ABSTRACT
This chapter discusses periodic structures such as fluctuated and banded structures for lead–bismuth alloys and tin–cadmium metallic alloys. Lead–25 at% bismuth and lead–33 at% bismuth alloys were made from 99.99% lead and 99.99% bismuth in an argon atmosphere. According to the phase diagram, the lead–25 at% bismuth alloy is a hypoperitectic composition, while the lead–33 at% bismuth alloy is hyperperitectic. Tin–cadmium alloys were made from 99.9% tin and 99.99% cadmium in a silica crucible under an argon atmosphere. The banded and fluctuated structures observed in peritectic alloys can be regarded as periodic structures formed during solidification. Morphological maps have been reported for peritectic alloys and criteria are used to explain the phase and morphology selection, i.e. maximum interface temperature and/or maximum growth rate. The periodic structures observed in peritectic alloys, including the banded structure, the incomplete banded structure, and the competitive structure, are thus considered to be intrinsic for peritectic alloys in the region of planar front growth.
