12th International Conference on Magnesium Alloys and their Applications (Mg 2021): Corrosion II
Program Organizers: Alan Luo, Ohio State University; Mihriban Pekguleryuz, McGill University; Sean Agnew, University of Virginia; John Allison, University of Michigan; Karl Kainer; Eric Nyberg, Kaiser Aluminum Trentwood; Warren Poole, University of British Columbia; Kumar Sadayappan, CanmetMATERIALS; Bruce Williams, Canmetmaterials Natural Resources Canada; Stephen Yue, Mcgill University

Wednesday 10:50 AM
June 16, 2021
Room: Contributed IV
Location: Virtual

Session Chair: Amir Eliezer, SCE


Effect of Microstructure on Corrosion Behavior of Cold-rolled Mg-Li-Al Alloy: Taiki Morishige1; Hayato Ikoma1; Toshihide Takenaka1; 1Kansai University
    Mg-Li system alloy has excellent formability at room temperature due to their crystal structure. However, exfoliation corrosion appears during progress of corrosion. Therefore, it is difficult to apply for the actual metallic products without corrosion protection. Previously, the suppression of exfoliation could be attained by recrystallization of cold-rolled alloy. The microstructural characteristics were completely changed by recrystallization, so the detailed investigation is required for explanation of exfoliation corrosion origination. In this study, the origination of exfoliation corrosion of Mg-14 mass%Li-1 mass%Al alloy with various microstructures such as as-rolled, only recovered and recrystallized state. As the results, the induced strain during severe deformation is major factor of expression of exfoliation corrosion.

Oxygen Reduction during Degradation of Magnesium: Cheng Wang1; Di Mei1; Mikhail Zheludkevich1; Sviatlana Lamaka1; 1Helmholtz-Zentrum Geesthacht
     Understanding fundamental mechanisms of magnesium degradation is vital for predicting its corrosion behaviour, developing new alloys and establishing reliable research methodologies. Hydrogen evolution reaction is widely regarded as the only cathodic process during corrosion of magnesium. Hence, tracing the amount of released hydrogen was thought to be a reliable measure of degradation rate. Recently, we have shown, by different methods, that oxygen reduction reaction (ORR) is important secondary cathodic reaction. In this work, we quantify rate of ORR for different grades of Mg.Contrary to expected, oxygen consumption was the highest during corrosion of ultra-high purity Mg, and slower for rapidly corroding commercial-purity Mg. This phenomena was linked with the growth rate, thickness, morphology and permeability of Mg(OH)2 layer that blocks the access of dissolved oxygen to electrochemically active Mg/MgO interface.

The Role of Native Oxides on the Corrosion Mechanism of Laves Phases in Mg-Al-Ca Composites: Daniela Zander1; Markus Felten1; Jakub Nowak1; Patrick Grünewald2; Florian Schäfer2; Christian Motz2; 1RWTH Aachen University; 2Saarland University
     Magnesium-Aluminum-Calcium composites are characterized by thermally stable Laves phases, which enable high-temperature material applications. Nevertheless, immersing the material into an electrolyte causes an increased corrosion rate as a consequence of micro galvanic effects among the Laves phases and the matrix. The Volta potential difference determined under atmospheric conditions on a freshly polished surface using Scanning Kelvin Probe Force Microscopy (SKPFM) is a valid measure for the micro galvanic coupling and the dynamic growth kinetics of a native oxide film.In the present study, the time-dependent native oxide film formation of Magnesium-Aluminum-Calcium alloys is analyzed via in situ SKPFM measurements. An inhomogeneous evolution of the Volta potential on the Laves phases compared to the matrix indicates heterogeneous native oxide formation. Dependent on the stability of the native oxide film in strongly alkaline electrolytes, the conducted measurements evaluate the corrosion behavior under these conditions.

Effects of Phase Fractions on Mechanical and Corrosion Properties of Mg-0.5Ca-0.5Mn-xZn Alloys: Thomas Avey1; Alan Luo1; David Dean1; 1Ohio State University
    Magnesium alloys have the potential to be used in new bioabsorbable medical devices because of their similar elastic response as bone, low toxicity, and lightweight. Current commercial Mg alloys are lacking in mechanical strength or corrosion resistance or contain harmful elements. Mg-Ca-Zn alloys have been of particular interest due to their balanced corrosion resistance and mechanical properties. By using a phase-based CALPHAD (CALculation of PHAse Diagrams) approach, microstructure with the most desirable mechanical properties and lowest corrosion rate can be designed. The three secondary phases that are under investigation are Mg2Ca, Ca2Mg6Zn3, and MgZn. Four compositions, Mg-0.5Ca-xZn (x=0, 0.5, 1.2, 2) were selected that were calculated through CALPHAD to contain different amounts of these phases. Corrosion rate is determined through weight loss measurements after immersion in SBF (Simulated Body Fluid). Mechanical properties are measured by ASTM E9 tensile and compression tests

Cancelled
Adjustable Corrosion Kinetic by Microstructure Design of Biodegradable ZX11: Veronika Franziska Chaineux1; Stefanie Mergenthaler1; Daniela Zander1; 1RWTH Aachen University
     Biodegradable magnesium-calcium-zinc alloys are promising alloys for tailor made property design. It is well known that the corrosion kinetic of Mg-Ca-Zn is still subject of matter and needs to be improved. Therefore, controlling of corrosion mechanism by adjusting microstructure, alloying elements and impurities is still an important research focus.The present study therefore aims at a tailor-made adjustment of the local change of microstructural features by providing zones with different grain sizes, grain orientations and distributions of secondary precipitates to investigate their effects on the corrosion progress of biodegradable ZX11. The results were obtained by XRD, SEM and EBSD and correlated with ICP-MS analysis data of the used Hanks' balanced salt solution. A change of the corrosion kinetics and underlying mechanisms of ZX11 as a function of specific modifications of microstructures, as mentioned above, was observed and allows the adjustment of tailor-made corrosion kinetics by using an improved production process.