Particles can have a mechanical, chemical or electrochemical interaction with an advancing stress corrosion crack. Particles with elastic modulii greater than the matrix will induce a repulsive force on the crack and particles with elastic modulii less than the matrix will induce an attractive force. Chemical interactions include particles that dissolve and alter crack-tip chemistry while electrochemical interactions include particles that are either anodic or cathodic to the advancing crack. Particles that are anodic to the crack, may impede crack advance until totally dissolved or until the particle/matrix interface dissolves. These particles may be highly polarized because of their contact with the matrix such as Al3Mg2 particles on grain boundaries of aged AA5083. Particles that are cathodic to the advancing crack may cause local hydrogen reduction that accelerates crack advance around or through the particle. Examples of these crack-tip/particle interactions for Al-Mg and Mg-Al alloys are described.
Revised: September 23, 2009 |
Published: January 1, 2001
Citation
Jones R.H., D.R. Baer, M.J. Danielson, C.F. Windisch, and J.S. Vetrano. 2001.Interactions of Crack-Tips with Electrochemically Active Particles. In Corrosion and corrosion prevention of low density metals and alloys, Electrochemical Society Proceedings Volume, edited by BA Shaw, RG Buchheit, JP Moran, 2000-23, 322-333. Pennington, New Jersey:Electrochemical Society.PNNL-SA-33802.