C03 – Corrosion mechanism influenced by metallic-intermetallic interfaces and composites

PI: Daniela Zander (RWTH Aachen University, KKS)

SFB researcher: Markus Felten (RWTH Aachen University, KKS)

The aim of this project is to explore corrosion mechanisms by 2D and 3D investigations that serve as a basis for developing a mechanistic understanding of the influence of complex intermetallic phases, such as Al2Ca, Mg2Ca, (Mg, Al)2Ca, within a complex microstructure consisting of intermetallic skeleton, matrix and nano-precipitates on aqueous corrosion. Electrochemical and microstructural (SEM, HR-TEM (B01), ICP-MS) 2D studies after corrosion are expected to give valuable insights into the electrochemical properties and reactions, e.g. dissolution, passivity, of the intermetallic phases acting between different phases. 3D studies, e.g., by "quasi" in-situ synchrotron tomography, are expected to give a sufficient basis for developing a mechanistic understanding of the corrosion process, influenced by, e.g., volume fraction, phase distribution, and morphology. In order to contribute to the defect phase diagrams DPD surfaces and DPD boundaries, the following key scientific questions are addressed:

• What is the influence of complex intermetallic phases and their interfaces on localized corrosion mechanism within the microstructure of Mg-Al-Ca alloys, consisting of intermetallic skeleton, matrix and secondary phases?
• How can these be transferred to a generalized mechanistic corrosion model?
• How can these be transferred to a microstructure-corrosion correlation function?

Methods

• Direct current (DC) / alternating current (AC) corrosion measurements
• Scanning vibrating electrode techniques / Scanning ion selective electrode techniques (SVET/SIET)
• Inductively coupled plasma mass spectrometry (ICP-MS)
• X-ray photoelectron spectroscopy (XPS)
• X-ray diffraction (XRD)
• In-situ TEM (with B01)
• Scanning electron microscopy (SEM + EDS)
• (quasi) in-situ synchrotron tomography and XANES/XRF (DESY, ESRF, BESSY)