MORPHOLOGICAL EVOLUTION OF LAMELLAR STRUCTURES - THE CU-AL EUTECTOID

The growth and morphological evolution of the Cu-Al eutectoid were inv estigated. Cu-Al pearlite is shown to exhibit direction steps at the i nterlamellar heterophase boundary which maintain a (111)(x) parallel t o(110)(gamma) habit plane. The Cu-Al pearlite is also demonstrated to possess a complex three-dimensional morphology which explains the vari ety of structures observed in two dimensional sections. Termination mi gration and conventional coarsening are the dominant mechanisms of mor phological evolution in the temperature range 788-828 K. A new termina tion generation mechanism and a facetting phenomenon make minor contri butions to shape change. Choice of the operative mechanism(s) in a giv en grown lamellar structure (e.g. eutectoid or eutectic) is affected b y both crystallography and interfacial structure. (C) 1997 Acta Metall urgica Inc.