The Effect of the Structure-Phase State of Iron-Cementite Nanocomposites on Local Activation Processes

A. V. Syugaev*, S. F. Lomaeva*, S. M. Reshetnikov**, A. S. Shuravin**,

E. F. Sharafeeva**, and D. V. Surnin*

*Physicotechnical Institute, Ural Division, Russian Academy of Sciences, ul. Kirova 132, Izhevsk, 426000 Russia

**Udmurtia State University, Universitetskaya 1, Izhevsk, 426034 Russia

Received June 21, 2007

Abstract — Studies of the local activation of iron–cementite nanocomposites (NC) revealed the step-wise increase in their resistance to pitting with an increase in the Fe₃C content (~50 mass %) or with the formation of an ordered cementite network structure. The corrosion process is determined by the chemical state of carbon, namely, free or bound into carbides. The free carbon evolution leads to depassivation and the transition to structure-selective corrosion

PACS numbers: 81.07.Bc, 82.45 Bb