| Budget Amount *help |
¥15,100,000 (Direct Cost: ¥15,100,000)
Fiscal Year 2004: ¥700,000 (Direct Cost: ¥700,000)
Fiscal Year 2003: ¥2,800,000 (Direct Cost: ¥2,800,000)
Fiscal Year 2002: ¥11,600,000 (Direct Cost: ¥11,600,000)
|
|---|
| Research Abstract |
The influence of gravity on the solidification of monotectic or eutectic alloys has been investigated under microgravity environments. However, in most of the previous experiments, e.g., in free fall systems, in aircraft or in space laboratories, the growth rate was too high to realize the planar solid/liquid interface. This is due to the limitation of the time for solidification. In order to study the influence of gravity on the microstructure of directionally solidified Al-In monotectic alloy, Ag-Si and Al-Si eutectic alloys, and Ni base-super alloy both the downward and upward unidirectional solidifications(U.D.S.) were carried out. In the case of the downward U.D.S. by the current Bridgman method, This causes a shrinkage cavity at the solid/liquid interface during solidification.
(1)Regarding the unidirectional solidifications of Al-In alloy, the Monotectic L_2 phase grows continuously in both growth directions. However, the morphology in the downward U.D.S. shows a tendency to form a so-called "banded structure."
(2)In the case of the upward U.D.S. of the Ag-Si alloy, the eutectic Si phase grows continuously and its morphology shows the typical faceted/non-faceted eutectic structure. On the other hand, in the case of the downward U.D.S., the eutectic Si phase grows discontinuously and disperses in the α-Ag phase with a diameter of several micrometers.
(3)The eutectic Si phase of the Al-Si grows continuously regardless of the growth direction. There is no morphological difference between the upward and the downward U.D.S. specimens.
(4)The formation of freckle structure is greatly affected by the Solidification direction. This means that the formation of freckle structure is controlled with the convection due to the gravity.
|
