| タイトル | Effect of Stepwise Pressure Change on Porosity Evolution during Directional Solidification in Small Cylindrical Channels |
| 著者（英） | Blandford, B.T.; Grugel, R.N.; Cox, M.C.; Lee, C.P.; Anilkumar, A.V. |
| 著者所属（英） | NASA Marshall Space Flight Center |
| 発行日 | 2008-01-01 |
| 言語 | eng |
| 内容記述 | Controlled directional solidification experiments were performed in capillary channels, using nitrogen-saturated succinonitrile, to examine the effect of an in-situ stepwise processing pressure increase on an isolated pore evolution. Two experiments were performed using different processing pressure input profiles. The results indicate that a processing pressure increase has a transient effect on pore growth geometry characterized by an initial phase of decreasing pore diameter, followed by a recovery phase of increasing pore diameter. The experimental results also show that processing pressure can be used as a control parameter to either increase or terminate porosity formation. A theoretical model is introduced which indicates that the pore formation process is limited by the diffusion of solute-gas through the melt, and that the observed response toa pressure increase is attributed to the re-equilibration of solute concentration in the melt associated with the increased melt pressure. |
| NASA分類 | Chemistry and Materials (General) |
| 権利 | Copyright |
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