LAMELLAR/ROD TRANSITION IN Al-Cu ALLOYS

摘要

A binary eutectic generally forms a lamellar or a rod eutectic structure, and the transition between them largely depends on the volume fraction of the minor constituent in the eutectic structure. Through detailed experimental studies in the Al-Cu system, we have examined the regimes of the stability of these two morphologies and characterized the dynamics of the transition. We have found that the transition is not sharp and the two morphologies co-exist over a range of volume fractions. Theoretical ideas have been presented for this co-existence regime and a modified criterion for the lamellar/rod transition is proposed.