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Vol.28, No.2, 103 ~ 111, 1990
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| Title |
| Microstructures of Rapidly Solidified and Annealed Ni - base Superalloys ( On the Rapidly quenched Structures by Melt spining and the Segregationless Phenomenon ) |
| 윤의박Eui Park Yoon, 정홍철Hong Chul Jeong, 나형용Hyung Yong Ra, 장재규Jai Kyu Jang, 조순형Soon Hyung Cho |
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| Abstract |
| In this study, Ni-Al alloys and Ni-Al-Ti alloys were rapidly solidified by melt-spinning. The resulting ribbon microstructures were studied using light microscopy and transmission electron microscopy. By extrapolating experimental results obtained at low cooling rates, the cooling rates of ribbon by melt-spinning technique were approximately determined. The cooling rates of ribbon range from 9×10⁴K/s-1.2×10^6 K/s for 60-80 ㎛ thickness. Growth rates by thermal analysis vary from 0.18 ㎝/sec to 4.7 ㎝/sec in these alloys. The formation of γ` in the Ni-7.55 wt%Al, Ni-5.94 wt%Al-2.19 wt%Ti and Ni-8.30 wt %Al-2.85 wt%Ti alloys can be suppressed by melt spinning. The high hardness observed in these alloys after heat treatment is due to the subsequent development of small, ordered precipitations in the fine-grained matrix. And, grain boundary segregation could was suppressed, with increasing cooling rate. |
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