한국주조공학회

Eutectic and off-eutectic Al-Fe alloys were unidirectionally solidified at the solidification rate of 1-50 mm/min under the temperature gradients 75-80°C/cm. The investigation has been carried out for the microstructural variation, phase transition, mechanical properties by means of detafled analyses of stress-strai11, micro-Vickers hardness and scanning electron micrography. The thermal stability at elevated temperature has been studied on Al-Al6Fe eutectic alloy held at 600°C for 0~ 150 hours. When the solidification rate was less than 1omm/min, the X-ray diffraction and EDS analysis showed the presence of Al3Fe compound. As the solidification rate more than 20 mm/min, Al-Al3Fe eutectic phase was transfered into Al-Al6Fe eutectic phase. The mechanical properties of unidirectionally solidified off-eutectic Al-Fe alloy is better than those of unidirectionally solidified eutecic Al-Fe alloy Maximum ultimate tensile strength was obtained in Al-2.25% Fe alloy which was unidirectionally solidified at the solidification rate of 20 mm/min. The metastable Al-Al6Fe phase was transferred into stable Al-Al3Fe phase at 600°C held for 150 hours.