Direct observation of Lomer-Cottrell locks during strain hardening in nanocrystalline nickel by in situ TEM.

ABSTRACT: Strain hardening capability is critical for metallic materials to achieve high ductility during plastic deformation. A majority of nanocrystalline metals, however, have inherently low work hardening capability with few exceptions. Interpretations on work hardening mechanisms in nanocrystalline metals are still controversial due to the lack of in situ experimental evidence. Here we report, by using an in situ transmission electron microscope nanoindentation tool, the direct observation of dynamic work hardening event in nanocrystalline nickel. During strain hardening stage, abundant Lomer-Cottrell (L-C) locks formed both within nanograins and against twin boundaries. Two major mechanisms were identified during interactions between L-C locks and twin boundaries. Quantitative nanoindentation

SUBMITTER: Lee JH 

PROVIDER: S-EPMC3544074 | biostudies-literature | 2013

REPOSITORIES: biostudies-literature