Mechanical size-effects in miniaturized and bulk materials

Interfaces and surfaces can impose substantial mechanical size-effects on materials. The deformation mechanisms become increasingly constrained when microstructural and/or geometrical dimensions decrease. This effect can improve, for example, the creep resistance of a bulk lamellar material, but it may cause failure for a miniaturized material component due to high internal stresses. Several dislocation mechanisms causing size-dependent flow stresses for (sub)micron-sized metals and metallic thin films are addressed in this paper and the current understanding of size-effects in miniaturized and bulk materials is reviewed. The beneficial application of mechanical size-effects is demonstrated for TiAl alloys and nanostructured hard coatings.