ABSTRACT
We present a summary of recent work on nanocrystalline inclusions embedded in a solid matrix. The effects of elastic constraints, crystallographic symmetry, shape and size are illustrated with two specific examples of inclusions in binary A1 alloys. Ge precipitates in dispersion hardening Al-Ge based alloys are shown to be controlled by internal twinning. By comparison, Pb inclusions in binary Al-Pb alloys are free of twins and other defects, and exhibit behaviour that depends strongly on size, shape and interface structure..
