Coherent twin-oriented Al3Sc-based precipitates in Al matrix

Shanmugam S.; Peterlechner M.; Iskandar M.R.; Saikia U.; Kulitckii V.; Lipińska-Chwałek M.; Mayer J.; Rösner H.; Hickel T.; Divinski S.V.; Wilde G.

Abstract

Al3(Sc,Zr,Ti) nanoparticles with an ideal twin-type orientation relationship to Al host matrix were found in cold-rolled and subsequently annealed Al-based alloy. Atomic-scale investigations using high-resolution scanning transmission electron microscopy identified particles that form prominent coherent (111) twin-type interfaces along their longer facets and semi-coherent twin interfaces on their shorter facets. Ab-initio calculations showed that a coherent Al/Al3Sc twin-like phase boundary corresponds to a local energy minimum. A model is proposed explaining the formation of the twin orientation relationship of an Al3Sc nanoparticle with the Al host matrix.