high-pressure experiment. In the X-ray diffraction pattern of Bi-10-30Sb alloys, a broad peak was detected at 2rheta=30-40deg.and the peak was thereafter disappeared and, instead, the normal pressure phase was observed. In the microstructure, a fine-grained structure was observed and considered to appear as a result of phase transformation from a high-pressure phase to the normal-pressure one. In Bi-20at%In alloy solidified under high-pressure, no distinct change was observed in the X-ray diffraction pattern. However, an increase in the amount of Bi/BiIn eutectic was found, suggesting that the eutectic composition was shifted to Bi-rich side, and the high-pressure phase diagram of Bi-In system was estimated. In the X-ray diffraction pattern of Al-40at%Ge alloy, solidified at about 20kbar, the peaks of metastable phases, gamma_1 (Al_2Ge) and gamma_2 (AlGe), were detected and these metastable phases still existed after 2 months. The gamma_1 and gamma_2 phases were appeared as a laminar eutectic in the BSE comp. image and the average Ge concentration of the gamma_1/gamma_2 eutectic was found to be higher by 8at%Ge than that of normal eutectic, alphaAl/dia.cub.Ge. The high-pressure phase diagram of Al-Ge system was estimated and the critical pressure for the generation of the gamma_1/gamma_2 eutectic was estimated to be 10-20kbar.
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Research Products
(4 results)
