Morphological Variation of the Fe/Cr-containing Intermetallic Phase in the Al-Si casting Alloy as a Function of Cooling Rate: Time-Resolved Radiography

摘要

Effects of Cr addition on the morphology of the β-Al_5FeSi phase formed in the aluminum alloys were studied as a function of cooling rate by time-resolved radiography. The Cr addition to the iron-contaminated Al alloys modified the needle-like β-Al_5FeSi into a faceted dendritic α-AlFeCrSi phase under a uni-directional solidification condition in a vacuum chamber. Time-resolved radiography of the formation of the a-AlFeCrSi phase revealed the transition of its morphology from cubic crystal at about 10K/min of cooling rate to equiaxed dendrite of faceted arms at about 50K/min. of cooling rate.