Formation and transformation of intermetallic particles in a strip-cast Al-0.8Fe-0.6Si alloy

The majority of the particles at the surface of a strip-cast Al 0.8Fe-0.6Si alloy were identified as beta-AlFeSi. There were a relatively small number of alpha-AlFeSi and Si particles while no evidence for binary Al-Fe phases was available. The center of the strip revealed a similar distribution of intermetallic particles with beta-AlFeSi still being the dominant constituent. While Si dissolved rapidly into the aluminium matrix, the interdendritic network, mostly of beta stringers, was gradually replaced by a uniform dispersion of alpha-AlFeSi particles during heat treatments. The phases identified in deformed and undeformed samples after 8 hour heat treatments in the temperature range 540 to 600 degrees C were identical. The transformation of beta-AlFeSi was accelerated, however, in those samples which have received a cold-rolling pass before the heat treatment. Finally, only the hexagonal alpha has prevailed in all samples after extended holding at 600 degrees C.