Oxidation of Manganese-Containing Aluminium Alloys: Oxidation of Molten Mn-Containing Al Alloys in Various Atmospheres
An oxidation study was performed on 99.99% Al, Al1%Mn and Al5%Mn materials, both in
a thermogravimetric furnace, and in a muffle furnace. The mass gain behaviour for these
materials was studied and compared for dierent temperatures and surface preparations,
and was compared to previous work on Al1Mn.
Curve fitting was used with the thermogravimetric data in an attempt to develop a math-
ematical model to describe oxidation in the Al1%Mn materials, but a satisfactory model
could not be found.
The oxidized materials were then analyzed in the Scanning Electron Microscope using
EDS and Auger microprobe analysis, both for chemical composition and to analyze the
structure of the oxide that was formed.
The main findings from the thermogravimetric work are as follows:
1. Error analysis showed that the mass measurement errors were at least two orders of
magnitude smaller than the mass measurements, so any dierences between samples
was due to dierent oxidation behaviour in the sample.
2. There was inconsistent oxidation behaviour for the Al1Mn surface-cleaned TGA
samples; for six identical samples and experiments, ve samples showed comparable
results, while one sample showed much larger mass gain.
3. Sample preparation has a large in
uence on oxidation behaviour in the mue fur-
4. Mn content has an in
uence on oxidation behavior; there was a trend of increasing
oxidation with increasing Mn content in the mue furnace samples.
The main ndings from the SEM analysis of the oxidized 99.99% Al, Al1%Mn and
Al5%Mn materials are as follows:
1. The oxides formed on the Al1Mn and Al5Mn materials were thicker and dierent
than those found on 99.99% Al
2. The oxides formed on the Al1Mn and Al5Mn materials did not contain Mn oxides
3. The oxides formed on the Al1Mn and Al5Mn materials had small particles of Mn
metal completely surrounded by Al2O3
4. Mn-rich particles were found in the interior of the Al1Mn and Al5Mn samples
5. Small clusters of Mn metal were found among the Al2O3 particles on the surface of
the Al1Mn and Al5Mn samples
Glow Discharge Optical Emission Spectroscopy showed that there was no measurable Mn
on the surface of an as-extruded Al1Mn strip, and the Mn was decient to a depth of
some 100nm from the surface. A similar Al1Mn extruded strip that had 50m of the
surface mechanically removed also did not contain Mn on the surface, and had a similar
Mn prole to the as-extruded strip.
A qualitative physical model of oxidation was suggested, based on thermogravimetric
Place, publisher, year, edition, pages
Institutt for materialteknologi , 2013. , 113 p.
IdentifiersURN: urn:nbn:no:ntnu:diva-22707Local ID: ntnudaim:9865OAI: oai:DiVA.org:ntnu-22707DiVA: diva2:651709
Tranell, Gabriella, FørsteamanuensisKvithyld, AnneEngh, Thorvald