Abstract
Conditions for the pore formation in an Al-4%Cu alloy were examined by the unidirectional solidification technique. Gas pressure in pores and negative pressure due to solidification contraction were calculated from the gas content, and the quantity of pores with the metallographic method. Main results obtained were as follows:
(1) Gas pressure in pores was 2 to 5 atms at the pore formation temperature.
(2) Initial gas content required for gas pore formation increased with an increase in solidification rate. When there was not enough gas for pore formation, a shrinkage pore was formed.
(3) When the solidification rates were 3, 6, 12, and 60cm/hr, the negative pressures were 1, 1.5, 2 and 5 atms respectively.
(4) The critical gas content for pore formation was approximately 0.15cc/100g.
